Comparison of preoxygenation efficiency measured by the oxygen reserve index between high-flow nasal oxygenation and facemask ventilation: A randomized controlled trial

Abstract BackgroundThe novel high-flow nasal oxygenation is gaining popularity for preoxygenation. The oxygen reserve index (ORI), which is a non-invasive and innovative modality that reflects the arterial oxygen content, are recently introduced in general anesthesia. In our study, we compared the preoxygenation efficiency of high-flow nasal oxygenation and facemask ventilation using the ORI in adult patients undergoing general anesthetic induction for non-emergent surgery.MethodsThis single-center, two-group, randomized controlled trial included 197 patients aged ≥20 years who underwent orotracheal intubation for general anesthesia for elective surgery. The patients were randomly allocated to receive preoxygenation via facemask ventilation or high-flow nasal oxygenation. The ORI was monitored continuously during anesthetic induction period until the endotracheal intubation was completed, and compared between the two groups. The primary outcome was the highest ORI value achieved by oxygenation. The secondary outcome was the time required to reach the highest ORI observed during the induction of anesthesia.ResultsThe ORI increased during preoxygenation in all patients and tended to decrease from the injection of the neuromuscular blockers to the completion of intubation. At 1 minute of preoxygenation, the ORI was significantly higher in the high-flow nasal oxygenation group (0.34 ± 0.33) than in the facemask ventilation group (0.21 ± 0.28; P = 0.003). The highest ORI was not significantly different between the two groups (0.68 ± 0.25 in the high-flow nasal oxygenation group vs. 0.70 ± 0.28 in the facemask ventilation group; P = 0.505). The time required to reach the highest ORI value was not significantly different between the two groups (3.1 ± 2.2 minutes in the high-flow nasal oxygenation group and 3.6 ± 2.2 minutes in the facemask ventilation group; P = 0.113).ConclusionsHigh-flow nasal oxygenation results in an ORI-measured oxygenation state similar to that provided by facemask ventilation during the general anesthesia induction. We conclude that high-flow nasal oxygenation is a feasible and alternative preoxygenation technique for facemask ventilation.Trial RegistrationThis study was registered at clinicaltrials.gov (registration number: NCT04291339, registration date: 02/03/2020)