Background: Trauma produces profound inflammatory and immune responses. A second hit such as an infection further disrupts the inflammatory cascade. Inflammatory responses, following traumatic injuries, infections, or both, are emerging as biologic mediators of cardiac disease including myocardial ischemia and infarction. Inflammation-induced and stress-related cardiac damage are increasingly recognized in patients with critical illness. It is believed that cardiac dysfunction is the result of alterations in the inflammatory and immune cascades. Urinary tract infections (UTIs) and ventilator-associated pneumonia (VAP) are associated with increased mortality in trauma patients. UTIs and VAPs induced inflammatory responses. We postulate that increased mortality seen in trauma patients with infections is caused by increased rates of cardiac injury.
Methods: This is a retrospective review of prospectively collected data. All trauma patients admitted to the intensive care unit at our Level I trauma center during 5 years were included in the analysis. Proportional hazard regression analysis was performed to predict suspicion of cardiac injury (troponin ordered), any cardiac injury (troponin > 0.15 ng/mL), or severe cardiac injury (troponin > 1 ng/mL) using age, sex, Injury Severity Score (ISS), pulmonary disease (chronic obstructive pulmonary disease), heart failure, hypertension, diabetes, and the presence of a UTI or VAP. A similar proportion hazard regression was performed to predict mortality.
Results: In the model to predict any cardiac injury, chronic obstructive pulmonary disease (hazards ratio [HR], 1.9; p = 0.02), ISS (HR, 1.01; p = 0.04), VAP (HR, 5.6; p < 0.01), and UTI (HR, 2.4; p = 0.03) were significant. Neither VAP nor UTI predicted severe cardiac injury. In the model to predict death, any cardiac injury was not associated with mortality, but severe cardiac injury and UTI were associated with mortality as age increased.
Conclusion: Infectious complications have been associated with increased mortality in trauma patients. Our data demonstrate that development of VAP or UTI is associated with an increased risk of developing cardiac injury in trauma patients, which may contribute to subsequent increased mortality.
Level of evidence: Prognostic/epidemiologic study, level III.