The "fever workup" and respiratory culture practice in critically ill trauma patients

Fever and leukocytosis (FAL) in critically ill patients often triggers a "workup" that includes a respiratory secretion culture (RCx). We evaluated our respiratory culture practice associated with FAL. We hypothesized that FAL would be associated with a RCx, but would not be associated with a positive culture or treating a respiratory infection in critically injured patients during their first 14 intensive care unit (ICU) days.

An 18-month retrospective analysis was performed on consecutive ICU trauma patients admitted for 2 days or more to a level I trauma center. Data collected included demographics, injuries, RCxs (bronchoalveolar lavage or tracheal aspirate), maximum daily temperature, and a daily leukocyte count during the first 14 ICU days.

A total of 510 patients with a mean age of 49 and injury severity score of 19 were evaluated for a total of 3839 patient-days. Two hundred eleven patients had 489 RCxs obtained (2.4 RCxs/patient); 94 (19%) were obtained on consecutive days. Obtaining a RCx was associated with fever (relative risk, 4.8; 95% confidence interval, 4.1-5.8) and the combination of FAL (relative risk, 2.6; 95% confidence interval, 2.2-3.1), but not leukocytosis alone. Fever, leukocytosis, or FAL did not predict a positive RCx. One hundred twenty-eight patients were treated for a respiratory infection. Treatment of respiratory infections was contrary to the RCx results 24% of the time. The sensitivity and specificity of a positive RCx being associated with respiratory infection were 97% and 46%, respectively.

Fever and leukocytosis were associated with the decision to obtain RCxs but were not associated with positive RCxs in our ICU practice. Respiratory secretion culture results had a low specificity and did not consistently impact treatment decisions. Factors other than fever and leukocytosis alone should influence the decision to obtain RCxs during the first 14 days in the ICU after trauma.