Objective: To evaluate repeat surfactant therapy for the treatment of respiratory failure associated with postsurfactant slump in extremely low birth weight infants (ELBW) by characterizing the population of premature infants who develop postsurfactant slump and measuring their response to a secondary course of surfactant therapy.
Study design: A retrospective analysis of a cohort of all patients admitted over a 3-year period with birth weights <1000 g (ELBW infants). Information was collected by chart review and the patients were categorized into three distinct groups for analysis. Initial surfactant only, patients who received surfactant replacement therapy only for respiratory distress syndrome (RDS); repeat surfactant, patients who received both initial surfactant replacement for RDS and repeat surfactant therapy for postsurfactant slump (defined as respiratory failure after 6 days of age), and no surfactant, patients in whom no surfactant was ever administered. A respiratory severity score (RSS) was used to measure the severity of lung disease and response to surfactant therapy.
Results: Over 3 years, there were 165 ELBW infants who could develop postsurfactant slump and be eligible for repeat surfactant therapy. There were 39 infants who never received any surfactant therapy estimated gestational age (EGA) 27.7 +/- 1.7, birth weight 856 +/- 109 g) either at birth or after 6 days of life. There were 126 patients treated for RDS with initial surfactant replacement therapy (EGA 25.6 +/- 1.9 weeks, birth weight 713 +/- 179 g). Out of these RDS patients, 101 improved with an initial course of surfactant therapy (EGA 26 +/- 1.8, birth weight 751 +/- 143 g), but 25 (20% of the patients with RDS) developed postsurfactant slump and received a repeat course of surfactant therapy (EGA 24.7 +/- 1.2, birth weight 647 +/- 120 g). The repeat surfactant group (postsurfactant slump) was significantly more premature and had significantly lower birth weights compared to both the initial surfactant only group and the no surfactant ever group. Logistic regression analysis revealed that lack of antenatal steroids, earlier gestational age, and the receiving of 2 or more doses of surfactant to treat the initial RDS were significantly associated with receiving repeat surfactant therapy for postsurfactant slump. Of the 25 patients treated with a repeat course of surfactant therapy more than 70% of patients (n = 18) had an improvement in their lung disease with a 15% reduction in their RSS. This improvement was significant at all time points evaluated (12, 24, and 48 h).
Conclusion: We found that a repeat course of surfactant therapy, after day of life 6, led to a significant improvement in hypoxemic respiratory failure in premature infants with postsurfactant slump. Infants who received repeat surfactant therapy were born at a significantly earlier gestational age, had significantly smaller birth weight and had significantly worse lung disease. They were significantly less likely to have received antenatal steroids and were significantly more likely to have received multiple doses of surfactant to treat their initial RDS. A repeat course of surfactant therapy for patients with postsurfactant slump appeared beneficial in the short-term. These initial findings would support performing randomized control trials of repeat surfactant therapy for postsurfactant slump.