High- versus low-intensity noninvasive ventilation in hypercapnic chronic obstructive pulmonary disease: a systematic review and meta-analysis

Noninvasive ventilation (NIV) is widely used in acute and chronic respiratory failure, but the comparative clinical benefits of high- versus low-intensity noninvasive positive pressure ventilation (NPPV) in hypercapnic chronic obstructive pulmonary disease (COPD) remain uncertain. We conducted a systematic review and meta-analysis of randomized controlled trials comparing high-intensity NPPV (HI-NPPV) with low-intensity NPPV (LI-NPPV) in adults with hypercapnic COPD, analyzing acute exacerbations and stable chronic disease separately. PubMed/MEDLINE, Embase, Scopus, Web of Science, the Cochrane Library, and LILACS were searched without date restrictions. Random-effects models were used to pool mean differences (MD) or standardized mean differences (SMD) with 95% confidence intervals. Eight randomized trials were included. In acute exacerbations, HI-NPPV was associated with a significant reduction in daytime arterial carbon dioxide tension (PaCO₂) compared with LI-NPPV (MD -20.72 mmHg, 95% CI -36.12 to -5.31; I² = 89%). In stable chronic hypercapnic COPD, the reduction in PaCO₂ was not statistically significant (MD -6.31 mmHg, 95% CI -16.64 to 4.03; I² = 89%). HI-NPPV was also associated with a significant improvement in dyspnea overall (SMD -0.89, 95% CI -1.45 to -0.32), with effects observed in both chronic (SMD -0.66) and acute settings (SMD -1.46). No clear benefit was demonstrated for all-cause mortality or endotracheal intubation rates. The certainty of evidence ranged from low to very low due to heterogeneity and methodological limitations. In conclusion, HI-NPPV provides greater reductions in hypercapnia during acute exacerbations and moderate improvements in dyspnea compared with LI-NPPV. However, evidence for benefits in hard clinical outcomes remains limited.