SURFACTANT THERAPY FAILURE IDENTIFIES INFANTS AT RISK FOR PULMONARY MORTALITY

Objective.-To characterize the clinical features of infants who do not respond to surfactant therapy. Design.-Patient series, chart review. Setting.-Academic referral neonatal intensive care unit. Patients/Sele ction.-Ninety-nine consecutive infants with respiratory distress syndr ome who received surfactant therapy and 107 infants from the 2 years p rior to initiation of surfactant therapy matched for birth weight, rac e, sex, gestational age, chronological age, and disease severity. Meas urements/Results.-Oxygen index was used to quantitate response to surf actant therapy. A 25% decrease in oxygen index 6 hours after the first surfactant dose was significantly different from that of the matched historical cohort (P=.04). Oxygen index decreased 25% or more in 49 in fants, the response group, while oxygen index decreased less than 25% or increased following therapy in the remaining 50 infants, the nonres ponse group. Pulmonary interstitial emphysema occurred more frequently in the nonresponse group. The only deaths from pulmonary causes at 10 days of age or younger occurred in the nonresponse group (n=11). Conc lusions.-Pulmonary processes unresponsive to surfactant therapy contri bute to morbidity and mortality in newborn respiratory distress syndro me. Classifying respiratory distress syndrome as ''surfactant responsi ve'' or 'surfactant unresponsive'' offers a scheme by which to investi gate alternative explanations and interventions for newborn respirator y distress syndrome.