Prolonged airway and systemic inflammatory reactions after smoke inhalation

Study objectives: Smoke inhalation has a prolonged, negative effect on pulmonary function. The immediate change in the airway after smoke inhalation is an intense inflammatory reaction. Obstructive airway disease commonly occurs several years after smoke inhalation, but few studies have focused on long-term reactions in the airway. This study investigated the long-term effects of smoke inhalation, by examining airway responsiveness, airway inflammation, and systemic effects. Design: Cross-sectional study. Patients: We assessed victims (n = 9) of smoke inhalation 6 months after they were exposed. Interventions: We studied the clinical symptoms, laboratory data, and pulmonary functions of the patients. We also performed the nonspecific bronchial challenge test with methacholine on these patients. In some patients, we reviewed pathologic specimens of bronchi and measured cytokines (tumor necrosis factor [TNF]-alpha, interferon [INF]-gamma, and interleukin [IL]-2) in serum and BAIL fluid. Results: All the subjects complained of a productive cough, and three subjects had a mild degree of dyspnea on exertion. All but one subject had airway hyperresponsiveness to methacholine. The pulmonary function test results, however, were within normal limits, except for one subject who had a mild obstructive pattern of pulmonary function. Bronchial mucosal biopsy (n = 2) showed inflammatory changes with lymphocyte infiltration. Significantly greater concentrations of TNF-alpha (mean, 1,346.4 pg/mL vs 61.2 pg/mL; p < 0.05) and IFN-gamma (mean, 540.9 pg/mL vs 26.7 pg/mL; p < 0.05) were seen in the serum (n = 4) compared with control subjects. The serum IL-2 level was also increased (mean, 136.8 pg/mL vs undetectable); however, the increase was not significant compared with the control subjects. Conclusions: These data suggest that inflammatory reactions in the airways and peripheral blood continue for at least 6 months after smoke inhalation.