Poor response to surfactant therapy in RDS-infant with early patent ductus arteriosus.

ABSTRACT

A prospective study was conducted to evaluate the effect (Alvofact by Boehringer Ingelheim) on oxygen and mean airway pressure (MAP) requirements and improvements in the alveolar-arterial partial pressure of oxygen gradient (A-a PO2 gradient) in 32 preterm infants with respiratory distress syndrome (RDS), 16 infants in each group. The diagnosis of PDA was made in the presence of hyperactive precordium and/or a systolic murmur heard at upper left sternal border and confirmed by echocardiography when available, or by autopsy. The mean birthweight (1180 vs 1079 g,p=0.35) and the mean age at receiving surfactant (5.5hr vs 7.8hr, p 0.234) of the two groups were not statistically different but the initial severity of RDS in infants with early PDA (Group 1) was more. In Group 1, improvements in oxygen requirements were significant at 1 hr after treatment (p=0.01) but became nonsiginificant at 24 hours (p=.06). Sustained improvements in A-a PO2 gradient were found at 48 hrs (p=0.012). Improvements in MAP were significant at day 14 after treatment (p=0.03). In infants without early PDA (Group 2), improvements in oxygen requirement were significant at 30 min after treatment (p=0.027). Improvements in MAP and A-a PO2 gradient were significant at 5 min after treatment. Improvements in A-a PO2 gradient appeared nonsignificant at 48 and 72 hours when PDA was present and subsequently appeared significant again at 96 hours when PDA was closed by indomethacin. Mortality was significantly reduced (11 vs 2, p=0.003) in Group 2. Because only 9 infants in Group 1 lived longer than 28 days trends suggested a lower incidence of bronchpulmonary dysplasia in Group 2 (7 in 9 vs 5 in 14, p=0.083). In conclusion, RDS-infants with PDA prior to surfactant therepy have poor and transient responses to surfactant and were associated with higher mortality and higher incidence of brochopulmonary dysplasia. Early closure of PDA may benefit these infants.