Purpose: This study aimed to evaluate the clinical outcomes of high-flow nasal cannula (HFNC) compared with conventional oxygen therapy (COT) in patients with hypercapnic chronic obstructive pulmonary disease (COPD), including arterial partial pressure of carbon dioxide (PaCO₂), arterial partial pressure of oxygen (PaO₂), respiratory rate (RR), treatment failure, exacerbation rates, adverse events and comfort evaluation.
Patients and Methods: PubMed, EMBASE and the Cochrane Library were retrieved from inception to September 30, 2022. Eligible trials were randomized controlled trials and crossover studies comparing HFNC and COT in hypercapnic COPD patients. Continuous variables were reported as mean and standard derivation and calculated by weighted mean differences (MD), while dichotomous variables were shown as frequency and proportion and calculated by odds ratio (OR), with the 95% confidence intervals (Cl). Statistical analysis was performed using RevMan 5.4 software.
Results: Eight studies were included, five with acute hypercapnia and three with chronic hypercapnia. In acute hypercapnic COPD, short-term HFNC reduced PaCO₂ (MD − 1.55, 95% CI: − 2.85 to − 0.25, I² = 0%, p < 0.05) and treatment failure (OR 0.54, 95% CI: 0.33 to 0.88, I² = 0%, p< 0.05), but there were no significant differences in PaO₂ (MD − 0.36, 95% CI: − 2.23 to 1.52, I² = 45%, p=0.71) and RR (MD − 1.07, 95% CI: − 2.44 to 0.29, I² = 72%, p=0.12). In chronic hypercapnic COPD, HFNC may reduce COPD exacerbation rates, but there was no advantage in improving PaCO₂ (MD − 1.21, 95% CI: − 3.81 to 1.39, I² = 0%, p=0.36) and PaO₂ (MD 2.81, 95% CI: − 1.39 to 7.02, I² = 0%, p=0.19).
Conclusion: Compared with COT, short-term HFNC reduced PaCO₂ and the need for escalating respiratory support in acute hypercapnic COPD, whereas long-term HFNC reduced COPD exacerbations rates in chronic hypercapnia. HFNC has great potential for treating hypercapnic COPD.
Keywords: nasal high-flow oxygen therapy, conventional oxygen therapy, hypercapnia, chronic obstructive pulmonary disease, meta-analysis