PHYSIOLOGICAL ANALYSIS OF PULMONARY HEMODYNAMICS IN INFANTS WITH PULMONARY HYPERTENSION ASSOCIATED

Abstract

Pulmonary hypertension is a serious complication in patients with bronchopulmonary dysplasia. The author studied the effect of tolazoline and 100% oxygen on pulmonary hemodynamics in 12 infants including 11 who were oxygen-dependent with bronchopulmonary dysplasia and pulmonary hypertension. Cardiac catheterizations were performed on all cases, at 4 months to 4 years of age. Mean pulmonary arterial pressure and pulmonary vascular resistance were measured (1) before and after tolazoline injection (1 mg/kg, into the main pulmonary artery), then after a 30-minute stabilization period, (2) before and after a 5-minute 100% oxygen inhalation period. In room air, the arterial O2 saturation values were 87 ± 6 %, the mean pulmonary artery pressure values were 39 ± 4 mmHg, the pulmonary vascular resistance values were 7.7 ± 1.2 Wood units·m2. After tolazoline injection and the 5-minute 100% oxygen inhalation, the mean pulmonary artery pressure decreased significantly (p<0.01). The percent decrease in mean pulmonary artery pressure after inhaling 100% oxygen for 5 minutes was greater than that after tolazoline injection (p<0.05). There were no correlations between the percent decrease in mean pulmonary artery pressure after the 100% oxygen inhalation and that following tolazoline injection. The percent decrease in mean pulmonary artery pressure after 100% oxygen inhalation was inversely related to the arterial oxygen saturation in room air (r=0.68, p<0.05), while that after tolazoline injection was not.