Associations between the intraoperative fraction of inspired intraoperative oxygen administration and days alive and out of hospital after surgery

Background

There is limited knowledge about the effect of liberal intraoperative oxygen on non-infectious complications and overall recovery from surgery.

Methods

In this retrospective cohort study, we investigated associations between mean intraoperative fraction of inspired oxygen (FiO₂), and outcome in adults undergoing elective surgery lasting more than 2 h at a large metropolitan New Zealand hospital from 2012 to 2020. Patients were divided into low, medium, and high oxygen groups (FiO₂ ≤ 0.4, 0.41–0.59, ≥0.6). The primary outcome was days alive and out of hospital at 90 days (DAOH₉₀). The secondary outcomes were post-operative complications and admission to the ICU.

Results

We identified 15,449 patients who met the inclusion criteria. There was no association between FiO₂ and DAOH₉₀ when high FiO₂ was analysed according to three groups. Using high FiO₂ as the reference group there was an adjusted mean (95% confidence interval [CI]) difference of 0.09 (−0.06 to 0.25) days (P = 0.25) and 0.28 (−0.05 to 0.62) days (P = 0.2) in the intermediate and low oxygen groups, respectively. Low FiO₂ was associated with increased surgical site infection: the adjusted odds ratio (OR) for low compared with high FiO₂ was 1.53 (95% CI 1.12–2.10). Increasing FiO₂ was associated with respiratory complications: the adjusted OR associated with each 10% point increase in FiO₂ was 1.17 (95% CI 1.08–1.26) and the incidence of being admitted to an ICU had an adjusted OR of 1.1 (95% CI 1.03–1.18).

Conclusions

We found potential benefits, and risks, associated with liberal intraoperative oxygen administration indicating that randomised controlled trials are warranted.