RESPIRATORY MECHANICS BEFORE AND AFTER LATE ARTIFICIAL SURFACTANT RESCUE

Objective: To assess the effect of late administration of synthetic su rfactant (Exosurf) on the ventilatory function of premature infants wi th hyaline membrane disease (HMD). Methodology: Prospective non-random ized study in the Neonatal Intensive Care Unit (NICU) of a major refer ral hospital. The patients included two groups of premature infants wi th a birthweight between 750 and 2000g who developed HMD. In group 1 w ith moderate to severe HMD, 2x5mL/kg doses of Exosurf were given 12h a part (first dose given at a mean age of 18.7 +/- 3.4h [mean +/- s.e.m. ]). In group 2 with milder HMD, no surfactant was given. Results: Sign ificant reductions (P<0.05) in the fraction of inspired oxygen (Flo(2) ) occurred 6h after surfactant administration (24h of life) and by 48h (64h of life) in group 2. These improvements in gas exchange preceded improvements in passive respiratory compliance which occurred 24 h af ter 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 signific ant (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 explain ed by modifications of respiratory compliance.