Nasal high-flow use in stable copd and during exacerbation: a systematic review and meta-analysis

Introduction: The effects of high-flow nasal cannula (HFNC) on COPD patients are controversial. We aimed to investigate the effects of HFNC in stable COPD patients and during an exacerbation, compared to conventional oxygen therapy (COT) or noninvasive ventilation (NIV). Methods: A literature search was performed from the electronic databases until April 25, 2022 without language restrictions. Randomized and observational studies comparing HFNC with COT or NIV were included. The need for intubation/reintubation was the primary outcome. Secondary outcomes included treatment failure, mortality, length of hospital and ICU stay, exercise endurance time, Borg score, and comfort score. This study was registered on PROSPERO (CRD42021256238). Results: We included 12 studies (1601 patients) for treating COPD exacerbation, 7 studies (565 patients) for facilitating extubation, 10 studies (412 patients) for patients during exercise training, 4 physiologic studies (100 patients) for short-term treatment (30-60 mins), and 6 studies (658 patients) for long-term domiciliary use (4 weeks to one year). When HFNC was compared with NIV in patients with COPD under initial respiratory support and post-extubation, no significant differences were found in the risk of intubation among 4 RCTs with 297 patients (RR 0.90, 95%CI 0.46 to 1.76) and reintubation among 7 RCTs with 502 patients (RR 1.35, 95%CI 0.73 to 2.50). While HFNC was compared to COT during initial respiratory treatment for patients with COPD exacerbation, a lower risk of treatment failure was found (RR 0.58, 95%CI 0.37 to 0.89). When HFNC was compared with long-term oxygen therapy for domiciliary use, the risk of COPD exacerbations was significantly reduced (RR 0.76, 95% CI 0.58 to 0.99). During short-term use (within 2 hours), comfort scores and Borg scores between HFNC and COT were similar. HFNC was associated with a longer exercise endurance time (SMD 0.24, 95% CI 0.01 to 0.47) in patients requiring oxygen. Conclusions: HFNC might be used as an alternative to NIV for COPD exacerbation with mild-moderate hypercapnia under close monitoring and is a potential domiciliary treatment for stable COPD. More RCTs with a large sample size are needed in this population.