Assessment of Combined Muscarinic Antagonist and Fibrinolytic Therapy for Inhalation Injury

Abstract

This study tests the hypothesis that muscarinic receptor antagonist therapy with tiotropium bromide (tiotropium; TIO), alone or in combination with tissue plasminogen activator (TPA), can attenuate pulmonary dysfunction in sheep after smoke inhalation and burn injury. The study consisted of four study groups, sham (uninjured), control (injured and untreated), TIO (injured and treated with nebulized TIO), and TIO + TPA (injured and treated with nebulized TIO and TPA). Cardiopulmonary and ventilatory parameters were monitored for 48 hours. After killing the animal, airway obstruction, submucosal gland neutrophilia, parenchyma histopathology, and lung wet to dry weight ratios were measured. PaO2/FiO2 was significantly improved in the TIO group compared with the control group at 48 hours, 301 ± 149 vs 99 ± 33, respectively, P < .05. At 48 hours, peak airway pressures in the control, TIO, and TIO + TPA groups were 35 ± 6, 24 ± 7, and 26 ± 10, respectively, with the mean of the TIO group being significantly different from that of the control group, P < .05. A trend of decreased airway obstruction was seen in the treated animals compared with controls; however, the differences were not statistically significant. The TIO and TIO + TPA groups exhibited significant decreases in gland neutrophilia compared with the control group, P < .05. No differences in parenchyma histopathology and lung edema between injured control and treated groups were observed. Nebulization of TIO was effective in improving pulmonary performance and reducing bronchial submucosal gland neutrophilia in sheep after smoke inhalation and burn injury. There was no additive benefit to the inclusion of nebulized TPA with TIO.