PULMONARY VASCULAR EFFECTS OF POSTOPERATIVE ANESTHESIA IN CONGENITAL DIAPHRAGMATIC HERNIA

Abstract

Because of persistent high mortality of patients(pts)with congenital diaphragmatic hernia (CDH), symptomatic within hours of birth, from persistent fetal circulation(PFC); we designed a protocol to assess the physiologic effects of general anesthesia(GA) after repair of CDH. In 12 months 10 pts, presenting at < 7hrs of age, underwent repair of left sided CDH. Cardiac catheterization was performed immediately after surgery. Postoperatively GA was maintained with fentanyl and pancuronium; using rapid ventilation (2 Hz-FiO2 1.0). Pulmonary artery(PA)and aortic pressures and prepost ductal PaO2s were continuously recorded. The ratio of shunt to total systemic blood flow(Qs/Qt) was calculated and recorded throughout the postoperative period. Three pts with severely hypoplastic lungs never improved and died from hypoxia and acidosis. Seven pts initially achieved a PaO2>150 torr after surgery 6(86%)survived; overall survival 60%. All 7pts who entered the 'honeymoon' period had a low pulmonary vascular resistance(PVR); 5 later developed suprasystemic PVR and PFC. In all but one, who died at 14 days of age, the PVR was controlled by fentanyl and ventilatory adjustments without the use of vasodilators. The Qs/Qt was initially greater than 50% in all but 2pts decreasing to less than 15% by 48hrs in all survivors. While closely monitoring the PA pressure and PaO2 the pts were gradually weaned from pressure ventilation and oxygen. These preliminary data suggest that those pts with CDH who enter the 'honeymoon' period after repair have sufficient lung tissue to survive. Prolonged GA with fentanyl may blunt the reactivity of the PVR allowing postnatal maturation of the pulmonary circulation, obviating the need for potentially dangerous vasodilators. When coupled with careful monitoring these techniques may improve the survival of pts with CDH.