Respiratory tract pathology in patients with severe burns

The histologic spectrum, pathogenesis, and clinical correlates of tracheobronchial and pulmonary lesions were studied by autopsy in six children and 27 adult burn victims. The burns covered a mean total body surface area of 57.7 +/- 23%. The mean survival time was 17.6 +/- 14.3 days. Patients over 60 years tended to survive longer than younger adults, but older patients had less extensive burns (P less than .01). Moderate or severe renal failure was an important clinical complication in 19 patients (58%). Diffuse alveolar damage (DAD) was observed in 16 patients, acute bronchopneumonia in seven patients, and necrotizing pneumonia in seven patients. Both DAD and pneumonia coexisted in 11 patients. Children most consistently developed pneumonia, 6 out of 6 versus 4 out of 17 younger adults (P less than .05). Factors which may have contributed to the pathogenesis of DAD included septicemia (12 patients), hypotension (nine patients), necrotizing pneumonia (six patients), and oxygen toxicity (four patients), in addition to the common presence of inhalational injury. The onset of DAD appeared late in eight patients with long survival periods, suggesting causal factors other than inhalational injury. However, survival rate did not differ in patients with or without DAD, and there was no correlation between DAD and the extent of burns. Airway lesions reflected the length of survival and showed the following sequence of changes: (1) mucosal necrosis and denudation, (2) acute inflammation and ulceration, and (3) squamous metaplasia. Endotracheal intubation injury and superinfection were confounding factors beyond the first few days of survival.