PULMONARY DYSFUNCTION AFTER PRIMARY CLOSURE OF AN ABDOMINAL-WALL DEFECT AND ITS IMPROVEMENT WITH BRONCHODILATORS

To determine the extent of pulmonary dysfunction following primary clo sure of an abdominal wall defect, we obtained pulmonary function tests (PFT) in 11 newborn infants with gastroschisis and 6 with large ompha loceles admitted to a newborn ICU in a children's hospital. Patients w ere 1 to 30 days of age at the time of the PFT; all required endotrach eal intubation and mechanical ventilation for operative procedures or for postoperative ventilatory support. Full-term infants (n = 21) unde rgoing minor surgical procedures provided comparative measurements. Fl ow-volume curves were obtained with manual inflation of the lungs foll owed by forced deflation using negative pressure, or by passive expira tion, under sedation and pharmacologic paralysis. Deflation flow-volum e curves gave measurements of forced vital capacity (FVC) and maximal expiratory flow at 25% of vital capacity from residual volume (MEF25). Modified passive mechanics technique gave passive expiratory curves t hat provided measurements of respiratory system compliance (Crs) and r esistance (Rrs). Tests were done: within 48 h (period A), 3-7 days (pe riod B), and 8-30 days after surgical repair (period C). Pulmonary fun ction testing after nebulized 0.1% isoetharine (a bronchodilator), to test for bronchial reactivity, began midway during the study period in 15 patients. Preoperative and postoperative tests were obtained in 5 patients. Closure of an abdominal wall defect decreased FVC, Crs, and MEF25 by up to 50% of normal, reference values after surgery (P < 0.05 ). FVC and MEF25 approached values of normal infants' by 4 weeks, wher eas Crs remained 50% lower. Bronchodilators improved FVC by 21% and ME F25 by up to 48% during the first week of life (both, P < 0.05), but M EF25/FVC was not significantly altered, reflecting the opening of new lung units with no effect on upstream conductance. Bronchodilators may benefit babies who have respiratory difficulties following closure of abdominal wall defects.