Lung lavage and surfactant replacement for hydrochloric acid aspiration in rabbits

Abstract

Hydrochloric acid (0.1 N, 5.0 m1.kg^‐1 in total) was administered intratracheally to 28 adult rabbits anesthetized with pentobarbital and mechanically ventilated with pure oxygen. When the Pao₂ decreased to 14.1 ± 2.8 kPa (mean±s.d.), the Paco₂ increased to 8.9±2.5 kPa, and the minute ventilation (V_E) decreased to 51 ± 8% of the baseline value, animals were divided into 4 groups. The deteriorated values did not improve in the non‐treated (control) animals, whereas the animals treated with lung lavage and surfactant replacement showed a significant increase in Paco₂, to 35.1 ± 12.2 kPa, and maintained lower Paco₂, and larger V_E, than the controls. These parametea showed no significant improvement with surfactant replacement alone, and deteriorated further with lung lavage alone. The minimum surface tension (γmin) of the edema fluid that accumulated in the airways after acid administration was 22.5 ± 1.7 mN · m^‐1, and was not lowered by adding surfactant preparation (10 mg.ml^‐1) whose original γmin was < 2 mN · m^‐1. We concluded that surfactant inhibition by edema fluid was a cause of respiratory failure, and that lung lavage followed by surfactant replacement might be of therapeutic value for acid aspiration.