Heparin-binding protein and Endothelin-1 in critical COVID-19

Heparin-binding protein and Endothelin-1 in critical COVID-19 | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Heparin-binding protein and Endothelin-1 in critical COVID-19 Jesper Eriksson, Halla Halldorsdottir, Olav Rooyackers, Jonathan Grip, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9173002/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 14 You are reading this latest preprint version Abstract Background Heparin-binding protein (HBP) is an inflammatory protein released by activated polymorphonuclear white cells. It has been suggested as a predictor of sepsis progression and organ dysfunction and plays a role in the pathophysiology of endothelial dysfunction. Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor with pro-inflammatory effects, and high levels are found in patients with sepsis and acute respiratory distress syndrome. We investigated HBP and ET-1 plasma levels in critical COVID-19 disease with the aim of evaluating whether they were associated with 60-day mortality or the need for invasive mechanical ventilation (IMV). These levels were compared with those of a cohort of post-trauma intensive care unit (ICU) patients. Methods We included 96 patients with critical COVID-19 disease in 2020 and ten post-trauma ICU patients. Blood samples were collected at ICU admission, and plasma levels of HBP and ET-1 were measured. Clinical and laboratory data were collected until ICU discharge or death. Results In COVID-19 patients, plasma levels of HBP were markedly increased, with a median level of 150 ng/ml (IQR 47–299), compared to 13.3 ng/ml (IQR 8.8–62.1), p < 0.0001 in the trauma ICU patients. There was no association between HBP levels and 60-day mortality or need for IMV. The levels of ET-1 were 1.6 pg/ml (IQR 1.2–1.9) in the COVID-19 cohort and 2.0 pg/ml (IQR 1.2–2.8), p = 0.25 in the trauma ICU cohort. COVID-19 patients requiring IMV hade higher ET-1 levels than those who did not require such treatment; however, no association was found in a logistic regression model when adjusted for age, sex and body mass index. There was no correlation between plasma HBP and ET-1 levels. Inflammatory parameters such as C-reactive protein, procalcitonin, ferritin, and interleukin-6, were elevated but did not distinguish survivors from non-survivors. Conclusion While HBP levels are markedly elevated in critical COVID-19, they do not predict outcomes at ICU admission. ET-1 levels were also not linked to mortality or the need for IMV. Heparin-binding protein endothelin-1 COVID-19 invasive mechanical ventilation intensive care unit mortality Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction The COVID-19 pandemic has posed significant challenges to healthcare systems worldwide. While the pathophysiology of COVID-19 is still being elucidated, numerous studies have documented that patients who initially appear relatively stable can experience rapid clinical deterioration within a few days. This decline is often characterised by uncontrolled pulmonary inflammation, acute respiratory distress syndrome (ARDS), and multiple organ failure ( 1 – 4 ). The concept of a cytokine storm, marked by elevated levels of cytokines, has been proposed as a contributing factor to this process ( 5 , 6 ). However, virus-mediated damage, combined with dysregulated inflammatory responses involving non-cytokine biomarkers, is also recognised as playing a significant role in disease progression ( 7 – 10 ). The ARDS associated with COVID-19 involves a complex interplay of epithelial and endothelial cell injury, leading to fluid leakage into the interstitium and alveoli ( 11 , 12 ). This vascular damage precipitates systemic endotheliitis, leukocyte adhesion, platelet activation ( 12 – 14 ), and the development of a pro-thrombotic state ( 14 – 16 ). The specific contributions and temporal dynamics of epithelial versus endothelial injury in COVID-19 remain unclear, potentially causing variations in circulating plasma markers throughout the disease course ( 17 ). The neutrophil protein heparin-binding protein (HBP) has emerged as a biomarker in sepsis, demonstrating the ability to predict unfavourable outcomes such as multiple organ failure and mortality ( 18 – 22 ). Plasma concentrations > 15 ng/ml at intensive care unit (ICU) admission have been associated with increased mortality ( 22 ). Moreover, plasma HBP levels are significantly elevated in viral influenza A (H1N1) pneumonia ( 23 ). In the context of COVID-19, HBP elevation has been observed before the onset of organ failure when sampled early in the disease course ( 24 ). Furthermore, elevated HBP levels have been linked to severe respiratory failure and increased mortality rates ( 24 – 26 ). Heparin-binding protein is stored in secretory and primary granules in polymorphonuclear neutrophils (PMN). This multifunctional inflammatory protein is released when PMNs are activated through membrane bound β-2 integrin binding on the endothelial lining ( 27 ) or by circulating proteins such as streptococcal M-protein and fibrinogen ( 28 ). Heparin-binding protein induces cytoskeletal changes in the endothelial lining, leading to intercellular gap formation, increased vascular permeability, and organ failure ( 27 , 29 ). Dysregulation of the endothelium-derived vasodilator nitric oxide (NO) and the vasoconstrictor peptide endothelin-1 (ET-1) ( 30 ) has been implicated in the pathophysiology of COVID-19-associated endothelial dysfunction, resulting from the direct invasion of endothelial cells by the virus ( 14 , 31 , 32 ). Endothelin-1 serves as a potent inflammatory vasoconstrictor mediator released primarily by endothelial cells ( 33 ). Elevated ET-1 levels have been correlated with conditions such as hypertension ( 34 ), heart failure ( 35 ), pulmonary hypertension ( 36 , 37 ) and sepsis ( 38 ). In pulmonary arterial hypertension, increased ET-1 levels are associated with fibrosis and vascular remodelling, suggesting a potential benefit of ET-1 receptor antagonists ( 39 ). Numerous studies have demonstrated elevated ET-1 levels in ARDS ( 40 – 42 ). Recent evidence suggests that patients with mild COVID-19 infection have lower ET-1 levels compared to hospitalised counterparts ( 30 ). However, ET-1 levels can remain persistently elevated up to three months post-COVID-19, coinciding with increased inflammatory cytokine levels ( 43 ). Higher ET-1 levels have been linked to severe COVID-19 and mortality ( 30 , 43 – 45 ). Supporting a pathophysiological role of ET-1 in COVID-19, a recently published study showed that the dual ET A and ET B receptor antagonist bosentan reduced the risk of hospitalisation and thrombosis in high risk COVID-19 patients ( 46 ). Despite data suggesting the potential involvement of ET-1 and HBP in the pathophysiology of critical COVID-19, their role remains largely unclear ( 47 ), with a limited number of studies assessing the levels of these biomarkers in COVID-19 patients. In particular, data on biomarker levels in critically ill, ICU-admitted patients remain scarce. Regarding ET-1 and HBP, we have previously shown an association between plasma levels of these biomarkers in experimental sepsis, where ET-receptor antagonism reduced plasma HBP levels, and ET-1 administration in non-septic conditions resulted in a dose-dependent increase in plasma HBP ( 48 ). The aim of the study was to investigate the plasma levels of HBP and ET-1 at ICU admission in critical COVID-19 and their association with 60-day mortality and need for IMV. Methods Study design and participants. This observational cohort study was performed between April-October 2020 at the Karolinska University Hospital, Sweden, a tertiary referral centre, covering an urban area of approximately 2.4 million inhabitants. During this period, specific COVID-19 ICUs were established. Patients were admitted to these units primarily due to severe respiratory failure requiring advanced respiratory support, such as high-flow nasal oxygen, non-invasive mechanical ventilation, or IMV. Patients 18 years or older with confirmed SARS-CoV-2 infection by polymerase chain reaction were eligible for inclusion upon admission to the COVID-ICU. The main reasons for not including all eligible patients were limited research nurse availability, failure to obtain informed consent from the patient or closest relative, or inability of the patient to understand the study protocol. For comparison of HBP and ET-1 values, plasma samples were collected from ten ICU-admitted trauma patients. Data collection Admittance data and clinical parameters were retrieved from the Swedish Intensive Care Register and electronic patient data management systems (Clinisoft ® , GE, Barrington IL), including patient medical records (Take Care ® , CompuGroup Medical, Koblenz, Germany). Information was collected on demographic data, laboratory results, comorbidities, hospital and ICU admissions, respiratory and circulatory parameters, and outcomes such as mortality and continuous renal replacement therapy (CRRT). Data was collected during ICU stay, until discharge or death, whichever occurred first. Variables of interest included age, sex, body mass index (BMI), and comorbidities. Simplified acute physiology score (SAPS) III, time from symptom onset to hospital admission, ICU admission, and death, as well as laboratory data, were recorded. Treatments such as prone positioning, muscle relaxation, CRRT, steroids, and specific therapies such as interleukin (IL)-blockers and anticoagulation, were documented. Clinical outcome data were available for all patients. Blood sampling and biomarker analysis Blood samples were drawn within 24 hours of ICU admission from an indwelling cannula into plasma preparation tubes (PPT) (BD Vacutainer ® PPT TM, Becton Dickinson, New Jersey, USA). The tubes were centrifuged in 1200 G for 10 minutes at 4°C and stored at -80 °C. After storage the plasma was separated from the tubes and stored again at -80° until biomarker analysis. Heparin-binding protein was analysed in duplicates using the Axis-Shield HBP microtiter plate enzyme-linked immunosorbent assay (ELISA, Axis-Shield Diagnostics, Dundee, United Kingdom). Endothelin-1 was analysed using the Quantikine Ò ELISA (R&D Systems Ò Inc., Minneapolis, USA). Routine laboratory measurements were obtained from the established clinical routine laboratory assays at the Karolinska University Hospital Laboratory. Outcomes The primary outcome was the association between plasma levels of HBP and ET-1 in critical COVID-19 disease and 60-day mortality from hospital admission. The secondary outcome was the association between these levels and the need for subsequent IMV during the ICU stay. Statistics Nonparametric methods were used to analyse data. Comparisons of continuous variables were performed using the Mann-Whitney two-tailed test. Categorical variables were assessed using Fisher´s exact test. A p-value of <0.05 was considered statistically significant. Continuous data are presented as median ± interquartile range (IQR) and depicted as box plots. Categorical data are presented as proportions and percentages. Outcomes were assessed using multivariable logistic regression analyses, adjusted for age, sex, and BMI. Goodness of fit and model discrimination were determined using the Hosmer-Lemeshow test. Comparison between plasma HBP and ET-1 collected in PPT tubes or citrated tubes was performed using Spearman correlation as well as Mann-Whitney two-tailed test. The predictive properties of the biomarkers were analysed with receiver operating characteristic curves (ROC) and presented as area under the curve (AUC) with corresponding confidence interval (CI). Statistical analyses were performed using Prism 9 (Graphpad Inc., San Diego, USA). Results A total of 96 patients with critical COVID-19 were included and analysed in the study, with the vast majority (96%) enrolled between April and June 2020. Heparin-binding protein measurements were available for 78 patients and ET-1 measurements for 92 patients. In four patients HBP samples were missing, and in 14 individuals, complications with the Axis- Shield ELISA rendered the values unusable. Additionally, ET-1 sample were missing in four patients. A flowchart and demographic data for inclusion of critical COVID-19 patients admitted to ICU is presented in Figure 1 and in Table 1. Patient characteristics, treatment and blood sampling Patient characteristics and outcomes are summarized in Table 1 and 2. The median time from the onset of COVID-19 symptoms to hospital admission was 8 days (IQR 6-11), and to ICU admittance, 10 days (IQR 8-14). The cohort was characterised by severe respiratory failure, with 61 of 96 patients (64 %) requiring IMV during their ICU stay. The vast majority (76 %) were male and 76 % had pre-existing medical conditions. The median length of ICU stay was 12 days (IQR 5-21). All patients exhibited laboratory signs of inflammation, including elevated C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6) and ferritin levels, while white blood cell count (WBC) remained within normal ranges. The median time from ICU admission to HBP and ET-1 blood sampling was 15 hours (IQR 9-23). In most patients (72 %), other laboratory data measurements were taken within six hours before or after the HBP and ET-1 sample. For the remaining 28 %, samples were taken within 12 hours of the HBP/ET-1 sample. No patient was treated with hydroxychloroquine, while four patients received remdesivir. Approximately half of the patients received steroids during the first seven ICU days and 25 % of all patients had been given steroids before blood sampling. Similarly, 22 % of the patients received monoclonal antibodies against IL-1 or IL-6 of which seven patients received this treatment before blood sampling. A comparison between patients receiving steroids and monoclonal antibodies showed no significant influence on HBP or ET-1 levels (data not shown). All patients, except one, received low molecular weight heparin (LMWH), specifically dalteparin, during their ICU stay. The exception was a patient treated with a heparin infusion due to extracorporeal membrane oxygenation, which was initiated after blood sampling. Comparison of test tubes To investigate if PPT test tubes (containing EDTA as anticoagulant and a gel plug separating plasma during centrifugation) interfere with the HBP-ELISA which is recommended for human citrated plasma only, we compared PPT tubes with standard tubes containing citrate. In the ten severely injured trauma ICU patients the HBP and ET-1 levels using the PPT tubes were 13.3 ng/ml (IQR 8.8-62.1) and 2.0 pg/ml (IQR 1.2-2.8), respectively. The levels in citrated tubes were 7.0 ng/ml (IQR 4.8-40.1) and 1.9 pg/ml (IQR 1.0-2.5), respectively. The HBP and ET-1 levels in the PPT test tubes were consequently higher than in the citrate tubes but the difference was not significant (Supplementary Table 1). There was a strong correlation between HBP and ET-1 values between these different test tubes (Fig. 2). Heparin-binding protein, endothelin-1 and patient outcomes Mortality The 60-day mortality after hospital admission was 17.8 %. All the deceased patients were male and died during hospital stay. The median time from COVID-19 symptoms to death was 33 days (IQR 23-45). The median HBP and ET-1 levels at admission were 150 ng/ml (IQR 47-299) and 1.6 pg/ml (IQR 1.2-1.9), respectively. There was no significant difference in plasma HBP levels between patients who survived and those who died (141 ng/ml; IQR 50-292 and 193 ng/ml; IQR 34-545, respectively), p=0.64, (Table 1, Fig. 3A). Similarly, there was no difference in plasma ET-1 levels between surviving patients (1.6 pg/ml; IQR 1.1–1.9) and deceased patients (1.7 pg/ml; IQR 1.4–1.9), p=0.30, (Table 1, Fig. 3C). Patients who died were more frequently treated with IMV as well as CRRT. They also had a longer ICU stay compared to surviving patients (Table 1). There was no significant difference in CRP, WBC, ferritin, D-dimer, or thrombocyte count between patients who died and those who survived. Heparin-binding protein or ET-1 levels did not correlate with any of these laboratory parameters (data not shown), except that HBP correlated with WBC, (r=0.33, P=0.004). Moreover, there was no significant correlation between HBP and ET-1, (Supplementary Fig. 1). In a logistic regression model adjusted for age, sex and BMI, neither HBP nor ET-1 was significantly associated with mortality (OR 1.000; 95%CI 0.999-1.001 and OR 1.095; 95%CI 0.489-2.252, respectively). The model demonstrated good calibration using the Hosmer-Lemeshow test. Receiver operating characteristic curves were used to evaluate prediction of mortality in all patients. The AUC was non-significant for HBP, ET-1, CRP, PCT, WBC, HBP/WBC, thrombocyte count, D-dimer, IL-6 and ferritin (Fig. 4A and B; Supplementary Fig. 2). There was no difference in LMWH dosage before HBP sampling or during ICU stay between surviving patients and those who succumbed to the disease (Table 1). Mechanical ventilation The majority of patients admitted to the ICU (61 out of 96; 64%) received IMV during their stay, with 58 (95%) of these patients being intubated within 72 hours. One patient was intentionally managed solely with non-invasive ventilation due to end-stage lung disease. The HBP levels upon admission were comparable between patients who required IMV and those who did not during their ICU stay (Table 2, Fig. 3B). However, ET -1 levels were significantly higher (1.7 pg/ml; IQR 1.3-2.0) in patients requiring IMV compared to those who did not (1.4 pg/ml; IQR 1.0-1.7), p=0.004, (Table 2, Fig. 3D). In a logistic regression model, adjusted for age, sex and BMI neither HBP nor ET-1 showed a significant association with IMV (OR 1.001; 95%CI 1.000-1.004 and OR 1.854; 95%CI 0.916-4.303, respectively). The model demonstrated good calibration. Receiver operating characteristic curves were used to evaluate prediction of subsequent IMV after the initial plasma sampling. The AUCs were non-significant for both HBP and ET-1 (Fig. 4C and D). Patients requiring IMV were significantly older. Twenty percent of these patients received CRRT compared to none in non-IMV group. Similarly, they had significantly higher CRP levels with a median of 207 mg/L (IQR 136-284) compared to 133 mg/L (IQR 99-235) in the group that did not receive IMV. Procalcitonin and IL-6 at admission were also significantly higher, whereas other laboratory parameters were similar (Table 2). The majority (74 %) were empirically treated with antibiotics during the first seven ICU days; however, no data were available on the actual rate of secondary bacterial pneumonia. Discussion In this study, we measured plasma levels of HBP and ET-1 at ICU admission in critically ill COVID-19 patients. The HBP levels were markedly elevated, more than tenfold higher compared to a group of post-trauma ICU patients. There was no significant difference in plasma levels of HBP or ET-1 between 60-day survivors and non-survivors. Heparin-binding protein levels were not associated with the need for IMV treatment whereas plasma ET-1 levels were higher in patients requiring IMV. However, after adjusting for sex, age and BMI, no significant association was observed between plasma ET-1 levels and need for IMV. There are a some previous studies in which HBP levels above 30 ng/ml in COVID-19 patients distinguished those who developed organ failure or severe respiratory failure requiring IMV from those with a more favourable disease course ( 24 , 25 ). Other studies have found increased mortality using a HBP cutoff at 13.5 or 35 ng/ml ( 49 , 50 ). In these studies, the patients were included already at hospital admission, a much earlier stage of the disease. Our study cohort had considerably higher HBP levels, with a median level of 150 ng/ml (IQR 47–299) at inclusion. A possible explanation is that all patients in our study had already developed signs of severe organ failure ten days after onset of a symptomatic virus infection. Furthermore, our patients exhibited remarkably high inflammatory markers. It appears that the discriminative properties of HBP are lost at these high levels. Interpreting HBP levels across studies should be approached with caution, as the timing of HBP sampling in relation to disease severity and progression may vary significantly. To our knowledge, no published data are available on HBP levels from the severe acute respiratory syndrome (SARS) outbreak in 2002–2004, a disease caused by SARS-CoV-1. However, in a study from Finland, IMV-treated patients with viral pneumonia caused by H1N1 (swine flu) had a median HBP level of 152 ng/ml at ICU admission, which aligns with the levels observed in our cohort ( 23 ). Although the authors reported higher HBP levels in IMV-treated patients than in non-IMV-treated patients, they found no association between admission HBP levels and the development of ARDS or severe sepsis/septic shock. These findings, together with those of the current study, suggest that in certain critical forms of viral infections, HBP levels may be markedly elevated, but their discriminatory capacity is diminished. According to the manufacturer of the HBP-Axis-Shield ELISA, sampling should be done in test tubes using citrate as an anticoagulant. To ensure that the high levels of HBP were not caused by the PPT/EDTA sampling tubes, we aimed to compare HBP measurements between PPT/EDTA and citrate tubes. As the number of COVID-19 patients decreased by the time the HBP measurements were available, we could not include COVID-19 patients for this comparison. Therefore, we included ten post-trauma ICU patients with presumably elevated levels of HBP for these measurements. Although, these patients had lower HBP levels (13.3 ng/ml; IQR 8.8–62.1), we found a strong correlation between HBP levels analysed from different tubes. As the name implies, heparins bind to HBP, and our group, along with others, has previously shown that heparins, including LMWH, can elevate the plasma HBP levels ( 51 , 52 ). Therefore, it is possible that LMWH contributed to the high levels found in our study, as the majority of patients received dalteparin before blood sampling. Considering that several hours had passed between LMWH administration in most patients, the effects of LMWH on plasma HBP concentration might have diminished ( 52 ). Unfortunately, anti-factor Xa levels were not routinely measured. There are a few studies reporting repeated measures of HBP during COVID-19 disease. The studies show varying levels depending on when the sample is taken during the course of the disease, but generally, decreasing levels are observed once clinical stability is reached ( 24 – 26 , 53 ). It was not possible to measure HBP levels repeatedly in our study. In a recently published study HBP levels were repeatedly measured during ICU stay in critical COVID-19 patients. Notably, all patients were treated with therapeutic doses of LMWH or heparin infusion, and the overall mean HBP level was 202 ng/ml ( 53 ). Some patients had extremely high values, similar to those observed in our cohort. Moreover, HBP levels were strongly associated with disease severity and remained elevated throughout the ICU stay. Interestingly, patients receiving heparin had higher plasma HBP compared to those treated with LMWH. However, the effects and timing of heparin administration in relation to blood sampling was not considered ( 53 ). The pathophysiology of respiratory dysfunction in ARDS and especially when caused by SARS-CoV-2 infection is not fully understood. Endothelial and epithelial dysfunction, along with systemic inflammation and microvascular hyperpermeability, are key features of ARDS, regardless of the underlying cause ( 54 ). It is highly probable that HBP is involved in this process, as both in vitro and in vivo studies have demonstrated its ability to open the endothelial lining ( 12 , 29 , 55 ). Endothelin-1 contributes to the pathophysiology of pulmonary artery hypertension, commonly seen in ARDS, and is associated with proliferative, fibrotic, and thrombogenic vascular remodelling ( 36 , 56 ). We found slightly elevated levels of ET-1 in our patients compared to the normal levels reported in healthy subjects ( 43 , 44 ) and those provided from the manufacturer of our ELISA. Patients receiving IMV had higher levels compared to patients not receiving this treatment. As the majority of the patients required IMV treatment shortly after ICU admission, we speculate that this group may have been more hypoxic at the time of blood sampling given that hypoxia is known to increase ET-1 secretion ( 57 , 58 ). In addition, the clearance of ET-1 could be disrupted in ARDS caused by COVID-19. Animal and human studies have established the pulmonary vascular endothelium as a major site for ET-1 removal through the endothelial ET B subtype receptors ( 59 – 63 ). Therefore, the elevated levels of ET-1 could be caused by increased production, reduced removal or a combination of both. Patients requiring IMV were also significantly older, which could have impacted the ET-1 levels ( 64 – 66 ). There are a few studies confirming high levels of ET-1 in COVID-19, with increasing levels in severely ill compared to patients with milder disease ( 30 ). In addition, the levels seem to remain elevated even three months after the infection ( 43 ). In a previous study on porcine endotoxemia, we observed an association between HBP and ET-1, where systemic ET-receptor antagonism markedly reduced plasma HBP levels, while ET-1 administration in control animals dose-dependently increased plasma HBP levels ( 48 ). However, in the present study on a severe viral disease, we found no correlation between plasma HBP and ET-1. Endothelial dysfunction is a complex phenomenon, and other mechanism may also be involved. This study has several limitations. It is a single-centre study with a limited cohort of COVID-19 patients. Moreover, as we could only obtain samples at admission, it was not possible to assess temporal changes in HBP in relation to outcome measures. The study lacks HBP and ET-1 samples from healthy controls and includes only a small group of post-trauma ICU patients. Nevertheless, we believe that that the HBP levels observed in our cohort are among the highest reported in the literature and significantly exceed those described in other severe conditions, such as sepsis ( 22 ), cardiac arrest ( 67 ), cardiac surgery ( 51 ), or trauma ( 68 ). Patients were included at a time when COVID-19 was a novel disease, and clinical experience regarding treatment strategies, such as timing of IMV initiation, was limited. Similarly, uncertainties regarding the timing and dosing of steroids, immunotherapy, and anticoagulative treatments may have influenced outcomes. As this study was conducted during the first wave of the COVID-19 pandemic, it remains uncertain whether our findings are applicable to later variants of the virus or to disease presentation in vaccinated individuals. Conclusions We found markedly elevated plasma levels of HBP at ICU admission in patients with critical COVID-19. Among these patients, no association was found between plasma HBP and 60-day mortality or the need for IMV during the ICU stay. Plasma levels of ET-1 were modestly elevated upon ICU admission but were not associated with mortality or the need for IMV. Abbreviations AUC Area under the curve ARDS Acute respiratory distress syndrome BMI Body mass index CI Confidence interval CRP C-reactive protein CRRT Continuous renal replacement therapy ELISA Enzyme-linked immunosorbent assay ET-1 Endothelin-1 HBP Heparin-binding protein ICU Intensive care unit IQR Interquartile range IL Interleukin IMV Invasive mechanical ventilation LMWH Low molecular weight heparin OR Odds ratio PCT Procalcitonin PPT Plasma preparation tubes PMN Polymorphonuclear neutrophils ROC Receiver operating characteristic curve SAPS Simplified acute physiology score SARS Severe acute respiratory syndrome WBC white blood cell count Declarations Ethical approval and consent to participate This study was designed in accordance with the Declaration of Helsinki and approved by the Swedish Ethical Review Authority (approval numbers 2020-01302, 2017/1324-31). Written consent was provided from the patient or a close relative when the patient was unable to provide consent. Presumed consent was used in COVID-19 patients who died before consent could be provided. Consent for publication Not applicable. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests Not applicable. Funding This study was supported by the Swedish Research Council, the Swedish Heart Lung Foundation, the Swedish Carnegie Hero Funds, Funds from Karolinska Institutet and Swedish Society of Medicine. Financial support was also provided through the regional agreement on medical and clinical research (ALF) between Stockholm County Council and Karolinska Institutet. None of the funding agents engaged in the study design, data collection, data analysis, and manuscript preparation or publication decisions. Authors' contributions Concept and design HH, JE, JG, OR, JM, AO, EW; methodology HH, JE, JG, OR, JM, AO, EW; data curation HH, JG, JM; formal analysis HH, JE; investigation HH, JE, AO, EW; resources OR, AO, EW; drafting of the manuscript HH, EW; review and editing of the manuscript JE, JG, OR, JM, AO. All authors reviewed and approved the final version of the manuscript. Acknowledgement The authors thank clinical research nurses Kristina Kilsand, Nicolas Tardif and Tove Jakobsson for assistance with recruitment of patients and collecting samples. We are especially thankful to research engineer Anette Ebberyd for measuring HBP end ET-1. We also thank all the staff at the Karolinska University Hospital for their cooperation. References Huang C, Wang Y, Li X, Ren L, Zhao J, Hu Y, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020;395(10223):497-506. Chen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet. 2020;395(10223):507-13. Wang D, Hu B, Hu C, Zhu F, Liu X, Zhang J, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA : the journal of the American Medical Association. 2020;323(11):1061-9. Chen T, Wu D, Chen H, Yan W, Yang D, Chen G, et al. Clinical characteristics of 113 deceased patients with coronavirus disease 2019: retrospective study. Bmj. 2020;368:m1091. Del Valle DM, Kim-Schulze S, Huang HH, Beckmann ND, Nirenberg S, Wang B, et al. An inflammatory cytokine signature predicts COVID-19 severity and survival. Nat Med. 2020;26(10):1636-43. Zhu Z, Cai T, Fan L, Lou K, Hua X, Huang Z, et al. Clinical value of immune-inflammatory parameters to assess the severity of coronavirus disease 2019. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases. 2020;95:332-9. Leisman DE, Ronner L, Pinotti R, Taylor MD, Sinha P, Calfee CS, et al. Cytokine elevation in severe and critical COVID-19: a rapid systematic review, meta-analysis, and comparison with other inflammatory syndromes. Lancet Respir Med. 2020;8(12):1233-44. Qin C, Zhou L, Hu Z, Zhang S, Yang S, Tao Y, et al. Dysregulation of Immune Response in Patients With Coronavirus 2019 (COVID-19) in Wuhan, China. Clin Infect Dis. 2020;71(15):762-8. Diao B, Wang C, Tan Y, Chen X, Liu Y, Ning L, et al. Reduction and Functional Exhaustion of T Cells in Patients With Coronavirus Disease 2019 (COVID-19). Frontiers in immunology. 2020;11:827. Chen G, Wu D, Guo W, Cao Y, Huang D, Wang H, et al. Clinical and immunological features of severe and moderate coronavirus disease 2019. J Clin Invest. 2020;130(5):2620-9. Bussani R, Schneider E, Zentilin L, Collesi C, Ali H, Braga L, et al. Persistence of viral RNA, pneumocyte syncytia and thrombosis are hallmarks of advanced COVID-19 pathology. EBioMedicine. 2020;61:103104. Joffre J, Rodriguez L, Matthay ZA, Lloyd E, Fields AT, Bainton RJ, et al. COVID-19-associated Lung Microvascular Endotheliopathy: A "From the Bench" Perspective. Am J Respir Crit Care Med. 2022;206(8):961-72. Scavone M, Ghali C, Calogiuri M, Sala M, Bossi E, Mencarini T, et al. Impairment of platelet function in both mild and severe COVID-19 patients. British journal of haematology. 2023;203(4):656-67. Varga Z, Flammer AJ, Steiger P, Haberecker M, Andermatt R, Zinkernagel AS, et al. Endothelial cell infection and endotheliitis in COVID-19. Lancet. 2020;395(10234):1417-8. Pons S, Fodil S, Azoulay E, Zafrani L. The vascular endothelium: the cornerstone of organ dysfunction in severe SARS-CoV-2 infection. Crit Care. 2020;24(1):353. Kruse JM, Zickler D, Ludemann WM, Piper SK, Gotthardt I, Ihlow J, et al. Evidence for a thromboembolic pathogenesis of lung cavitations in severely ill COVID-19 patients. Scientific reports. 2021;11(1):16039. Leisman DE, Mehta A, Thompson BT, Charland NC, Gonye ALK, Gushterova I, et al. Alveolar, Endothelial, and Organ Injury Marker Dynamics in Severe COVID-19. Am J Respir Crit Care Med. 2022;205(5):507-19. Fisher J, Russell JA, Bentzer P, Parsons D, Secchia S, Morgelin M, et al. Heparin-Binding Protein (HBP): A Causative Marker and Potential Target for Heparin Treatment of Human Sepsis-Induced Acute Kidney Injury. Shock. 2017;48(3):313-20. Fisher J, Linder A. Heparin-binding protein: a key player in the pathophysiology of organ dysfunction in sepsis. Journal of internal medicine. 2017;281(6):562-74. Linder A, Christensson B, Herwald H, Bjorck L, Akesson P. Heparin-binding protein: an early marker of circulatory failure in sepsis. Clin Infect Dis. 2009;49(7):1044-50. Linder A, Arnold R, Boyd JH, Zindovic M, Zindovic I, Lange A, et al. Heparin-Binding Protein Measurement Improves the Prediction of Severe Infection With Organ Dysfunction in the Emergency Department. Crit Care Med. 2015;43(11):2378-86. Linder A, Akesson P, Inghammar M, Treutiger CJ, Linner A, Sunden-Cullberg J. Elevated plasma levels of heparin-binding protein in intensive care unit patients with severe sepsis and septic shock. Crit Care. 2012;16(3):R90. Kaukonen KM, Linko R, Herwald H, Lindbom L, Ruokonen E, Ala-Kokko T, et al. Heparin-binding protein (HBP) in critically ill patients with influenza A(H1N1) infection. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2013. Mellhammar L, Thelaus L, Elén S, Fisher J, Linder A. Heparin binding protein in severe COVID-19-A prospective observational cohort study. PLoS One. 2021;16(4):e0249570. Saridaki M, Metallidis S, Grigoropoulou S, Vrentzos E, Lada M, Argyraki K, et al. Integration of heparin-binding protein and interleukin-6 in the early prediction of respiratory failure and mortality in pneumonia by SARS-CoV-2 (COVID-19). Eur J Clin Microbiol Infect Dis. 2021;40(7):1405-12. Xue M, Zeng Y, Qu HQ, Zhang T, Li N, Huang H, et al. Heparin-binding protein levels correlate with aggravation and multiorgan damage in severe COVID-19. ERJ Open Res. 2021;7(1). Gautam N, Olofsson AM, Herwald H, Iversen LF, Lundgren-Akerlund E, Hedqvist P, et al. Heparin-binding protein (HBP/CAP37): a missing link in neutrophil-evoked alteration of vascular permeability. Nat Med. 2001;7(10):1123-7. Herwald H, Cramer H, Morgelin M, Russell W, Sollenberg U, Norrby-Teglund A, et al. M protein, a classical bacterial virulence determinant, forms complexes with fibrinogen that induce vascular leakage. Cell. 2004;116(3):367-79. Bentzer P, Fisher J, Kong HJ, Morgelin M, Boyd JH, Walley KR, et al. Heparin-binding protein is important for vascular leak in sepsis. Intensive Care Med Exp. 2016;4(1):33. Abraham GR, Kuc RE, Althage M, Greasley PJ, Ambery P, Maguire JJ, et al. Endothelin-1 is increased in the plasma of patients hospitalised with Covid-19. Journal of molecular and cellular cardiology. 2022;167:92-6. Fodor A, Tiperciuc B, Login C, Orasan OH, Lazar AL, Buchman C, et al. Endothelial Dysfunction, Inflammation, and Oxidative Stress in COVID-19-Mechanisms and Therapeutic Targets. Oxid Med Cell Longev. 2021;2021:8671713. Janaszak-Jasiecka A, Siekierzycka A, Ploska A, Dobrucki IT, Kalinowski L. Endothelial Dysfunction Driven by Hypoxia-The Influence of Oxygen Deficiency on NO Bioavailability. Biomolecules. 2021;11(7). Yanagisawa M, Kurihara H, Kimura S, Tomobe Y, Kobayashi M, Mitsui Y, et al. A novel potent vasoconstrictor peptide produced by vascular endothelial cells. Nature. 1988;332(6163):411-5. Miyamori I, Takeda Y, Yoneda T, Takeda R. Endothelin-1 release from mesenteric arteries of spontaneously hypertensive rats. J Cardiovasc Pharmacol. 1991;17 Suppl 7:S408-10. Sakai S, Miyauchi T, Kobayashi M, Yamaguchi I, Goto K, Sugishita Y. Inhibition of myocardial endothelin pathway improves long-term survival in heart failure. Nature. 1996;384(6607):353-5. Giaid A, Yanagisawa M, Langleben D, Michel RP, Levy R, Shennib H, et al. Expression of endothelin-1 in the lungs of patients with pulmonary hypertension. The New England journal of medicine. 1993;328(24):1732-9. Cacoub P, Dorent R, Maistre G, Nataf P, Carayon A, Piette C, et al. Endothelin-1 in primary pulmonary hypertension and the Eisenmenger syndrome. The American journal of cardiology. 1993;71(5):448-50. Voerman HJ, Stehouwer CD, van Kamp GJ, Strack van Schijndel RJ, Groeneveld AB, Thijs LG. Plasma endothelin levels are increased during septic shock. Crit Care Med. 1992;20(8):1097-101. Jin Q, Chen D, Zhang X, Zhang F, Zhong D, Lin D, et al. Medical Management of Pulmonary Arterial Hypertension: Current Approaches and Investigational Drugs. Pharmaceutics. 2023;15(6). Druml W, Steltzer H, Waldhausl W, Lenz K, Hammerle A, Vierhapper H, et al. Endothelin-1 in adult respiratory distress syndrome. Am Rev Respir Dis. 1993;148(5):1169-73. Mitaka C, Hirata Y, Nagura T, Tsunoda Y, Amaha K. Circulating endothelin-1 concentrations in acute respiratory failure. Chest. 1993;104(2):476-80. Langleben D, DeMarchie M, Laporta D, Spanier AH, Schlesinger RD, Stewart DJ. Endothelin-1 in acute lung injury and the adult respiratory distress syndrome. Am Rev Respir Dis. 1993;148(6 Pt 1):1646-50. Willems LH, Nagy M, Ten Cate H, Spronk HMH, Groh LA, Leentjens J, et al. Sustained inflammation, coagulation activation and elevated endothelin-1 levels without macrovascular dysfunction at 3 months after COVID-19. Thromb Res. 2022;209:106-14. Haffke M, Freitag H, Rudolf G, Seifert M, Doehner W, Scherbakov N, et al. Endothelial dysfunction and altered endothelial biomarkers in patients with post-COVID-19 syndrome and chronic fatigue syndrome (ME/CFS). J Transl Med. 2022;20(1):138. Bermejo-Martin JF, Garcia-Mateo N, Motos A, Resino S, Tamayo L, Ryan Murua P, et al. Effect of viral storm in patients admitted to intensive care units with severe COVID-19 in Spain: a multicentre, prospective, cohort study. Lancet Microbe. 2023;4(6):e431-e41. Shahbazi S, Vahdat Shariatpanahi Z, Shahbazi E. Bosentan for high-risk outpatients with COVID-19 infection: a randomized, double blind, placebo-controlled trial. EClinicalMedicine. 2023;62:102117. Nabeh OA, Matter LM, Khattab MA, Esraa M. "The possible implication of endothelin in the pathology of COVID-19-induced pulmonary hypertension". Pulmonary pharmacology & therapeutics. 2021;71:102082. Persson BP, Halldorsdottir H, Lindbom L, Rossi P, Herwald H, Weitzberg E, et al. Heparin-binding protein (HBP/CAP37) - a link to endothelin-1 in endotoxemia-induced pulmonary oedema? Acta anaesthesiologica Scandinavica. 2014;58(5):549-59. Acar T, Ertekin B, Yortanli M, Kocak S. Prognostic value of heparin-binding protein for mortality in severe COVID-19 pneumonia. Biomarkers in medicine. 2022;16(13):981-91. Kyriazopoulou E, Dalekos GN, Metallidis S, Poulakou G, Papanikolaou IC, Tzavara V, et al. Heparin-Binding Protein Levels Predict Unfavorable Outcome in Covid-19 Pneumonia: A Post Hoc Analysis of the Save Trial. Shock. 2024;61(3):395-9. Sterner N, Fisher J, Thelaus L, Ketteler C, Lemez S, Dardashti A, et al. The Dynamics of Heparin-Binding Protein in Cardiothoracic Surgery-A Pilot Study. Journal of cardiothoracic and vascular anesthesia. 2021. Halldorsdottir H, Lindbom L, Ebberyd A, Oldner A, Weitzberg E. The effect of heparins on plasma concentration of heparin-binding protein: a pilot study. BJA Open. 2024;9:100256. Neb H, Talbot SR, Ruskowski K, Brkic D, Sonntagbauer M, Adam EH, et al. High Heparanase Level in Survivors of Covid-19 - Indicator of Vascular and Pulmonary Recovery? Shock. 2022;58(6):514-23. Thompson BT, Chambers RC, Liu KD. Acute Respiratory Distress Syndrome. The New England journal of medicine. 2017;377(6):562-72. Lin Q, Shen J, Shen L, Zhang Z, Fu F. Increased plasma levels of heparin-binding protein in patients with acute respiratory distress syndrome. Crit Care. 2013;17(4):R155. Banecki K, Dora KA. Endothelin-1 in Health and Disease. International journal of molecular sciences. 2023;24(14). Cargill RI, Kiely DG, Clark RA, Lipworth BJ. Hypoxaemia and release of endothelin-1. Thorax. 1995;50(12):1308-10. Ferri C, Bellini C, De Angelis C, De Siati L, Perrone A, Properzi G, et al. Circulating endothelin-1 concentrations in patients with chronic hypoxia. J Clin Pathol. 1995;48(6):519-24. Fukuroda T, Fujikawa T, Ozaki S, Ishikawa K, Yano M, Nishikibe M. Clearance of circulating endothelin-1 by ETB receptors in rats. Biochem Biophys Res Commun. 1994;199(3):1461-5. Dupuis J, Goresky CA, Fournier A. Pulmonary clearance of circulating endothelin-1 in dogs in vivo: exclusive role of ETB receptors. Journal of applied physiology. 1996;81(4):1510-5. Wagner OF, Vierhapper H, Gasic S, Nowotny P, Waldhausl W. Regional effects and clearance of endothelin-1 across pulmonary and splanchnic circulation. European journal of clinical investigation. 1992;22(4):277-82. Weitzberg E, Ahlborg G, Lundberg JM. Differences in vascular effects and removal of endothelin-1 in human lung, brain, and skeletal muscle. Clin Physiol. 1993;13(6):653-62. Dupuis J, Cernacek P, Tardif JC, Stewart DJ, Gosselin G, Dyrda I, et al. Reduced pulmonary clearance of endothelin-1 in pulmonary hypertension. American heart journal. 1998;135(4):614-20. White M, Courtemanche M, Stewart DJ, Talajic M, Mikes E, Cernacek P, et al. Age- and gender-related changes in endothelin and catecholamine release, and in autonomic balance in response to head-up tilt. Clinical science. 1997;93(4):309-16. Sayama H, Nakamura Y, Saito N, Konoshita M. Does the plasma endothelin-1 concentration reflect atherosclerosis in the elderly? Gerontology. 1999;45(6):312-6. Vassiliou AG, Roumpaki A, Keskinidou C, Athanasiou N, Tsipilis S, Jahaj E, et al. Transpulmonary Plasma Endothelin-1 Arterial:Venous Ratio Differentiates Survivors from Non-Survivors in Critically Ill Patients with COVID-19-Induced Acute Respiratory Distress Syndrome. International journal of molecular sciences. 2024;25(19). Ristagno G, Masson S, Tiainen M, Bendel S, Bernasconi R, Varpula T, et al. Elevated plasma heparin-binding protein is associated with early death after resuscitation from cardiac arrest. Crit Care. 2016;20(1):251. Halldorsdottir HD, Eriksson J, Persson BP, Herwald H, Lindbom L, Weitzberg E, et al. Heparin-binding protein as a biomarker of post-injury sepsis in trauma patients. Acta anaesthesiologica Scandinavica. 2018. Tables Table 1. Patient characteristics and outcomes for 60-day survivors and non-survivors. Patient characteristics All (n=96) Dead (n=17) Surviving (n=79) P Age,years 61 (53-66) 65 (57-68) 60 (53-66) ns Male 73 (76) 17 (100) 56 (71) ** BMI 28 (25-31) 26 (24-32) 28 (26-31) ns Comorbidity No previous medical history Cardiovascular disease Lung disease Diabetes I or II Chronic kidney disease Chronic GI/liver disease Immunocompromised Any malignancy 23 (24) 54 (56) 20 (21) 31(32) 7 (7) 7(7) 9 (9) 11 (11) 2 (12) 9 (53) 4 (24) 5 (29) 2 (12) 1 (6) 3 (24) 4 (24) 21 (27) 45 (57) 16 (20) 26 (33) 5 (6) 6 (8) 6 (9) 7 (9) ns ns ns ns ns ns ns ns Time from symptom to hospital admission, days 8 (6-11) n=94 6 (4-12) n=16 8 (6-11) n=78 ns Time from symptom to ICU admission, days 10 (8-14) n=94 10 (6–13) n=16 10 (8-14) n=78 ns Time from symptom to death, days 33 (23-45) n=16 Time from hospital admission to death, days 22 (18-38) n=17 SAPS III score 51 (47-57) 51 (49-62) 49 (46-56) ns Hospital duration, days 21 (16-38) 22 (19-38) 21 (15-39) ns ICU duration, days 12 (5-21) 22 (17-36) 9 (5-16) **** CRRT 12 (13) 6 (35) 6 (8) ** IMV 61 (64) 16 (94) 45 (57) ** IMV days 9 (0-18) 17 (14-35) 6 (0-14) **** Prone position 69 (72) 16 (94) 53 (67) * Steroids first 7 days at ICU 53 (55) 14 (82) 39 (49) * Steroids before HBP test 24 (25) n=93 5 (29) n=15 19 (24) n=78 ns Remdesivir 4 (4) 2 (12) 2 (3) ns Monoclonal antibody 21 (22) 4 (24) 17 (22) ns LMWH dose before HBP test 5000 (5000-7500) n=91 5000 (5000-7500) n=15 5000 (5000-7500) n=76 ns HBP ng/ml 150 (47-299) n=78 193 (34-545) n=15 141 (50-292) n=63 ns ET-1 pg/ml 1.6 (1.2-1.9) n=92 1.7 (1.4-1.9) n=16 1.6 (1.1-1.9) n=76 ns WBC x10(9)/L 8.4 (6.4-10.9) 9.1 (5.8-11.7) 8.2 (6.5-10.7) ns PCT µg/L 0.6 (0.2–1.4) 0.9 (0.5-1.7) 0.5 (0.2-1.1) ns CRP mg/L 176 (123-257) 207 (126-261) 169 (114-255) ns HBP/WBC ratio 16.2 (6.7-41.0) n=78 24.2 (6.3-67.3) n=15 14.6 (6.8-39.0) n=63 ns D-Dimer mg/L 1.2 (0.7-2.6) n=74 1.3 (0.8-3.8) n=13 1.2 (0.7-2.6) n=61 ns Thrombocytes x10(9)/L 265 (202-312) 240 (217-297) 270 (199-330) ns IL-6 ng/L 132 (62-324) n=46 215 (129-393) n=9 110 (52-308) n=37 ns Ferritin µg/L 1419 (699-2153) n=51 1738 (1272-2052) n=10 1251 (607-2183) n=41 ns Data displayed as median (interquartile range) for continuous variables and number (%) for categorical variables. BMI, body mass index; GI, gastrointestinal; ICU, intensive care unit; SAPS, simplified acute physiology score; CRRT, continuous renal replacement therapy; IMV, invasive mechanical ventilator; HBP, heparin-binding protein; LMWH, low molecular weight heparin (value in units); ET-1, endothelin-1; WBC, white blood cell; PCT, procalcitonin; CRP, C-reactive protein; IL-6, interleukin-6. Monoclonal antibody refers to IL-1 or IL-6 blockers. Groups compared with Mann-Whitney two tailed test for continuous data and Fisher exact test for categorical data. * Denotes p<0.05, ** p<0.01, **** denotes p<0.0001. Table 2. Patient characteristics and outcome of patients treated with or without invasive mechanical ventilation. Patient characteristics All (n=96) IMV YES (n=61) IMV NO (n=35) P Age 61 (53-66) 62 (57-67) 57 (50-65) * Male 73 (76) 45 (73) 28 (80) ns BMI 28 (25-31) 28 (25-31) 28 (25-31) ns Comorbidity No previous medical history Cardiovascular disease Lung disease Diabetes I or II Chronic kidney disease Chronic GI/liver disease Immunocompromised Any malignancy 23 (24) 54 (56) 20 (21) 31(32) 7 (7) 7(7) 9 (9) 11 (11) 14 (23) 34 (56) 13 (21) 18 (30) 6 (10) 7 (11) 7 (12) 9 (15) 9 (26) 20 (57) 7 (20) 13 (37) 1 (3) 0 (0) 2 (6) 2 (6) ns ns ns ns ns * ns ns Time from symptom to hospital admission, days 8 (6-11) n=94 8 (5-11) 10 (7-12) ns Time from symptom to ICU admission, days 10 (8-14) n=94 10 (7-13) 11 (9-14) ns Dead 17 (18) 16 (26) 1 (3)† ** Time from symptom to death, days 35 (24-45) n=15 5 Time from hospital admission to death, days 25 (18-38) n=16 1 SAPS 51 (47-57) 53 (49-60) 47 (44-50) **** Hospital duration, days 21 (16-38) 30 (21-49) 14 (10-17) **** ICU duration days 12 (5-21) 17 (12-27) 4 (2-6) **** CRRT 12 (13) 12 (20) 0 (0) ** IMV days 15 (9-27) IMV on ICU admission day 31 (51) IMV during the first 3 ICU days 58 (95) Prone position 69 (72) 42 (69) 27 (77) ns Steroids first 7 days at ICU 53 (55) 32 (52) 14 (40) ns Steroids before HBP test 24 (25) n=93 12(20) 12 (34) ns Remdesivir 4 (4) 4 (7) 0 (0) ns Monoclonal antibody 21 (22) 14 (23) 7 (20) ns LMWH dose before HBP test 5000 (5000-7500) n=91 5000 (5000-7500) n=56 5000 (5000-7500) n=35 ns HBP ng/ml 150 (47-299) n=78 150 (40-430) n=48 160 (59-284) n=30 ns ET-1 pg/ml 1.6 (1.2-1.9) n=92 1.7 (1.3-2.0) n=57 1.4 (1.0-1.7) n=35 ** WBC x10(9)/L 8.4 (6.4-10.9) 8.2 (6.1-11.2) 8.5 (6.7-10.0) ns PCT µg/L 0.6 (0.2–1.4) 0.9 (0.4-1.8) 0.3 (0.1-0.6) **** CRP mg/L 176 (123-257) 207 (136-284) 133 (99-235) ** HBP/WBC ratio 16.2 (6.7-41.0) n=78 18.0 (5.6-49.0) n=48 15.0 (7.3-35.3) n=30 ns D-Dimer mg/L 1.2 (0.7-2.6) n=74 1.3 (0.8-2.8) n=45 1.1 (0.6-1.8) n=29 ns Thrombocytes x10(9)/L 265 (202-312) 262 (203-305) 277 (200-363) ns IL-6 ng/L 132 (62.3-324.0) n=46 211 (80-454.8) n=30 74 (31.3-221.8) n=16 * Ferritin µg/L 1419 (699-2153) n=51 1419 (824-2209) n=33 1285 (537-2168) n=18 ns Data displayed as median (interquartile range) for continuous variables and number (%) for categorical variables. BMI, body mass index; GI, gastrointestinal; ICU, intensive care unit; SAPS, simplified acute physiology score; CRRT, continuous renal replacement therapy; IMV, invasive mechanical ventilator; HBP, heparin-binding protein; LMWH, low molecular weight heparin (value in units); ET-1, endothelin-1; WBC, white blood cell; PCT, procalcitonin; CRP, C-reactive protein; IL-6, interleukin-6. Monoclonal antibody refers to IL-1 or IL-6 blockers. Groups compared with Mann-Whitney two tailed test for continuous data and Fisher exact test for categorical data. *Denotes p<0.05, ** p<0.01, **** denotes p<0.0001. † One patient died with restrictions of medical treatments, including mechanical ventilation. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9173002","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":622996339,"identity":"37b25159-5e21-499e-b73d-3ff93316c6db","order_by":0,"name":"Jesper Eriksson","email":"","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":false,"prefix":"","firstName":"Jesper","middleName":"","lastName":"Eriksson","suffix":""},{"id":622996340,"identity":"cba27fb2-6c04-436a-a0d6-695089feca0f","order_by":1,"name":"Halla Halldorsdottir","email":"data:image/png;base64,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","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":true,"prefix":"","firstName":"Halla","middleName":"","lastName":"Halldorsdottir","suffix":""},{"id":622996341,"identity":"d4692ee1-ed38-4499-883b-671cd3d99e99","order_by":2,"name":"Olav Rooyackers","email":"","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":false,"prefix":"","firstName":"Olav","middleName":"","lastName":"Rooyackers","suffix":""},{"id":622996342,"identity":"18a913e7-1057-4976-bde9-6ce7cab520bb","order_by":3,"name":"Jonathan Grip","email":"","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":false,"prefix":"","firstName":"Jonathan","middleName":"","lastName":"Grip","suffix":""},{"id":622996345,"identity":"a9302da8-116c-433d-83f0-f7fc95d911ed","order_by":4,"name":"Johan Mårtensson","email":"","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":false,"prefix":"","firstName":"Johan","middleName":"","lastName":"Mårtensson","suffix":""},{"id":622996347,"identity":"7c44d42d-30fa-4e23-986b-5d83e832c2c2","order_by":5,"name":"Eddie Weitzberg","email":"","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":false,"prefix":"","firstName":"Eddie","middleName":"","lastName":"Weitzberg","suffix":""},{"id":622996348,"identity":"0ebd8be8-0053-438f-8744-fb2768c963b6","order_by":6,"name":"Anders Oldner","email":"","orcid":"","institution":"Karolinska Institutet","correspondingAuthor":false,"prefix":"","firstName":"Anders","middleName":"","lastName":"Oldner","suffix":""}],"badges":[],"createdAt":"2026-03-19 21:23:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9173002/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9173002/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107448010,"identity":"b67b296b-fb51-4759-981c-0614a094c84c","added_by":"auto","created_at":"2026-04-21 14:56:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":25843,"visible":true,"origin":"","legend":"\u003cp\u003ePatient flowchart. ICU, intensive care unit.\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-9173002/v1/3a3fa2fd445f773841738508.png"},{"id":107448073,"identity":"aa84035d-8b85-47cd-afb4-fa5d6648a2e5","added_by":"auto","created_at":"2026-04-21 14:56:34","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":29625,"visible":true,"origin":"","legend":"\u003cp\u003eComparison of heparin-binding protein (HBP) and endothelin-1 (ET-1) measurements in samples collected in plasma preparation tubes (PPT) containing EDTA and citrated test tubes. Correlation between HBP measurements (A) and ET-1 measurements (B) PPT tubes or citrated test tubes.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-9173002/v1/a524a1ddece7f8c3c7feedca.png"},{"id":107448098,"identity":"4adb1a21-2674-4a0d-88e3-ec5908ad2d17","added_by":"auto","created_at":"2026-04-21 14:56:39","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":28368,"visible":true,"origin":"","legend":"\u003cp\u003eHeparin-binding protein (HBP) and endothelin-1 (ET-1) levels in critical COVID-19 patients. 60-day survivors vs. non-survivors (A and C, respectively). Patients requiring invasive mechanical ventilation (IMV) or not (B and D, respectively). Data displayed as Tukey box and whisker plots with the median indicated by the horizonal line. ** denotes p \u0026lt;0.01.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-9173002/v1/9a12101eba4fc8e0675c33ea.png"},{"id":107448063,"identity":"e7162a8d-41db-456b-967a-67fb8e591213","added_by":"auto","created_at":"2026-04-21 14:56:32","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":196588,"visible":true,"origin":"","legend":"\u003cp\u003ePredictive performance of biomarkers. Receiver operating characteristic (ROC) for prediction of mortality and invasive mechanical ventilation. A) Heparin-binding protein (HBP) and 60-day mortality (n=78), B) Endothelin-1 (ET-1) and 60-day mortality (n=92), C) HBP and invasive mechanical ventilation (n=50), D) ET-1 and invasive mechanical ventilation (n=55). Area under the curve (AUC) values and 95% confidence interval.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-9173002/v1/c420601bb2e374e2588a26f7.jpeg"},{"id":107448222,"identity":"a5a6319f-e28b-4948-9dbb-45b3be9cc399","added_by":"auto","created_at":"2026-04-21 14:56:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":922125,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9173002/v1/c29225a3-80d5-4852-8fca-ff1058b79ec0.pdf"},{"id":107448062,"identity":"c2defea2-3f93-4508-8932-f68a3d96f4c7","added_by":"auto","created_at":"2026-04-21 14:56:32","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":208999,"visible":true,"origin":"","legend":"","description":"","filename":"Supplement.docx","url":"https://assets-eu.researchsquare.com/files/rs-9173002/v1/9a70f62de23b6f81eaa86114.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003e\u003cstrong\u003eHeparin-binding protein and Endothelin-1 in critical COVID-19\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe COVID-19 pandemic has posed significant challenges to healthcare systems worldwide. While the pathophysiology of COVID-19 is still being elucidated, numerous studies have documented that patients who initially appear relatively stable can experience rapid clinical deterioration within a few days. This decline is often characterised by uncontrolled pulmonary inflammation, acute respiratory distress syndrome (ARDS), and multiple organ failure (\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe concept of a cytokine storm, marked by elevated levels of cytokines, has been proposed as a contributing factor to this process (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). However, virus-mediated damage, combined with dysregulated inflammatory responses involving non-cytokine biomarkers, is also recognised as playing a significant role in disease progression (\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe ARDS associated with COVID-19 involves a complex interplay of epithelial and endothelial cell injury, leading to fluid leakage into the interstitium and alveoli (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). This vascular damage precipitates systemic endotheliitis, leukocyte adhesion, platelet activation (\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e), and the development of a pro-thrombotic state (\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). The specific contributions and temporal dynamics of epithelial versus endothelial injury in COVID-19 remain unclear, potentially causing variations in circulating plasma markers throughout the disease course (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe neutrophil protein heparin-binding protein (HBP) has emerged as a biomarker in sepsis, demonstrating the ability to predict unfavourable outcomes such as multiple organ failure and mortality (\u003cspan additionalcitationids=\"CR19 CR20 CR21\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Plasma concentrations\u0026thinsp;\u0026gt;\u0026thinsp;15 ng/ml at intensive care unit (ICU) admission have been associated with increased mortality (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). Moreover, plasma HBP levels are significantly elevated in viral influenza A (H1N1) pneumonia (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the context of COVID-19, HBP elevation has been observed before the onset of organ failure when sampled early in the disease course (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). Furthermore, elevated HBP levels have been linked to severe respiratory failure and increased mortality rates (\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHeparin-binding protein is stored in secretory and primary granules in polymorphonuclear neutrophils (PMN). This multifunctional inflammatory protein is released when PMNs are activated through membrane bound β-2 integrin binding on the endothelial lining (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e) or by circulating proteins such as streptococcal M-protein and fibrinogen (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). Heparin-binding protein induces cytoskeletal changes in the endothelial lining, leading to intercellular gap formation, increased vascular permeability, and organ failure (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDysregulation of the endothelium-derived vasodilator nitric oxide (NO) and the vasoconstrictor peptide endothelin-1 (ET-1) (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e) has been implicated in the pathophysiology of COVID-19-associated endothelial dysfunction, resulting from the direct invasion of endothelial cells by the virus (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eEndothelin-1 serves as a potent inflammatory vasoconstrictor mediator released primarily by endothelial cells (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e). Elevated ET-1 levels have been correlated with conditions such as hypertension (\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e), heart failure (\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e), pulmonary hypertension (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e) and sepsis (\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e). In pulmonary arterial hypertension, increased ET-1 levels are associated with fibrosis and vascular remodelling, suggesting a potential benefit of ET-1 receptor antagonists (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNumerous studies have demonstrated elevated ET-1 levels in ARDS (\u003cspan additionalcitationids=\"CR41\" citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e). Recent evidence suggests that patients with mild COVID-19 infection have lower ET-1 levels compared to hospitalised counterparts (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). However, ET-1 levels can remain persistently elevated up to three months post-COVID-19, coinciding with increased inflammatory cytokine levels (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e). Higher ET-1 levels have been linked to severe COVID-19 and mortality (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan additionalcitationids=\"CR44\" citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSupporting a pathophysiological role of ET-1 in COVID-19, a recently published study showed that the dual ET\u003csub\u003eA\u003c/sub\u003e and ET\u003csub\u003eB\u003c/sub\u003e receptor antagonist bosentan reduced the risk of hospitalisation and thrombosis in high risk COVID-19 patients (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eDespite data suggesting the potential involvement of ET-1 and HBP in the pathophysiology of critical COVID-19, their role remains largely unclear (\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e), with a limited number of studies assessing the levels of these biomarkers in COVID-19 patients. In particular, data on biomarker levels in critically ill, ICU-admitted patients remain scarce.\u003c/p\u003e \u003cp\u003eRegarding ET-1 and HBP, we have previously shown an association between plasma levels of these biomarkers in experimental sepsis, where ET-receptor antagonism reduced plasma HBP levels, and ET-1 administration in non-septic conditions resulted in a dose-dependent increase in plasma HBP (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe aim of the study was to investigate the plasma levels of HBP and ET-1 at ICU admission in critical COVID-19 and their association with 60-day mortality and need for IMV.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eStudy design and participants.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis observational cohort study was performed between April-October 2020 at the Karolinska University Hospital, Sweden, a tertiary referral centre, covering an urban area of approximately 2.4 million inhabitants. During this period, specific COVID-19 ICUs were established. Patients were admitted to these units primarily due to severe respiratory failure requiring advanced respiratory support, such as high-flow nasal oxygen, non-invasive mechanical ventilation, or IMV.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePatients 18 years or older with confirmed SARS-CoV-2 infection by polymerase chain reaction were eligible for inclusion upon admission to the COVID-ICU. The main reasons for not including all eligible patients were limited research nurse availability, failure to obtain informed consent from the patient or closest relative, or inability of the patient to understand the study protocol.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor comparison of HBP and ET-1 values, plasma samples were collected from ten ICU-admitted trauma patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData collection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAdmittance data and clinical parameters were retrieved from the Swedish Intensive Care Register and electronic patient data management systems (Clinisoft\u003csup\u003e\u0026reg;\u003c/sup\u003e, GE, Barrington IL), including patient medical records (Take Care\u003csup\u003e\u0026reg;\u003c/sup\u003e, CompuGroup Medical, Koblenz, Germany). Information was collected on demographic data, laboratory results, comorbidities, hospital and ICU admissions, respiratory and circulatory parameters, and outcomes such as mortality and continuous renal replacement therapy (CRRT).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eData was collected during ICU stay, until discharge or death, whichever occurred first. Variables of interest included age, sex, body mass index (BMI), and comorbidities. Simplified acute physiology score (SAPS) III, time from symptom onset to hospital admission, ICU admission, and death, as well as laboratory data, were recorded. Treatments such as prone positioning, muscle relaxation, CRRT, steroids, and specific therapies such as interleukin (IL)-blockers and anticoagulation, were documented. Clinical outcome data were available for all patients.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBlood sampling and biomarker analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBlood samples were drawn within 24 hours of ICU admission from an indwelling cannula into plasma preparation tubes (PPT) (BD Vacutainer\u003csup\u003e\u0026reg;\u003c/sup\u003ePPT TM, Becton Dickinson, New Jersey, USA). The tubes were centrifuged in 1200 G for 10 minutes at 4\u0026deg;C and stored at -80 \u0026deg;C. After storage the plasma was separated from the tubes and stored again at -80\u0026deg; until biomarker analysis.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHeparin-binding protein was analysed in duplicates using the Axis-Shield HBP microtiter plate enzyme-linked immunosorbent assay (ELISA, Axis-Shield Diagnostics, Dundee, United Kingdom). Endothelin-1 was analysed using the Quantikine\u003csup\u003e\u0026Ograve;\u003c/sup\u003eELISA (R\u0026amp;D Systems\u003csup\u003e\u0026Ograve;\u003c/sup\u003e Inc., Minneapolis, USA). Routine laboratory measurements were obtained from the established clinical routine laboratory assays at the Karolinska University Hospital Laboratory.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOutcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe primary outcome was the association between plasma levels of HBP and ET-1 in critical COVID-19 disease and 60-day mortality from hospital admission. The secondary outcome was the association between these levels and the need for subsequent IMV during the ICU stay.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNonparametric methods were used to analyse data. Comparisons of continuous variables were performed using the Mann-Whitney two-tailed test. Categorical variables were assessed using Fisher\u0026acute;s exact test. A p-value of \u0026lt;0.05 was considered statistically significant. Continuous data are presented as median \u0026plusmn; interquartile range (IQR) and depicted as box plots. Categorical data are presented as proportions and percentages.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOutcomes were assessed using multivariable logistic regression analyses, adjusted for age, sex, and BMI. Goodness of fit and model discrimination were determined using the Hosmer-Lemeshow test. Comparison between plasma HBP and ET-1 collected in PPT tubes or citrated tubes was performed using Spearman correlation as well as Mann-Whitney two-tailed test.\u003c/p\u003e\n\u003cp\u003eThe predictive properties of the biomarkers were analysed with receiver operating characteristic curves (ROC) and presented as area under the curve (AUC) with corresponding confidence interval (CI). Statistical analyses were performed using Prism 9 (Graphpad Inc., San Diego, USA).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 96 patients with critical COVID-19 were included and analysed in the study, with the vast majority (96%) enrolled between April and June 2020. Heparin-binding protein measurements were available for 78 patients and ET-1 measurements for 92 patients.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn four patients HBP samples were missing, and in 14 individuals, complications with the Axis- Shield ELISA rendered the values unusable. Additionally, ET-1 sample were missing in four patients.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA flowchart and demographic data for inclusion of critical COVID-19 patients admitted to ICU is presented in Figure 1 and in Table 1.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatient characteristics, treatment and blood sampling\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePatient characteristics and outcomes are summarized in Table 1 and 2. The median time from the onset of COVID-19 symptoms to hospital admission was 8 days (IQR 6-11), and to ICU admittance, 10 days (IQR 8-14).\u003c/p\u003e\n\u003cp\u003eThe cohort was characterised by severe respiratory failure, with 61 of 96 patients (64 %) requiring IMV during their ICU stay.\u0026nbsp;The vast majority (76 %) were male and 76 % had pre-existing medical conditions. The median length of ICU stay was 12 days (IQR 5-21).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll patients exhibited laboratory signs of inflammation, including elevated C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6) and ferritin levels, while white blood cell count (WBC) remained within normal ranges.\u003c/p\u003e\n\u003cp\u003eThe median time from ICU admission to HBP and ET-1 blood sampling was 15 hours (IQR 9-23). In most patients (72 %), other laboratory data measurements were taken within six hours before or after the HBP and ET-1 sample. For the remaining 28 %, samples were taken within 12 hours of the HBP/ET-1 sample.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eNo patient was treated with hydroxychloroquine, while four patients received remdesivir. Approximately half of the patients received steroids during the first seven ICU days and 25 % of all patients had been given steroids before blood sampling. Similarly, 22 % of the patients received monoclonal antibodies against IL-1 or IL-6 of which seven patients received this treatment before blood sampling.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA comparison between patients receiving steroids and monoclonal antibodies showed no significant influence on HBP or ET-1 levels (data not shown).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll patients, except one, received low molecular weight heparin (LMWH), specifically dalteparin, during their ICU stay. The exception was a patient treated with a heparin infusion due to extracorporeal membrane oxygenation, which was initiated after blood sampling.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eComparison of test tubes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo investigate if PPT test tubes (containing EDTA as anticoagulant and a gel plug separating plasma during centrifugation) interfere with the HBP-ELISA which is recommended for human citrated plasma only, we compared PPT tubes with standard tubes containing citrate. In the ten severely injured trauma ICU patients the HBP and ET-1 levels using the PPT tubes were 13.3 ng/ml (IQR 8.8-62.1) and 2.0 pg/ml (IQR 1.2-2.8), respectively. The levels in citrated tubes were 7.0 ng/ml (IQR 4.8-40.1) and 1.9 pg/ml (IQR 1.0-2.5), respectively. The HBP and ET-1 levels in the PPT test tubes were consequently higher than in the citrate tubes but the difference was not significant (Supplementary Table 1). There was a strong correlation between HBP and ET-1 values between these different test tubes (Fig. 2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHeparin-binding protein, endothelin-1 and patient outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMortality\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe 60-day mortality after hospital admission was 17.8 %. All the deceased patients were male and died during hospital stay. The median time from COVID-19 symptoms to death was 33 days (IQR 23-45).\u003c/p\u003e\n\u003cp\u003eThe median HBP and ET-1 levels at admission were 150 ng/ml (IQR 47-299) and 1.6 pg/ml (IQR 1.2-1.9), respectively. There was no significant difference in plasma HBP levels between patients who survived and those who died (141 ng/ml; IQR 50-292 and 193 ng/ml; IQR 34-545, respectively), p=0.64, (Table 1, Fig. 3A). Similarly, there was no difference in plasma ET-1 levels between surviving patients (1.6 pg/ml; IQR 1.1\u0026ndash;1.9) and deceased patients (1.7 pg/ml; IQR 1.4\u0026ndash;1.9), p=0.30, (Table 1, Fig. 3C).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePatients who died were more frequently treated with IMV as well as CRRT. They also had a longer ICU stay compared to surviving patients (Table 1). There was no significant difference in CRP, WBC, ferritin, D-dimer, or thrombocyte count between patients who died and those who survived. Heparin-binding protein or ET-1 levels did not correlate with any of these laboratory parameters (data not shown), except that HBP correlated with WBC, (r=0.33, P=0.004). Moreover, there was no significant correlation between HBP and ET-1, (Supplementary Fig. 1).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn a logistic regression model adjusted for age, sex and BMI, neither HBP nor ET-1 was significantly associated with mortality (OR 1.000; 95%CI 0.999-1.001 and OR 1.095; 95%CI 0.489-2.252, respectively). The model demonstrated good calibration using the Hosmer-Lemeshow test.\u003c/p\u003e\n\u003cp\u003eReceiver operating characteristic curves were used to evaluate prediction of mortality in all patients. The AUC was non-significant for HBP, ET-1, CRP, PCT, WBC, HBP/WBC, thrombocyte count, D-dimer, IL-6 and ferritin (Fig. 4A and B; Supplementary Fig. 2).\u0026nbsp;There was no difference in LMWH dosage before HBP sampling or during ICU stay between surviving patients and those who succumbed to the disease (Table 1).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMechanical ventilation\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eThe majority of patients admitted to the ICU (61 out of 96; 64%) received IMV during their stay, with 58 (95%) of these patients being intubated within 72 hours. One patient was intentionally managed solely with non-invasive ventilation due to end-stage lung disease.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe HBP levels upon admission were comparable between patients who required IMV and those who did not during their ICU stay (Table 2, Fig. 3B). However, ET -1 levels were significantly higher (1.7 pg/ml; IQR 1.3-2.0) in patients requiring IMV compared to those who did not (1.4 pg/ml; IQR 1.0-1.7), p=0.004, (Table 2, Fig. 3D).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn a logistic regression model, adjusted for age, sex and BMI neither HBP nor ET-1 showed a significant association with IMV (OR 1.001; 95%CI 1.000-1.004 and OR 1.854; 95%CI 0.916-4.303, respectively). The model demonstrated good calibration.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eReceiver operating characteristic curves were used to evaluate prediction of subsequent IMV after the initial plasma sampling. The AUCs were non-significant for both HBP and ET-1 (Fig. 4C and D).\u003c/p\u003e\n\u003cp\u003ePatients requiring IMV were significantly older. Twenty percent of these patients received CRRT compared to none in non-IMV group. Similarly, they had significantly higher CRP levels with a median of 207 mg/L (IQR 136-284) compared to 133 mg/L (IQR 99-235) in the group that did not receive IMV. Procalcitonin and IL-6 at admission were also significantly higher, whereas other laboratory parameters were similar (Table 2). The majority (74 %) were empirically treated with antibiotics during the first seven ICU days; however, no data were available on the actual rate of secondary bacterial pneumonia.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this study, we measured plasma levels of HBP and ET-1 at ICU admission in critically ill COVID-19 patients. The HBP levels were markedly elevated, more than tenfold higher compared to a group of post-trauma ICU patients. There was no significant difference in plasma levels of HBP or ET-1 between 60-day survivors and non-survivors.\u003c/p\u003e \u003cp\u003eHeparin-binding protein levels were not associated with the need for IMV treatment whereas plasma ET-1 levels were higher in patients requiring IMV. However, after adjusting for sex, age and BMI, no significant association was observed between plasma ET-1 levels and need for IMV.\u003c/p\u003e \u003cp\u003eThere are a some previous studies in which HBP levels above 30 ng/ml in COVID-19 patients distinguished those who developed organ failure or severe respiratory failure requiring IMV from those with a more favourable disease course (\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e). Other studies have found increased mortality using a HBP cutoff at 13.5 or 35 ng/ml (\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e). In these studies, the patients were included already at hospital admission, a much earlier stage of the disease. Our study cohort had considerably higher HBP levels, with a median level of 150 ng/ml (IQR 47\u0026ndash;299) at inclusion. A possible explanation is that all patients in our study had already developed signs of severe organ failure ten days after onset of a symptomatic virus infection. Furthermore, our patients exhibited remarkably high inflammatory markers. It appears that the discriminative properties of HBP are lost at these high levels.\u003c/p\u003e \u003cp\u003eInterpreting HBP levels across studies should be approached with caution, as the timing of HBP sampling in relation to disease severity and progression may vary significantly. To our knowledge, no published data are available on HBP levels from the severe acute respiratory syndrome (SARS) outbreak in 2002\u0026ndash;2004, a disease caused by SARS-CoV-1. However, in a study from Finland, IMV-treated patients with viral pneumonia caused by H1N1 (swine flu) had a median HBP level of 152 ng/ml at ICU admission, which aligns with the levels observed in our cohort (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Although the authors reported higher HBP levels in IMV-treated patients than in non-IMV-treated patients, they found no association between admission HBP levels and the development of ARDS or severe sepsis/septic shock. These findings, together with those of the current study, suggest that in certain critical forms of viral infections, HBP levels may be markedly elevated, but their discriminatory capacity is diminished.\u003c/p\u003e \u003cp\u003eAccording to the manufacturer of the HBP-Axis-Shield ELISA, sampling should be done in test tubes using citrate as an anticoagulant. To ensure that the high levels of HBP were not caused by the PPT/EDTA sampling tubes, we aimed to compare HBP measurements between PPT/EDTA and citrate tubes. As the number of COVID-19 patients decreased by the time the HBP measurements were available, we could not include COVID-19 patients for this comparison. Therefore, we included ten post-trauma ICU patients with presumably elevated levels of HBP for these measurements. Although, these patients had lower HBP levels (13.3 ng/ml; IQR 8.8\u0026ndash;62.1), we found a strong correlation between HBP levels analysed from different tubes.\u003c/p\u003e \u003cp\u003eAs the name implies, heparins bind to HBP, and our group, along with others, has previously shown that heparins, including LMWH, can elevate the plasma HBP levels (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e). Therefore, it is possible that LMWH contributed to the high levels found in our study, as the majority of patients received dalteparin before blood sampling. Considering that several hours had passed between LMWH administration in most patients, the effects of LMWH on plasma HBP concentration might have diminished (\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e). Unfortunately, anti-factor Xa levels were not routinely measured.\u003c/p\u003e \u003cp\u003eThere are a few studies reporting repeated measures of HBP during COVID-19 disease. The studies show varying levels depending on when the sample is taken during the course of the disease, but generally, decreasing levels are observed once clinical stability is reached (\u003cspan additionalcitationids=\"CR25\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). It was not possible to measure HBP levels repeatedly in our study.\u003c/p\u003e \u003cp\u003eIn a recently published study HBP levels were repeatedly measured during ICU stay in critical COVID-19 patients. Notably, all patients were treated with therapeutic doses of LMWH or heparin infusion, and the overall mean HBP level was 202 ng/ml (\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e). Some patients had extremely high values, similar to those observed in our cohort. Moreover, HBP levels were strongly associated with disease severity and remained elevated throughout the ICU stay. Interestingly, patients receiving heparin had higher plasma HBP compared to those treated with LMWH. However, the effects and timing of heparin administration in relation to blood sampling was not considered (\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe pathophysiology of respiratory dysfunction in ARDS and especially when caused by SARS-CoV-2 infection is not fully understood. Endothelial and epithelial dysfunction, along with systemic inflammation and microvascular hyperpermeability, are key features of ARDS, regardless of the underlying cause (\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e). It is highly probable that HBP is involved in this process, as both \u003cem\u003ein vitro\u003c/em\u003e and \u003cem\u003ein vivo\u003c/em\u003e studies have demonstrated its ability to open the endothelial lining (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eEndothelin-1 contributes to the pathophysiology of pulmonary artery hypertension, commonly seen in ARDS, and is associated with proliferative, fibrotic, and thrombogenic vascular remodelling (\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e). We found slightly elevated levels of ET-1 in our patients compared to the normal levels reported in healthy subjects (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e) and those provided from the manufacturer of our ELISA. Patients receiving IMV had higher levels compared to patients not receiving this treatment. As the majority of the patients required IMV treatment shortly after ICU admission, we speculate that this group may have been more hypoxic at the time of blood sampling given that hypoxia is known to increase ET-1 secretion (\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e). In addition, the clearance of ET-1 could be disrupted in ARDS caused by COVID-19. Animal and human studies have established the pulmonary vascular endothelium as a major site for ET-1 removal through the endothelial ET\u003csub\u003eB\u003c/sub\u003e subtype receptors (\u003cspan additionalcitationids=\"CR60 CR61 CR62\" citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e). Therefore, the elevated levels of ET-1 could be caused by increased production, reduced removal or a combination of both. Patients requiring IMV were also significantly older, which could have impacted the ET-1 levels (\u003cspan additionalcitationids=\"CR65\" citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e). There are a few studies confirming high levels of ET-1 in COVID-19, with increasing levels in severely ill compared to patients with milder disease (\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). In addition, the levels seem to remain elevated even three months after the infection (\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn a previous study on porcine endotoxemia, we observed an association between HBP and ET-1, where systemic ET-receptor antagonism markedly reduced plasma HBP levels, while ET-1 administration in control animals dose-dependently increased plasma HBP levels (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e). However, in the present study on a severe viral disease, we found no correlation between plasma HBP and ET-1. Endothelial dysfunction is a complex phenomenon, and other mechanism may also be involved.\u003c/p\u003e \u003cp\u003eThis study has several limitations. It is a single-centre study with a limited cohort of COVID-19 patients. Moreover, as we could only obtain samples at admission, it was not possible to assess temporal changes in HBP in relation to outcome measures. The study lacks HBP and ET-1 samples from healthy controls and includes only a small group of post-trauma ICU patients. Nevertheless, we believe that that the HBP levels observed in our cohort are among the highest reported in the literature and significantly exceed those described in other severe conditions, such as sepsis (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e), cardiac arrest (\u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e), cardiac surgery (\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e), or trauma (\u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e68\u003c/span\u003e). Patients were included at a time when COVID-19 was a novel disease, and clinical experience regarding treatment strategies, such as timing of IMV initiation, was limited. Similarly, uncertainties regarding the timing and dosing of steroids, immunotherapy, and anticoagulative treatments may have influenced outcomes. As this study was conducted during the first wave of the COVID-19 pandemic, it remains uncertain whether our findings are applicable to later variants of the virus or to disease presentation in vaccinated individuals.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eWe found markedly elevated plasma levels of HBP at ICU admission in patients with critical COVID-19. Among these patients, no association was found between plasma HBP and 60-day mortality or the need for IMV during the ICU stay. Plasma levels of ET-1 were modestly elevated upon ICU admission but were not associated with mortality or the need for IMV.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eAUC Area under the curve\u003c/p\u003e\n\u003cp\u003eARDS Acute respiratory distress syndrome\u003c/p\u003e\n\u003cp\u003eBMI Body mass index\u003c/p\u003e\n\u003cp\u003eCI Confidence interval\u003c/p\u003e\n\u003cp\u003eCRP C-reactive protein\u003c/p\u003e\n\u003cp\u003eCRRT Continuous renal replacement therapy\u003c/p\u003e\n\u003cp\u003eELISA Enzyme-linked immunosorbent assay\u003c/p\u003e\n\u003cp\u003eET-1 Endothelin-1\u003c/p\u003e\n\u003cp\u003eHBP Heparin-binding protein \u003c/p\u003e\n\u003cp\u003eICU Intensive care unit\u003c/p\u003e\n\u003cp\u003eIQR Interquartile range\u003c/p\u003e\n\u003cp\u003eIL Interleukin\u003c/p\u003e\n\u003cp\u003eIMV Invasive mechanical ventilation\u003c/p\u003e\n\u003cp\u003eLMWH Low molecular weight heparin\u003c/p\u003e\n\u003cp\u003eOR Odds ratio\u003c/p\u003e\n\u003cp\u003ePCT Procalcitonin\u003c/p\u003e\n\u003cp\u003ePPT Plasma preparation tubes\u003c/p\u003e\n\u003cp\u003ePMN Polymorphonuclear neutrophils\u003c/p\u003e\n\u003cp\u003eROC Receiver operating characteristic curve\u003c/p\u003e\n\u003cp\u003eSAPS Simplified acute physiology score\u003c/p\u003e\n\u003cp\u003eSARS Severe acute respiratory syndrome\u003c/p\u003e\n\u003cp\u003eWBC white blood cell count\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthical approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was designed in accordance with the Declaration of Helsinki and approved by the Swedish Ethical Review Authority (approval numbers 2020-01302, 2017/1324-31). Written consent was provided from the patient or a close relative when the patient was unable to provide consent. Presumed consent was used in COVID-19 patients who died before consent could be provided. \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Swedish Research Council, the Swedish Heart Lung Foundation, the Swedish Carnegie Hero Funds, Funds from Karolinska Institutet and Swedish Society of Medicine. Financial support was also provided through the regional agreement on medical and clinical research (ALF) between Stockholm County Council and Karolinska Institutet. None of the funding agents engaged in the study design, data collection, data analysis, and manuscript preparation or publication decisions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConcept and design HH, JE, JG, OR, JM, AO, EW; methodology HH, JE, JG, OR, JM, AO, EW; data curation HH, JG, JM; formal analysis HH, JE; investigation HH, JE, AO, EW; resources OR, AO, EW; drafting of the manuscript HH, EW; review and editing of the manuscript JE, JG, OR, JM, AO. \u0026nbsp;All authors reviewed and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank clinical research nurses Kristina Kilsand, Nicolas Tardif and Tove Jakobsson for assistance with recruitment of patients and collecting samples. We are especially thankful to research engineer Anette Ebberyd for measuring HBP end ET-1. We also thank all the staff at the Karolinska University Hospital for their cooperation.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHuang C, Wang Y, Li X, Ren L, Zhao J, Hu Y, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet. 2020;395(10223):497-506.\u003c/li\u003e\n\u003cli\u003eChen N, Zhou M, Dong X, Qu J, Gong F, Han Y, et al. Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. Lancet. 2020;395(10223):507-13.\u003c/li\u003e\n\u003cli\u003eWang D, Hu B, Hu C, Zhu F, Liu X, Zhang J, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. JAMA : the journal of the American Medical Association. 2020;323(11):1061-9.\u003c/li\u003e\n\u003cli\u003eChen T, Wu D, Chen H, Yan W, Yang D, Chen G, et al. Clinical characteristics of 113 deceased patients with coronavirus disease 2019: retrospective study. Bmj. 2020;368:m1091.\u003c/li\u003e\n\u003cli\u003eDel Valle DM, Kim-Schulze S, Huang HH, Beckmann ND, Nirenberg S, Wang B, et al. An inflammatory cytokine signature predicts COVID-19 severity and survival. Nat Med. 2020;26(10):1636-43.\u003c/li\u003e\n\u003cli\u003eZhu Z, Cai T, Fan L, Lou K, Hua X, Huang Z, et al. Clinical value of immune-inflammatory parameters to assess the severity of coronavirus disease 2019. International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases. 2020;95:332-9.\u003c/li\u003e\n\u003cli\u003eLeisman DE, Ronner L, Pinotti R, Taylor MD, Sinha P, Calfee CS, et al. Cytokine elevation in severe and critical COVID-19: a rapid systematic review, meta-analysis, and comparison with other inflammatory syndromes. Lancet Respir Med. 2020;8(12):1233-44.\u003c/li\u003e\n\u003cli\u003eQin C, Zhou L, Hu Z, Zhang S, Yang S, Tao Y, et al. Dysregulation of Immune Response in Patients With Coronavirus 2019 (COVID-19) in Wuhan, China. Clin Infect Dis. 2020;71(15):762-8.\u003c/li\u003e\n\u003cli\u003eDiao B, Wang C, Tan Y, Chen X, Liu Y, Ning L, et al. Reduction and Functional Exhaustion of T Cells in Patients With Coronavirus Disease 2019 (COVID-19). Frontiers in immunology. 2020;11:827.\u003c/li\u003e\n\u003cli\u003eChen G, Wu D, Guo W, Cao Y, Huang D, Wang H, et al. Clinical and immunological features of severe and moderate coronavirus disease 2019. J Clin Invest. 2020;130(5):2620-9.\u003c/li\u003e\n\u003cli\u003eBussani R, Schneider E, Zentilin L, Collesi C, Ali H, Braga L, et al. Persistence of viral RNA, pneumocyte syncytia and thrombosis are hallmarks of advanced COVID-19 pathology. EBioMedicine. 2020;61:103104.\u003c/li\u003e\n\u003cli\u003eJoffre J, Rodriguez L, Matthay ZA, Lloyd E, Fields AT, Bainton RJ, et al. COVID-19-associated Lung Microvascular Endotheliopathy: A \u0026quot;From the Bench\u0026quot; Perspective. Am J Respir Crit Care Med. 2022;206(8):961-72.\u003c/li\u003e\n\u003cli\u003eScavone M, Ghali C, Calogiuri M, Sala M, Bossi E, Mencarini T, et al. Impairment of platelet function in both mild and severe COVID-19 patients. British journal of haematology. 2023;203(4):656-67.\u003c/li\u003e\n\u003cli\u003eVarga Z, Flammer AJ, Steiger P, Haberecker M, Andermatt R, Zinkernagel AS, et al. Endothelial cell infection and endotheliitis in COVID-19. Lancet. 2020;395(10234):1417-8.\u003c/li\u003e\n\u003cli\u003ePons S, Fodil S, Azoulay E, Zafrani L. The vascular endothelium: the cornerstone of organ dysfunction in severe SARS-CoV-2 infection. Crit Care. 2020;24(1):353.\u003c/li\u003e\n\u003cli\u003eKruse JM, Zickler D, Ludemann WM, Piper SK, Gotthardt I, Ihlow J, et al. Evidence for a thromboembolic pathogenesis of lung cavitations in severely ill COVID-19 patients. Scientific reports. 2021;11(1):16039.\u003c/li\u003e\n\u003cli\u003eLeisman DE, Mehta A, Thompson BT, Charland NC, Gonye ALK, Gushterova I, et al. Alveolar, Endothelial, and Organ Injury Marker Dynamics in Severe COVID-19. Am J Respir Crit Care Med. 2022;205(5):507-19.\u003c/li\u003e\n\u003cli\u003eFisher J, Russell JA, Bentzer P, Parsons D, Secchia S, Morgelin M, et al. Heparin-Binding Protein (HBP): A Causative Marker and Potential Target for Heparin Treatment of Human Sepsis-Induced Acute Kidney Injury. Shock. 2017;48(3):313-20.\u003c/li\u003e\n\u003cli\u003eFisher J, Linder A. Heparin-binding protein: a key player in the pathophysiology of organ dysfunction in sepsis. Journal of internal medicine. 2017;281(6):562-74.\u003c/li\u003e\n\u003cli\u003eLinder A, Christensson B, Herwald H, Bjorck L, Akesson P. Heparin-binding protein: an early marker of circulatory failure in sepsis. Clin Infect Dis. 2009;49(7):1044-50.\u003c/li\u003e\n\u003cli\u003eLinder A, Arnold R, Boyd JH, Zindovic M, Zindovic I, Lange A, et al. Heparin-Binding Protein Measurement Improves the Prediction of Severe Infection With Organ Dysfunction in the Emergency Department. Crit Care Med. 2015;43(11):2378-86.\u003c/li\u003e\n\u003cli\u003eLinder A, Akesson P, Inghammar M, Treutiger CJ, Linner A, Sunden-Cullberg J. Elevated plasma levels of heparin-binding protein in intensive care unit patients with severe sepsis and septic shock. Crit Care. 2012;16(3):R90.\u003c/li\u003e\n\u003cli\u003eKaukonen KM, Linko R, Herwald H, Lindbom L, Ruokonen E, Ala-Kokko T, et al. Heparin-binding protein (HBP) in critically ill patients with influenza A(H1N1) infection. Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. 2013.\u003c/li\u003e\n\u003cli\u003eMellhammar L, Thelaus L, El\u0026eacute;n S, Fisher J, Linder A. Heparin binding protein in severe COVID-19-A prospective observational cohort study. PLoS One. 2021;16(4):e0249570.\u003c/li\u003e\n\u003cli\u003eSaridaki M, Metallidis S, Grigoropoulou S, Vrentzos E, Lada M, Argyraki K, et al. Integration of heparin-binding protein and interleukin-6 in the early prediction of respiratory failure and mortality in pneumonia by SARS-CoV-2 (COVID-19). Eur J Clin Microbiol Infect Dis. 2021;40(7):1405-12.\u003c/li\u003e\n\u003cli\u003eXue M, Zeng Y, Qu HQ, Zhang T, Li N, Huang H, et al. Heparin-binding protein levels correlate with aggravation and multiorgan damage in severe COVID-19. ERJ Open Res. 2021;7(1).\u003c/li\u003e\n\u003cli\u003eGautam N, Olofsson AM, Herwald H, Iversen LF, Lundgren-Akerlund E, Hedqvist P, et al. Heparin-binding protein (HBP/CAP37): a missing link in neutrophil-evoked alteration of vascular permeability. Nat Med. 2001;7(10):1123-7.\u003c/li\u003e\n\u003cli\u003eHerwald H, Cramer H, Morgelin M, Russell W, Sollenberg U, Norrby-Teglund A, et al. M protein, a classical bacterial virulence determinant, forms complexes with fibrinogen that induce vascular leakage. Cell. 2004;116(3):367-79.\u003c/li\u003e\n\u003cli\u003eBentzer P, Fisher J, Kong HJ, Morgelin M, Boyd JH, Walley KR, et al. Heparin-binding protein is important for vascular leak in sepsis. Intensive Care Med Exp. 2016;4(1):33.\u003c/li\u003e\n\u003cli\u003eAbraham GR, Kuc RE, Althage M, Greasley PJ, Ambery P, Maguire JJ, et al. Endothelin-1 is increased in the plasma of patients hospitalised with Covid-19. Journal of molecular and cellular cardiology. 2022;167:92-6.\u003c/li\u003e\n\u003cli\u003eFodor A, Tiperciuc B, Login C, Orasan OH, Lazar AL, Buchman C, et al. Endothelial Dysfunction, Inflammation, and Oxidative Stress in COVID-19-Mechanisms and Therapeutic Targets. Oxid Med Cell Longev. 2021;2021:8671713.\u003c/li\u003e\n\u003cli\u003eJanaszak-Jasiecka A, Siekierzycka A, Ploska A, Dobrucki IT, Kalinowski L. Endothelial Dysfunction Driven by Hypoxia-The Influence of Oxygen Deficiency on NO Bioavailability. Biomolecules. 2021;11(7).\u003c/li\u003e\n\u003cli\u003eYanagisawa M, Kurihara H, Kimura S, Tomobe Y, Kobayashi M, Mitsui Y, et al. A novel potent vasoconstrictor peptide produced by vascular endothelial cells. Nature. 1988;332(6163):411-5.\u003c/li\u003e\n\u003cli\u003eMiyamori I, Takeda Y, Yoneda T, Takeda R. Endothelin-1 release from mesenteric arteries of spontaneously hypertensive rats. J Cardiovasc Pharmacol. 1991;17 Suppl 7:S408-10.\u003c/li\u003e\n\u003cli\u003eSakai S, Miyauchi T, Kobayashi M, Yamaguchi I, Goto K, Sugishita Y. Inhibition of myocardial endothelin pathway improves long-term survival in heart failure. Nature. 1996;384(6607):353-5.\u003c/li\u003e\n\u003cli\u003eGiaid A, Yanagisawa M, Langleben D, Michel RP, Levy R, Shennib H, et al. Expression of endothelin-1 in the lungs of patients with pulmonary hypertension. The New England journal of medicine. 1993;328(24):1732-9.\u003c/li\u003e\n\u003cli\u003eCacoub P, Dorent R, Maistre G, Nataf P, Carayon A, Piette C, et al. Endothelin-1 in primary pulmonary hypertension and the Eisenmenger syndrome. The American journal of cardiology. 1993;71(5):448-50.\u003c/li\u003e\n\u003cli\u003eVoerman HJ, Stehouwer CD, van Kamp GJ, Strack van Schijndel RJ, Groeneveld AB, Thijs LG. Plasma endothelin levels are increased during septic shock. Crit Care Med. 1992;20(8):1097-101.\u003c/li\u003e\n\u003cli\u003eJin Q, Chen D, Zhang X, Zhang F, Zhong D, Lin D, et al. Medical Management of Pulmonary Arterial Hypertension: Current Approaches and Investigational Drugs. Pharmaceutics. 2023;15(6).\u003c/li\u003e\n\u003cli\u003eDruml W, Steltzer H, Waldhausl W, Lenz K, Hammerle A, Vierhapper H, et al. Endothelin-1 in adult respiratory distress syndrome. Am Rev Respir Dis. 1993;148(5):1169-73.\u003c/li\u003e\n\u003cli\u003eMitaka C, Hirata Y, Nagura T, Tsunoda Y, Amaha K. Circulating endothelin-1 concentrations in acute respiratory failure. Chest. 1993;104(2):476-80.\u003c/li\u003e\n\u003cli\u003eLangleben D, DeMarchie M, Laporta D, Spanier AH, Schlesinger RD, Stewart DJ. Endothelin-1 in acute lung injury and the adult respiratory distress syndrome. Am Rev Respir Dis. 1993;148(6 Pt 1):1646-50.\u003c/li\u003e\n\u003cli\u003eWillems LH, Nagy M, Ten Cate H, Spronk HMH, Groh LA, Leentjens J, et al. Sustained inflammation, coagulation activation and elevated endothelin-1 levels without macrovascular dysfunction at 3 months after COVID-19. Thromb Res. 2022;209:106-14.\u003c/li\u003e\n\u003cli\u003eHaffke M, Freitag H, Rudolf G, Seifert M, Doehner W, Scherbakov N, et al. Endothelial dysfunction and altered endothelial biomarkers in patients with post-COVID-19 syndrome and chronic fatigue syndrome (ME/CFS). J Transl Med. 2022;20(1):138.\u003c/li\u003e\n\u003cli\u003eBermejo-Martin JF, Garcia-Mateo N, Motos A, Resino S, Tamayo L, Ryan Murua P, et al. Effect of viral storm in patients admitted to intensive care units with severe COVID-19 in Spain: a multicentre, prospective, cohort study. Lancet Microbe. 2023;4(6):e431-e41.\u003c/li\u003e\n\u003cli\u003eShahbazi S, Vahdat Shariatpanahi Z, Shahbazi E. Bosentan for high-risk outpatients with COVID-19 infection: a randomized, double blind, placebo-controlled trial. EClinicalMedicine. 2023;62:102117.\u003c/li\u003e\n\u003cli\u003eNabeh OA, Matter LM, Khattab MA, Esraa M. \u0026quot;The possible implication of endothelin in the pathology of COVID-19-induced pulmonary hypertension\u0026quot;. Pulmonary pharmacology \u0026amp; therapeutics. 2021;71:102082.\u003c/li\u003e\n\u003cli\u003ePersson BP, Halldorsdottir H, Lindbom L, Rossi P, Herwald H, Weitzberg E, et al. Heparin-binding protein (HBP/CAP37) - a link to endothelin-1 in endotoxemia-induced pulmonary oedema? Acta anaesthesiologica Scandinavica. 2014;58(5):549-59.\u003c/li\u003e\n\u003cli\u003eAcar T, Ertekin B, Yortanli M, Kocak S. Prognostic value of heparin-binding protein for mortality in severe COVID-19 pneumonia. Biomarkers in medicine. 2022;16(13):981-91.\u003c/li\u003e\n\u003cli\u003eKyriazopoulou E, Dalekos GN, Metallidis S, Poulakou G, Papanikolaou IC, Tzavara V, et al. Heparin-Binding Protein Levels Predict Unfavorable Outcome in Covid-19 Pneumonia: A Post Hoc Analysis of the Save Trial. Shock. 2024;61(3):395-9.\u003c/li\u003e\n\u003cli\u003eSterner N, Fisher J, Thelaus L, Ketteler C, Lemez S, Dardashti A, et al. The Dynamics of Heparin-Binding Protein in Cardiothoracic Surgery-A Pilot Study. Journal of cardiothoracic and vascular anesthesia. 2021.\u003c/li\u003e\n\u003cli\u003eHalldorsdottir H, Lindbom L, Ebberyd A, Oldner A, Weitzberg E. The effect of heparins on plasma concentration of heparin-binding protein: a pilot study. BJA Open. 2024;9:100256.\u003c/li\u003e\n\u003cli\u003eNeb H, Talbot SR, Ruskowski K, Brkic D, Sonntagbauer M, Adam EH, et al. High Heparanase Level in Survivors of Covid-19 - Indicator of Vascular and Pulmonary Recovery? Shock. 2022;58(6):514-23.\u003c/li\u003e\n\u003cli\u003eThompson BT, Chambers RC, Liu KD. Acute Respiratory Distress Syndrome. The New England journal of medicine. 2017;377(6):562-72.\u003c/li\u003e\n\u003cli\u003eLin Q, Shen J, Shen L, Zhang Z, Fu F. Increased plasma levels of heparin-binding protein in patients with acute respiratory distress syndrome. Crit Care. 2013;17(4):R155.\u003c/li\u003e\n\u003cli\u003eBanecki K, Dora KA. Endothelin-1 in Health and Disease. International journal of molecular sciences. 2023;24(14).\u003c/li\u003e\n\u003cli\u003eCargill RI, Kiely DG, Clark RA, Lipworth BJ. Hypoxaemia and release of endothelin-1. Thorax. 1995;50(12):1308-10.\u003c/li\u003e\n\u003cli\u003eFerri C, Bellini C, De Angelis C, De Siati L, Perrone A, Properzi G, et al. Circulating endothelin-1 concentrations in patients with chronic hypoxia. J Clin Pathol. 1995;48(6):519-24.\u003c/li\u003e\n\u003cli\u003eFukuroda T, Fujikawa T, Ozaki S, Ishikawa K, Yano M, Nishikibe M. Clearance of circulating endothelin-1 by ETB receptors in rats. Biochem Biophys Res Commun. 1994;199(3):1461-5.\u003c/li\u003e\n\u003cli\u003eDupuis J, Goresky CA, Fournier A. Pulmonary clearance of circulating endothelin-1 in dogs in vivo: exclusive role of ETB receptors. Journal of applied physiology. 1996;81(4):1510-5.\u003c/li\u003e\n\u003cli\u003eWagner OF, Vierhapper H, Gasic S, Nowotny P, Waldhausl W. Regional effects and clearance of endothelin-1 across pulmonary and splanchnic circulation. European journal of clinical investigation. 1992;22(4):277-82.\u003c/li\u003e\n\u003cli\u003eWeitzberg E, Ahlborg G, Lundberg JM. Differences in vascular effects and removal of endothelin-1 in human lung, brain, and skeletal muscle. Clin Physiol. 1993;13(6):653-62.\u003c/li\u003e\n\u003cli\u003eDupuis J, Cernacek P, Tardif JC, Stewart DJ, Gosselin G, Dyrda I, et al. Reduced pulmonary clearance of endothelin-1 in pulmonary hypertension. American heart journal. 1998;135(4):614-20.\u003c/li\u003e\n\u003cli\u003eWhite M, Courtemanche M, Stewart DJ, Talajic M, Mikes E, Cernacek P, et al. Age- and gender-related changes in endothelin and catecholamine release, and in autonomic balance in response to head-up tilt. Clinical science. 1997;93(4):309-16.\u003c/li\u003e\n\u003cli\u003eSayama H, Nakamura Y, Saito N, Konoshita M. Does the plasma endothelin-1 concentration reflect atherosclerosis in the elderly? Gerontology. 1999;45(6):312-6.\u003c/li\u003e\n\u003cli\u003eVassiliou AG, Roumpaki A, Keskinidou C, Athanasiou N, Tsipilis S, Jahaj E, et al. Transpulmonary Plasma Endothelin-1 Arterial:Venous Ratio Differentiates Survivors from Non-Survivors in Critically Ill Patients with COVID-19-Induced Acute Respiratory Distress Syndrome. International journal of molecular sciences. 2024;25(19).\u003c/li\u003e\n\u003cli\u003eRistagno G, Masson S, Tiainen M, Bendel S, Bernasconi R, Varpula T, et al. Elevated plasma heparin-binding protein is associated with early death after resuscitation from cardiac arrest. Crit Care. 2016;20(1):251.\u003c/li\u003e\n\u003cli\u003eHalldorsdottir HD, Eriksson J, Persson BP, Herwald H, Lindbom L, Weitzberg E, et al. Heparin-binding protein as a biomarker of post-injury sepsis in trauma patients. Acta anaesthesiologica Scandinavica. 2018.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1. Patient characteristics and outcomes for 60-day survivors and non-survivors.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePatient characteristics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAll\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=96)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDead\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=17)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSurviving\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=79)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eAge,years\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e61 (53-66)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e65 (57-68)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e60 (53-66)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e73 (76)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e17 (100)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e56 (71)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eBMI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e28 (25-31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e26 (24-32)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e28 (26-31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eComorbidity\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;No previous medical history\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Cardiovascular disease\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Lung disease\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Diabetes I or II\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Chronic kidney disease\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Chronic GI/liver disease\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Immunocompromised\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Any malignancy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e23 (24)\u003c/p\u003e\n \u003cp\u003e54 (56)\u003c/p\u003e\n \u003cp\u003e20 (21)\u003c/p\u003e\n \u003cp\u003e31(32)\u003c/p\u003e\n \u003cp\u003e7 (7)\u003c/p\u003e\n \u003cp\u003e7(7)\u003c/p\u003e\n \u003cp\u003e9 (9)\u003c/p\u003e\n \u003cp\u003e11 (11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e2 (12)\u003c/p\u003e\n \u003cp\u003e9 (53)\u003c/p\u003e\n \u003cp\u003e4 (24)\u003c/p\u003e\n \u003cp\u003e5 (29)\u003c/p\u003e\n \u003cp\u003e2 (12)\u003c/p\u003e\n \u003cp\u003e1 (6)\u003c/p\u003e\n \u003cp\u003e3 (24)\u003c/p\u003e\n \u003cp\u003e4 (24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e21 (27)\u003c/p\u003e\n \u003cp\u003e45 (57)\u003c/p\u003e\n \u003cp\u003e16 (20)\u003c/p\u003e\n \u003cp\u003e26 (33)\u003c/p\u003e\n \u003cp\u003e5 (6)\u003c/p\u003e\n \u003cp\u003e6 (8)\u003c/p\u003e\n \u003cp\u003e6 (9)\u003c/p\u003e\n \u003cp\u003e7 (9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from symptom to hospital admission, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e8 (6-11)\u0026nbsp;n=94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e6 (4-12) n=16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e8 (6-11)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from symptom to ICU admission, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e10 (8-14)\u0026nbsp;n=94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e10 (6\u0026ndash;13)\u0026nbsp;n=16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e10 (8-14)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from symptom to death, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e33 (23-45)\u0026nbsp;n=16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from hospital admission to death, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e22 (18-38)\u0026nbsp;n=17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eSAPS III score\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e51 (47-57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e51 (49-62)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e49 (46-56)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eHospital duration, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e21 (16-38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e22 (19-38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e21 (15-39)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eICU duration, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e12 (5-21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e22 (17-36)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e9 (5-16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;****\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eCRRT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e12 (13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e6 (35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e6 (8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIMV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e61 (64)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e16 (94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e45 (57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIMV days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e9 (0-18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e17 (14-35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e6 (0-14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e****\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eProne position\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e69 (72)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e16 (94)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e53 (67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eSteroids first 7 days at ICU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e53 (55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e14 (82)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e39 (49)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eSteroids before HBP test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e24 (25)\u0026nbsp;n=93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e5 (29)\u0026nbsp;n=15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e19 (24)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eRemdesivir\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e4 (4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e2 (12)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e2 (3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eMonoclonal antibody\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e21 (22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e4 (24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e17 (22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eLMWH dose before HBP test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e5000 (5000-7500)\u0026nbsp;n=91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e5000 (5000-7500)\u0026nbsp;n=15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e5000 (5000-7500)\u0026nbsp;n=76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eHBP ng/ml\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e150 (47-299)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e193 (34-545)\u0026nbsp;n=15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e141 (50-292)\u0026nbsp;n=63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eET-1 pg/ml\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1.6 (1.2-1.9) n=92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e1.7 (1.4-1.9) n=16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1.6 (1.1-1.9) n=76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eWBC x10(9)/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e8.4 (6.4-10.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e9.1 (5.8-11.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e8.2 (6.5-10.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003ePCT\u0026nbsp;\u0026micro;g/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e0.6 (0.2\u0026ndash;1.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e0.9 (0.5-1.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e0.5 (0.2-1.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eCRP mg/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e176 (123-257)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e207 (126-261)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e169 (114-255)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eHBP/WBC ratio\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e16.2 (6.7-41.0)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e24.2 (6.3-67.3)\u0026nbsp;n=15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e14.6 (6.8-39.0)\u0026nbsp;n=63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eD-Dimer mg/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1.2 (0.7-2.6)\u0026nbsp;n=74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e1.3 (0.8-3.8)\u0026nbsp;n=13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1.2 (0.7-2.6)\u0026nbsp;n=61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eThrombocytes x10(9)/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e265 (202-312)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e240 (217-297)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e270 (199-330)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIL-6 ng/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e132 (62-324)\u0026nbsp;n=46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e215 (129-393)\u0026nbsp;n=9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e110 (52-308)\u0026nbsp;n=37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eFerritin\u0026nbsp;\u0026micro;g/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1419 (699-2153)\u0026nbsp;n=51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e1738 (1272-2052)\u0026nbsp;n=10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1251 (607-2183)\u0026nbsp;n=41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eData displayed as median (interquartile range) for continuous variables and number (%) for categorical variables. BMI, body mass index; GI, gastrointestinal; ICU, intensive care unit; SAPS, simplified acute physiology score; CRRT, continuous renal replacement therapy; IMV, invasive mechanical ventilator; HBP, heparin-binding protein; LMWH, low molecular weight heparin (value in units); ET-1, endothelin-1; WBC, white blood cell; PCT, procalcitonin; CRP, C-reactive protein; IL-6, interleukin-6. Monoclonal antibody refers to IL-1 or IL-6 blockers. Groups compared with Mann-Whitney two tailed test for continuous data and Fisher exact test for categorical data. * Denotes p\u0026lt;0.05, ** p\u0026lt;0.01, **** denotes p\u0026lt;0.0001.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 2. Patient characteristics and outcome of patients treated with or without invasive mechanical ventilation.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePatient characteristics\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAll\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=96)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIMV\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;YES (n=61)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eIMV\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eNO (n=35)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eAge\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e61 (53-66)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e62 (57-67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e57 (50-65)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e73 (76)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e45 (73)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e28 (80)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eBMI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e28 (25-31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e28 (25-31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e28 (25-31)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eComorbidity\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;No previous medical history\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Cardiovascular disease\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Lung disease\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Diabetes I or II\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Chronic kidney disease\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Chronic GI/liver disease\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Immunocompromised\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp;Any malignancy\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e23 (24)\u003c/p\u003e\n \u003cp\u003e54 (56)\u003c/p\u003e\n \u003cp\u003e20 (21)\u003c/p\u003e\n \u003cp\u003e31(32)\u003c/p\u003e\n \u003cp\u003e7 (7)\u003c/p\u003e\n \u003cp\u003e7(7)\u003c/p\u003e\n \u003cp\u003e9 (9)\u003c/p\u003e\n \u003cp\u003e11 (11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e14 (23)\u003c/p\u003e\n \u003cp\u003e34 (56)\u003c/p\u003e\n \u003cp\u003e13 (21)\u003c/p\u003e\n \u003cp\u003e18 (30)\u003c/p\u003e\n \u003cp\u003e6 (10)\u003c/p\u003e\n \u003cp\u003e7 (11)\u003c/p\u003e\n \u003cp\u003e7 (12)\u003c/p\u003e\n \u003cp\u003e9 (15)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e9 (26)\u003c/p\u003e\n \u003cp\u003e20 (57)\u003c/p\u003e\n \u003cp\u003e7 (20)\u003c/p\u003e\n \u003cp\u003e13 (37)\u003c/p\u003e\n \u003cp\u003e1 (3)\u003c/p\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003cp\u003e2 (6)\u003c/p\u003e\n \u003cp\u003e2 (6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from symptom to hospital admission, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e8 (6-11)\u0026nbsp;n=94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e8 (5-11)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e10 (7-12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from symptom to ICU admission, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e10 (8-14)\u0026nbsp;n=94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e10 (7-13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e11 (9-14)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eDead\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e17 (18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e16 (26)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1 (3)\u0026dagger;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from symptom to death, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e35 (24-45)\u0026nbsp;n=15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eTime from hospital admission to death, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e25 (18-38)\u0026nbsp;n=16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eSAPS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e51 (47-57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e53 (49-60)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e47 (44-50)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e****\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eHospital duration, days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e21 (16-38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e30 (21-49)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e14 (10-17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e****\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eICU duration days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e12 (5-21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e17 (12-27)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e4 (2-6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e****\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eCRRT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e12 (13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e12 (20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIMV days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e15 (9-27)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIMV on ICU admission day\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e31 (51)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIMV during the first 3 ICU days\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e58 (95)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eProne position\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e69 (72)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e42 (69)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e27 (77)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eSteroids first 7 days at ICU\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e53 (55)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e32 (52)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e14 (40)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eSteroids before HBP test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e24 (25)\u0026nbsp;n=93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e12(20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e12 (34)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eRemdesivir\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e4 (4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e4 (7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eMonoclonal antibody\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e21 (22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e14 (23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e7 (20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eLMWH dose before HBP test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e5000 (5000-7500)\u0026nbsp;n=91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e5000 (5000-7500)\u0026nbsp;n=56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e5000 (5000-7500)\u0026nbsp;n=35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eHBP ng/ml\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e150 (47-299)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e150 (40-430)\u0026nbsp;n=48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e160 (59-284)\u0026nbsp;n=30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e\u0026nbsp;ns\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eET-1 pg/ml\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e1.6 (1.2-1.9)\u0026nbsp;n=92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e1.7 (1.3-2.0)\u0026nbsp;n=57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1.4 (1.0-1.7)\u0026nbsp;n=35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eWBC x10(9)/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e8.4 (6.4-10.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e8.2 (6.1-11.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e8.5 (6.7-10.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003ePCT\u0026nbsp;\u0026micro;g/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e0.6 (0.2\u0026ndash;1.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e0.9 (0.4-1.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e0.3 (0.1-0.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e****\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eCRP mg/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e176 (123-257)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e207 (136-284)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e133 (99-235)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e**\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eHBP/WBC ratio\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e16.2 (6.7-41.0)\u0026nbsp;n=78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e18.0 (5.6-49.0)\u0026nbsp;n=48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e15.0 (7.3-35.3)\u0026nbsp;n=30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eD-Dimer mg/L\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e1.2 (0.7-2.6)\u0026nbsp;n=74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e1.3 (0.8-2.8)\u0026nbsp;n=45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1.1 (0.6-1.8)\u0026nbsp;n=29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eThrombocytes x10(9)/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e265 (202-312)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e\u0026nbsp;262 (203-305)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e277 (200-363)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eIL-6 ng/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e132 (62.3-324.0)\u0026nbsp;n=46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e211 (80-454.8)\u0026nbsp;n=30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e74 (31.3-221.8)\u0026nbsp;n=16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003e*\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 215px;\"\u003e\n \u003cp\u003eFerritin\u0026nbsp;\u0026micro;g/L\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 154px;\"\u003e\n \u003cp\u003e1419 (699-2153)\u0026nbsp;n=51\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 174px;\"\u003e\n \u003cp\u003e1419 (824-2209)\u0026nbsp;n=33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 153px;\"\u003e\n \u003cp\u003e1285 (537-2168)\u0026nbsp;n=18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 51px;\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eData displayed as median (interquartile range) for continuous variables and number (%) for categorical variables. BMI, body mass index; GI, gastrointestinal; ICU, intensive care unit; SAPS, simplified acute physiology score; CRRT, continuous renal replacement therapy; IMV, invasive mechanical ventilator; HBP, heparin-binding protein; LMWH, low molecular weight heparin (value in units); ET-1, endothelin-1; WBC, white blood cell; PCT, procalcitonin; CRP, C-reactive protein; IL-6, interleukin-6. Monoclonal antibody refers to IL-1 or IL-6 blockers. Groups compared with Mann-Whitney two tailed test for continuous data and Fisher exact test for categorical data. *Denotes p\u0026lt;0.05, ** p\u0026lt;0.01, **** denotes p\u0026lt;0.0001. \u0026dagger; One patient died with restrictions of medical treatments, including mechanical ventilation.\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Heparin-binding protein, endothelin-1, COVID-19, invasive mechanical ventilation, intensive care unit, mortality","lastPublishedDoi":"10.21203/rs.3.rs-9173002/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9173002/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eHeparin-binding protein (HBP) is an inflammatory protein released by activated polymorphonuclear white cells. It has been suggested as a predictor of sepsis progression and organ dysfunction and plays a role in the pathophysiology of endothelial dysfunction. Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor with pro-inflammatory effects, and high levels are found in patients with sepsis and acute respiratory distress syndrome. We investigated HBP and ET-1 plasma levels in critical COVID-19 disease with the aim of evaluating whether they were associated with 60-day mortality or the need for invasive mechanical ventilation (IMV). These levels were compared with those of a cohort of post-trauma intensive care unit (ICU) patients.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe included 96 patients with critical COVID-19 disease in 2020 and ten post-trauma ICU patients. Blood samples were collected at ICU admission, and plasma levels of HBP and ET-1 were measured. Clinical and laboratory data were collected until ICU discharge or death.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eIn COVID-19 patients, plasma levels of HBP were markedly increased, with a median level of 150 ng/ml (IQR 47\u0026ndash;299), compared to 13.3 ng/ml (IQR 8.8\u0026ndash;62.1), p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001 in the trauma ICU patients. There was no association between HBP levels and 60-day mortality or need for IMV. The levels of ET-1 were 1.6 pg/ml (IQR 1.2\u0026ndash;1.9) in the COVID-19 cohort and 2.0 pg/ml (IQR 1.2\u0026ndash;2.8), p\u0026thinsp;=\u0026thinsp;0.25 in the trauma ICU cohort. COVID-19 patients requiring IMV hade higher ET-1 levels than those who did not require such treatment; however, no association was found in a logistic regression model when adjusted for age, sex and body mass index. There was no correlation between plasma HBP and ET-1 levels. Inflammatory parameters such as C-reactive protein, procalcitonin, ferritin, and interleukin-6, were elevated but did not distinguish survivors from non-survivors.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eWhile HBP levels are markedly elevated in critical COVID-19, they do not predict outcomes at ICU admission. ET-1 levels were also not linked to mortality or the need for IMV.\u003c/p\u003e","manuscriptTitle":"Heparin-binding protein and Endothelin-1 in critical COVID-19","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-21 14:54:41","doi":"10.21203/rs.3.rs-9173002/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-27T18:35:48+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-14T12:59:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"204848459514236376340581756501092653896","date":"2026-04-13T13:44:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"87277426210580866339396511590393019545","date":"2026-04-13T08:01:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"260180619149948981938874070251809034334","date":"2026-04-11T17:44:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-10T21:27:26+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"119846686281595395930278332755699751551","date":"2026-04-10T18:48:43+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-10T15:44:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"55455507049407743145070875308707851613","date":"2026-04-10T13:06:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-10T12:20:39+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-27T22:00:54+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-27T21:54:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-25T18:20:53+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Anesthesiology","date":"2026-03-25T16:53:06+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-anesthesiology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bane","sideBox":"Learn more about [BMC Anesthesiology](http://bmcanesthesiol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/bane","title":"BMC Anesthesiology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3db906c9-241b-4c51-b8f5-9d412fb7cec4","owner":[],"postedDate":"April 21st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-07T20:53:44+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-21 14:54:41","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9173002","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9173002","identity":"rs-9173002","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}