Objectives: To determine whether fatal pulmonary hypoplasia, as assessed by functional residual capacity (FRC), can be distinguished from other reversible causes of respiratory failure in infants with congenital diaphragmatic hernia (CDH).
Methods: In the present study, 25 term neonates having CDH without other anomalies (mean birth weight +/- SD, 3.25 +/- 0.50 kg) were enrolled prospectively into a protocol evaluating pulmonary function. Lung compliance (CL) and FRC were measured before diaphragmatic repair and compared with the highest oxygenation index (OI) and lowest PaCO2, also obtained preoperatively. Pulmonary function assessment was repeated after diaphragm repair on postoperative days 3 and 7. CL was determined by esophageal manometry and pneumotachography, and FRC was determined by helium dilution.
Results: Fifteen infants (60%) survived to hospital discharge. Eighteen (72%) required extracorporeal membrane oxygenation (ECMO) for support, and of these, 8 (44%) survived. PaCO2 was similar preoperatively in infants grouped as survivors without ECMO, survivors with ECMO, and nonsurvivors. In nonsurvivors (all of whom received ECMO), the preoperative OI was significantly higher (51 +/- 21), CL was less (0.11 +/- 0.04 mL/cm of water per kg), and FRC was smaller (4.5 +/- 1.0 mL/kg) than in the survivors who required ECMO (26 +/- 18, 0.18 +/- 0.08 mL/cm of water per kg, and 12 +/- 5 mL/kg, respectively), as well as in the survivors without ECMO, (6 +/- 2, 0.32 +/- 0.16 mL/cm of water per kg, and 15.8 +/- 4 mL/kg, respectively). The group surviving with ECMO had a higher OI than the infants surviving without ECMO. All nonsurviving infants had FRCs of less than 9.0 mL/kg preoperatively. In contrast, only 2 of the 15 survivors had preoperative FRCs less than 9 mL/kg.
Conclusions: The results of this study suggest that preoperative assessment of FRC may predict fatal pulmonary hypoplasia in most infants with CDH.