Congenital diaphragmatic hernia: immediate preoperative and postoperative oxygen gradients identify patients requiring prolonged respiratory support.

We reviewed 22 patients with congenital diaphragmatic hernias in whom operative repair was undertaken within 24 hours of age, in the period between 1970 and 1981. An improvement in survival rates since 1977 was observed. Preoperative pH, PO2, and alveolar-arterial O2 gradients (P[A-a]O2) were found to have predictive value. Patients with P(A-a)O2 greater than 500 torr both before and immediately after surgery did not survive. After an initial improvement in oxygenation some infants experienced a period of deterioration beginning at approximately 12 to 24 hours, peaking at 36 hours and improvement by 72 hours after surgery. Special attention should be directed toward maintaining aggressive cardiopulmonary support during this critical period. Reducing support prematurely may accentuate right-to-left shunting via fetal channels.