Safety of 80% vs 30–35% fraction of inspired oxygen in patients undergoing surgery: a systematic review and meta-analysis

Abstract

Background: Evidence-based guidelines from the World Health Organization (WHO) have recommended a high (80%) fraction of inspired oxygen (FiO 2 ) to reduce surgical site infection in adult surgical patients undergoing general anaesthesia with tracheal intubation. However, there is ongoing debate over the safety of high FiO 2 . We performed a systematic review to define the relative risk of clinically relevant adverse events (AE) associated with high FiO 2 . Methods: We reviewed potentially relevant articles from the WHO review supporting the recommendation, including an updated (July 2018) search of EMBASE and PubMed for randomised and non-randomised controlled studies reporting AE in surgical patients receiving 80% FiO 2 compared with 30e35% FiO 2 . We assessed study quality and performed meta-analyses of risk ratios (RR) comparing 80% FiO 2 against 30e35% for major complications, mortality, and intensive care admission. Results: We included 17 moderateegood quality trials and two non-randomised studies with serious-critical risk of bias. No evidence of harm with high FiO 2 was found for major AE in the meta-analysis of randomised trials: atelectasis RR 0.91 [95% confidence interval (CI) 0.59e1.42); cardiovascular events RR 0.90 (95% CI 0.32e2.54); intensive care admission RR 0.93 (95% CI 0.7e1.12); and death during the trial RR 0.49 (95% CI 0.17e1.37). One non-randomised study reported that high FiO 2 was associated with major respiratory AE [RR 1.99 (95% CI 1.72e2.31)]. Conclusions: No definite signal of harm with 80% FiO 2 in adult surgical patients undergoing general anaesthesia was demonstrated and there is little evidence on safety-related issues to discourage its use in this population.

Perioperative Hyperoxyphobia: Justified or Not? Benefits and Harms of Hyperoxia during Surgery

“…It has been theorised that hyperoxic vasoconstriction may lead to decreased tissue oxygenation [28][29][30], which might culminate in increased rates of myocardial infarction or stroke in patients treated with high perioperative FiO 2 . However, when regarding cardiovascular AE, a meta-analysis of three studies showed no signal of increased ratios of these AE in patients receiving high FiO 2 [12]. Data on the incidence of stroke and transitory cerebral ischemia are available from only one trial; no increased incidence was found in patients who received high instead of normal FiO 2 [31].…”

“…However, each of these trials had low mortality rates with wide confidence intervals, including unity. A recent systematic review and meta-analysis indicated that there was no association between high perioperative FiO 2 and short-term mortality (relative risk; RR = 0.49, 95% CI; 0.17-1.37) or long-term mortality (RR = 0.96, 95% CI; 0.65-1.42) [12].…”

“…Multiple studies report on adverse effects such as pneumonia or composite measures of respiratory complications [14,15,18,26]. A meta-analysis of all but the most recent of these studies demonstrated no increase in respiratory AE after 30 min to 4 h perioperative administration of 0.80 versus 0.30-0.35 FiO 2 , nor was there a difference in the incidence of postoperative atelectasis [12]. A post-hoc analysis [27] of over 5000 patients enrolled in a cohort study [22] confirmed that perioperative 0.80 FiO 2 does not worsen pulmonary outcome.…”

“…This guideline, developed without the involvement of anaesthetists, added to the discussion and elicited several letters from around the world criticising its conclusions [2][3][4][5][6], especially when some of the trials demonstrating a positive effect on SSI were retracted or came under scrutiny [7][8][9][10]. Recently, the World Health Organisation updated its guidelines, (now also with the support of anaesthetists), based on a new systematic review excluding the questionable trials [11], and an independent review specifically focussing on potential adverse effects of hyperoxia [12]. Although the strength of the recommendation was changed from strong to conditional, the general advice to ventilate intubated surgical patients with 0.80 FiO 2 was upheld [13].…”

PROtective Ventilation with a low versus high Inspiratory Oxygen fraction(PROVIO) and its effects on postoperative pulmonary complications:protocol for a randomized controlled trial

“…Questions have been raised about the use of oxygen in ventilated patients undergoing elective surgery. Recent systematic review revealed that the trials of this decade about the effects of FiO 2 on SSI have been inconclusive, and we should also focus on clinically relevant pulmonary side-effects and other adverse events [22][23][24][25]. In addtion, exposure to oxygen is related to adverse effects in critically ill patients [26,27].…”