High‐Flow Nasal Oxygen Versus Conventional Oxygen Therapy and Non‐Invasive Ventilation for Acute Respiratory Failure in the Emergency Department: A Systematic Review and Meta‐Analysis

This systematic review and meta‐analysis compares the use of high‐flow nasal oxygen (HFNO) with conventional oxygen therapy (COT) and non‐invasive ventilation (NIV) in the management of acute respiratory failure (ARF) in the emergency department (ED). A comprehensive search of relevant sources was undertaken. Randomised controlled trials (RCTs) assessing adult patients (≥ 18 years) treated in the ED for ARF and comparing HFNO to COT/NIV were included. The primary outcome was the need for endotracheal intubation and mechanical ventilation (IMV). Secondary outcomes included physiological and biochemical parameters, ICU admission, hospital length of stay, dyspnoea scores and mortality. A total of 17 RCTs (1955 patients) were included. There was a significant reduction in IMV favouring the HFNO group compared to COT and NIV (RR 0.64, 95% CI 0.47–0.88). HFNO showed significant improvements in RR, SpO 2 , PaO 2 and Modified Borg Dyspnoea Scale. Subgroup analysis showed reduced rates of IMV with HFNO compared to COT (RR 0.61, 95% CI 0.41–0.91), but not compared to NIV (RR 0.69, 95% CI 0.42–1.14). HFNO additionally showed a reduction of IMV compared to NIV and COT in undifferentiated patients (RR 0.61, 95% CI 0.41–0.93), but not in exacerbations of COPD or acute heart failure. Ten of the 17 studies had at least some concern for risk of bias, with several analyses having notable heterogeneity. HFNO showed a significant reduction in rates of IMV, improvement in peripheral oxygen saturations, PaO 2 , respiratory rate and patient dyspnoea scores compared to COT and NIV.