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Excerpt
The impact of surfactant therapy on survival and neurodevelopmental outcome was examined in a retrospective cohort study of 891 infants born at 23 to 26 weeks of gestational age. The 421 infants born in 1982–1987, before the advent of rescue therapy with natural surfactant, were compared with 470 infants born in 1990–1994, when surfactant was available. Motor function and cognitive ability were monitored at intervals up to 2 years of age. In addition, brainstem-evoked audiometric responses were examined, and the infants were evaluated ophthalmologically. For cognitive screening, the Diagnostic Inventory for Screening Children and the Bayley Scales of Infant Development were used.
Mortality decreased significantly in the postsurfactant years for infants inborn at 24 and 26 weeks’ gestational age. Mortality also declined with advancing gestational age and increasing birth weight in both the pre- and postsurfactant groups. Mortality was significantly higher among surfactant-treated infants (49 vs. 34%), a difference significant at the P = .04 level. The mortality risk also was greater for offspring of multiple pregnancies, growth-restricted infants, and those with severe intraventricular hemorrhage. Female infants, black infants, and those given dexamethasone had a survival advantage. Of infants born in the postsurfactant era, 57% actually received rescue surfactant therapy. The rate was significantly higher for outborn infants. Rates of chronic lung disease and bilateral blindness declined over time, whereas the incidence of cerebral palsy, cognitive deficit, and aided sensorineural hearing loss remained quite stable. In both time periods, 65% of surviving infants had no neurodevelopmental impairment. The risk of severe impairment decreased over time. Neurodevelopmental outcomes were similar for surfactant-treated infants and untreated survivors.
These findings indicate that surfactant is not the sole reason for improved survival of extremely premature infants. At the same time, it seems advantageous for these infants to be born at high-risk perinatal centers.
(This retrospective case-control study of a large cohort of extremely low-birth weight infants in Central East and Northern Ontario evaluated the impact of “rescue” surfactant therapy on survival and developmental outcome through 24 months of age. Births that occurred before the use of surfactant therapy (1982–1987) were compared with those that occurred after surfactant therapy was introduced (1990–1994). Surfactant was administered to infants who developed signs and symptoms of respiratory distress syndrome and was therefore defined as “rescue” therapy. Although the study showed no change in overall mortality of infants born between 23 and 26 weeks’ gestation between the two periods, there was a significant reduction in chronic lung disease and severe developmental impairment in infants born in the period of surfactant use. Also, the study found a significant improvement in survival in the postsurfactant era for infants at 24 and 26 weeks’ gestation who were born in the tertiary center as compared with those of the same gestational age who were transported after birth in regional hospitals.
In the period of surfactant therapy, the death rate for infants who received rescue treatment was higher than those who did not, but this is surely a reflection of the severity of illness in the surfactant treat group. In other words, “rescue” surfactant treatment was a marker for severity of illness. A review of the recent evidence found that prophylactic as compared with “rescue” administration of surfactant significantly decreased infant mortality and morbidity (RF Soll, Cochrane Database of Systematic Reviews, Issue 4, 2000).
