A Placebo-Controlled Experimental Study of Steroid Inhalation Therapy in Ammonia-Induced Lung Injury

Abstract

Background: The use of corticosteroids in toxic lung injury caused by exposure to an irritating gas such its ammonia has not been adequately studied. Objective: To evaluate the effects of budesonide inhalation in a rabbit model of toxic lung injury induced by ammonia. Design: Randomized, blind placebo-controlled laboratory investigation employing 16 New Zealand White rabbits. Lung injury was induced by inhalation of a defined amount of aerosolized ammonia. Thirty minutes later, the rabbits were randomized to receive either inhalation therapy with 0.5 mg budesonide or placebo. After another 2 hours, a second treatment inhalation, identical to the first one, was administered. Results: Airway pressures, hemodynamics, and gas exchange were measured at baseline, 5, and 15 minutes after ammonia administration and every 30 minutes during a 6-hour period after the first blind inhalation of corticosteroids or placebo. The ammonia inhalation resulted in an acute severe lung injury, detected after 15 minutes its a decrease in Pao₂ from 23.3 (±3.6) to 11.0 (±3.6) kPa (p < 0.005) and an increase in peak airway pressure from 13 (±2) to 17 (±2) cm H₂O (p <0.005). During the 6-hour observation period, the blood gas parameters improved gradually in all rabbits. In comparison with placebo, budesonide did not result in improved gas exchange or reduced airway pressure levels during the observation period. Conclusion: In this animal model corticosteroid inhalation therapy had no effect on ammonia-induced lung injury.