Is high-flow safer than low-flow nasal oxygenation for procedural sedation?

Abstract

Each year, millions of patients in North America undergo gastrointestinal endoscopic procedures under propofol sedation without serious sequelae. The most common complication is transient non-life-threatening oxygen desaturation, which can be managed and reversed by airway maneuvers and/or adjusting the depth of sedation. Oxygen desaturation during a procedure is a surrogate outcome, but some important ‘‘hard’’ outcomes with patient and economic consequences include tracheal intubation, delayed ambulatory discharge, or unanticipated hospital admission. In the literature, different outcomes have been used to define ‘‘desaturation’’ as an adverse outcome. Some authors use a pulse oximetry (SpO2) cutoff of 92% to define desaturation, while others may use 85%. In this issue of the Journal, Kim et al. used a SpO2 cutoff of 90% to define desaturation. Irrespective of the cutoff values, all grades of hypoxia come under one umbrella term ‘‘desaturation’’. Kim et al. compared two methods of oxygen delivery in patients undergoing endoscopic retrograde cholangiopancreatography, which is a gastrointestinal endoscopic procedure commonly performed under deep sedation in the prone position. The authors randomized patients to receive oxygen using either high-flow nasal oxygen (HFNO) or conventional nasal cannula. The primary outcome of the lowest oxygen saturation measured via pulse oximetry during the procedure was found to be higher in the HFNO group than in the conventional nasal cannula group (99.8 vs 95.1%). The secondary outcomes of incidence of hypoxemia (defined as desaturation \\ 90% [0% vs 19.4%]), duration of hypoxemia (0 vs 17.4 sec), procedure interruptions due to airway intervention like discontinuing sedation (0 vs 25%), patient stimulation (0 vs 27.8%), jaw thrust maneuver (0 vs 27.8%). and end-tidal CO2 (30.4 vs 33.9 mmHg) at the end of the procedure were also better in the HFNO group. Even though the lowest SpO2 recorded in the conventional nasal cannula group was significantly lower than in the HFNO group, an oxygen saturation of 95.1% is quite acceptable in the clinical setting. Moreover, the incidence of hypoxemia of 19% for a short period of 17 sec may not be considered a clinically significant outcome. Nevertheless, the authors provided a novel and impactful clinical insight by showing that HFNO can provide excellent oxygen delivery and adequate oxygenation without any airway intervention in this challenging clinical context. The authors suggest that during this procedure, HFNO may be considered a safe, standard oxygen delivery method as compared with the use of conventional nasal cannula. The findings of Kim et al. are consistent with the results of a recently published meta-analysis which showed that the use of HFNO increased patient safety with significant reduction in episodes of oxygen desaturation, as well as the need for airway intervention. The meta-analysis included three randomized-controlled trials with 2,113 patients undergoing procedural sedation, where 1,052 patients received HFNO and 1,061 patients received conventional M. Nagappa, MD (&) Department of Anesthesia & Perioperative Medicine, London Health Sciences Centre and St. Joseph Health Care, Western University, Schulich School of Medicine and Dentistry, London, ON, Canada e-mail: [email protected]