Efficacy of high-flow nasal oxygenation during induction of general anaesthesia in parturients living with obesity: a two-centre, prospective, randomised clinical trial.

Abstract

High-flow nasal oxygenation has been shown to improve oxygenation during induction of anaesthesia in parturients who are not obese. However, data on the efficacy of high-flow nasal oxygen in parturients living with obesity are lacking. This study investigated the effects of high-flow nasal oxygenation on pre-oxygenation and apnoea oxygenation during tracheal intubation in parturients living with obesity. This prospective, randomised clinical trial was conducted at two tertiary hospitals and included parturients with BMI > 30 kg.m^-2 undergoing scheduled caesarean delivery under general anaesthesia. Parturients were allocated randomly to standard facemask or high-flow nasal oxygen groups (oxygen flow rates 10 l.min^-1 and 50 l.min^-1, respectively). The primary outcome measure was arterial partial pressure of oxygen after 3 min of pre-oxygenation. 54 patients completed the study. The arterial partial pressure of oxygen after 3 min of pre-oxygenation was significantly lower in parturients allocated to the standard facemask group compared with those allocated to the high-flow nasal oxygen group (mean (SD) 40.1 (8.9) kPa vs. 53.8 (9.7) kPa, p < 0.001). End-tidal oxygen concentration on commencing ventilation was also lower in parturients allocated to the standard facemask group compared with those allocated to the high flow-nasal oxygen group (mean (SD) 78.3 (5.38)% vs. 86.2 (5.10)%, p < 0.001). The arterial partial pressure of carbon dioxide post tracheal intubation and fetal outcomes were similar in both groups. Pre-oxygenation using high-flow nasal oxygenation provided a higher arterial partial pressure of oxygen and end-tidal oxygen concentration during general anaesthesia induction than standard facemask oxygenation in parturients living with obesity; however, the differences were not clinically meaningful. High-flow nasal oxygenation may be considered as an alternative option for pre-oxygenation during rapid sequence induction in parturients living with obesity.