Mean Arterial Pressure (MAP) influence on free flap oxygen saturation (StO2) measured by Near-Infrared Spectroscopy

Mean Arterial Pressure (MAP) influence on free flap oxygen saturation (StO2) measured by Near-Infrared Spectroscopy | 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 Mean Arterial Pressure (MAP) influence on free flap oxygen saturation (StO2) measured by Near-Infrared Spectroscopy Massimiliano Gilli, Umberto Committeri, Gabriele Monarchi, federica sacchi, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5790282/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 27 Feb, 2025 Read the published version in European Journal of Plastic Surgery → Version 1 posted 7 You are reading this latest preprint version Abstract Background Free flap monitoring techniques still rely on gold standard methods such as skin color evaluation, temperature, and puncture tests that are time-consuming, discontinuous, and prone to human error. Near-Infrared Spectroscopy represents a continuous, non-invasive technique that aims to avoid subjective errors by detecting early stages of vascular compromise, providing enough time for successful salvage surgery. Methods This retrospective study includes 56 patients undergoing microvascular reconstruction and 24-hour NIRS monitoring. All other patients without detailed MAP charts were excluded. The NIRS system used was the HemoSphere-ForeSight by Edwards Lifesciences; this platform enabled the detection of StO2 values and their integration with real-time intra-arterial catheter-detected MAP values. Data were recorded by an adhesive sensor, chosen according to the height and width of the flap. Results Forty-seven (83%) patients showed a positive correlation between MAP and StO2 data (ρs > 0.450, p < 0.0001), validating the theory that MAP values positively correlate with flap perfusion, tissue oxygenation, and survival rate. Nine patients did not show a direct correlation between MAP and StO2 data; their values were influenced by vasopressors or psychophysical conditions during their admission to the Intensive Care Unit (ICU) after surgery. Conclusion Comparing MAP and StO2 values, their trend charts play a crucial role in flap monitoring, contributing to the best possible survival rate outcome and, if necessary, leading to micro-anastomosis checks and eventual flap salvage surgery. MAP data analysis should, indeed, be considered in future guidelines for free flap monitoring techniques. Near-Infrared Spectroscopy NIRS Free flap monitoring MAP StO2 Reconstructive surgery Figures Figure 1 Figure 2 Introduction In the head and neck area, the reconstruction of surgical defects has become an absolute necessity [ 1 , 2 ]. A monitoring method for head and neck free flaps was considered helpful at the beginning of the reconstructive technique. In the last two decades, Near-Infrared Spectroscopy (NIRS) has been used as an effective procedure in free flap monitoring, showing 99.1% sensitivity and 99.9% specificity in recognizing potential flap failure, leading to possible flap salvage surgery [ 3 ]. Its fast learning curve and wide diffusion explain why NIRS has been adopted by many hospital wards such as pediatric surgery, neurosurgery, vascular surgery, and ENT surgery, while clinical examination, which includes skin color, temperature, and puncture tests, requires clinical expertise and experience [ 1 , 4 ]. Although standard flap examination remains the gold standard, this approach tends to be time-consuming and prone to error. This explains why different non-invasive devices have been proposed. NIRS is a technology that aims to provide real-time control of tissue hemodynamics by monitoring values such as arterial pressure (MAP) and mean tissue oxygen saturation, compared to other devices such as implantable Doppler [ 5 ]. Current literature on NIRS technology shows its effective use in detecting compromised flaps with a low false-positive and false-negative rate [ 3 ]. The primary objective of this article is to determine a potential connection between mean arterial pressure (MAP) chart values and flap oxygen saturation (StO2). Methods This retrospective study included 56 patients undergoing microvascular reconstruction procedures and 24-hour NIRS monitoring after surgery. All types of free flaps used are summarized in Table 1 . Table 1 Table all kind of free flaps used for reconstructions, explaning when they were used for oncological reconstruction, secondary reconstruction or reconstruction for benign condition (benign tumor or osteonecrosis): Fibular Flap (FF), Iliac Crest Flap (ICF), Antero-Lateral Thight Flap comprehensive of muscular component (ALT Muscle F), Antero-Lateral Thight Fascio-cutaneous Flap (ALT Thin F), Radial Forearm (RF) FF ICF ALT Muscle F ALT Thin F RF Oncology 14 8 9 8 2 41 Benign Condition 6 3 / / / 9 Secondary reconstruction 3 1 1 1 / 6 23 12 10 9 2 56 (Table 1 ) Patients undergoing surgery for malignant tumors, benign pathologies, and secondary reconstructions were included in this study. Patients whose MAP or StO2 data could not be continuously recorded were excluded from this study. The NIRS system used was the HemoSphere-ForeSight by Edwards Lifesciences: the HemoSphere platform enabled the detection of StO2 values and their integration with real-time intra-arterial catheter-detected MAP values. Data were recorded by an adhesive sensor as shown in Fig. 1 , chosen according to the height and width of the flap, with an investigation depth of 1.25 cm, 2 cm, and 2.5 cm. Figure 1 HemoSphere-ForeSight sensor (2 cm investigation depth) applied on a free fibula osteocutaneous flap All data refer to the first 24 hours after surgery. All patients were monitored in the Intensive Care Unit (ICU) during the first 24 hours post-surgery. The Keller algorithm was chosen to intercept and prevent potential failure [ 6 ]. This algorithm works on the coexistence of three conditions: reduction of tissue saturation by at least 30%, reduction of tissue saturation by 20%/hour, and sustained saturation drop over time for at least thirty minutes. Spearman's rank correlation coefficient (ρs) was used to demonstrate a correlation between MAP and StO2: A coefficient ρs > 0.450 was considered positive (p < 0.001). Results A total of 56 reconstructive procedures were performed for defects in the head and neck region. Of these patients, 31 (55%) were male, and 25 (45%) were female. The average age of the patients who underwent surgery was 51 years, with a minimum age of 19 years and a maximum of 83 years. In none of the 56 cases considered was there necrosis of the reconstructive flap. Forty-one patients underwent primary reconstruction for oncological issues, 9 patients for benign conditions (osteonecrosis or benign tumors), and 6 patients underwent secondary reconstructions, as shown in Table 1 . Among the 56 patients studied, 16 had hypertension, and 9 had diabetes mellitus. The mean StO2 among all flaps was 82%, with the highest individual flap StO2 recorded at 89% for a fibular flap and the lowest at 64% for an iliac crest flap. The mean MAP values for the 56 patients were 81 mmHg, with a maximum of 92 mmHg in one patient and a minimum of 68 mmHg. A positive correlation (ρs > 0.450, p < 0.0001) was found between StO2 and MAP in 47 of the 56 patients examined, as shown in Table 2 . Table 2 Correlation of MAP e StO2 curves, expressed in numbers and percentage. It is also expressed the number of patients that showed correlation per each kind of free flap FF ICF ALT Muscle F ALT Thin F RF ρs > 0.450 21 9 8 7 2 47 (84%) Total 23 12 10 9 2 56 (100%) (Table 2 ) It was not possible to conduct an analysis to determine whether certain types of flaps showed a greater tendency to correlate between StO2 and MAP due to insufficient sample size. In all 9 remaining patients, vasopressors (norepinephrine) were administered via continuous infusion during the first 24 hours post-operatively. The average dosage of the infusion was 0.06 mcg/kg/min. The initiation of norepinephrine infusion showed a decoupling of the StO2 and MAP curves in all 9 patients, with a significant rise in MAP values throughout the infusion period, accompanied by a concurrent decrease in StO2 values, as shown in Fig. 2 , which reports the average MAP and StO2 values of the 9 patients. Figure 2 shows the mean MAP e StO2 values in the first 24 hours of the 9 patients showing discoupling of the MAP and StO2 curves (ps = -0.0389) The average StO2 values for these 9 patients were 79%, while the average MAP values were 72 mmHg. Discussion The findings from this study provide valuable insights into the outcomes of 56 reconstructive procedures in patients with head and neck defects. The choice of the reconstructive option has an anatomical and surgical basis. All fibular and iliac crest pedicles were checked preoperatively by angio-TC scan, and the anterolateral thigh flap cutaneous perforators were located using a Doppler ultrasonography scanner [ 7 ]. A slightly male predominance (55%) was observed, and the average age of 51 years indicates that these procedures are commonly performed on middle-aged adults. The idea that there is a correlation between StO2 and MAP in free flaps arose because it was noticed that as StO2 values decreased, there was a concomitant decrease in MAP values. The decrease in patients' MAP values would relate to a reduced peripheral flap perfusion, with a simultaneous decrease in the tissue saturation rate. Such hemodynamic concepts are universally recognized when applied to a patient in a state of shock; therefore, one of the primary objectives is to maintain MAP at 65 mmHg [ 8 , 9 ]. MAP control reduces the risk of peripheral phenomena such as stasis, thrombosis, CID, multiorgan failure syndrome (MOF), and eventually death. Numerous hemodynamic studies have supported the theory of a correlation between StO2 and MAP in non-transferred tissue [ 9 ]. It has never been verified whether the correlation between pressure and saturation is equally valid for the tissues of a microvascular reconstructive flap. This correlation cannot be assumed without being demonstrated, as the tissues of a transplanted flap may differ from other tissues [ 10 , 11 ]. There could be many eventual drawbacks, such as a loss in vascular tone due to sympathetic/parasympathetic nervous system disruption; moreover, many metabolites such as ROS, ATP, NO, lactates, and others are released during the surgical procedure and its consequent ischemia [ 12 , 13 ]. The two main hypotheses are that MAP and StO2 values in a free flap are directly linked, and that StO2 decrease is due to a reduction in tissue perfusion and not to a vascular pedicle defect or other vascular complications [ 14 ]. A positive correlation between MAP and StO2 was observed in 47 patients (ρs > 0.450, p < 0.0001). This correlation emphasizes the critical role of mean arterial pressure in ensuring adequate flap perfusion, which is crucial for flap viability [ 10 ]. The implication is that maintaining optimal blood pressure should be a priority in perioperative care, not only for patient homeostasis but also because poor blood pressure control could affect the outcome of free flap reconstructive surgery. Increasing knowledge in this field could lead to better postoperative monitoring protocols, allowing clinicians to identify cases of flap failure with greater precision. Further research is necessary due to the inability to analyze the correlation in specific flap types because of the limited sample sizes. The mean StO2 level of 82% suggests good tissue perfusion of the flaps. In the literature, there is no clear indication of a minimum level required for free flaps, but tissue saturation above 60% is generally considered satisfactory [ 4 ]. One of the fibular flaps showed the highest StO2 (89%), while one of the iliac crest flaps showed the minimum StO2 recorded (64%). These differences may be attributed to many factors: anatomical variations, surgical techniques, or even patient-related factors such as pre-existing vascular conditions. One of the factors that may affect this is the diameter of the vascular pedicle. It is known that the average diameter of the peroneal artery is greater than that of the Deep Circumflex Iliac Artery [ 15 ]. The sample size of this study is not sufficient to demonstrate that a vascular pedicle with a larger diameter involves a higher average tissue saturation. This hypothesis, if verified in the future, could lead to a different interpretation of NIRS saturation data based on the type of reconstructive flap chosen. Data recording will continue, allowing further exploration of this hypothesis in future work. The administration of norepinephrine in the nine patients who exhibited decoupling between StO2 and MAP curves raises a complex question. Although norepinephrine effectively increased MAP as desired, a slight drop in StO2 values was also noted. This could indicate that regional blood flow may be compromised, potentially due to vasoconstriction of local blood vessels [ 15 , 16 ]. This finding raises critical questions about the timing and necessity of vasopressor use in this context. Careful monitoring and possibly alternative strategies should be considered to maintain adequate perfusion without compromising tissue oxygenation. It is important to note that in none of the 9 patients did the norepinephrine infusion affect flap vitality, and in each case, when the infusion stopped, StO2 naturally increased to previous levels. FinaNIRS sensors have been successfully used in all patients undergoing reconstructive surgery, and can also be effectively used in the oral cavity [ 17 ]. Conclusion Appropriate MAP values are important to support patients' vital signs and flap homeostasis. The current diagnostic criteria do not include these values in free flap monitoring; only StO2 and time factors are used. Understanding the potential link between MAP and StO2 trend values could play an important role in achieving the best possible outcome in survival rates and, if necessary, leading to anastomosis checks and eventual flap salvage surgery. If the hypothesis of a direct correlation is supported by further data and studies, this could lead to new scenarios in flap monitoring, such as including MAP values in future guidelines. This could eventually change the current medical approach. Declarations The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. The authors have no relevant financial or non-financial interests to disclose. All authors contributed to the study conception and design. All authors read and approved the final manuscript. This study was performed in line with the principles of the Declaration of Helsinki. This is an observational study. The S. Maria della Misericordia Hospital Research Ethics Committee has confirmed that no ethical approval is required. Informed consent was obtained from all individual participants included in the study. The authors affirm that human research participants provided informed consent for publication of the images in Figure 1. Author Contribution Massimiliano Gilli: Study idea and work coordinatorUmberto Committeri: data collectionGabriele Monarchi: data analisysfederica sacchi: introduction and methods authorgiulio cirignaco: results and discussion authorangela rosa caso: tables and figures managerfrancesco giovacchini: validation of the studyvaleria mitro: english revisorantonio tullio: supervision References Giovacchini F, Gilli M, Mitro V et al (2021) Rapid prototyping: Applications in oral and maxillofacial surgery. J Oral Med Oral Surg 2021;27:11 Giovacchini F, Monarchi G, Mitro V et al (2021) Maxilla reconstruction using a free fibula flap and virtual planning. Chirurgia 34(5):227–231 Kagaya Y, Miyamoto S (2018) A systematic review of near-infrared spectroscopy in flap monitoring: Current basic and clinical evidence and prospects. J Plast Reconstr aesthetic surgery: JPRAS 71(2):246–257. https://doi.org/10.1016/j.bjps.2017.10.020 Han ZF, Guo LL, Liu LB, Li Q, Zhou J, Wei AZ, Guo PF (2016) A comparison of the Cook-Swartz Doppler with conventional clinical methods for free flap monitoring: A systematic review and a meta-analysis. Int J Surg (London England) 32:109–115. https://doi.org/10.1016/j.ijsu.2016.06.034 Newton E, Butskiy O, Shadgan B, Prisman E, Anderson DW (2020) Outcomes of free flap reconstructions with near-infrared spectroscopy (NIRS) monitoring: A systematic review. Microsurgery 40(2):268–275. https://doi.org/10.1002/micr.30526 Keller A (2009) A new diagnostic algorithm for early prediction of vascular compromise in 208 microsurgical flaps using tissue oxygen saturation measurements. Ann Plast Surg 62(5):538–543. https://doi.org/10.1097/SAP.0b013e3181a47ce8 Giovacchini F, Pignataro LV, Mitro V, Gilli M, Tullio A Comparison of RFF and ALT flap in head and neck reconstruction: one single center experience (2023). Chirurgia 36:196–203. 10.23736/S0394-9508.22.05499-7 Levy MM, Evans LE, Rhodes A (2018) The Surviving Sepsis Campaign Bundle: 2018 update. Intensive Care Med 44(6):925–928. https://doi.org/10.1007/s00134-018-5085-0 Mok G, Hendin A, Reardon P, Hickey M, Gray S, Yadav K (2021) Macrocirculatory and Microcirculatory Endpoints in Sepsis Resuscitation. J Intensive Care Med 36(12):1385–1391. https://doi.org/10.1177/0885066620982585 Pattani KM, Byrne P, Boahene K, Richmon J (2010) What makes a good flap go bad? A critical analysis of the literature of intraoperative factors related to free flap failure. Laryngoscope 120(4):717–723. https://doi.org/10.1002/lary.20825 Motakef S, Mountziaris PM, Ismail IK, Agag RL, Patel A (2015) Perioperative management for microsurgical free tissue transfer: survey of current practices with a comparison to the literature. J Reconstr Microsurg 31(5):355–363. https://doi.org/10.1055/s-0035-1546422 Edmunds MC, Czopek A, Wigmore SJ, Kluth DC (2014) Paradoxical effects of heme arginate on survival of myocutaneous flaps. Am J Physiol Regul Integr Comp Physiol 306(1):R10–R22. https://doi.org/10.1152/ajpregu.00240.2013 Siemionow M, Arslan E (2004) Ischemia/reperfusion injury: a review in relation to free tissue transfers. Microsurgery 24(6):468–475. https://doi.org/10.1002/micr.20060 Creteur J (2008) Muscle StO2 in critically ill patients. Curr Opin Crit Care 14(3):361–366. https://doi.org/10.1097/MCC.0b013e3282fad4e1 Lonie S, Herle P, Paddle A, Pradhan N, Birch T, Shayan R (2016) Mandibular reconstruction: meta-analysis of iliac- versus fibula-free flaps. ANZ J Surg 86(5):337–342. https://doi.org/10.1111/ans.13274 Sato K, Kamii H, Shimizu H, Kato M (2007) Masui 56(6):634–638 Yousef KM, Crago E, Chang Y, Lagattuta TF, Mahmoud K, Shutter L, Balzer JR, Pinsky MR, Friedlander RM, Hravnak M (2018) Vasopressor Infusion After Subarachnoid Hemorrhage Does Not Increase Regional Cerebral Tissue Oxygenation. J Neurosci nursing: J Am Association Neurosci Nurses 50(4):225–230. https://doi.org/10.1097/JNN.0000000000000382 Gilli M, Giovacchini F, Mitro V et al (2025) Near-Infrared Spectroscopy Sensors, Which Type to Choose and How to Fix it in Cranio- and Maxillo-facial Reconstructive Surgery: Tip and Tricks. J Maxillofac Oral Surg. https://doi.org/10.1007/s12663-024-02426-8 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 27 Feb, 2025 Read the published version in European Journal of Plastic Surgery → Version 1 posted Editorial decision: Revision requested 06 Feb, 2025 Reviews received at journal 05 Feb, 2025 Reviewers agreed at journal 22 Jan, 2025 Reviewers invited by journal 16 Jan, 2025 Editor assigned by journal 09 Jan, 2025 Submission checks completed at journal 09 Jan, 2025 First submitted to journal 08 Jan, 2025 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-5790282","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":400538703,"identity":"0cdea550-ef50-4022-a03d-500d87a497bb","order_by":0,"name":"Massimiliano 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1","display":"","copyAsset":false,"role":"figure","size":251289,"visible":true,"origin":"","legend":"\u003cp\u003eHemoSphere-ForeSight sensor (2 cm investigation depth) applied on a free fibula osteocutaneous flap\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-5790282/v1/38935947937e8ab91d3763b7.png"},{"id":73703040,"identity":"b3b3931d-52d6-47c0-b790-5d75ad5afb0a","added_by":"auto","created_at":"2025-01-13 17:37:01","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":124559,"visible":true,"origin":"","legend":"\u003cp\u003eshows the mean MAP e StO2 values in the first 24 hours of the 9 patients showing discoupling of the MAP and StO2 curves (ps = -0.0389)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-5790282/v1/25912c4f4b10b926f3ae0583.png"},{"id":77622801,"identity":"a5a62ce2-e7f3-44db-9b04-aa97ce2cda4e","added_by":"auto","created_at":"2025-03-03 16:10:26","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":918232,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5790282/v1/4cefc446-621b-4f97-b1f0-605ca79e3d0d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mean Arterial Pressure (MAP) influence on free flap oxygen saturation (StO2) measured by Near-Infrared Spectroscopy","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn the head and neck area, the reconstruction of surgical defects has become an absolute necessity [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. A monitoring method for head and neck free flaps was considered helpful at the beginning of the reconstructive technique. In the last two decades, Near-Infrared Spectroscopy (NIRS) has been used as an effective procedure in free flap monitoring, showing 99.1% sensitivity and 99.9% specificity in recognizing potential flap failure, leading to possible flap salvage surgery [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Its fast learning curve and wide diffusion explain why NIRS has been adopted by many hospital wards such as pediatric surgery, neurosurgery, vascular surgery, and ENT surgery, while clinical examination, which includes skin color, temperature, and puncture tests, requires clinical expertise and experience [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough standard flap examination remains the gold standard, this approach tends to be time-consuming and prone to error. This explains why different non-invasive devices have been proposed. NIRS is a technology that aims to provide real-time control of tissue hemodynamics by monitoring values such as arterial pressure (MAP) and mean tissue oxygen saturation, compared to other devices such as implantable Doppler [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCurrent literature on NIRS technology shows its effective use in detecting compromised flaps with a low false-positive and false-negative rate [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The primary objective of this article is to determine a potential connection between mean arterial pressure (MAP) chart values and flap oxygen saturation (StO2).\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis retrospective study included 56 patients undergoing microvascular reconstruction procedures and 24-hour NIRS monitoring after surgery. All types of free flaps used are summarized in Table\u0026nbsp;\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\u003eTable all kind of free flaps used for reconstructions, explaning when they were used for oncological reconstruction, secondary reconstruction or reconstruction for benign condition (benign tumor or osteonecrosis): Fibular Flap (FF), Iliac Crest Flap (ICF), Antero-Lateral Thight Flap comprehensive of muscular component (ALT Muscle F), Antero-Lateral Thight Fascio-cutaneous Flap (ALT Thin F), Radial Forearm (RF)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eICF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eALT Muscle F\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eALT Thin F\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOncology\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBenign Condition\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSecondary reconstruction\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e56\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\u003e(Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003ePatients undergoing surgery for malignant tumors, benign pathologies, and secondary reconstructions were included in this study. Patients whose MAP or StO2 data could not be continuously recorded were excluded from this study. The NIRS system used was the HemoSphere-ForeSight by Edwards Lifesciences: the HemoSphere platform enabled the detection of StO2 values and their integration with real-time intra-arterial catheter-detected MAP values. Data were recorded by an adhesive sensor as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, chosen according to the height and width of the flap, with an investigation depth of 1.25 cm, 2 cm, and 2.5 cm.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e HemoSphere-ForeSight sensor (2 cm investigation depth) applied on a free fibula osteocutaneous flap\u003c/p\u003e \u003cp\u003eAll data refer to the first 24 hours after surgery. All patients were monitored in the Intensive Care Unit (ICU) during the first 24 hours post-surgery. The Keller algorithm was chosen to intercept and prevent potential failure [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This algorithm works on the coexistence of three conditions: reduction of tissue saturation by at least 30%, reduction of tissue saturation by 20%/hour, and sustained saturation drop over time for at least thirty minutes. Spearman's rank correlation coefficient (ρs) was used to demonstrate a correlation between MAP and StO2: A coefficient ρs\u0026thinsp;\u0026gt;\u0026thinsp;0.450 was considered positive (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 56 reconstructive procedures were performed for defects in the head and neck region. Of these patients, 31 (55%) were male, and 25 (45%) were female. The average age of the patients who underwent surgery was 51 years, with a minimum age of 19 years and a maximum of 83 years. In none of the 56 cases considered was there necrosis of the reconstructive flap. Forty-one patients underwent primary reconstruction for oncological issues, 9 patients for benign conditions (osteonecrosis or benign tumors), and 6 patients underwent secondary reconstructions, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eAmong the 56 patients studied, 16 had hypertension, and 9 had diabetes mellitus. The mean StO2 among all flaps was 82%, with the highest individual flap StO2 recorded at 89% for a fibular flap and the lowest at 64% for an iliac crest flap. The mean MAP values for the 56 patients were 81 mmHg, with a maximum of 92 mmHg in one patient and a minimum of 68 mmHg. A positive correlation (ρs\u0026thinsp;\u0026gt;\u0026thinsp;0.450, p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001) was found between StO2 and MAP in 47 of the 56 patients examined, as shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelation of MAP e StO2 curves, expressed in numbers and percentage. It is also expressed the number of patients that showed correlation per each kind of free flap\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eICF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eALT Muscle F\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eALT Thin F\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eρs\u0026thinsp;\u0026gt;\u0026thinsp;0.450\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e47 (84%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTotal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e56 (100%)\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\u003e(Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eIt was not possible to conduct an analysis to determine whether certain types of flaps showed a greater tendency to correlate between StO2 and MAP due to insufficient sample size. In all 9 remaining patients, vasopressors (norepinephrine) were administered via continuous infusion during the first 24 hours post-operatively. The average dosage of the infusion was 0.06 mcg/kg/min. The initiation of norepinephrine infusion showed a decoupling of the StO2 and MAP curves in all 9 patients, with a significant rise in MAP values throughout the infusion period, accompanied by a concurrent decrease in StO2 values, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, which reports the average MAP and StO2 values of the 9 patients.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the mean MAP e StO2 values in the first 24 hours of the 9 patients showing discoupling of the MAP and StO2 curves (ps = -0.0389)\u003c/p\u003e \u003cp\u003eThe average StO2 values for these 9 patients were 79%, while the average MAP values were 72 mmHg.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe findings from this study provide valuable insights into the outcomes of 56 reconstructive procedures in patients with head and neck defects. The choice of the reconstructive option has an anatomical and surgical basis. All fibular and iliac crest pedicles were checked preoperatively by angio-TC scan, and the anterolateral thigh flap cutaneous perforators were located using a Doppler ultrasonography scanner [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. A slightly male predominance (55%) was observed, and the average age of 51 years indicates that these procedures are commonly performed on middle-aged adults.\u003c/p\u003e \u003cp\u003eThe idea that there is a correlation between StO2 and MAP in free flaps arose because it was noticed that as StO2 values decreased, there was a concomitant decrease in MAP values. The decrease in patients' MAP values would relate to a reduced peripheral flap perfusion, with a simultaneous decrease in the tissue saturation rate. Such hemodynamic concepts are universally recognized when applied to a patient in a state of shock; therefore, one of the primary objectives is to maintain MAP at 65 mmHg [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. MAP control reduces the risk of peripheral phenomena such as stasis, thrombosis, CID, multiorgan failure syndrome (MOF), and eventually death.\u003c/p\u003e \u003cp\u003eNumerous hemodynamic studies have supported the theory of a correlation between StO2 and MAP in non-transferred tissue [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. It has never been verified whether the correlation between pressure and saturation is equally valid for the tissues of a microvascular reconstructive flap. This correlation cannot be assumed without being demonstrated, as the tissues of a transplanted flap may differ from other tissues [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. There could be many eventual drawbacks, such as a loss in vascular tone due to sympathetic/parasympathetic nervous system disruption; moreover, many metabolites such as ROS, ATP, NO, lactates, and others are released during the surgical procedure and its consequent ischemia [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. The two main hypotheses are that MAP and StO2 values in a free flap are directly linked, and that StO2 decrease is due to a reduction in tissue perfusion and not to a vascular pedicle defect or other vascular complications [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA positive correlation between MAP and StO2 was observed in 47 patients (ρs\u0026thinsp;\u0026gt;\u0026thinsp;0.450, p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). This correlation emphasizes the critical role of mean arterial pressure in ensuring adequate flap perfusion, which is crucial for flap viability [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The implication is that maintaining optimal blood pressure should be a priority in perioperative care, not only for patient homeostasis but also because poor blood pressure control could affect the outcome of free flap reconstructive surgery. Increasing knowledge in this field could lead to better postoperative monitoring protocols, allowing clinicians to identify cases of flap failure with greater precision. Further research is necessary due to the inability to analyze the correlation in specific flap types because of the limited sample sizes.\u003c/p\u003e \u003cp\u003eThe mean StO2 level of 82% suggests good tissue perfusion of the flaps. In the literature, there is no clear indication of a minimum level required for free flaps, but tissue saturation above 60% is generally considered satisfactory [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. One of the fibular flaps showed the highest StO2 (89%), while one of the iliac crest flaps showed the minimum StO2 recorded (64%). These differences may be attributed to many factors: anatomical variations, surgical techniques, or even patient-related factors such as pre-existing vascular conditions. One of the factors that may affect this is the diameter of the vascular pedicle. It is known that the average diameter of the peroneal artery is greater than that of the Deep Circumflex Iliac Artery [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The sample size of this study is not sufficient to demonstrate that a vascular pedicle with a larger diameter involves a higher average tissue saturation. This hypothesis, if verified in the future, could lead to a different interpretation of NIRS saturation data based on the type of reconstructive flap chosen. Data recording will continue, allowing further exploration of this hypothesis in future work.\u003c/p\u003e \u003cp\u003eThe administration of norepinephrine in the nine patients who exhibited decoupling between StO2 and MAP curves raises a complex question. Although norepinephrine effectively increased MAP as desired, a slight drop in StO2 values was also noted. This could indicate that regional blood flow may be compromised, potentially due to vasoconstriction of local blood vessels [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. This finding raises critical questions about the timing and necessity of vasopressor use in this context. Careful monitoring and possibly alternative strategies should be considered to maintain adequate perfusion without compromising tissue oxygenation. It is important to note that in none of the 9 patients did the norepinephrine infusion affect flap vitality, and in each case, when the infusion stopped, StO2 naturally increased to previous levels. FinaNIRS sensors have been successfully used in all patients undergoing reconstructive surgery, and can also be effectively used in the oral cavity [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAppropriate MAP values are important to support patients' vital signs and flap homeostasis. The current diagnostic criteria do not include these values in free flap monitoring; only StO2 and time factors are used. Understanding the potential link between MAP and StO2 trend values could play an important role in achieving the best possible outcome in survival rates and, if necessary, leading to anastomosis checks and eventual flap salvage surgery. If the hypothesis of a direct correlation is supported by further data and studies, this could lead to new scenarios in flap monitoring, such as including MAP values in future guidelines. This could eventually change the current medical approach.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eThis study was performed in line with the principles of the Declaration of Helsinki. This is an observational study. The S. Maria della Misericordia Hospital Research Ethics Committee has confirmed that no ethical approval is required.\u003c/p\u003e\n\u003cp\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003eThe authors affirm that human research participants provided informed consent for publication of the images in Figure 1.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMassimiliano Gilli: Study idea and work coordinatorUmberto Committeri: data collectionGabriele Monarchi: data analisysfederica sacchi: introduction and methods authorgiulio cirignaco: results and discussion authorangela rosa caso: tables and figures managerfrancesco giovacchini: validation of the studyvaleria mitro: english revisorantonio tullio: supervision\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGiovacchini F, Gilli M, Mitro V et al (2021) Rapid prototyping: Applications in oral and maxillofacial surgery. J Oral Med Oral Surg 2021;27:11\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGiovacchini F, Monarchi G, Mitro V et al (2021) Maxilla reconstruction using a free fibula flap and virtual planning. Chirurgia 34(5):227\u0026ndash;231\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKagaya Y, Miyamoto S (2018) A systematic review of near-infrared spectroscopy in flap monitoring: Current basic and clinical evidence and prospects. 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J Reconstr Microsurg 31(5):355\u0026ndash;363. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1055/s-0035-1546422\u003c/span\u003e\u003cspan address=\"10.1055/s-0035-1546422\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEdmunds MC, Czopek A, Wigmore SJ, Kluth DC (2014) Paradoxical effects of heme arginate on survival of myocutaneous flaps. Am J Physiol Regul Integr Comp Physiol 306(1):R10\u0026ndash;R22. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1152/ajpregu.00240.2013\u003c/span\u003e\u003cspan address=\"10.1152/ajpregu.00240.2013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSiemionow M, Arslan E (2004) Ischemia/reperfusion injury: a review in relation to free tissue transfers. 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J Neurosci nursing: J Am Association Neurosci Nurses 50(4):225\u0026ndash;230. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/JNN.0000000000000382\u003c/span\u003e\u003cspan address=\"10.1097/JNN.0000000000000382\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGilli M, Giovacchini F, Mitro V et al (2025) Near-Infrared Spectroscopy Sensors, Which Type to Choose and How to Fix it in Cranio- and Maxillo-facial Reconstructive Surgery: Tip and Tricks. J Maxillofac Oral Surg. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s12663-024-02426-8\u003c/span\u003e\u003cspan address=\"10.1007/s12663-024-02426-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\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":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plastic-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejps","sideBox":"Learn more about [European Journal of Plastic Surgery](https://link.springer.com/journal/238)","snPcode":"238","submissionUrl":"https://submission.nature.com/new-submission/238/3","title":"European Journal of Plastic Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Near-Infrared Spectroscopy, NIRS, Free flap monitoring, MAP, StO2, Reconstructive surgery","lastPublishedDoi":"10.21203/rs.3.rs-5790282/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5790282/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eFree flap monitoring techniques still rely on gold standard methods such as skin color evaluation, temperature, and puncture tests that are time-consuming, discontinuous, and prone to human error. Near-Infrared Spectroscopy represents a continuous, non-invasive technique that aims to avoid subjective errors by detecting early stages of vascular compromise, providing enough time for successful salvage surgery.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis retrospective study includes 56 patients undergoing microvascular reconstruction and 24-hour NIRS monitoring. All other patients without detailed MAP charts were excluded. The NIRS system used was the HemoSphere-ForeSight by Edwards Lifesciences; this platform enabled the detection of StO2 values and their integration with real-time intra-arterial catheter-detected MAP values. Data were recorded by an adhesive sensor, chosen according to the height and width of the flap.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eForty-seven (83%) patients showed a positive correlation between MAP and StO2 data (ρs\u0026thinsp;\u0026gt;\u0026thinsp;0.450, p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), validating the theory that MAP values positively correlate with flap perfusion, tissue oxygenation, and survival rate. Nine patients did not show a direct correlation between MAP and StO2 data; their values were influenced by vasopressors or psychophysical conditions during their admission to the Intensive Care Unit (ICU) after surgery.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eComparing MAP and StO2 values, their trend charts play a crucial role in flap monitoring, contributing to the best possible survival rate outcome and, if necessary, leading to micro-anastomosis checks and eventual flap salvage surgery. MAP data analysis should, indeed, be considered in future guidelines for free flap monitoring techniques.\u003c/p\u003e","manuscriptTitle":"Mean Arterial Pressure (MAP) influence on free flap oxygen saturation (StO2) measured by Near-Infrared Spectroscopy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-13 17:36:56","doi":"10.21203/rs.3.rs-5790282/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-02-06T11:55:51+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-06T01:53:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"104567353889099655005605713152819194211","date":"2025-01-22T14:38:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-16T16:45:45+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-09T15:14:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-09T15:12:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Plastic Surgery","date":"2025-01-08T15:10:59+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-plastic-surgery","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejps","sideBox":"Learn more about [European Journal of Plastic Surgery](https://link.springer.com/journal/238)","snPcode":"238","submissionUrl":"https://submission.nature.com/new-submission/238/3","title":"European Journal of Plastic Surgery","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ef1d46e2-f728-4709-9573-a4a02e302cbb","owner":[],"postedDate":"January 13th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-03T16:06:17+00:00","versionOfRecord":{"articleIdentity":"rs-5790282","link":"https://doi.org/10.1007/s00238-025-02288-4","journal":{"identity":"european-journal-of-plastic-surgery","isVorOnly":false,"title":"European Journal of Plastic Surgery"},"publishedOn":"2025-02-27 15:57:58","publishedOnDateReadable":"February 27th, 2025"},"versionCreatedAt":"2025-01-13 17:36:56","video":"","vorDoi":"10.1007/s00238-025-02288-4","vorDoiUrl":"https://doi.org/10.1007/s00238-025-02288-4","workflowStages":[]},"version":"v1","identity":"rs-5790282","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5790282","identity":"rs-5790282","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}