Babybodyplethysmography in infants and children with congenital heart disease and pulmonary hypertension

We investigated pulmonary mechanics in 46 children (27 males, 19 females) w ith congenital heart defects with left-to-right shunt and pulmonary hyperte nsion. Patients ranged in age from 6 weeks to 4 years. Babybodyplethysmogra phy studies were performed before corrective heart surgery, and again at 2 weeks and 6 months after surgery. Preoperative pulmonary function data were compared to hemodynamic data obtained during cardiac catheterization: pulm onary artery pressure, oxygen saturation, and ratios of pulmonary to system ic blood flow (Qp/Qs) and vascular resistance (Rp/Rs). Airway resistance wa s elevated before surgery to 148% of predicted and it dropped significantly to normal levels, 104% of predicted, only 6 months after surgery. Function al residual capacity (FRCpleth) was increased to 127% of predicted before s urgery and normalized significantly to 101% of predicted within the same ti me period. On the other hand, breathing frequency and minute volume, indexe d to body weight, decreased significantly in the 2 weeks after surgery. Sta tistical analysis of the hemodynamic data and lung function tests showed on ly a poor linear correlation between functional residual capacity and oxyge n saturation in the pulmonary artery (r = 0.26-0.37) and the Rp/Rs ratio (r = 0.38). Airway resistance also correlated poorly with the Qp/Qs and Rp/Rs ratios (both r = 0.29). In young children with heart defects with increase d pulmonary blood flow and pulmonary hypertension, lung mechanics are abnor mal leading to bronchial obstruction and hyperinflation. Additional studies of dynamic lung compliance and elastance will be needed to look for inters titial lung alterations in these patients. (C) 1998 Elsevier Science Irelan d Ltd. All rights reserved.