RESUMO
Hemodynamic effects of orally-administered nifedipine were evaluated in 12 patients with pulmonary hypertension secondary to severe COPD after short-term (30 and 60 minutes) treatment and then again in eight of these 12 patients after long-term (average 55 days) treatment. Pulmonary vascular resistance (PVR) decreased from 426 +/- 52 to 294 +/- 28 dynes.s.cm-5 (p less than 0.001) after therapy with 20 mg sublingual nifedipine (at 60 minutes). Cardiac index (CI) increased from 3.7 +/- 0.2 to 4.6 +/- 0.3 L/min/m2 (p less than 0.001). There was a decrease in mean pulmonary artery pressure (MPAP) only in 4/12 patients after Nifedipine. There was no significant fall in PaO2, while PvO2 and oxygen delivery (CI X CaO2) increased significantly 60 minutes after administration of sublingual nifedipine. PVR decreased from 482 +/- 82 to 374 +/- 44 dynes.s.cm-5 (p less than 0.05) after long-term nifedipine therapy. The changes in PVR and CI 60 minutes after administration of nifedipine in the patients on long-term treatment were similar to those observed with the same doses of nifedipine before initiation of therapy. Despite beneficial hemodynamic effects in two of eight patients, there was progressive clinical worsening. The benefit of long-term administration of nifedipine is difficult to predict on the basis of short-term effects.