SURFACTANT TREATMENT OF RESPIRATORY-FAILURE INDUCED BY HYDROCHLORIC-ACID ASPIRATION IN RATS

Background: The surfactant system seems to be involved in the pathophy siology of respiratory failure caused by hydrochloric acid (HCI) aspir ation. This study was an investigation of the effect of different trea tment strategies using an exogenous surfactant preparation on lung fun ction of rats suffering from respiratory failure after intratracheal H Cl instillation. Methods. In rats anesthetized with halothane, nitrous oxide, and oxygen, tracheotomy was performed and the lungs were mecha nically ventilated. Respiratory failure was induced by intratracheal i nstillation of HCI (0.1 N, 3 ml/kg). After the Pa(O2) decreased to <20 0 mmHg, the animals were randomly divided into five groups. Group I re ceived no treatment; group II received a natural surfactant preparatio n intratracheally (200 mg/kg); group M underwent bronchoalveolar lavag e (BAL) with saline, followed by surfactant treatment (200 mg/kg); and groups IV and V underwent BAL with saline and a diluted surfactant su spension (3.3 mg/ml in 30 ml/kg), respectively. Groups IV and V receiv ed a second and third BAL 60 and 120 min after the first lavage. Blood gas analysis and protein measurements in BAL fluids were performed. R esults. Gas exchange improved in Groups III and V only. Protein concen trations were high in all BAL fluids. In the rats receiving BAL three times (groups IV and V), a decrease in protein concentration was obser ved. Conclusions. From these results, it was concluded that plasma-der ived proteins (which are known to inhibit surfactant function) are was hed out of the alveoli by BAL, resulting in improved efficacy of surfa ctant treatment.