Noninvasive respiratory support for preoxygenation in emergency intubation: a systematic review and network meta-analysis

Background: The benefits of preoxygenation with noninvasive respiratory support (NRS), including high-flow oxygen therapy (HFOT) and noninvasive ventilation (NIV), compared to conventional oxygen therapy (COT) during emergency endotracheal intubation (ETI) remain unclear. This network meta-analysis aims to evaluate whether preoxygenation with NRS is more effective than COT in minimising the lowest recorded peripheral capillary oxygen saturation (S pO2 ) during emergency ETI. Methods: A comprehensive literature search was conducted (PROSPERO-CRD42024606842) across Medline, Embase and Scopus. The PICOS criteria were: P: critically ill adult patients requiring emergency ETI; I: randomisation for receiving preoxygenation with NRS; C: randomisation for COT; O: the lowest recorded S pO2 during emergency intubation (and additional secondary outcomes); S: randomised clinical trials (RCTs). Results: 15 RCTs (2939 patients) met the inclusion criteria. Compared to COT, all NRS methods improved the lowest S pO2 during emergency ETI (mean difference for HFOT was 1.50, 95% CI 0.43-2.58, p=0.006; for NIV was 3.30, 95% CI 1.81-4.79, p<0.001) (low evidence). Moreover, NIV reduced the occurrence of severe desaturations (S pO2 <80%) (OR 0.31, 95% CI 0.15-0.61, p<0.001) (very low evidence). Finally, preoxygenation with NRS did not increase the risk of complications (including aspiration, hypotension, barotrauma, arrhythmia or cardiac arrest), and no differences were found in postintubation gas exchange, mechanical ventilation or mortality compared to COT. Interpretation: During emergency ETI in critical care areas, despite a low certainty of evidence, preoxygenation with NRS overperformed COT in maintaining S pO2 . Only NIV reduced the incidence of severe desaturation, while the risk of complications and adverse events was similar across different preoxygenation devices.