High‐flow nasal cannula oxygen versus conventional oxygen for hypercapnic chronic obstructive pulmonary disease: A meta‐analysis of randomized controlled trials

Low-concentration oxygen is an established way for the treatment of chronic obstructive pulmonary disease (COPD) with Type II respiratory failure. Hypercapnia can complicate both COPD exacerbations and stable COPD. Treating with noninvasive ventilation (NIV) can reduce carbon dioxide tension in arterial (PaCO2 ) in hypercapnic COPD. As an open system, high-flow nasal cannula oxygen (HFNC) is easy to tolerate and use. More researches are needed to focus on how HFNC is used to treat COPD patients with hypercapnic respiratory failure.The Cochrane Library, Medline, EMBASE, and CINAHL database were retrieved from inception to October 2019. Eligible trials were clinical randomized controlled trials comparing the effects of HFNC and conventional oxygen on hypercapnic COPD patients. Two researchers assessed the quality of each study and extracted the data into RevMan 5.3 independently. The primary outcome was PaCO2 and the secondary outcome was PaO2 .Four RCTs with 329 patients were included. The research results indicated that PaCO2 in the HFNC group was similar to the conventional oxygen group. No significant difference were observed in PaCO2 (MD -0.98, CI: -2.67 to 0.71, Z = 1.14, p = 0.25) and PaO2 (MD -0.72, CI: -6.99 to 5.55, Z = 0.23, p = 0.82) between the HFNC group and conventional oxygen group.Our meta-analysis showed no difference in PO2 and PCO2 between the HFNC and conventional oxygen. But we should treat this conclusion with caution because the number of studies and participants is small and, there is heterogeneity in the PaO2 and PCO2 measurements between stable and AECOPD.