Oral Sildenafil has No Acute Effect on Diffusion Capacity Measurements inPatients with Diffuse Parenchymal Lung Disease and Pulmonary Hypertension

Abstract

Diffuse parenchymal lung diseases have diverse etiology and treatment often requires individualization taking into consideration comorbidities. Pulmonary hypertension represents one such comorbidity which, when present, worsens prognosis and confounds approach to treatment. Sildenafil is a pulmonary vasodilator, which has recently generated considerable interest for use in patients with diffuse parenchymal lung disease and concomitant pulmonary hypertension. We wondered whether acute administration of oral sildenafil affects the diffusion capacity measurement, which is a tool for serially monitoring patients with diffuse parenchymal lung diseases. Methods: 15 patients with diffuse parenchymal lung disease and pulmonary hypertension (WHO Class III) had diffusion capacity measurements and 6 minute walk test performed before and after receiving sildenafil 20 mg orally. CT scans of the chest were scored to determine burden of interstitial lung disease. Results: The mean change in DLCO after administration of oral sildenafil was -0.26 ± 0.94 ml/min/mmHg (p=0.30) and -0.41 ± 2.84 % predicted (p=0.58). The average 6 minute walk distance at baseline was 363.28 ± 141 meters. After oral administration of sildenafil, 6 minute walk distance was 369 ± 116 meters (p=0.63). No correlation was observed between composite radiology scores and DLCO measurements or change in DLCO and radiology scores (p=0.43 and p=0.17 respectively). Conclusion: We found no acute change in diffusion capacity after a single dose of oral sildenafil in patients with diffuse parenchymal lung disease and pulmonary hypertension.