Effects of nifedipine and oxygen on pulmonary haemodynamics in severe scoliosis.

In the present study the response of the pulmonary circulation to a vasodilator agent (nifedipine) and to low-flow oxygen (FiO2 35%) has been studied both at rest and during exercise (steady state, 25 W) in nine patients with severe scoliosis (spinal curve + 100 degrees, FVC 38%). All patients were dyspneic on exertion and had had at least one episode of right heart failure. The mean pulmonary artery pressure (Pap) ranged from 13 to 37 mmHg at rest and ranged from 30 to 75 mmHg during exercise. Standard exercise, performed 60 min after 20 mg sublingual nifedipine, was associated with a reduction in mean Pap (49 mmHg) as compared with exercise performed during the control period (58 mmHg, p less than 0.001). Pulmonary vascular resistance (PVR) on exercise decreased more on nifedipine (28.9%) than on oxygen (13.9%) (p less than 0.05). Our results suggest that nifedipine improves pulmonary haemodynamics in patients with severe scoliosis complicated by cor pulmonale.