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

Summary Introduction 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. Methods 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. Results 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. Discussion 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.