The effectiveness of vasodilators on chronic obstructive pulmonary disease: A systematic review and meta-analysis

Chronic obstructive pulmonary disease (COPD) is a complex progressive disease. Some vasodilators have been reported with therapeutic potential to protect vascular function therefore may delay the progression of COPD. We searched PubMed, Embase, Cochrane Library, Web of Science, OVID and Clinicaltrials.gov database for eligible randomized controlled trials (RCTs) published before January 1, 2024. RCTs which treatment with vasodilators to COPD patients were included. Gas-blood exchange indicators were the primary outcomes, and ventilation function and quality of life indicators were the secondary outcomes. Mean differences with 95% confidence intervals were extracted. Subgroup analysis of vasodilator category and COPD complicated with or without pulmonary hypertension (PH) were performed. The risk of bias was assessed using Cochrane risk of bias tool, and the meta-analysis was conducted. Twenty studies with a total sample size of 986 were included. The results showed that the 2 types of drugs in vasodilators included PDE-5 inhibitors could improve DLCO (MD = 6.56 [95% CI (1.74, 11.39)], P = .008) and iNO could reduce PaCO2 (MD = -0.10 [95% CI (-0.17, -0.03)], P = .006). Vasodilators could reduce PaCO2 in COPD complicated with PH (COPD-PH) (MD = -0.10 [95% CI (-0.17, -0.03)], P = .006). There were no statistically significant differences in FEV1 (MD = 0.02 [95% CI (-0.11, 0.16)], P = .74), FEV1% predicted (MD = 0.07 [95% CI (-1.90, 2.05)], P = .94), FEV1/FVC (MD = 0.70 [95% CI (-4.02, 5.42)], P = .77) and VE/VCO2 (MD = -0.17 [95% CI (-2.39, 2.05)], P = .88) levels. The total SGRQ score was significantly lower in vasodilator groups (MD = -5.53 [95% CI (-9.81, -1.24)], P = .01). The therapeutic effects of vasodilators for COPD are controversial. In this meta-analysis, vasodilators have benefits in improving gas-blood exchange function and quality of life in COPD patients. However, vasodilators may have a limited capacity to improve pulmonary function.