A multicenter randomized masked comparison trial of synthetic surfactant versus calf lung surfactant extract in the prevention of neonatal respiratory distress syndrome

OBJECTIVE

To compare the efficacy and safety of a synthetic surfactant (Exosurf Neonatal, Burroughs Wellcome Co) and a surfactant extract of calf lung lavage (Infasurf, IND #27,169, ONY, Inc) in the prevention of neonatal respiratory distress syndrome (RDS).

DESIGN AND SETTING

Ten-center randomized masked comparison trial.

PATIENTS

Premature infants (n = 871) <29 weeks gestational age by best obstetric estimate.

INTERVENTIONS

Infants were randomly assigned to a course of treatment with Exosurf Neonatal (n = 438) or Infasurf (n = 433) at birth, and if still intubated, at 12 and 24 hours of age. Crossover treatment was allowed within 72 hours of age if severe respiratory failure (defined as two consecutive a/A PO2 ratios </=.10) persisted after three doses of the randomized surfactant.

PRIMARY OUTCOME MEASURES

Three primary outcome measures of efficacy [the incidence of RDS; the incidence of RDS death; and the incidence of survival without bronchopulmonary dysplasia at 28 days after birth] were compared using linear regression techniques.

RESULTS

Of 871 randomized infants, 18 infants did not receive treatment with a study surfactant, and 25 infants did not meet all eligibility criteria. The primary analysis of efficacy was performed in the 846 eligible infants and analysis of safety outcomes in the 853 infants who received study surfactant. Demographic characteristics did not differ between the two treatment groups. Compared with Exosurf, Infasurf treatment resulted in a 62% decrease in the incidence of RDS (Infasurf, 16% vs Exosurf, 42%) and a 70% decrease in RDS death (Infasurf, 1.7% vs Exosurf, 5.4%) but did not increase the incidence of survival without bronchopulmonary dysplasia at 28 days. Treatment with Infasurf resulted in significant improvement in several secondary outcome measures. Infasurf-treated infants had lower average FIO2 (Infasurf, .33 [SEM] vs Exosurf, .42; difference .08; 95% confidence interval [CI], .06 to .11) and average mean airway pressure (Infasurf, 6.0 cm H2O vs Exosurf, 7.1 cm H2O; difference 1.1 cm H2O; 95% CI, .7 to 1.6 cm H2O) for the first 72 hours of life. Crossover surfactant treatment was significantly less frequent in the Infasurf compared with the Exosurf group (Infasurf, 1% vs Exosurf, 6%). Complications (bradycardia, clinical airway obstruction, and transcutaneous arterial desaturation) associated with second and third, but not initial, surfactant treatments were observed more frequently in the Infasurf treatment group. Infasurf-treated infants had significantly less air leak (</=7 days) (Infasurf, 8% vs Exosurf, 14%; adjusted relative risk [ARR] .55; 95% CI, .37 to .81). Severe intraventricular hemorrhage (IVH) (grade 3 and 4) did not differ between the two groups (Infasurf, 11.8% vs Exosurf, 8.3%; ARR 1.41; 95% CI, .94 to 2.09) but total IVH occurred more frequently in Infasurf-treated infants (Infasurf, 39.0% vs Exosurf, 29.9%; ARR, 1.30; 95% CI, 1.08 to 1.57).

CONCLUSION

Significant reductions in the incidence of RDS, the severity of early respiratory disease, the incidence of pulmonary air leaks associated with RDS, and the mortality attributable to RDS suggest that Infasurf is a more effective surfactant preparation than Exosurf Neonatal in the prophylaxis of RDS. However, Infasurf prophylaxis as used in this study was also associated with a greater risk of total but not severe IVH.

Developmental outcome in extremely premature infants. Impact of surfactant

Advances in neonatology, particularly surfactant, have enabled us to significantly improve mortality in the extremely low-birth-weight prematurely born infant. The impact on morbidity remains less clear but decidedly optimistic as the preponderance of the data currently available suggests that although we have not improved outcome in this high-risk group of infants, neither have we increased the percentage of infants with significant impairments. But overall morbidity remains high, especially for the smallest and earliest survivors. There is a growing body of research that supports the idea that with modification of the stressful impact of the NICU environment on the physiologically unstable and vulnerable premature infant, we may be able to improve developmental outcome. We are already seeing even very small infants extubated at a younger age and ready for discharge home well before their originally anticipated "due date." Within this setting we have unequalled opportunity to positively impact development by caring for the infants in a supportive environment that integrates parents as primary caretakers who are comfortable and competent at the time of the infant's discharge home. Further research endeavors should be enlightening in this regard.

The role of the neonatal intensive care nurse in the delivery room

The experienced Neonatal Intensive Care Unit (NICU) nurse is a crucial member of the delivery room resuscitation team. In a survey of tertiary centers, the neonatal nurse was the most consistent member of the team in attendance at high risk deliveries. This nursing role, including rationale, preparation for, and future potential, is explored in this article.

Impact of antenatal dexamethasone administration on respiratory distress syndrome in surfactant-treated infants

Neonatal lung disease is primarily responsible for the perinatal morbidity and mortality associated with preterm birth. Recently exogenous surfactant replacement therapy has been used to prevent or treat respiratory distress syndrome. As part of a multicenter, preventive trial between February 1986 and December 1988 using calf-lung surfactant extract, we treated 147 infants with single dose calf-lung surfactant extract. We analyzed this experience to evaluate the possibility that antenatal steroids may be additive (with calf-lung surfactant extract) in reducing both the incidence and severity of respiratory distress syndrome. Although a reduction in the incidence of respiratory distress syndrome was observed among the 33 neonates exposed to antenatal dexamethasone when compared with the 114 infants given calf-lung surfactant extract alone, the difference was not significant (37.7% vs. 24.2% p = 0.15). However, comparison of neonatal subsets previously shown to benefit most from steroid use revealed an additive effect between calf-lung surfactant extract and dexamethasone in reducing both the incidence and severity of respiratory distress syndrome. Of the 99 singleton pregnancies, only 2 of 16 infants treated with calf-lung surfactant extract and dexamethasone developed respiratory distress syndrome, compared with the 33 of 83 calf-lung surfactant extract cases (p less than 0.05). A similar reduction was observed in infants between 28 and 32 weeks' gestation (calf-lung surfactant extract, 21 of 79 vs. calf-lung surfactant extract and dexamethasone, 0 of 24; p less than 0.05). A reduction in disease severity was observed in male offspring (moderate or severe respiratory distress syndrome only; 22 of 63 vs. 2 of 22; p less than 0.05). Potential confounding variables (e.g., gestational age at birth, birth weight, exposure to tocolytics before delivery, fetal pH at birth) were similar in all comparisons. We conclude that an additive effect between dexamethasone and calf-lung surfactant extract is observed in selected cases. It may therefore be appropriate to maximize antenatal steroid use in centers where exogenous surfactant is available.