Effects of sildenafil on gas exchange, ventilatory, and sensory responses to exercise in subjects with mild-to-moderate COPD: A randomized cross-over trial
Abstract
Excess exercise ventilation (high ventilation (V̇E)/carbon dioxide output (V̇CO2)) contributes significantly to dyspnea and exercise intolerance since the earlier stages of chronic obstructive pulmonary disease (COPD). A selective pulmonary vasodilator (inhaled nitric oxide) has shown to increase exercise tolerance secondary to lower V̇E/V̇CO2 and dyspnea in this patient population. We aimed to assess whether a clinically more practical option - oral sildenafil - would be associated with similar beneficial effects. In a randomized, placebo-controlled study, twenty-four patients with mild-to-moderate COPD completed, on different days, two incremental cardiopulmonary exercise tests (CPET) one hour after sildenafil or placebo. Eleven healthy participants performed a CPET in a non-interventional visit for comparative purposes with patients when receiving placebo. Patients (FEV1= 69.4 ± 13.5 % predicted) showed higher ventilatory demands (V̇E/V̇CO2), worse pulmonary gas exchange, and higher dyspnea during exercise compared to controls (FEV1= 98.3 ±11.6 % predicted). Contrary to our expectations, however, sildenafil (50 mg; N= 15) did not change exertional V̇E/V̇CO2, dead space/tidal volume ratio, operating lung volumes, dyspnea, or exercise tolerance compared to placebo (P>0.05). Due to the lack of significant beneficial effects, nine additional patients were trialed with a higher dose (100 mg). Similarly, active intervention was not associated with positive physiological or…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 15 participants or records.
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