Functional Residual Capacity (FRC) Does Not Predict Response to Surfactant in Preterm Infants

ABSTRACT We tested the hypothesis that the initial functional residual capacity (FRC) of preterm infants with hyaline membrane disease (HMD) could predict the response to surfactant replacement (Survanta, 4 mL/kg/dose), with a better initial FRC being correlated with a greater improvement in PaO 2 , a/A PO 2 ratio, and FRC. Thirty-four preterm infants were studied on 41 occasions. FRC and arterial blood gases were measured immediately prior to treatment. FRC was measured by the helium dilution method. Arterial blood gases were measured again after 30, 60, and 120 minutes. FRC was measured after 120 minutes. Twenty-seven treatments resulted in an increase in PaO 2 >10 mmHg (responders); 14 did not (nonresponders). There was no correlation between initial FRC, change in FRC, and change in PaO 2 (R 2 = 0.07). These results suggest that there is no relationship between initial FRC and response to surfactant treatment.