Pneumonia in patients with severe burns - A classification according to the concept of the carrier state

Objective: To establish baseline values of pneumonia incidence and mortalit y and to distinguish primary endogenous from secondary endogenous and exoge nous pneumonias in a homogeneous patient population with severe burns. Design: Cohort study. Setting: A six-bed burn ICU. Patients: All patients of greater than or equal to 14 years admitted to the ICU between January 1995 and June 1996 with a total body surface area burn of greater than or equal to 20%. Intervention: Collection of data on surveillance samples from throat and re ctum on admission and twice weekly afterward, and pneumonias during the ICU stay. Measurements and results: Fifty-six patients fulfilled the criteria of the study. Mean age was 43 +/- 19.8 years; total body surface area burn, 41 +/- 18.2%; the area of full-thickness burn was 24 +/- 17.7%. Forty-one patient s required mechanical ventilation. Twenty-seven patients (48%) experienced 31 episodes of pneumonia. Twenty-one pneumonias were of primary endogenous development, ie, caused by potential pathogens carried in the admission flo ra. There were 14 secondary endogenous and 2 exogenous infections caused by microorganisms acquired on the burn unit. Inhalation injury was identified in 26 patients. The pneumonia rate was two times higher in the subset of p atients with inhalation injury compared with the group of patients without inhalation injury (p < 0.001). Overall mortality was 25%. Conclusions: This study shows that pneumonia in burn patients is mainly an endogenous problem. Interventions that prevent the development of endogenou s infections deserve prospective evaluation in patients with severe burns.