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The monitoring of oxygen therapy when patients are admitted to medical and surgical wards could be important because exposure to excessive oxygen administration (EOA) may have fatal consequences. We aimed to investigate the association between EOA, monitored by wireless pulse oximeter, and nonfatal serious adverse events (SAEs) and mortality within 30 days. We included patients in the Capital Region of Copenhagen between 2017 and 2018. Patients were hospitalized due to acute exacerbation of chronic obstructive pulmonary disease (AECOPD) or after major elective abdominal cancer surgery, and all were treated with oxygen supply. Patients were divided into groups by their exposure to EOA: no exposure, exposure for 1-59 min or exposure over 60 min. The primary outcome was SAEs or mortality within 30 days. We retrieved data from 567 patients for a total of 43,833 h, of whom, 63% were not exposed to EOA, 26% had EOA for 1-59 min and 11% had EOA for ≥60 min. Nonfatal SAEs or mortality within 30 days developed in 24%, 12% and 22%, respectively, and the adjusted odds ratio for this was 0.98 (95% CI, 0.96-1.01) for every 10 min. increase in EOA, without any subgroup effects. In conclusion, we did not observe higher frequencies of nonfatal SAEs or mortality within 30 days in patients exposed to excessive oxygen administration.

Background: The reliability of near-infrared spectroscopy (NIRS) for measuring cerebral oxygenation (ScO 2 ) is controversial due to the possible contamination from extracranial tissues. We compared ScO 2 measured with the NIRS optode on the forehead, the skull and the dura mater in anaesthetised patients undergoing craniotomy. We hypothesised that ScO 2 measured directly on the skull and the dura mater would differ from ScO 2 measured on the skin., Methods: This prospective observational study included 17 adult patients scheduled for elective craniotomy. After induction of general anaesthesia, ScO 2 was measured on the forehead skin, as well as on the skull and on the dura mater in the surgical field. The primary comparison was the difference in ScO 2 measured on the dura mater and on ScO 2 measured on the skin; secondary comparisons were the differences in ScO 2 on the skull and ScO 2 on the skin and the dura mater, respectively. Data were described with median (5%-95% range) and analysed with the Wilcoxon signed-rank test., Results: ScO 2 values on the dura mater were obtained in 11 patients, and median ScO 2 (48%, 29%-95%) did not differ significantly from ScO 2 on the skin (73%, 49%-92%; p = .052), median difference -25% (-35.6% to -1.2%). ScO 2 on the skull (N = 16) was lower than that on the skin (63% [43%-79%] vs. 75% [61%-94%]; p = .0002), median difference -10% (-20.8 to -3.0)., Conclusion: In adults undergoing craniotomy, NIRS-based ScO 2 measured on the dura mater did not reach statistically significantly lower values than ScO 2 measured on the skin, whereas values on the skull were lower than on the skin, indicating a contribution from scalp tissue to the signal., (© 2023 The Authors. Acta Anaesthesiologica Scandinavica published by John Wiley & Sons Ltd on behalf of Acta Anaesthesiologica Scandinavica Foundation.)

Introduction: The use of high fraction of inspired oxygen (FiO 2 ) intraoperatively for the prevention of surgical site infection (SSI) remains controversial. Promising results of early randomised controlled trials (RCT) have been replicated with varying success and subsequent meta-analysis are equivocal. Recent advancements in perioperative care, including the increased use of laparoscopic surgery and pneumoperitoneum and shifts in fluid and temperature management, can affect peripheral oxygen delivery and may explain the inconsistency in reproducibility. However, the published data provides insufficient detail on the participant level to test these hypotheses. The purpose of this individual participant data meta-analysis is to assess the described benefits and harms of intraoperative high FiO 2 compared with regular (0.21-0.40) FiO 2 and its potential effect modifiers., Methods and Analysis: Two reviewers will search medical databases and online trial registries, including MEDLINE, Embase, CENTRAL, CINAHL, ClinicalTrials.gov and WHO regional databases, for randomised and quasi-RCT comparing the effect of intraoperative high FiO 2 (0.60-1.00) to regular FiO 2 (0.21-0.40) on SSI within 90 days after surgery in adult patients. Secondary outcome will be all-cause mortality within the longest available follow-up. Investigators of the identified trials will be invited to collaborate. Data will be analysed with the one-step approach using the generalised linear mixed model framework and the statistical model appropriate for the type of outcome being analysed (logistic and cox regression, respectively), with a random treatment effect term to account for the clustering of patients within studies. The bias will be assessed using the Cochrane risk-of-bias tool for randomised trials V.2 and the certainty of evidence using Grading of Recommendations, Assessment, Development and Evaluation methodology. Prespecified subgroup analyses include use of mechanical ventilation, nitrous oxide, preoperative antibiotic prophylaxis, temperature (<35°C), fluid supplementation (<15 mL/kg/hour) and procedure duration (>2.5 hour)., Ethics and Dissemination: Ethics approval is not required. Investigators will deidentify individual participant data before it is shared. The results will be submitted to a peer-review journal., Prospero Registration Number: CRD42018090261., Competing Interests: Competing interests: SWdJ reports receipt of grants from Photonics in Healthcare, Integra LifeSciences and Ethicon outside the submitted. PM reports receipt of grants or contracts from the Australian National Health and Medical Research Council (NHMRC), Practitioner Fellowship and Projects Grants, payment of expert testimony from Avant Medical Indemnity, and participation on a Data Safety Monitoring Board of Advisory Board for the SNAP, TOPIC-2 and BONANZA trials. AF reports receipt of institutional grants from the Australian Research Council Discovery Project and National Health and Medical Research Council Ideas outside the submitted work and participation on a Data Safety Monitoring Board or Advisory Board for the Australian Kidney Trials Research Network (INCH-HD, IMPEDE, TEQCH-PD, PHOSPHATE, BEST Fluids, N3RO trial, CKD-FIX, IMPROVE-FIX). RG reports participation on Steering Committee for the IntuBot Innosuisse Projekt and has a leadership role as ERC Director of Guidelines and ILCOR, and ILCOR Task Force Chair on Education, Implementation and Team, and Treasurer of European Airway Management society, and reports receipt without any payment of airway equipment for the research of the following: Intersurgical, Karl Storz, Verathon, Aircraft Medical, Prodol Meditec, Venner Medical, Kingsystems, Medtronic, Ambu, VBM, Radiometer, Sentec and Fisher & Paykel. AK reports receipt of grants or contracts from Potrero Medical, Rehabtronics and The 37Company outside the submitted work and participation on a Data Safety Monitoring Board of Advisory Board in Directed systems, Potrero Medical and BioAgel Laboratories. JM-O reports voluntary participation as a panellist in the updated WHO Guidelines on high versus low FiO2 in 2018 and voluntary coinvestigator in the PENGUIN trial of high versus low FiO2 for SSI prevention in abdominal surgery in low-income and middle-income settings with GlobalSurg Collaborative. MGWD reports participation on a Data Safety Monitoring Board or Advisory Board for the following trials: DANCE, SPHINX, ICONIC, SAFE, PACER, LEARNS, RECAP and BIOPEX2. CF reports receipt fees for lectures and educational events from Getinge and Medtronic outside the submitted work. CMS reports receipts of institutional grants from NICHD outside the submitted work. MB reports receipt of institutional grants from KCI/3M, Johnson & Johnson, New Compliance, BD Bard, Gore, Telabio, GDM, Medtronic and Smith & Nephew outside the submitted work, and participation on the Data Monitoring Committee of the EXTEND trial. MWH reports receipt of institutional grants from ZonMw outside the submitted work, consulting institutional fees from IDD Pharma outside the submitted work, institutional payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from CSL Behring outside the submitted work and has a leadership role in DGAI, ISAP and IARS (Anaesthesia and Analgesia). The other authors declare no conflict of interest., (© World Health Organization 2023. Licensee BMJ.)

Purpose: Postoperative monitoring of circulation and respiration is pivotal to guide intervention strategies and ensure patient outcomes. Transcutaneous blood gas monitoring (TCM) may allow for noninvasive assessment of changes in cardiopulmonary function after surgery, including a more direct assessment of local micro-perfusion and metabolism. To form the basis for studies assessing the clinical impact of TCM complication detection and goal-directed-therapy, we examined the association between clinical interventions in the postoperative period and changes in transcutaneous blood gasses., Methods: Two-hundred adult patients who have had major surgery were enrolled prospectively and monitored with transcutaneous blood gas measurements (oxygen (TcPO 2 ) and carbon dioxide (TcPCO 2 )) for 2 h in the post anaesthesia care unit, with recording of all clinical interventions. The primary outcome was changes in TcPO 2 , secondarily TcPCO 2 , from 5 min before a clinical intervention versus 5 min after, analysed with paired t-test., Results: Data from 190 patients with 686 interventions were analysed. During clinical interventions, a mean change in TcPO 2 of 0.99 mmHg (95% CI-1.79-0.2, p = 0.015) and TcPCO 2 of-0.67 mmHg (95% CI 0.36-0.98, p < 0.001) was detected., Conclusion: Clinical interventions resulted in significant changes in transcutaneous oxygen and carbon dioxide. These findings suggest future studies to assess the clinical value of changes in transcutaneous PO2 and PCO2 in a postoperative setting., Trial Registry: Clinical trial number: NCT04735380., Clinical Trial Registry: https://clinicaltrials.gov/ct2/show/NCT04735380., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Background: Patients with acute hypoxemic respiratory failure in the intensive care unit (ICU) are treated with supplemental oxygen, but the benefits and harms of different oxygenation targets are unclear. We hypothesized that using a lower target for partial pressure of arterial oxygen (Pao 2 ) would result in lower mortality than using a higher target., Methods: In this multicenter trial, we randomly assigned 2928 adult patients who had recently been admitted to the ICU (≤12 hours before randomization) and who were receiving at least 10 liters of oxygen per minute in an open system or had a fraction of inspired oxygen of at least 0.50 in a closed system to receive oxygen therapy targeting a Pao 2 of either 60 mm Hg (lower-oxygenation group) or 90 mm Hg (higher-oxygenation group) for a maximum of 90 days. The primary outcome was death within 90 days., Results: At 90 days, 618 of 1441 patients (42.9%) in the lower-oxygenation group and 613 of 1447 patients (42.4%) in the higher-oxygenation group had died (adjusted risk ratio, 1.02; 95% confidence interval, 0.94 to 1.11; P = 0.64). At 90 days, there was no significant between-group difference in the percentage of days that patients were alive without life support or in the percentage of days they were alive after hospital discharge. The percentages of patients who had new episodes of shock, myocardial ischemia, ischemic stroke, or intestinal ischemia were similar in the two groups (P = 0.24)., Conclusions: Among adult patients with acute hypoxemic respiratory failure in the ICU, a lower oxygenation target did not result in lower mortality than a higher target at 90 days. (Funded by the Innovation Fund Denmark and others; HOT-ICU ClinicalTrials.gov number, NCT03174002.)., (Copyright © 2021 Massachusetts Medical Society.)

Introduction: Hyperoxia after cardiac arrest may be associated with higher mortality, and trials have found that excess oxygen administration in patients with myocardial infarction is associated with increased infarct size. The effect of hyperoxia before cardiac arrest is sparsely investigated. Our aim was to assess the association between excessive oxygen administration before cardiac arrest and the extent of subsequent myocardial injury., Methods: We performed a retrospective study including patients who had in-hospital cardiac arrest during 2014 in the Capital Region of Denmark. We excluded patients without peripheral oxygen saturation measurements within 48 hours before cardiac arrest. Patients were divided in three groups of pre-arrest oxygen exposure, based on average peripheral oxygen saturation and supplemental oxygen. Primary outcome was peak troponin concentration within 30 days. Secondary outcomes included 30-day mortality. Data were analyzed using multiple logistic regression and Wilcoxon rank sum test., Results: Of 163 patients with cardiac arrest, 28 had excessive oxygen administration (17%), 105 had normal oxygen administration (64%) and 30 had insufficient oxygen administration (18%) before cardiac arrest. Peak troponin was median 224 ng/L in the excessive oxygen administration group vs 365 ng/L in the normal oxygen administration group (P = .54); 20 of 28 (71%) in the excessive oxygen administration group died within 30 days compared to 54 of 105 (51%) in the normal oxygen administration group. (OR 1.87, 95% CI 0.56-6.19) CONCLUSIONS: Excessive oxygen administration within 48 hours before in-hospital cardiac arrest was not statistically associated with significantly higher peak troponin or mortality., (© 2019 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Background: In critically ill patients, hypoxaemia is a common clinical manifestation of inadequate gas exchange in the lungs. Supplemental oxygen is therefore given to all critically ill patients. This can result in hyperoxaemia, and some observational studies have identified harms with hyperoxia. The objective of this systematic review is to critically assess the evidence of randomised clinical trials on the effects of higher versus lower inspiratory oxygen fractions or targets of arterial oxygenation in critically ill adult patients., Methods: We will search for randomised clinical trials in major international databases. Two authors will independently screen and select references for inclusion using Covidence, extract data and assess the methodological quality of the included randomised clinical trials using the Cochrane risk of bias tool. Any disagreement will be resolved by consensus. We will analyse the extracted data using Review Manager and Trial Sequential Analysis. To assess the quality of the evidence, we will create a 'Summary of Findings' table containing our primary and secondary outcomes using the GRADE assessment., Discussion: Supplemental oxygen administration is widely recommended in international guidelines despite lack of robust evidence of its effectiveness. To our knowledge, no systematic review of randomised clinical trials has investigated the effects of oxygen supplementation in critically ill patients. This systematic review will provide reliable evidence to better inform future trialists and decision-makers on clinical practice on supplemental oxygen administration in critically ill patients., (© 2018 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Background: Supplemental oxygen therapy is used for intensive care (ICU) patients with severe sepsis, but with no general guidelines and few safety data. The aim of this observational study was to describe the variability in oxygen administration as well as the association between partial pressure of arterial oxygen (PaO2 ) and mortality., Methods: We extracted data from two Scandinavian clinical trials of ICU patients with severe sepsis or septic shock. We calculated average PaO2 and fraction of inspired oxygen (FiO2 ) from trial inclusion and the following 5 days, and assessed the association between PaO2 and 90-day mortality., Results: The median PaO2 was 9.8 kPa [5-95% range 6.4-19.9] and FiO2 was 0.51 [5-95% range 0.27-1.00], respectively. Eight hundred and five of 1,770 patients (45%) died. The relative risk of mortality was 1.43 [95% CI: 1.19-1.65] in patients with average PaO2 < 8 kPa and 1.29 [95% CI: 0.84-1.68] in patients with average PaO2 ≥ 16 kPa, as compared to patients with average PaO2 10-12 kPa. The relative risk of mortality was 1.38 [95% CI: 1.17-1.58] in patients with an average FiO2 0.60-0.80 and 2.10 [95% CI: 1.88-2.23] in patients with an average FiO2  ≥ 0.80 as compared to patients with an average FiO2  ≤ 0.40., Conclusion: Administration of oxygen in patients with severe sepsis resulted in a wide range of PaO2 . Significantly higher mortality was observed in patients with an average PaO2 < 8 kPa and FiO2 ≥ 0.60. The results do not imply causation and the associations between average PaO2 and adverse outcomes have to be assessed further., (© 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Background: Available evidence on the effects of a high fraction of inspired oxygen (FIO2) of 60% to 90% compared with a routine fraction of inspired oxygen of 30% to 40%, during anaesthesia and surgery, on mortality and surgical site infection has been inconclusive. Previous trials and meta-analyses have led to different conclusions on whether a high fraction of supplemental inspired oxygen during anaesthesia may decrease or increase mortality and surgical site infections in surgical patients., Objectives: To assess the benefits and harms of an FIO2 equal to or greater than 60% compared with a control FIO2 at or below 40% in the perioperative setting in terms of mortality, surgical site infection, respiratory insufficiency, serious adverse events and length of stay during the index admission for adult surgical patients.We looked at various outcomes, conducted subgroup and sensitivity analyses, examined the role of bias and applied trial sequential analysis (TSA) to examine the level of evidence supporting or refuting a high FIO2 during surgery, anaesthesia and recovery., Search Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, BIOSIS, International Web of Science, the Latin American and Caribbean Health Science Information Database (LILACS), advanced Google and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) up to February 2014. We checked the references of included trials and reviews for unidentified relevant trials and reran the searches in March 2015. We will consider two studies of interest when we update the review., Selection Criteria: We included randomized clinical trials that compared a high fraction of inspired oxygen with a routine fraction of inspired oxygen during anaesthesia, surgery and recovery in individuals 18 years of age or older., Data Collection and Analysis: Two review authors extracted data independently. We conducted random-effects and fixed-effect meta-analyses, and for dichotomous outcomes, we calculated risk ratios (RRs). We used published data and data obtained by contacting trial authors.To minimize the risk of systematic error, we assessed the risk of bias of the included trials. To reduce the risk of random errors caused by sparse data and repetitive updating of cumulative meta-analyses, we applied trial sequential analyses. We used Grades of Recommendation, Assessment, Development and Evaluation (GRADE) to assess the quality of the evidence., Main Results: We included 28 randomized clinical trials (9330 participants); in the 21 trials reporting relevant outcomes for this review, 7597 participants were randomly assigned to a high fraction of inspired oxygen versus a routine fraction of inspired oxygen.In trials with an overall low risk of bias, a high fraction of inspired oxygen compared with a routine fraction of inspired oxygen was not associated with all-cause mortality (random-effects model: RR 1.12, 95% confidence interval (CI) 0.93 to 1.36; GRADE: low quality) within the longest follow-up and within 30 days of follow-up (Peto odds ratio (OR) 0.99, 95% CI 0.61 to 1.60; GRADE: low quality). In a trial sequential analysis, the required information size was not reached and the analysis could not refute a 20% increase in mortality. Similarly, when all trials were included, a high fraction of inspired oxygen was not associated with all-cause mortality to the longest follow-up (RR 1.07, 95% CI 0.87 to 1.33) or within 30 days of follow-up (Peto OR 0.83, 95% CI 0.54 to 1.29), both of very low quality according to GRADE. Neither was a high fraction of inspired oxygen associated with the risk of surgical site infection in trials with low risk of bias (RR 0.86, 95% CI 0.63 to 1.17; GRADE: low quality) or in all trials (RR 0.87, 95% CI 0.71 to 1.07; GRADE: low quality). A high fraction of inspired oxygen was not associated with respiratory insufficiency (RR 1.25, 95% CI 0.79 to 1.99), serious adverse events (RR 0.96, 95% CI 0.65 to 1.43) or length of stay (mean difference -0.06 days, 95% CI -0.44 to 0.32 days).In subgroup analyses of nine trials using preoperative antibiotics, a high fraction of inspired oxygen was associated with a decrease in surgical site infections (RR 0.76, 95% CI 0.60 to 0.97; GRADE: very low quality); a similar effect was noted in the five trials adequately blinded for the outcome assessment (RR 0.79, 95% CI 0.66 to 0.96; GRADE: very low quality). We did not observe an effect of a high fraction of inspired oxygen on surgical site infections in any other subgroup analyses., Authors' Conclusions: As the risk of adverse events, including mortality, may be increased by a fraction of inspired oxygen of 60% or higher, and as robust evidence is lacking for a beneficial effect of a fraction of inspired oxygen of 60% or higher on surgical site infection, our overall results suggest that evidence is insufficient to support the routine use of a high fraction of inspired oxygen during anaesthesia and surgery. Given the risk of attrition and outcome reporting bias, as well as other weaknesses in the available evidence, further randomized clinical trials with low risk of bias in all bias domains, including a large sample size and long-term follow-up, are warranted.

Background: A high perioperative inspiratory oxygen fraction (FiO2) may reduce the frequency of surgical site infection. Perioperative atelectasis is caused by absorption, compression and reduced function of surfactant. It is well accepted, that ventilation with 100% oxygen for only a few minutes is associated with significant formation of atelectasis. However, it is still not clear if a longer period of 80% oxygen results in more atelectasis compared to a low FiO2.Our aim was to assess if a high FiO2 is associated with impaired oxygenation and decreased pulmonary functional residual capacity (FRC)., Methods: Thirty-five patients scheduled for laparotomy for ovarian cancer were randomized to receive either 30% oxygen (n = 15) or 80% oxygen (n = 20) during and for 2 h after surgery. The oxygenation index (PaO2/FiO2) was measured every 30 min during anesthesia and 90 min after extubation. FRC was measured the day before surgery and 2 h after extubation by a rebreathing method using the inert gas SF6., Results: Five min after intubation, the median PaO2/FiO2 was 69 kPa [53-71] in the 30%-group vs. 60 kPa [47-69] in the 80%-group (P = 0.25). At the end of anesthesia, the PaO2/FiO2 was 58 kPa [40-70] vs. 57 kPa [46-67] in the 30%- and 80%-group, respectively (P = 0.10). The median FRC was 1993 mL [1610-2240] vs. 1875 mL [1545-2048] at baseline and 1615 mL [1375-2318] vs. 1633 mL [1343-1948] postoperatively in the 30%- and 80%-group, respectively (P = 0.70)., Conclusion: We found no significant difference in oxygenation index or functional residual capacity between patients given 80% and 30% oxygen for a period of approximately 5 hours., Trial Registration: ClinicalTrials.gov Identifier: NCT00637936.

Purpose of Review: Supplemental oxygen is often administered during anesthesia and in critical illness to treat hypoxia, but high oxygen concentrations are also given for a number of other reasons such as prevention of surgical site infection (SSI). The decision to use supplemental oxygen is, however, controversial, because of large heterogeneity in the reported results and emerging reports of side-effects. The aim of this article is to review the recent findings regarding benefits and harms of oxygen therapy in anesthesia and acute medical conditions., Recent Findings: Large randomized trials have not found significant reductions in SSI with 80% oxygen during and after abdominal surgery and cesarean section. There is no documented benefit of hyperbaric oxygen treatment for acute ischemic stroke, and there is emerging data to suggest increased mortality with normobaric supplemental oxygen for myocardial infarction without heart failure. Survival and neurologic outcome seem to be adversely affected by hyperoxia in patients with return of spontaneous circulation after cardiac arrest., Summary: The benefits of supplemental oxygen are not yet confirmed, and new findings suggest that potential side-effects should be considered if the inspired oxygen concentration is increased above what is needed to maintain normal arterial oxygen saturation.