Intraoperative Inspiratory Oxygen Fraction and Myocardial Injury After Noncardiac Surgery: Results From an International Observational Study in Relation to Recent Controlled Trials

Pedersen SS 1 , Holse C 1 , Mathar CE 1 , Chan MTV 2 , Sessler DI 3 , Liu Y 4 Show all authors , Zhang L 5 , Kurz A 3 , Jacka M 6 , Torborg A 7 , Biyase T 7 , Montes FR 8 , Wang CY 9 , Pettit S 10 , Devereaux PJ 10 , Meyhoff CS 1

Affiliations 

  • 1 From the Department of Anaesthesia and Intensive Care, Copenhagen University Hospital - Bispebjerg and Frederiksberg, Copenhagen, Denmark
  • 2 Department of Anaesthesia and Intensive Care, Prince of Wales Hospital, Hong Kong Special Administrative Region, China
  • 3 Department of Outcomes Research, Cleveland Clinic, Cleveland, Ohio
  • 4 Departments of Anesthesia and Intensive Care
  • 5 Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China
  • 6 Walter C. Mackenzie Health Sciences Centre, Edmonton, University of Alberta, Canada
  • 7 Discipline of Anaesthesiology and Critical Care, Inkosi Albert Luthuli Central Hospital, Nelson R. Mandela School of Medicine, University of KwaZulu-Natal, Congella, KwaZulu-Natal, South Africa
  • 8 Fundacion Cardioinfantil, Bogota, Colombia
  • 9 Department of Anaesthesiology, University of Malaya, Kuala Lumpur, Malaysia
  • 10 Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
Anesth Analg, 2022 Nov 01;135(5):1021-1030.
PMID: 35417425 DOI: 10.1213/ANE.0000000000006042

Abstract

BACKGROUND: Two trials reported that a high inspiratory oxygen fraction (F io2 ) does not promote myocardial infarction or death. Observational studies can provide larger statistical strength, but associations can be due to unobserved confounding. Therefore, we evaluated the association between intraoperative F io2 and cardiovascular complications in a large international cohort study to see if spurious associations were observed.

METHODS: We included patients from the Vascular events In noncardiac Surgery patIents cOhort evaluatioN (VISION) study, who were ≥45 years of age, scheduled for overnight hospital admission, and had intraoperative F io2 recorded. The primary outcome was myocardial injury after noncardiac surgery (MINS), and secondary outcomes included mortality and pneumonia, all within 30 postoperative days. Data were analyzed with logistic regression, adjusted for many baseline cardiovascular risk factors, and illustrated in relation to findings from 2 recent controlled trials.

RESULTS: We included 6588 patients with mean age of 62 years of whom 49% had hypertension. The median intraoperative F io2 was 0.46 (5%-95% range, 0.32-0.94). There were 808 patients (12%) with MINS. Each 0.10 increase in median F io2 was associated with a confounder-adjusted increase in odds for MINS: odds ratio (OR), 1.17 (95% confidence interval [CI], 1.12-1.23; P < .0001). MINS occurred in contrast with similar frequencies and no significant difference in controlled trials (2240 patients, 194 events), in which patients were given 80% vs 30% oxygen. Mortality was 2.4% and was not significantly associated with a median F io2 (OR, 1.07; 95% CI, 0.97-1.19 per 0.10 increase; P = .18), and 2.9% of patients had pneumonia (OR, 1.05; 95% CI, 0.95-1.15 per 0.10 increase; P = .34).

CONCLUSIONS: We observed an association between intraoperative F io2 and risk of myocardial injury within 30 days after noncardiac surgery, which contrasts with recent controlled clinical trials. F io2 was not significantly associated with mortality or pneumonia. Unobserved confounding presumably contributed to the observed association between F io2 and myocardial injury that is not supported by trials.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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