Pneumonia in patients with severe burns : a classification according to the concept of the carrier state

To establish baseline values of pneumonia incidence and mortality and to distinguish primary endogenous from secondary endogenous and exogenous pneumonias in a homogeneous patient population with severe burns.

Cohort study.

A six-bed burn ICU.

All patients of > or = 14 years admitted to the ICU between January 1995 and June 1996 with a total body surface area burn of > or = 20%.

Collection of data on surveillance samples from throat and rectum on admission and twice weekly afterward, and pneumonias during the ICU stay.

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 patients required mechanical ventilation. Twenty-seven patients (48%) experienced 37 episodes of pneumonia. Twenty-one pneumonias were of primary endogenous development, ie, caused by potential pathogens carried in the admission flora. 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 patients with inhalation injury compared with the group of patients without inhalation injury (p < 0.001). Overall mortality was 25%.

This study shows that pneumonia in burn patients is mainly an endogenous problem. Interventions that prevent the development of endogenous infections deserve prospective evaluation in patients with severe burns.