Short-Term Outcomes of Low Versus High Inspiratory Oxygen Fraction During Induction of General Anesthesia in Noncardiac Surgery: A Pragmatic Open-Label Randomized Non-Inferiority Trial

Background. High inspiratory oxygen fraction (FIO 2 ) is associated with increased perioperative pulmonary morbidity and postoperative mortality. However, the use of pure oxygen is still currently recommended during the anesthesia induction. Methods, This open-label randomized non-inferiority trial was conducted in two metropolitan hospitals at Southern Taiwan. A total of 302 surgical patients (ASA PC≤III) who received endotracheal general anesthesia (ETGA) were randomized to receive 100% (FIO 2 1.0) or 60% (FIO 2 0.6) oxygen during induction. The primary endpoint was presence of hypoxemia (SpO 2 ≤92%) during the induction of anesthesia. The secondary endpoint was the development of major complications immediately and within 3 days after surgery. Results. A total of 5 patients in the FIO 2 0.6 group developed hypoxemia during induction (3.9% vs 0% for FIO 2 0.6 vs FIO 2 1.0, respectively; P=0.167 for non-inferiority), suggesting that FIO 2 0.6 was inferior than FIO 2 1.0 for anesthesia induction. The mean lowest SpO 2 during induction was also significantly lower in FIO 2 0.6 group. Four patients reached the primary endpoint had increased body mass indexes (BMI>30 kg/m 2 ). However, the overall incidence of desaturation developed after removal of endotracheal tube was higher in FIO 2 1.0 group (1.4% vs 5.8%, FIO 2 0.6 vs FIO 2 1.0; odd ratio 0.22, 95% confidence interval 0.05-1.05; P=0.064). Conclusions. High fractions of oxygen should be used for oxygenation during induction of ETGA in general population, especially in the obese patients. However, the supplement of high FIO2 during induction was associated with increased hypoxemic events after removal of endotracheal tube that might have a more significant impact on perioperative care.