Nifedipine inhibits hypoxic pulmonary vasoconstriction during rest and exercise in patients with cystic fibrosis and cor pulmonale

Nifedipine has recently been reported to reduce pulmonary artery pressure and pulmonary vascular resistance during rest and exercise in adult patients with hypoxic pulmonary hypertension from chronic obstructive pulmonary disease. To determine whether nifedipine reduces pulmonary vascular resistance in patients with cor pulmonale from cystic fibrosis (CF), we studied 2 patients with severe CF lung disease during rest and exercise while breathing room air or receiving low-flow oxygen therapy. Nifedipine markedly lowered pulmonary vascular resistance and improved cardiac index and pulmonary pressure-flow relationships during all treatment conditions. Nifedipine did not substantially change arterial P(O₂), except for a slight decrease during exercise while receiving low-flow oxygen. Nifedipine, however, markedly increased oxygen delivery during rest and exercise. Both patients noted improved exercise tolerance with chronic nifedipine therapy. Nifedipine may be a useful adjuvant to supplement oxygen in the treatment of patients with CF and cor pulmonale.