[Histopathological and ultrastructural changes of canine tracheo-bronchi and lung parenchyma after smoke inhalation injury].

Thirty four male mongrel dogs weighing 10-14 kg were used and divided into 2 groups, i.e. experimental group (N-22) and control group (N-12). Animals of the experimental group were sacrificed at the end of 2 (N-5), 6 (N-7), and 24 (N-10) hr after injury. Tissue samples were taken from the trachea, right main bronchus and both lungs of both groups for LM; specimens for EM were taken from trachea, right main bronchus, right lobar bronchus, and right lung in experimental (N-20) and control groups (N-8). LM Findings: In experimental group, at 2 hr after injury, there were necrosis, hyperemia, edema and leucocytic infiltration in tracheal and main bronchial walls; and occasionally acute bronchitis, bronchiolitis, and lobular pneumonia were seen. The lesions became more marked and increased in frequency with the passage of time. At 6 hr, intra-alveolar edema as well as perivascular edematous or/and hemorrhagic cuffs were demonstrated and became more prominent at 24 hr. Goblet cells in the tracheo-bronchial mucosae showed increase in number. EM Findings: At 2 hr post-injury, there was interstitial edema of the thick portions of alveolar septa, presence of platelets and/or leucocytes in the lumina of capillaries, and slight intracellular edema of Type I and Type II pneumocytes. With the passage of time, these changes became more marked and increased in frequency. At 24 hr postinjury, proliferation of Type II pneumocytes might be found. The etiological factors and pathogenesis concerning smoke inhalation injury were briefly discussed.