High-Flow Nasal Cannula Therapy for Oxygenation During Rapid Sequence Intubation in the Emergency Department: A Systematic Review.

Background: Rapid Sequence Intubation (RSI) is a critical procedure in the Emergency Department (ED).The use of High Flow Nasal Cannula Oxygen Therapy (HFNC) has emerged as a means of pre-and apnoeic oxygenation during RSI.Considering the unique environment of the ED it is essential to understand if there is a clinical benefit to the use of HFNC during RSI in the ED to guide clinical practice.Objectives: This systematic review aims to evaluate the efficacy of HFNC as an oxygenation therapy during the apnoeic phase of RSI in the ED in comparison to existing pre-oxygenation therapies.Methods: A comprehensive literature search was conducted across 5 databases on 13 th October 2025 following PRISMA guidelines.Results: Four studies (500 patients) met the inclusion criteria.Two of the four studies reported increased safe apnoea duration with HFNC (p=0.006,p=0.104).However, there were no observed changes in clinical outcomes such as rates of mortality and number of desaturation events. Conclusion:HFNC may be considered as an oxygenation strategy during the apnoeic period of RSI in the ED, although evidence for clinically meaningful benefit remains limited.