Objective: To assess the effect of late administration of synthetic surfactant (Exosurf) on the ventilatory function of premature infants with hyaline membrane disease (HMD).
Methodology: Prospective non-randomized study in the Neonatal Intensive Care Unit (NICU) of a major referral hospital. The patients included two groups of premature infants with a birthweight between 750 and 2000 g who developed HMD. In group 1 with moderate to severe HMD, 2 x 5 mL/kg doses of Exosurf were given 12 h apart (first dose given at a mean age of 18.7 +/- 3.4 h [mean +/- s.e.m.]). In group 2 with milder HMD, no surfactant was given.
Results: Significant reductions (P < 0.05) in the fraction of inspired oxygen (FIO2) occurred 6 h after surfactant administration (24 h of life) and by 48 h (64 h of life) in group 2. These improvements in gas exchange preceded improvements in passive respiratory compliance which occurred 24 h after surfactant (42 h of life) and by 72 h (88 h of life) in group 2 (P < 0.01). In both groups pulmonary resistance increased and was significant (P < 0.05) by 48 h (66 h of life) in group 1.
Conclusions: Synthetic surfactant given as late as a mean age 18.7 +/- 3.4 h still improves gas exchange but these early improvements cannot be completely explained by modifications of respiratory compliance.