[Effect of 2 different dosages of a porcine surfactant on pulmonary gas exchange of premature infants with severe respiratory distress syndrome].

Background: Doses between 20 and 200 mg/kg body weight (bw) of different surfactant preparations have been recommended in clinical trials for the treatment of neonatal RDS; an optimal dose regimen of surfactant replacement therapy has not yet been defined. Aim of the present pilot study was the evaluation of pulmonary gas exchange in infants with severe RDS following the application of either a high (200 mg/kg bw) or a low (100 mg/kg bw) dose of a natural porcine surfactant (Curosurf).

Methods: 15 neonates were randomized to a high dose regimen, 17 infants to a low dose of surfactant. Apart from a lower 1 minute Apgar in the 100 mg/kg bw group, birth weight, gestational age, sex, 5 minute-Apgar and disease severity (arterial to alveolar oxygenation ratio (a/A-ratio): 0.10 +/- 0.03 [high dose], 0.11 +/- 0.06 [low dose], mean +/- SD) were well matched in both groups.

Results: Following surfactant instillation there was a rapid improvement in oxygenation in both groups. The a/A-ratio was slightly higher in the 200 mg/kg bw group during the first 12 hours following surfactant replacement, but statistically this was significantly higher only 4 hours after treatment (0.38 +/- 0.11 vs. 0.24 +/- 0.13, mean +/- SD, p < 0.05).

Conclusion: The dose of 100 mg/kg bw Curosurf resulted in a rapid improvement in oxygenation and ventilatory requirements; only during the first hours following surfactant replacement there was a slight further improvement with the higher dose of 200 mg/kg bw. The impact of different dose regimens on outcome parameters still has to be defined by a larger clinical trial.