Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK Helicopter Emergency Medical Service – a retrospective observational review of practice

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Non-invasive blood pressure measurement is susceptible to vibration and motion artefact, especially at extremes of hypotension and hypertension. Invasive arterial blood pressure (IABP) monitoring is a potential solution to these limitations. The aim of this study was to describe the largest series to date of patients in whom IABP monitoring was successfully initiated prehospital. Methods This retrospective observational study was conducted at East Anglian Air Ambulance, a UK helicopter emergency medical service (HEMS) which provides prehospital critical care in the East of England. It included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 and 20th April 2023. The following data were retrieved for all patients: sex; age; aetiology (medical cardiac arrest, other medical emergency, trauma); site of arterial cannulation; operator role (doctor/paramedic); the time of insertion and, where applicable, time of pre-hospital emergency anaesthesia, and return of spontaneous circulation following cardiac arrest. Characteristics of the sample were described as number (percentage) for categorical variables and mean (± standard deviation (SD)) or median (interquartile range = IQR) for continuous variables as appropriate. Results During the study period 13,556 patients were attended; IABP monitoring was initiated in 1083 (8.0%) cases (70.8% male; median age 59 years). 546 cases (50.4%) were of medical cardiac arrest: in 22.4% of these IABP monitoring was initiated during cardiopulmonary resuscitation. 322 (29.7%) were trauma cases, and the remaining 215 (19.9%) were medical emergencies. The patients were critically unwell: 981 (90.6%) required intubation, of which 789 (72.6%) underwent prehospital emergency anaesthesia; 609 (56.2%) received vasoactive medication. In 424 (39.2%) cases IABP monitoring was instituted en route to hospital. Conclusions This study describes over 1000 cases of prehospital arterial catheterisation and invasive blood pressure monitoring in a UK HEMS system and has demonstrated feasibility at scale with no clear signal of catheter-associated complications. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting. Vascular Access Blood Pressure Prehospital Intra-arterial blood pressure Air Ambulance Helicopter Emergency Medical Services Figures Figure 1 Figure 2 INTRODUCTION Accurate haemodynamic monitoring of critically unwell and injured patients is essential to identify adverse physiology and allow titration of interventions such as volume replacement, inotropes, and vasopressors. The standard for blood pressure monitoring in the prehospital setting is non-invasive blood pressure (NIBP) measurement, which is susceptible to vibration and motion artefact, compromising its accuracy ( 1 ). These inaccuracies are most prevalent in hypotensive and hypertensive patients – pathophysiological states frequently observed in Helicopter Emergency Medical Service (HEMS) patients ( 1 , 2 ) Invasive arterial blood pressure (IABP) monitoring is the standard of care for in-hospital critical care and presents a potential solution to the limitations observed with NIBP in the prehospital setting, where comparable levels of monitoring accuracy should ideally be obtained ( 3 ). It is currently unclear if prehospital IABP monitoring is feasible at scale, but the combination of higher-fidelity data and the ability to continue this level of monitoring into the early in-hospital phase of care may present the optimal solution ( 1 , 4 ). Previous work describes prehospital arterial catheterisation for IABP monitoring in small cohorts of patients, predominantly at physician discretion ( 4 , 5 , 6 ). In a recent survey of UK HEMS, 78% of respondents stated that IABP monitoring offers benefits to patient management ( 7 ). However, there are no descriptions of large numbers of prehospital IABP interventions, and none from the UK. East Anglian Air Ambulance (EAAA) HEMS is one of the largest providers of prehospital critical care in the UK and has been performing arterial catheterisation and IABP monitoring for the past ten years. The aim of this study was to describe a large series of patients in whom prehospital IABP monitoring was successfully established within a UK HEMS operation. METHODS Setting EAAA provides prehospital critical care in support of the statutory emergency medical service in the East of England (East of England Ambulance Service NHS Trust). EAAA operates from two bases (Cambridge and Norwich), deploying a prehospital critical care team comprised of a physician and critical care paramedic, in either an H145 helicopter or rapid response vehicle, depending on patient location, weather constraints, and time of day ( 8 ). Arterial catheterisation has been performed by EAAA clinicians since 2014. A 20G arterial cannula (BD Arterial Cannula with Flow Switch, Sandy, UT, USA) and an arterial pressure transducer (Edwards Truwave 3 cc, Edwards Lifesciences, Germany) are currently used for peripheral arterial cannulation. Additionally, femoral arterial cannulation using a 5Fr sheath introducer (MERIT Prelude, MERIT Medical, South Jordan, UT, USA) has been added to the list of standard procedures since June 2021. Ultrasound guidance is mandated for femoral catheterisation and is available for radial artery catheterisation at the discretion of the operating clinician (Butterfly iQ, Butterfly Net Inc, MA, US). As previously described ( 8 ) EAAA physicians are predominantly from an emergency medicine or anaesthesia background, with at least six years of post-graduate clinical experience, and competent in arterial catheterisation. Critical Care Paramedics (CCP) receive training in peripheral arterial catheterisation and point-of-care-ultrasound (POCUS), including vascular access, and then practice under physician supervision until achieving independent sign-off. Ultrasound-guided femoral arterial cannulation is formally trained as part of the local Specialist Percutaneous Emergency Aortic Resuscitation (SPEAR) programme utilising a Seldinger technique ( 9 , 10 ). Inclusion criteria This retrospective observational study included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 (initiation of the electronic medical record) and 20th April 2023 (last data available at data extraction). Patients without a single systolic IABP > 20mmHg were excluded. To ensure spurious and artefactual readings were not included in the analysis, cases which met any of the following criteria were manually reviewed: <10 minutes of data recorded; all IABP measurements were < 50mmHg; or all systolic IABP measurements were < 90mmHg (Table S1 ). EAAA undertakes a small volume of inter-hospital transfers – these cases were excluded as IABP monitoring is frequently initiated in-hospital prior to transfer. Data collection The following data were retrieved: sex; age in years; aetiology (medical cardiac arrest, other medical emergency, trauma); anatomical site of arterial cannulation; operator role (physician/CCP); mission result (conveyed by air, conveyed by road, or died at scene). The time of insertion and, where applicable, time of pre-hospital emergency anaesthesia (PHEA), and return of spontaneous circulation (ROSC) following cardiac arrest were also retrieved. To characterise interventions associated with IABP measurement, data were collected on the following: arterial blood gas analysis (CG8 + cartridge, iSTAT 1, Abbot Point of Care Inc, Abbot Park, IL, USA), intubation, PHEA, administration of blood products or intravenous crystalloid fluids, and vasoactive drugs (metaraminol, ephedrine, adrenaline). The EAAA clinical governance database (RLDatix, Richmond, UK) was cross-referenced to identify any serious untoward incidents associated with arterial catheterisation. IABP measurements were routinely downloaded from the prehospital monitor (ZOLL X Series Monitor/Defibrillator, ZOLL Medical Corporation of Asahi Kasei Corp., Tokyo) to the electronic medical record (HEMSbase, Medic One Systems Ltd, UK). Anonymised data were extracted from HEMSbase and stored in a secure data environment in Excel (Microsoft® Excel® for Microsoft 365, v2309), with data management and statistical analyses performed by a trained statistician using the R statistical programming language (R Core Team [2018]; R: A language and environment for statistical computing [R Foundation for Statistical Computing, Vienna, Austria]). Characteristics of the sample were described as number (percentage) for categorical variables and mean (± standard deviation (SD)) or median (interquartile range (IQR)) for continuous variables as appropriate. Ethical review This study met the UK Health Research Authority definition of service evaluation, and was registered with the EAAA Department of Research, Audit, Innovation, & Development (REF: EAAA 2023/01). The STROBE (Strengthening the Reporting of Observational studies in Epidemiology) reporting guideline was followed ( 11 ). RESULTS During the study period 13,556 patients were attended by EAAA. IABP monitoring was successfully initiated in 1083 (8.0%) of cases, which were included in the analysis; per protocol, Fig. 1. Figure 1 – Study flow diagram of patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring; 01/02/2015-20/04/2023. Figure 1 legend – EAAA = East Anglian Air Ambulance; IABP = intra-arterial blood pressure. *Cases were manually reviewed if there were less than 10 minutes of IABP measurements recorded, or all systolic IABP measurements were less than 90mmHg, or all mean arterial pressures on IABP were less than 50mmHg Cohort description The cases in the analysis comprised 70.8% male patients, with a median age of 59 years. IABP monitoring was predominantly initiated in medical cardiac arrest patients (50.4%). In 22.4% of cardiac arrest patients, IABP monitoring was established during cardiopulmonary resuscitation (CPR), with the remainder occurring after ROSC. N = 789 patients who underwent PHEA had IABP monitoring established (22.1% of all PHEA cases during the study period); in 166 (21.0%) IABP monitoring was initiated prior to induction of anaesthesia. The most prevalent anatomical site for catheterisation was the radial artery (n = 869, 80.2%), and n = 101 femoral catheterisations were performed, Table 1 . Table 1 Characteristics of patients with prehospital arterial line insertion and invasive arterial blood pressure monitoring (2014–2023), n = 1083 Male, n (%) 767 (70.8%) Female, n (%) 314 (29.0%) Unknown/other 2 Age in years, median [IQR] 59.0 [46.0–70.0] Patient aetiology Medical cardiac arrest, n (%) 546 (50.4%) Trauma, n (%) 322 (29.7%) Other Medical, n (%) 215 (19.9%) GCS score at primary survey 3/15, n (%) 592 (54.7%) 4–8/15, n (%) 285 (26.3%) 9–15/15, n (%) 171 (15.8%) Not recorded, n (%) 35 (3.2%) Anatomic site of arterial catheterisation Radial artery, n (%) 869 (80.2%) Femoral artery, n (%) 101 (9.3%) Brachial artery, n (%) 67 (6.2%) Other/undocumented, n (%) 46 (4.3%) Associated interventions ABG analysis, n (%) 591 (54.6%) Intubation, n (%) 981 (90.6%) Prehospital emergency anaesthesia, n (%) 789 (72.6%) Vasoactive drugs, n (%) 609 (56.2%) Fluid administration, n (%) 156 (14.4%) Blood products (since March 2018*), n (%) 47 (5.6%*) Table 1 : Characteristics of patients with prehospital arterial line insertion and invasive arterial blood pressure monitoring (2014–2023), n = 1083 Table 1 legend. GCS = Glasgow Coma Scale; ABG = arterial blood gas; *Blood products have been available routinely, outside of a trial context, since March 2018; during the study period 276 patients received a blood product transfusion. Professional group performing arterial catheterisation In n = 893 (82.5%) of cases the professional group performing arterial catheterisation was documented in the clinical notes; physicians performed the majority of cannulations (n = 704, 78.8%); CCPs performed the remainder (n = 189, 21.2%). Timing of invasive arterial blood pressure monitoring The median time interval from HEMS team arrival with patient to initiation of IABP monitoring was 27 (IQR: 15–42) minutes. IABP monitoring was often initiated during transport en route to hospital (n = 424, 39.2%): n = 196 (35.9%) in medical cardiac arrest patients; n = 151 (46.9%) in trauma patients, n = 77 (35.8%) in other medical patients (Table S2 ). Changes in arterial catheterisation over time We observed a substantial increase in the proportion of patients receiving IABP monitoring through the study period: from 3.1% in 2015, to 14.4% in 2022 – more than a four-fold increase. This increase was driven by the cohort of patients that received PHEA (72.6% of all cases) – there was also an increase in the proportion of patients with IABP monitoring initiated prior to induction of anaesthesia towards the end of the study period, representing more than 40% of PHEA patients from mid-2022 onwards (Fig. 2). Figure 2: The proportion of patients that received prehospital emergency anaesthesia who had initiation of invasive arterial blood pressure monitoring prior to induction of anaesthesia (2015–2023) Arterial catheterisation complications No immediate complications were reported during the study period. One patient developed acute limb ischemia requiring forearm fasciotomy and thrombectomy following prehospital catheterisation of the brachial artery. However, following independent in-hospital formal review it was unclear whether the ischemia was due to profound systemic hypotension or local arterial dissection secondary to catheterisation. DISCUSSION This study reports more than one thousand cases of arterial catheterisation and initiation of IABP monitoring in the prehospital phase of care for seriously unwell and injured patients. The most prevalent patient aetiology was medical cardiac arrest, and the majority of arterial lines were inserted peripherally in the radial artery. Almost all of the patients were intubated, and over half also benefited from arterial blood gas monitoring. In this system, one in five arterial lines were inserted by non-physicians, approximately 40% were inserted and transduced during transport, and there was only one reported potential arterial catheter-associated complication in ten years of practice. N = 3453 (25.5%) of all cases attended during the study period had a medical cardiac arrest aetiology, with patients often requiring advanced airway and post-ROSC circulatory support (including PHEA and administration of titrated inotropes). In this study, more than half of all arterial catheterisations were performed in patients presenting with OHCA (either during resuscitation or following ROSC). The use of IABP monitoring in these patients has been recommended in clinical guidelines, ( 12 ) but this has been perceived as challenging to deliver in the prehospital environment. The benefits of IABP monitoring intra-arrest include the ability to measure the efficacy of chest compressions, and to estimate coronary perfusion pressure (CPP). Previous studies have demonstrated the positive association between a CPP > 15mmHg and ROSC, ( 13 , 14 ) therefore when IABP monitoring has been established, individualized treatment can occur and the response to therapy can be measured beat-to-beat in real-time. Following ROSC, IABP monitoring allows for immediate detection of re-arrest and episodes of critical hypotension and can be used to accurately titrate vasopressors and inotropic medications. This study demonstrates that IABP monitoring can be delivered in this cohort and should therefore be considered by all HEMS providing critical care to medical cardiac arrest patients. Blunt head injury with associated loss of consciousness is a prevalent indication for UK HEMS deployment, due to the potential need for neuroprotective measures, including PHEA ( 15 ). Concomitant head injury was seen in 48% of critically injured, hypotensive trauma patients attended to by UK HEMS ( 16 ). Hypotension and hypertension in patients with traumatic brain injury is associated with increased mortality ( 17 ). Approximately one in five patients who undergo PHEA have post-induction hypotension within the first ten minutes of induction ( 2 ). Following the publication of this study, EAAA updated its PHEA standard operating procedure in July 2022, including a recommendation that clinicians consider IABP monitoring when performing PHEA, ideally prior to anaesthesia, in order to rapidly detect and mitigate haemodynamic compromise. Although there was no change in the total number of PHEA per quarter (median 56, IQR: 49–63), the number of PHEA patients who had IABP monitoring increased from 2021 onwards. Since late 2022, more than 40% of patients receiving a PHEA had IABP monitoring initiated prior to induction of anaesthesia, demonstrating this level of monitoring is feasible at scale in the prehospital environment for the most critically injured patients and should be considered by HEMS providing PHEA. Since publication of this new operating procedure, we have also reported that > 10% of PHEA patients experience post-induction critical hypertension ( 18 ) further emphasising the importance of high-fidelity blood pressure monitoring in this vulnerable group. However, in patients with critical airway compromise, or other time-critical pathology, PHEA may take priority over arterial catheterisation. Pre-PHEA IABP monitoring remains at clinician discretion, reflected by the fluctuations in its utilisation since 2022. Most arterial catheters were placed in the radial artery, where collateral flow through the ulnar artery reduces the risk of distal ischaemia that might be caused by radial arterial occlusion, spasm, or thrombosis. Whilst arterial catheterisation typically has low rates of thrombotic complications and nerve injury ( 19 ), and no immediate complications of arterial cannulation were reported during the study period, further work is required to explore any longer-term complications and the longevity of arterial catheters inserted prehospital. Limitations Whilst this is the largest study describing prehospital arterial catheterisation and IABP monitoring, the data are retrospective from a single centre and are limited by the challenging nature of prehospital data collection. This study is not able to report overall catheterisation success rate or detail the mechanics of arterial catheterisation (number of attempts, utilisation of ultrasound, professional group success rate). This precludes analysis of factors contributing to failure, or delays to insertion. Similarly, the group of patients in whom IABP was not measured includes an unknown number of patients in whom arterial catheterization may have been attempted but ultimately abandoned, so cannot be used as a comparator group. Conclusion This study describes over 1000 cases of prehospital arterial catheterisation and invasive blood pressure monitoring in a UK HEMS system, and has demonstrated feasibility at scale with no clear signal of catheter-associated complications. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting. Declarations Availability of data and materials The datasets used and analysed in this study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding There are no sources of funding to declare. Ethics approval and consent to participate This study met the UK Health Research Authority definition of service evaluation, and was registered with the EAAA Department of Research, Audit, Innovation, & Development (REF: EAAA 2023/01) Consent for publication Not applicable. Author contributions The study was conceived by RM and PR, with input from EDB, MB and EBGB. Data acquisition was undertaken by EDB, MB, KL and ZS. Data analysis was completed by EDB, MB, KL and ZS. The manuscript was drafted by EDB, MB and JP, with critical revisions by PR, JB, CE, RM and EBGB. All authors have agreed the final version. Acknowledgements Not applicable. References McMahon N, Hogg LA, Corfield AR, Exton AD. Comparison of non-invasive and invasive blood pressure in aeromedical care. Anaesthesia. 2012 Dec;67(12):1343-7 Price, J., Moncur, L., Lachowycz, K. et al. Predictors of post-intubation hypotension in trauma patients following prehospital emergency anaesthesia: a multi-centre observational study. Scand J Trauma Resusc Emerg Med 2023 doi:10.1186/s13049-023-01091-z Lockey DJ, Crewdson K, Lossius HM. Prehospital anaesthesia: the same but different. Br J Anaesth. 2014 Aug;113(2):211-9. Sende J, Jabre P, Leroux B, Penet C, Lecarpentier E, Khalid M, Margenet A, Marty J, Combes X. Invasive arterial blood pressure monitoring in an out-of-hospital setting: an observational study. Emerg Med J. 2009 Mar;26(3):210-2. Wildner G, Pauker N, Archan S, Gemes G, Rigaud M, Pocivalnik M, Prause G. Arterial line in prehospital emergency settings - A feasibility study in four physician-staffed emergency medical systems. Resuscitation. 2011 Sep;82(9):1198-201 Fok PT, Teubner D, Purdell-Lewis J, Pearce A. Predictors of Prehospital On-Scene Time in an Australian Emergency Retrieval Service. Prehosp Disaster Med. 2019 Jun;34(3):317-321 Morton S, Avery P, Payne J, OMeara M. Arterial Blood Gases and Arterial Lines in the Prehospital Setting: A Systematic Literature Review and Survey of Current United Kingdom Helicopter Emergency Medical Services. Air Med J. 2022 41(2):201-208 Price J, Lachowycz K, Steel A, Moncur L, Major R, Barnard EBG. Intubation success in prehospital emergency anaesthesia: a retrospective observational analysis of the Inter-Changeable Operator Model (ICOM). Scand J Trauma Resusc Emerg Med. 2022 8;30(1):44. Chana, M., Perkins, Z. ., Lendrum, R. ., & Sadek, S. (2021). A Practical Approach to Introducing Pre-Hospital Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA), the Problems Encountered and Lessons Learned. Journal of Endovascular Resuscitation and Trauma Management doi:10.26676/jevtm.v5i2.207 Brede JR, Lafrenz T, Krüger AJ, et al Resuscitative endovascular balloon occlusion of the aorta (REBOA) in non-traumatic out-of-hospital cardiac arrest: evaluation of an educational programme BMJ Open 2019. doi: 10.1136/bmjopen-2018-027980 von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med. 2007 doi: 10.1016/j.jclinepi.2007.11.008 Panchal AR, Bartos JA, Cabañas JG, Donnino MW, Drennan IR, Hirsch KG, Kudenchuk PJ, Kurz MC, Lavonas EJ, Morley PT, O'Neil BJ, Peberdy MA, Rittenberger JC, Rodriguez AJ, Sawyer KN, Berg KM; Adult Basic and Advanced Life Support Writing Group. Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2020 doi:10.1161/CIR.0000000000000916 Paradis NA, Martin GB, Rivers EP, et al. Coronary perfusion pressure and the return of spontaneous circulation in human cardiopulmonary resuscitation. JAMA. 1990;263:1106–13. Rivers EP, Lozon J, Enriquez E, Havstad SV, Martin GB, Lewandowski CA, Goetting MG, Rosenberg JA, Paradis NA, Nowak RM. Simultaneous radial, femoral, and aortic arterial pressures during human cardiopulmonary resuscitation. Crit Care Med. 1993 doi: 10.1097/00003246-199306000-00016. Carney N, Totten AM, O'Reilly C, Ullman JS, Hawryluk GW, Bell MJ, Bratton SL, Chesnut R, Harris OA, Kissoon N, Rubiano AM, Shutter L, Tasker RC, Vavilala MS, Wilberger J, Wright DW, Ghajar J. Guidelines for the Management of Severe Traumatic Brain Injury, Fourth Edition. Neurosurgery. 2017 Jan 1;80(1):6-15. Crombie N, Doughty HA, Bishop JRB, Desai A, Dixon EF, Hancox JM, Herbert MJ, Leech C, Lewis SJ, Nash MR, Naumann DN, Slinn G, Smith H, Smith IM, Wale RK, Wilson A, Ives N, Perkins GD; RePHILL collaborative group. Resuscitation with blood products in patients with trauma-related haemorrhagic shock receiving prehospital care (RePHILL): a multicentre, open-label, randomised, controlled, phase 3 trial. Lancet Haematol. 2022. doi:10.1016/S2352-3026(22)00040-0. Spaite DW, Hu C, Bobrow BJ, Chikani V, Barnhart B, Gaither JB, Denninghoff KR, Adelson PD, Keim SM, Viscusi C, Mullins T, Rice AD, Sherrill D. Association of Out-of-Hospital Hypotension Depth and Duration With Traumatic Brain Injury Mortality. Ann Emerg Med. 2017 Oct;70(4):522-530.e1. Sagi L, Price J, Lachowycz K, Starr Z, Major R, et al. Critical hypertension in trauma patients following prehospital emergency anaesthesia: a multi-centre retrospective observational study. Scand J Trauma Resus Emerg Med. In press. DOI: 10.1186/s13049-023-01167-w. Nuttall G, Burckhardt J, Hadley A, Kane S, Kor D, Marienau MS, Schroeder DR, Handlogten K, Wilson G, Oliver WC. Surgical and Patient Risk Factors for Severe Arterial Line Complications in Adults. Anesthesiology. 2016 Mar;124(3):590-7. doi: 10.1097/ALN.0000000000000967. Supplementary Files TableS1.docx TableS2.docx Cite Share Download PDF Status: Published Journal Publication published 12 Mar, 2024 Read the published version in Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine → Version 1 posted Editorial decision: Major Revision 01 Feb, 2024 Reviewers agreed at journal 03 Jan, 2024 Reviewers invited by journal 03 Jan, 2024 Editor assigned by journal 25 Dec, 2023 First submitted to journal 24 Dec, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-3801585","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":265102745,"identity":"def88503-007a-4162-b112-bd7464574a16","order_by":0,"name":"Emma D Butterfield","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0001-9076-6875","institution":"East Anglian Air Ambulance","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Emma","middleName":"D","lastName":"Butterfield","suffix":""},{"id":265102746,"identity":"ae6cdeff-5ad1-40b0-938b-1fae1925f790","order_by":1,"name":"Marco Bonsano","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Marco","middleName":"","lastName":"Bonsano","suffix":""},{"id":265102747,"identity":"eb1499ad-2232-428c-9081-54f6d5021c33","order_by":2,"name":"James Price","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"James","middleName":"","lastName":"Price","suffix":""},{"id":265102748,"identity":"968ae107-0196-48c3-942f-29008dd42afa","order_by":3,"name":"Kate Lachowycz","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kate","middleName":"","lastName":"Lachowycz","suffix":""},{"id":265102749,"identity":"30c0f533-161c-4b19-a666-93cd88c96a57","order_by":4,"name":"Zachary Starr","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Zachary","middleName":"","lastName":"Starr","suffix":""},{"id":265102750,"identity":"feaf8c93-10f4-49be-8844-79a6079d427a","order_by":5,"name":"Christopher Edmunds","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Christopher","middleName":"","lastName":"Edmunds","suffix":""},{"id":265102751,"identity":"d9b10ef2-3e1e-48d6-9511-1aa359c399b3","order_by":6,"name":"Jon Barratt","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jon","middleName":"","lastName":"Barratt","suffix":""},{"id":265102752,"identity":"7f3ef5b6-9650-4b0b-833c-e7fbca02d7e4","order_by":7,"name":"Rob Major","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Rob","middleName":"","lastName":"Major","suffix":""},{"id":265102753,"identity":"71c3da05-2e77-4c6b-aca2-9383cd4ccb56","order_by":8,"name":"Paul Rees","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Paul","middleName":"","lastName":"Rees","suffix":""},{"id":265102754,"identity":"3575e60b-43fa-45bc-8ed1-33f447ae1bf9","order_by":9,"name":"Ed B G Barnard","email":"","orcid":"","institution":"East Anglian Air Ambulance","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Ed","middleName":"B G","lastName":"Barnard","suffix":""}],"badges":[],"createdAt":"2023-12-24 18:38:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3801585/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3801585/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13049-024-01193-2","type":"published","date":"2024-03-12T15:01:34+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":49242482,"identity":"c082b239-1e58-4546-83c6-e323f460a603","added_by":"auto","created_at":"2024-01-05 18:29:57","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":16794,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eStudy flow diagram of patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring; 01/02/2015-20/04/2023.\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFigure 1 legend – EAAA = East Anglian Air Ambulance; IABP = intra-arterial blood pressure. *Cases were manually reviewed if there were less than 10 minutes of IABP measurements recorded, or all systolic IABP measurements were less than 90mmHg, or all mean arterial pressures on IABP were less than 50mmHg\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-3801585/v1/405c5e0aaee98b411f4c3f33.png"},{"id":49243378,"identity":"4537e495-de42-41ba-99af-4fff0fb4797c","added_by":"auto","created_at":"2024-01-05 18:37:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":7269,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eThe proportion of patients that received prehospital emergency anaesthesia who had initiation of invasive arterial blood pressure monitoring prior to induction of anaesthesia (2015-2023)\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-3801585/v1/33ab3ade2ec104a3e712e7dd.png"},{"id":52907644,"identity":"2a701807-ea35-4ff0-bea4-9a3dd63d5744","added_by":"auto","created_at":"2024-03-18 15:14:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":409433,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3801585/v1/f05f7b5e-ebfa-44aa-bb5d-99d3f5e66509.pdf"},{"id":49242488,"identity":"cca581e2-9b21-45c1-afc0-bc36f913eed8","added_by":"auto","created_at":"2024-01-05 18:29:57","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":13283,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1.docx","url":"https://assets-eu.researchsquare.com/files/rs-3801585/v1/37117b5591a2ca7f6c6f5ac3.docx"},{"id":49242484,"identity":"02f195d9-9ac7-4f00-a90a-944cf20c025a","added_by":"auto","created_at":"2024-01-05 18:29:57","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":14030,"visible":true,"origin":"","legend":"","description":"","filename":"TableS2.docx","url":"https://assets-eu.researchsquare.com/files/rs-3801585/v1/ccab15d37f270a7670e2d8db.docx"}],"financialInterests":"","formattedTitle":"Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK Helicopter Emergency Medical Service – a retrospective observational review of practice","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eAccurate haemodynamic monitoring of critically unwell and injured patients is essential to identify adverse physiology and allow titration of interventions such as volume replacement, inotropes, and vasopressors. The standard for blood pressure monitoring in the prehospital setting is non-invasive blood pressure (NIBP) measurement, which is susceptible to vibration and motion artefact, compromising its accuracy (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). These inaccuracies are most prevalent in hypotensive and hypertensive patients \u0026ndash; pathophysiological states frequently observed in Helicopter Emergency Medical Service (HEMS) patients (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eInvasive arterial blood pressure (IABP) monitoring is the standard of care for in-hospital critical care and presents a potential solution to the limitations observed with NIBP in the prehospital setting, where comparable levels of monitoring accuracy should ideally be obtained (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). It is currently unclear if prehospital IABP monitoring is feasible at scale, but the combination of higher-fidelity data and the ability to continue this level of monitoring into the early in-hospital phase of care may present the optimal solution (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003ePrevious work describes prehospital arterial catheterisation for IABP monitoring in small cohorts of patients, predominantly at physician discretion (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e). In a recent survey of UK HEMS, 78% of respondents stated that IABP monitoring offers benefits to patient management (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). However, there are no descriptions of large numbers of prehospital IABP interventions, and none from the UK. East Anglian Air Ambulance (EAAA) HEMS is one of the largest providers of prehospital critical care in the UK and has been performing arterial catheterisation and IABP monitoring for the past ten years. The aim of this study was to describe a large series of patients in whom prehospital IABP monitoring was successfully established within a UK HEMS operation.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSetting\u003c/h2\u003e \u003cp\u003eEAAA provides prehospital critical care in support of the statutory emergency medical service in the East of England (East of England Ambulance Service NHS Trust). EAAA operates from two bases (Cambridge and Norwich), deploying a prehospital critical care team comprised of a physician and critical care paramedic, in either an H145 helicopter or rapid response vehicle, depending on patient location, weather constraints, and time of day (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eArterial catheterisation has been performed by EAAA clinicians since 2014. A 20G arterial cannula (BD Arterial Cannula with Flow Switch, Sandy, UT, USA) and an arterial pressure transducer (Edwards Truwave 3 cc, Edwards Lifesciences, Germany) are currently used for peripheral arterial cannulation. Additionally, femoral arterial cannulation using a 5Fr sheath introducer (MERIT Prelude, MERIT Medical, South Jordan, UT, USA) has been added to the list of standard procedures since June 2021. Ultrasound guidance is mandated for femoral catheterisation and is available for radial artery catheterisation at the discretion of the operating clinician (Butterfly iQ, Butterfly Net Inc, MA, US).\u003c/p\u003e \u003cp\u003eAs previously described (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e) EAAA physicians are predominantly from an emergency medicine or anaesthesia background, with at least six years of post-graduate clinical experience, and competent in arterial catheterisation. Critical Care Paramedics (CCP) receive training in peripheral arterial catheterisation and point-of-care-ultrasound (POCUS), including vascular access, and then practice under physician supervision until achieving independent sign-off. Ultrasound-guided femoral arterial cannulation is formally trained as part of the local Specialist Percutaneous Emergency Aortic Resuscitation (SPEAR) programme utilising a Seldinger technique (\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eInclusion criteria\u003c/h2\u003e \u003cp\u003eThis retrospective observational study included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 (initiation of the electronic medical record) and 20th April 2023 (last data available at data extraction). Patients without a single systolic IABP\u0026thinsp;\u0026gt;\u0026thinsp;20mmHg were excluded. To ensure spurious and artefactual readings were not included in the analysis, cases which met any of the following criteria were manually reviewed: \u0026lt;10 minutes of data recorded; all IABP measurements were \u0026lt;\u0026thinsp;50mmHg; or all systolic IABP measurements were \u0026lt;\u0026thinsp;90mmHg (Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). EAAA undertakes a small volume of inter-hospital transfers \u0026ndash; these cases were excluded as IABP monitoring is frequently initiated in-hospital prior to transfer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eData collection\u003c/h2\u003e \u003cp\u003eThe following data were retrieved: sex; age in years; aetiology (medical cardiac arrest, other medical emergency, trauma); anatomical site of arterial cannulation; operator role (physician/CCP); mission result (conveyed by air, conveyed by road, or died at scene). The time of insertion and, where applicable, time of pre-hospital emergency anaesthesia (PHEA), and return of spontaneous circulation (ROSC) following cardiac arrest were also retrieved.\u003c/p\u003e \u003cp\u003eTo characterise interventions associated with IABP measurement, data were collected on the following: arterial blood gas analysis (CG8\u0026thinsp;+\u0026thinsp;cartridge, iSTAT 1, Abbot Point of Care Inc, Abbot Park, IL, USA), intubation, PHEA, administration of blood products or intravenous crystalloid fluids, and vasoactive drugs (metaraminol, ephedrine, adrenaline).\u003c/p\u003e \u003cp\u003eThe EAAA clinical governance database (RLDatix, Richmond, UK) was cross-referenced to identify any serious untoward incidents associated with arterial catheterisation.\u003c/p\u003e \u003cp\u003eIABP measurements were routinely downloaded from the prehospital monitor (ZOLL X Series Monitor/Defibrillator, ZOLL Medical Corporation of Asahi Kasei Corp., Tokyo) to the electronic medical record (HEMSbase, Medic One Systems Ltd, UK). Anonymised data were extracted from HEMSbase and stored in a secure data environment in Excel (Microsoft\u0026reg; Excel\u0026reg; for Microsoft 365, v2309), with data management and statistical analyses performed by a trained statistician using the R statistical programming language (R Core Team [2018]; R: A language and environment for statistical computing [R Foundation for Statistical Computing, Vienna, Austria]). Characteristics of the sample were described as number (percentage) for categorical variables and mean (\u0026plusmn;\u0026thinsp;standard deviation (SD)) or median (interquartile range (IQR)) for continuous variables as appropriate.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eEthical review\u003c/h2\u003e \u003cp\u003eThis study met the UK Health Research Authority definition of service evaluation, and was registered with the EAAA Department of Research, Audit, Innovation, \u0026amp; Development (REF: EAAA 2023/01). The STROBE (Strengthening the Reporting of Observational studies in Epidemiology) reporting guideline was followed (\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eDuring the study period 13,556 patients were attended by EAAA. IABP monitoring was successfully initiated in 1083 (8.0%) of cases, which were included in the analysis; per protocol, Fig.\u0026nbsp;1.\u003c/p\u003e \u003cp\u003e \u003cem\u003eFigure 1 \u0026ndash; Study flow diagram of patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring; 01/02/2015-20/04/2023.\u003c/em\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eFigure 1 legend \u0026ndash; EAAA\u0026thinsp;=\u0026thinsp;East Anglian Air Ambulance; IABP\u0026thinsp;=\u0026thinsp;intra-arterial blood pressure. *Cases were manually reviewed if there were less than 10 minutes of IABP measurements recorded, or all systolic IABP measurements were less than 90mmHg, or all mean arterial pressures on IABP were less than 50mmHg\u003c/em\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eCohort description\u003c/h2\u003e \u003cp\u003eThe cases in the analysis comprised 70.8% male patients, with a median age of 59 years. IABP monitoring was predominantly initiated in medical cardiac arrest patients (50.4%). In 22.4% of cardiac arrest patients, IABP monitoring was established during cardiopulmonary resuscitation (CPR), with the remainder occurring after ROSC.\u003c/p\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;789 patients who underwent PHEA had IABP monitoring established (22.1% of all PHEA cases during the study period); in 166 (21.0%) IABP monitoring was initiated prior to induction of anaesthesia. The most prevalent anatomical site for catheterisation was the radial artery (n\u0026thinsp;=\u0026thinsp;869, 80.2%), and n\u0026thinsp;=\u0026thinsp;101 femoral catheterisations were performed, Table \u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCharacteristics of patients with prehospital arterial line insertion and invasive arterial blood pressure monitoring (2014\u0026ndash;2023), n\u0026thinsp;=\u0026thinsp;1083\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale, n (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e767 (70.8%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e314 (29.0%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnknown/other\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge in years, median [IQR]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.0 [46.0\u0026ndash;70.0]\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatient aetiology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedical cardiac arrest, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e546 (50.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTrauma, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e322 (29.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther Medical, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e215 (19.9%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGCS score at primary survey\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3/15, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e592 (54.7%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u0026ndash;8/15, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e285 (26.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e9\u0026ndash;15/15, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e171 (15.8%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNot recorded, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35 (3.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnatomic site of arterial catheterisation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRadial artery, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e869 (80.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemoral artery, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e101 (9.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBrachial artery, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67 (6.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOther/undocumented, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e46 (4.3%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAssociated interventions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eABG analysis, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e591 (54.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIntubation, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e981 (90.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePrehospital emergency anaesthesia, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e789 (72.6%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVasoactive drugs, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e609 (56.2%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFluid administration, n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e156 (14.4%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlood products (since March 2018*), n (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e47 (5.6%*)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e: \u003cem\u003eCharacteristics of patients with prehospital arterial line insertion and invasive arterial blood pressure monitoring (2014\u0026ndash;2023), n\u0026thinsp;=\u0026thinsp;1083\u003c/em\u003e\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e \u003cem\u003elegend. GCS\u0026thinsp;=\u0026thinsp;Glasgow Coma Scale; ABG\u0026thinsp;=\u0026thinsp;arterial blood gas; *Blood products have been available routinely, outside of a trial context, since March 2018; during the study period 276 patients received a blood product transfusion.\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eProfessional group performing arterial catheterisation\u003c/h2\u003e \u003cp\u003eIn n\u0026thinsp;=\u0026thinsp;893 (82.5%) of cases the professional group performing arterial catheterisation was documented in the clinical notes; physicians performed the majority of cannulations (n\u0026thinsp;=\u0026thinsp;704, 78.8%); CCPs performed the remainder (n\u0026thinsp;=\u0026thinsp;189, 21.2%).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eTiming of invasive arterial blood pressure monitoring\u003c/h2\u003e \u003cp\u003eThe median time interval from HEMS team arrival with patient to initiation of IABP monitoring was 27 (IQR: 15\u0026ndash;42) minutes. IABP monitoring was often initiated during transport en route to hospital (n\u0026thinsp;=\u0026thinsp;424, 39.2%): n\u0026thinsp;=\u0026thinsp;196 (35.9%) in medical cardiac arrest patients; n\u0026thinsp;=\u0026thinsp;151 (46.9%) in trauma patients, n\u0026thinsp;=\u0026thinsp;77 (35.8%) in other medical patients (Table \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eChanges in arterial catheterisation over time\u003c/h2\u003e \u003cp\u003eWe observed a substantial increase in the proportion of patients receiving IABP monitoring through the study period: from 3.1% in 2015, to 14.4% in 2022 \u0026ndash; more than a four-fold increase.\u003c/p\u003e \u003cp\u003eThis increase was driven by the cohort of patients that received PHEA (72.6% of all cases) \u0026ndash; there was also an increase in the proportion of patients with IABP monitoring initiated prior to induction of anaesthesia towards the end of the study period, representing more than 40% of PHEA patients from mid-2022 onwards (Fig.\u0026nbsp;2).\u003c/p\u003e \u003cp\u003e \u003cem\u003eFigure 2: The proportion of patients that received prehospital emergency anaesthesia who had initiation of invasive arterial blood pressure monitoring prior to induction of anaesthesia (2015\u0026ndash;2023)\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eArterial catheterisation complications\u003c/h2\u003e \u003cp\u003eNo immediate complications were reported during the study period. One patient developed acute limb ischemia requiring forearm fasciotomy and thrombectomy following prehospital catheterisation of the brachial artery. However, following independent in-hospital formal review it was unclear whether the ischemia was due to profound systemic hypotension or local arterial dissection secondary to catheterisation.\u003c/p\u003e \u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study reports more than one thousand cases of arterial catheterisation and initiation of IABP monitoring in the prehospital phase of care for seriously unwell and injured patients. The most prevalent patient aetiology was medical cardiac arrest, and the majority of arterial lines were inserted peripherally in the radial artery. Almost all of the patients were intubated, and over half also benefited from arterial blood gas monitoring. In this system, one in five arterial lines were inserted by non-physicians, approximately 40% were inserted and transduced during transport, and there was only one reported potential arterial catheter-associated complication in ten years of practice.\u003c/p\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;3453 (25.5%) of all cases attended during the study period had a medical cardiac arrest aetiology, with patients often requiring advanced airway and post-ROSC circulatory support (including PHEA and administration of titrated inotropes). In this study, more than half of all arterial catheterisations were performed in patients presenting with OHCA (either during resuscitation or following ROSC). The use of IABP monitoring in these patients has been recommended in clinical guidelines, (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e) but this has been perceived as challenging to deliver in the prehospital environment. The benefits of IABP monitoring intra-arrest include the ability to measure the efficacy of chest compressions, and to estimate coronary perfusion pressure (CPP). Previous studies have demonstrated the positive association between a CPP\u0026thinsp;\u0026gt;\u0026thinsp;15mmHg and ROSC, (\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e) therefore when IABP monitoring has been established, individualized treatment can occur and the response to therapy can be measured beat-to-beat in real-time. Following ROSC, IABP monitoring allows for immediate detection of re-arrest and episodes of critical hypotension and can be used to accurately titrate vasopressors and inotropic medications.\u003c/p\u003e \u003cp\u003eThis study demonstrates that IABP monitoring can be delivered in this cohort and should therefore be considered by all HEMS providing critical care to medical cardiac arrest patients.\u003c/p\u003e \u003cp\u003eBlunt head injury with associated loss of consciousness is a prevalent indication for UK HEMS deployment, due to the potential need for neuroprotective measures, including PHEA (\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Concomitant head injury was seen in 48% of critically injured, hypotensive trauma patients attended to by UK HEMS (\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). Hypotension and hypertension in patients with traumatic brain injury is associated with increased mortality (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Approximately one in five patients who undergo PHEA have post-induction hypotension within the first ten minutes of induction (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Following the publication of this study, EAAA updated its PHEA standard operating procedure in July 2022, including a recommendation that clinicians consider IABP monitoring when performing PHEA, ideally prior to anaesthesia, in order to rapidly detect and mitigate haemodynamic compromise. Although there was no change in the total number of PHEA per quarter (median 56, IQR: 49\u0026ndash;63), the number of PHEA patients who had IABP monitoring increased from 2021 onwards. Since late 2022, more than 40% of patients receiving a PHEA had IABP monitoring initiated prior to induction of anaesthesia, demonstrating this level of monitoring is feasible at scale in the prehospital environment for the most critically injured patients and should be considered by HEMS providing PHEA. Since publication of this new operating procedure, we have also reported that \u0026gt;\u0026thinsp;10% of PHEA patients experience post-induction critical hypertension (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e) further emphasising the importance of high-fidelity blood pressure monitoring in this vulnerable group. However, in patients with critical airway compromise, or other time-critical pathology, PHEA may take priority over arterial catheterisation. Pre-PHEA IABP monitoring remains at clinician discretion, reflected by the fluctuations in its utilisation since 2022.\u003c/p\u003e \u003cp\u003eMost arterial catheters were placed in the radial artery, where collateral flow through the ulnar artery reduces the risk of distal ischaemia that might be caused by radial arterial occlusion, spasm, or thrombosis. Whilst arterial catheterisation typically has low rates of thrombotic complications and nerve injury (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e), and no immediate complications of arterial cannulation were reported during the study period, further work is required to explore any longer-term complications and the longevity of arterial catheters inserted prehospital.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eWhilst this is the largest study describing prehospital arterial catheterisation and IABP monitoring, the data are retrospective from a single centre and are limited by the challenging nature of prehospital data collection. This study is not able to report overall catheterisation success rate or detail the mechanics of arterial catheterisation (number of attempts, utilisation of ultrasound, professional group success rate). This precludes analysis of factors contributing to failure, or delays to insertion. Similarly, the group of patients in whom IABP was not measured includes an unknown number of patients in whom arterial catheterization may have been attempted but ultimately abandoned, so cannot be used as a comparator group.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study describes over 1000 cases of prehospital arterial catheterisation and invasive blood pressure monitoring in a UK HEMS system, and has demonstrated feasibility at scale with no clear signal of catheter-associated complications. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and analysed\u0026nbsp;in this study\u0026nbsp;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\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are no sources of funding to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study met the UK Health Research Authority definition of service evaluation, and was registered with the EAAA Department of Research, Audit, Innovation, \u0026amp; Development (REF: EAAA 2023/01)\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\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conceived by RM and PR, with input from EDB, MB and EBGB. Data acquisition was undertaken by EDB, MB, KL and ZS. Data analysis was completed by EDB, MB, KL and ZS. The manuscript was drafted by EDB, MB and JP, with critical revisions by PR, JB, CE, RM and EBGB. All authors have agreed the final version.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eMcMahon N, Hogg LA, Corfield AR, Exton AD. Comparison of non-invasive and invasive blood pressure in aeromedical care. Anaesthesia. 2012 Dec;67(12):1343-7\u003c/li\u003e\n \u003cli\u003ePrice, J., Moncur, L., Lachowycz, K.\u0026nbsp;et al.\u0026nbsp;Predictors of post-intubation hypotension in trauma patients following prehospital emergency anaesthesia: a multi-centre observational study.\u0026nbsp;Scand J Trauma Resusc Emerg Med\u0026nbsp;2023 doi:10.1186/s13049-023-01091-z\u003c/li\u003e\n \u003cli\u003eLockey DJ, Crewdson K, Lossius HM. Prehospital anaesthesia: the same but different. Br J Anaesth. 2014 Aug;113(2):211-9.\u003c/li\u003e\n \u003cli\u003eSende J, Jabre P, Leroux B, Penet C, Lecarpentier E, Khalid M, Margenet A, Marty J, Combes X. Invasive arterial blood pressure monitoring in an out-of-hospital setting: an observational study. Emerg Med J. 2009 Mar;26(3):210-2.\u003c/li\u003e\n \u003cli\u003eWildner G, Pauker N, Archan S, Gemes G, Rigaud M, Pocivalnik M, Prause G. Arterial line in prehospital emergency settings - A feasibility study in four physician-staffed emergency medical systems. Resuscitation. 2011 Sep;82(9):1198-201\u003c/li\u003e\n \u003cli\u003eFok PT, Teubner D, Purdell-Lewis J, Pearce A. Predictors of Prehospital On-Scene Time in an Australian Emergency Retrieval Service. Prehosp Disaster Med. 2019 Jun;34(3):317-321\u003c/li\u003e\n \u003cli\u003eMorton S, Avery P, Payne J, OMeara M. Arterial Blood Gases and Arterial Lines in the Prehospital Setting: A Systematic Literature Review and Survey of Current United Kingdom Helicopter Emergency Medical Services. Air Med J. 2022 41(2):201-208\u003c/li\u003e\n \u003cli\u003ePrice J, Lachowycz K, Steel A, Moncur L, Major R, Barnard EBG. Intubation success in prehospital emergency anaesthesia: a retrospective observational analysis of the Inter-Changeable Operator Model (ICOM). Scand J Trauma Resusc Emerg Med. 2022 8;30(1):44.\u003c/li\u003e\n \u003cli\u003eChana, M., Perkins, Z. ., Lendrum, R. ., \u0026amp; Sadek, S. (2021). A Practical Approach to Introducing Pre-Hospital Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA), the Problems Encountered and Lessons Learned. Journal of Endovascular Resuscitation and Trauma Management doi:10.26676/jevtm.v5i2.207\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eBrede\u0026nbsp;JR,\u0026nbsp;Lafrenz\u0026nbsp;T,\u0026nbsp;Kr\u0026uuml;ger\u0026nbsp;AJ, et al Resuscitative endovascular balloon occlusion of the aorta (REBOA) in non-traumatic out-of-hospital cardiac arrest: evaluation of an educational programme BMJ Open\u0026nbsp;2019.\u0026nbsp;doi:\u0026nbsp;10.1136/bmjopen-2018-027980\u003c/li\u003e\n \u003cli\u003evon Elm E, Altman DG, Egger M, Pocock SJ, G\u0026oslash;tzsche PC, Vandenbroucke JP; STROBE Initiative. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med. 2007 doi:\u003ca href=\"https://doi.org/10.1016/j.jclinepi.2007.11.008\" target=\"_blank\"\u003e10.1016/j.jclinepi.2007.11.008\u003c/a\u003e\u003c/li\u003e\n \u003cli\u003ePanchal AR, Bartos JA, Caba\u0026ntilde;as JG, Donnino MW, Drennan IR, Hirsch KG, Kudenchuk PJ, Kurz MC, Lavonas EJ, Morley PT, O\u0026apos;Neil BJ, Peberdy MA, Rittenberger JC, Rodriguez AJ, Sawyer KN, Berg KM; Adult Basic and Advanced Life Support Writing Group. Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2020 doi:10.1161/CIR.0000000000000916\u003c/li\u003e\n \u003cli\u003eParadis NA, Martin GB, Rivers EP, et al. Coronary perfusion pressure and the return of spontaneous circulation in human cardiopulmonary resuscitation. JAMA. 1990;263:1106\u0026ndash;13.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eRivers EP, Lozon J, Enriquez E, Havstad SV, Martin GB, Lewandowski CA, Goetting MG, Rosenberg JA, Paradis NA, Nowak RM. Simultaneous radial, femoral, and aortic arterial pressures during human cardiopulmonary resuscitation. Crit Care Med. 1993 doi: 10.1097/00003246-199306000-00016.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCarney N, Totten AM, O\u0026apos;Reilly C, Ullman JS, Hawryluk GW, Bell MJ, Bratton SL, Chesnut R, Harris OA, Kissoon N, Rubiano AM, Shutter L, Tasker RC, Vavilala MS, Wilberger J, Wright DW, Ghajar J. Guidelines for the Management of Severe Traumatic Brain Injury, Fourth Edition. Neurosurgery. 2017 Jan 1;80(1):6-15.\u003c/li\u003e\n \u003cli\u003eCrombie N, Doughty HA, Bishop JRB, Desai A, Dixon EF, Hancox JM, Herbert MJ, Leech C, Lewis SJ, Nash MR, Naumann DN, Slinn G, Smith H, Smith IM, Wale RK, Wilson A, Ives N, Perkins GD; RePHILL collaborative group. Resuscitation with blood products in patients with trauma-related haemorrhagic shock receiving prehospital care (RePHILL): a multicentre, open-label, randomised, controlled, phase 3 trial. Lancet Haematol. 2022. doi:10.1016/S2352-3026(22)00040-0.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSpaite DW, Hu C, Bobrow BJ, Chikani V, Barnhart B, Gaither JB, Denninghoff KR, Adelson PD, Keim SM, Viscusi C, Mullins T, Rice AD, Sherrill D. Association of Out-of-Hospital Hypotension Depth and Duration With Traumatic Brain Injury Mortality. Ann Emerg Med. 2017 Oct;70(4):522-530.e1.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSagi L, Price J, Lachowycz K, Starr Z, Major R, et al. Critical hypertension in trauma patients following prehospital emergency anaesthesia: a multi-centre retrospective observational study. Scand J Trauma Resus Emerg Med. In press. DOI: 10.1186/s13049-023-01167-w.\u003c/li\u003e\n \u003cli\u003eNuttall G, Burckhardt J, Hadley A, Kane S, Kor D, Marienau MS, Schroeder DR, Handlogten K, Wilson G, Oliver WC. Surgical and Patient Risk Factors for Severe Arterial Line Complications in Adults. Anesthesiology. 2016 Mar;124(3):590-7. doi: 10.1097/ALN.0000000000000967. \u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scandinavian-journal-of-trauma-resuscitation-and-emergency-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"stre","sideBox":"Learn more about [Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine](http://sjtrem.biomedcentral.com)","snPcode":"13049","submissionUrl":"https://submission.nature.com/new-submission/13049/3","title":"Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine","twitterHandle":"@SJTREM","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Vascular Access, Blood Pressure, Prehospital, Intra-arterial blood pressure, Air Ambulance, Helicopter Emergency Medical Services, ","lastPublishedDoi":"10.21203/rs.3.rs-3801585/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3801585/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAccurate haemodynamic monitoring of critically unwell and injured patients in the prehospital setting is essential. Non-invasive blood pressure measurement is susceptible to vibration and motion artefact, especially at extremes of hypotension and hypertension. Invasive arterial blood pressure (IABP) monitoring is a potential solution to these limitations. The aim of this study was to describe the largest series to date of patients in whom IABP monitoring was successfully initiated prehospital.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis retrospective observational study was conducted at East Anglian Air Ambulance, a UK helicopter emergency medical service (HEMS) which provides prehospital critical care in the East of England. It included all patients attended by EAAA who underwent arterial catheterisation and initiation of IABP monitoring between 1st February 2015 and 20th April 2023.\u003c/p\u003e\n\u003cp\u003eThe following data were retrieved for all patients: sex; age; aetiology (medical cardiac arrest, other medical emergency, trauma); site of arterial cannulation; operator role (doctor/paramedic); the time of insertion and, where applicable, time of pre-hospital emergency anaesthesia, and return of spontaneous circulation following cardiac arrest. Characteristics of the sample were described as number (percentage) for categorical variables and mean (± standard deviation (SD)) or median (interquartile range = IQR) for continuous variables as appropriate.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring the study period 13,556 patients were attended; IABP monitoring was initiated in 1083 (8.0%) cases (70.8% male; median age 59 years). 546 cases (50.4%) were of medical cardiac arrest: in 22.4% of these IABP monitoring was initiated during cardiopulmonary resuscitation. 322 (29.7%) were trauma cases, and the remaining 215 (19.9%) were medical emergencies. The patients were critically unwell: 981 (90.6%) required intubation, of which 789 (72.6%) underwent prehospital emergency anaesthesia; 609 (56.2%) received vasoactive medication. In 424 (39.2%) cases IABP monitoring was instituted en route to hospital.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study describes over 1000 cases of prehospital arterial catheterisation and invasive blood pressure monitoring in a UK HEMS system and has demonstrated feasibility at scale with no clear signal of catheter-associated complications. The high-fidelity of invasive arterial blood pressure monitoring with the additional benefit of arterial blood gas analysis presents an attractive translation of in-hospital critical care to the prehospital setting.\u003c/p\u003e","manuscriptTitle":"Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK Helicopter Emergency Medical Service – a retrospective observational review of practice","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-05 18:29:53","doi":"10.21203/rs.3.rs-3801585/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revision","date":"2024-02-01T07:20:35+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-01-03T11:33:34+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-01-03T11:30:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2023-12-25T23:00:00+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine","date":"2023-12-24T05:35:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scandinavian-journal-of-trauma-resuscitation-and-emergency-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"stre","sideBox":"Learn more about [Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine](http://sjtrem.biomedcentral.com)","snPcode":"13049","submissionUrl":"https://submission.nature.com/new-submission/13049/3","title":"Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine","twitterHandle":"@SJTREM","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e505524a-da5e-499b-b54e-def10d436ef9","owner":[],"postedDate":"January 5th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-03-18T15:10:06+00:00","versionOfRecord":{"articleIdentity":"rs-3801585","link":"https://doi.org/10.1186/s13049-024-01193-2","journal":{"identity":"scandinavian-journal-of-trauma-resuscitation-and-emergency-medicine","isVorOnly":false,"title":"Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine"},"publishedOn":"2024-03-12 15:01:34","publishedOnDateReadable":"March 12th, 2024"},"versionCreatedAt":"2024-01-05 18:29:53","video":"","vorDoi":"10.1186/s13049-024-01193-2","vorDoiUrl":"https://doi.org/10.1186/s13049-024-01193-2","workflowStages":[]},"version":"v1","identity":"rs-3801585","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3801585","identity":"rs-3801585","version":["v1"]},"buildId":"cBFmMYwuxLRRLfASyISRj","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}