The aim of the study was to investigate lung function and morphology in newborn rabbits with acute
respiratory failure induced by airway instillation of
albumin and to test whether the
therapeutic effect of exogenous modified natural
surfactant could be enhanced by addition of
dextran. Rabbits (gestational age 29 days) were ventilated with 100% O2 and tidal volume 8-10 ml/kg.
Respiratory failure was induced by tracheal instillation of
albumin (50 or 100mg/ml; 2 ml/kg) and the instillation was repeated 15 min later.
Surfactant (
Curosurf, 200mg/kg) with or without addition of
dextran (30 mg/ml) was administered 15 min after the second dose of
albumin and animals were then ventilated for another 60 min. In one series of experiments, instillation of
albumin was followed by administration of diluted
Curosurf (40 mg/kg) with or without
dextran (30 mg/ml). Animals with initial lung-thorax compliance (CLT)<0.6 ml/kg cm H2O were directly treated with
surfactant without previous instillation of
albumin. Animals treated with a larger dose of
Curosurf (200mg/kg) showed a significant increase in CLT at 60 min with no difference between groups receiving high or low dose of
albumin. Addition of
dextran to
Curosurf at high dose (200mg/kg) reduced the therapeutic response (P<0.05 vs.
Curosurf without
dextran).
After treatment with low-dose
Curosurf (40 mg/kg) CLT increased more prominently after Curosurf+dextran than after non-enriched
surfactant (P<0.05).
Dextran potentiated the treatment effect of
Curosurf at suboptimal dose (40 mg/kg) but not at high dose (200mg/kg) in animals with low-grade
surfactant deficiency or
respiratory failure induced by airway instillation of
albumin.