The Treatment Efficacy Of Lavage Administration Of Pulmonary Surfactant On Acute Lung Injury Induced By Hydrochloric Acid In Rabbits

Objective To investigate the effect of lavage administration of pulmonary surfactant on acute lung injury (ALI)induced by hydrochloric acid in rabbits.Methods After the rabbits were anesthetized, tracheotomies were performed and 0.0125N hydrochloric acid (12 ml/kg) was instilled into the lungs via endotracheal tube. The rabbits with PaO2 less than 150mmHg were randomly divided into four groups, with 5 each . The pulmonary surfactant (15 ml/kg ,12 mg/ml) was instilled via tracheal tube and drained thereafter in the lavage group (group L). The same volume of saline was used to substitute the pulmonary surfactant in the saline group (group S). The pulmonary surfactant (4 ml/kg, 45 mg/ml) was given in the instillation group (group I), and neither saline nor pulmonary surfactant was given in the mechanical ventilation group (group M). The rabbits were sacrificed after experiment, and the lungs were removed and fixed with 10% paraformaldehyde. Right middle and inferior lobes were embedded and cut in 5 u m thick sections. Histological changes were evaluated on sections stained with hematoxylinand eosin (HE) and examined under light microscope.Results In group L , PaO2 dramatically increased from less than 150mmHg to greater than 400mmHg at 30min after lavage (p < 0.01), and maintained thereafter through the whole 4 - hour observation period. The inspiratory peak pressure (Ppeak) decreased markedly (p < 0.01) soon after the lungs were lavaged, but gradually increased a little thereafter. PaO2 increased to 200mmHg at 30min after the pulmonary surfactant was tracheally instilled in the group I (p < 0.05), and then decreased to the level before pulmonary surfactant was delivered. In groups M and S, the blood gases and Ppeak showed no improvement during the observation period. The histological changes in group L manifested that alveoli were expanded, with a few neutrophils and red cells infiltration and a little serum protein aggregation in alveolar lumen. Compared with group L, there was more red cells infiltration in alveolar septum and alveoli were partially expanded in group I. group S and M showed that alveoli collapsed, with great number of neutrophils infiltration and inflammatory exudation.Conclusion Lavage administration of pulmonary surfactant seems to be a promising method in the treatment of acute lung injury induced by hydrochloric acid.