Identifying augmented renal clearance in trauma patients: Validation of the Augmented Renal Clearance in Trauma Intensive Care scoring system.

BACKGROUND: Augmented renal clearance (ARC) is common in trauma patients and associated with subtherapeutic antimicrobial concentrations. This study reported the incidence of ARC, identified ARC risk factors, and described a model to predict ARC (i.e., ARCTIC) that is specific to trauma patients. METHODS: Consecutive trauma patients who were admitted to the intensive care unit between March 2015 and January 2016 and had a measured creatinine clearance (CrCl) were considered for inclusion. Patients were excluded if their serum creatinine (SCr) was greater than 1.3 mg/dL. ARC was defined as a measured CrCl of 130 mL/min or greater. Demographic and trauma-specific variables were then compared, and multivariate analysis was performed. Using these results, a weighted scoring system was constructed and evaluated using receiver operating characteristic curve analysis. ARCTIC score cutoffs were chosen based on sensitivity, specificity, positive predictive value, and negative predictive value. The derived scoring system was then compared to a previously published scoring system for accuracy. RESULTS: There were 133 patients with a mean age of 48 ± 19 years and SCr of 0.8 ± 0.2 mg/dL. The mean measured CrCl was 168 ± 65 mL/min, and the incidence of ARC was 67%. Multivariate analysis revealed the following risk factors for ARC (age, <56: odds ratios [OR], 58.3; 95% confidence interval [CI], 5.2-658.9; age, 56 to 75: OR, 13.5; 95% CI, 1.2-151.7), SCr less than 0.7 mg/dL (OR, 12.5; 95% CI, 3-52.6), and male sex (OR, 6.9; 95% CI, 1.9-24.9). Using these results, the ARCTIC scoring system was: 4 points if younger than 56 years, 3 points if aged 56 years to 75 years, 3 points if SCr less than 0.7 mg/dL, and 2 points if male sex. Receiver operating characteristic curve analysis revealed an area (95% CI) of 0.813 (0.735-0.892) (p < 0.001). An ARCTIC score of 6 or higher had a sensitivity, specificity, positive predictive value, and negative predictive value of 0.843, 0.682, 0.843, and 0.682, respectively. CONCLUSION: The incidence of ARC in trauma patients is high. The ARCTIC score represents a practical, pragmatic system that can be easily applied at the bedside. An ARCTIC score of 6 or higher represents an appropriate cutoff to screen for ARC where antimicrobial adjustments should be considered. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level III.

The importance of empiric antibiotic dosing in critically ill trauma patients: Are we under-dosing based on augmented renal clearance and inaccurate renal clearance estimates?

BACKGROUND: An accurate assessment of creatinine clearance (CrCl) is essential when dosing medications in critically ill trauma patients. Trauma patients are known to experience augmented renal clearance (i.e., CrCl ≥130 mL/min), and the use of CrCl estimations may be inaccurate leading to under-/over-dosing of medications. As such, our Level I trauma center began using measured CrCl from timed urine collections to better assess CrCl. This study sought to determine the prevalence of augmented renal clearance and the accuracy of calculated CrCl in critically ill trauma patients. METHODS: This observational study evaluated consecutive ICU trauma patients with a timed 12-hour urine collection for CrCl. Data abstracted were patient demographics, trauma-related factors, and CrCl. Augmented renal clearance was defined as measured CrCl ≥130 mL/min. Bias and accuracy were determined by comparing measured and estimated CrCl using the Cockcroft-Gault and other formulas. Bias was defined as measured minus calculated CrCl, and accuracy was calculated CrCl that was within 30% of measured. RESULTS: There were 65 patients with a mean age of 48 years, serum creatinine (SCr) of 0.8 ± 0.3 mg/dL, and injury severity score of 22 ± 14. The incidence of augmented renal clearance was 69% and was more common when age was <67 years and SCr <0.8 mg/dL. Calculated CrCl was significantly lower than measured (131 ± 45 mL/min vs. 169 ± 70 mL/min, p < 0.001) and only moderately correlated (r = 0.610, p < 0.001). Bias was 38 ± 56 mL/min, which was independent of age quartile (p = 0.731). Calculated CrCl was inaccurate in 33% of patients and trauma-related factors were not predictive. CONCLUSION: The prevalence of augmented renal clearance in critically ill trauma patients is high. Formulas used to estimate CrCl in this population are inaccurate and could lead to under-dosing of medications. Measured CrCl should be used in this setting to identify augmented renal clearance and allow for more accurate estimates of renal function. LEVEL OF EVIDENCE: Prognostic/epidemiologic study, level III.

Trauma-associated pneumonia: time to redefine ventilator-associated pneumonia in trauma patients.

BACKGROUND: The high prevalence of ventilator-associated pneumonia (VAP) in trauma patients has been reported in the literature, but the reasons for this observation remain unclear. We hypothesize that trauma factors play critical roles in VAP etiology. METHODS: In this retrospective study, 1,044 ventilated trauma patients were identified from December 2010 to December 2013. Patient-level trauma factors were used to predict pneumonia as study endpoint. RESULTS: Ninety-five of the 1,044 ventilated trauma patients developed pneumonia. Rib fractures, pulmonary contusion, and failed prehospital intubation were significant predictors of pneumonia in a multivariate model. CONCLUSIONS: It is time to redefine VAP in trauma patients based on the effect of rib fractures, pulmonary contusions, and failed prehospital intubations. The Centers for Disease Control and Prevention definition of VAP needs to be modified to reflect the effect of trauma factors in the etiology of trauma-associated pneumonia.