The Effect of Early Positive Cultures on Mortality in Ventilated Trauma Patients

Abstract

Background: The purpose was to examine the incidence of positive cultures in a highly susceptible subset of trauma patients admitted to the surgical intensive care unit (SICU) for mechanical ventilation and to examine the impact of their timing on outcomes.

Patients and methods: A retrospective review was conducted of blunt trauma patients admitted to the SICU for mechanical ventilation at a level I trauma center over a five-year period. All urine, blood, and sputum cultures were abstracted. Patients with at least one positive culture were compared with those with negative or no cultures. The primary outcome was mortality. A Cox regression model with a time-dependent variable was utilized to calculate the adjusted hazard ratio (AHR).

Results: The median age of 635 patients meeting inclusion criteria was 46 and 74.2% were male. A total of 298 patients (46.9%) had at least one positive culture, with 28.9% occurring within two days of admission. Patients with positive cultures were more likely to be severely injured with an injury severity score (ISS) ≥16 (68.5% vs. 45.1%, p < 0.001). Overall mortality was 22%. Patients who had their first positive culture within two and three days from admission had a significantly higher AHR for mortality (AHR: 14.46, p < 0.001 and AHR: 10.59, p = 0.028, respectively) compared to patients with a positive culture at day six or later.

Conclusions: Early positive cultures are common among trauma patients requiring mechanical ventilation and are associated with higher mortality. Early identification with "damage control cultures" obtained on admission to aid with early targeted treatment might be justified.

Keywords: early cultures; infection; mortality; positive cultures; trauma; ventilated.