112. Physiological Signature of Bloodstream Infection in Critically Ill Patients

BACKGROUND: Bloodstream infection (BSI) is associated with high mortality rates in critically ill patients but is difficult to identify clinically. This uncertainty results in frequent blood culture testing, which exposes patients to additional costs and the potential harms of unnecessary antibiotics. Accordingly, we aimed to identify signatures in physiological data from critically ill adults that characterize BSI. METHODS: We reviewed all blood culture, vital sign, laboratory, and cardiorespiratory monitoring (CRM) data from patients admitted to the medical and surgical/trauma ICUs at the University of Virginia Medical Center from February 2011 to June 2015. Blood culture results were categorized as positive, negative, or contaminant. For the BSI population, we included data obtained within 12 hours before or 24 hours after the acquisition of a positive blood culture. The control population included data greater than 12 hours before or 24 hours after the acquisition of a positive blood culture, and all data from patients without BSI. We used multivariable logistic regression to identify the physiological characteristics of BSI. RESULTS: We analyzed 9,955 ICU admissions with 144 patient-years of vital sign and CRM data (1.3M hourly measurements). The average age was 59 years; the population was mostly Caucasian (81%) and male (56%). There were 5,671 (57%) admissions with ≥1 blood culture, and 744 (7%) had a BSI. The in-hospital mortality rate for patients with BSI was 28% vs. 12% for all others. The physiological signature of BSI was characterized by abnormalities in 12 parameters (Figure 1)—e.g., BSI was more likely in patients with a higher pulse and lower platelets. Several associations were nonlinear—e.g., temperature and WBC had U-shaped relationships with BSI. The internally validated C-statistic was 0.77. CONCLUSION: Statistical modeling revealed a clinically sensible physiological signature of BSI that could assist with bedside decisions regarding the utility of blood culture testing in critically ill adults. [Image: see text] DISCLOSURES: All authors: No reported disclosures.