Hypoxia-induced pulmonary hypertension: nifedipine only temporarily reduces pulmonary artery pressure and vascular tone.

Fifteen patients affected by hypoxia-induced pulmonary hypertension were studied before and during (1st and 8th week) nifedipine (180 mg/die) treatment. Nifedipine reduced pulmonary pressure (33 +/- 4 vs 26 +/- 3 mmHg, p less than 0.02) after 1 week of treatment; this pulmonary hypotensive effect was due to a reduction of pulmonary vascular tone as assessed by a reduction of Y-intercept on the pulmonary pressure/flow plot drawn from invasive recordings of pulmonary pressure/cardiac output obtained during exercise. Oxygen breathing effects on pulmonary pressure were also measured with and without nifedipine. Oxygen significantly reduced pulmonary pressure only in the absence of nifedipine regardless of the severity of pulmonary hypertension. Therefore nifedipine is not suitable for long-term treatment of hypoxia-induced pulmonary hypertension and inhibits O2 capability to reduce pulmonary pressure.