RATE OF SURFACTANT ADMINISTRATION INFLUENCES LUNG-FUNCTION AND GAS-EXCHANGE IN A SURFACTANT-DEFICIENT RABBIT MODEL

The aim of this study was to test whether the effect of surfactant tre atment on lung function in a surfactant-deficient animal model can be influenced by the rate at which surfactant is administered. Surfactant deficiency was induced in 18 New Zealand white rabbits (weighing appr ox. 1 kg each) by lung lavage with normal saline. The arterial/alveola r oxygen ratio (a/A ratio), functional residual capacity (FRC), dynami c compliance of the respiratory system (C-rs), tidal volume (V-T), alv eolar portion of the tidal volume (V-A) and arterial P-CO2 (P-a,P-CO2) were measured before and after ravage and 15, 30, 60, 90, and 120 min after administration of a single dose of surfactant (Survanta(R), 100 mg/kg). Two surfactant administration protocols were compared over a 2-h interval: an infusion lasting 4 min and an infusion over 2 min. Bo th administrations were given during continuous mechanical ventilation . The six lung function and gas exchange parameters improved significa ntly following surfactant administration over 2 min compared with a co ntrol group. However, only the a/A ratio and V-A improved following th e 4-min protocol. Comparison of the two intervention protocols yielded significantly differences in V-A and P-a,P-CO2, favoring the shorter administration, These results support the hypothesis that fast (2 min) administration of surfactant will improve its distribution to formerl y collapsed alveoli and results in better lung function, improved vent ilation, and (to a lesser extent) better oxygenation than prolonged in fusions (4 min). (C) 1998 Wiley-Liss, Inc.