High flow nasal oxygen versus conventional oxygen therapy in gastrointestinal endoscopy with conscious sedation: Systematic review and meta-analysis with trial sequential analysis

Objectives: Although conventional oxygen therapy (COT) is widely used, hypoxemia frequently occurs in gastrointestinal endoscopy with conscious sedation and can lead to life-threatening consequences. High flow nasal oxygen (HFNO) has been applied to improve oxygenation in clinical entities. However, its efficacy to prevent hypoxemia in gastrointestinal endoscopy with conscious sedation has not been evaluated. Methods: We searched databases to identify randomized controlled trials that compared the efficacy of HFNO with COT in gastrointestinal endoscopy with conscious sedation. The primary outcome was hypoxemia. Meta-analyses with trial sequential analysis were performed using a random-effects model. Results: Eight trials with 3212 patients were included. Compared with COT, HFNO significantly reduced the risk of hypoxemia (eight trials; 3212 patients; risk ratio 0.30; 95% confidence interval [CI] 0.13-0.70). Trial sequential analysis showed that the cumulative Z curve did not cross the monitoring or futility boundaries, nor reach the required information size line, indicating that more trials are needed to reach a definitive conclusion. Subgroup analyses indicated the superiority of HFNO over COT with respect to hypoxemia in patients at low risk and high risk. HFNO further improved the lowest oxygen saturation (four trials; 459 patients; mean difference 2.30, 95% CI 0.84-3.77). Conclusions: Compared with COT, HFNO can reduce the risk of hypoxemia and improve the lowest oxygen saturation in gastrointestinal endoscopy with conscious sedation. However, the results should be interpreted with caution due to substantial heterogeneity and limited evidence. Further studies are needed to verify the preliminary findings.