OPERATIVE CREATION OF LEFT-TO-RIGHT CARDIAC SHUNTS - PULMONARY FUNCTIONAL SEQUELAE

The creation of left to right cardiac shunts in neonates is frequently complicated by pulmonary morbidity in the immediate postoperative cou rse. To elucidate the pattern, severity, and cause of lung dysfunction , pulmonary function testing was performed preoperatively and 1, 3, an d 7 days postoperatively on 7 neonates undergoing Blalock-Taussig shun ting. Pulmonary mechanics (compliance, conductance) were determined wi th esophageal manometry and pneumotachography, and functional residual capacity was measured by the helium dilution technique. The infants h ad pulmonary function preoperatively that was similar to that of healt hy term neonatal controls. Significant decreases in compliance, conduc tance, and functional residual capacity were found on the first postop erative day (57%, 21%, and 53% of predicted, respectively). Alteration s in conductance were more severe than those in compliance, but both w ere low through postoperative day 3. Functional residual capacity was the least affected parameter and recovered by postoperative day 3. All parameters were normal by postoperative day 7. These data indicate th at shunting is associated with pulmonary morbidity through the third p ostoperative day that affects the airways more than the lung parenchym a. Pulmonary function studies of these infants may clarify the etiolog y of pulmonary dysfunction and have an impact on therapeutic strategie s used in neonates undergoing cardiac operations.