R. Won1, D. Plurad1, B. Putnam1, A. Neville1, S. Bricker1, F. Bongard1, J. Smith1, D. Y. Kim1 1Harbor-UCLA Medical Center,Trauma/Acute Care Surgery/Surgical Critical Care,Torrance, CA, USA
Introduction: The incidence and outcomes of acute kidney injury (AKI) among trauma patients who sustain direct renal trauma are not well-defined. Previous studies have demonstrated that the choice of operation undertaken in the management of renal injuries may not impact subsequent renal function. The objective of this study was to identify risk factors for the development of AKI among trauma patients sustaining renal trauma.
Methods: We performed a 10-year retrospective cohort analysis of our level 1 trauma center database to identify patients admitted to the hospital for >24 hours with a diagnosis of renal trauma. Grade of renal injury was determined using the American Association for the Surgery of Trauma (AAST) kidney injury scale, whereas AKI was defined according to the RIFLE classification (both glomerular filtration rate and urine output criteria). The primary outcome measure was the development of AKI. Secondary outcomes included the incidence of kidney-related complications and mortality. Multivariate logistic regression analysis was performed to identify independent predictors of AKI.
Results: Of 246 patients, 191 patients (78%) were managed non-operatively. Forty-three patients (17%) developed AKI (Risk, n=25; Injury, n=9; Failure, n=9), of which 7 (16%) required renal replacement therapy. Patients with AKI were older (35 vs. 28 years, p=0.03), more likely to present following a penetrating mechanism (p=0.02), and had a higher Injury Severity Score (26 vs. 20, p=0.02). There was an increased incidence of high-grade (IV/V) injuries among patients with AKI and these patients underwent nephrectomy more commonly (both p<0.03). Kidney-related complications (26 vs. 8%, p=0.0003) and mortality (14 vs. 2%, p=0.001) were increased among patients with AKI. On multivariate logistic regression analysis, high-grade injuries (OR=3.3, 95% CI=1.3-8.4; p=0.015) and nephrectomy (OR=3.0, 95% CI=1.1-8.7; p=0.04) were independently associated with the development of AKI.
Conclusion: AAST high-grade kidney injuries are associated with an increased risk for AKI as defined by the RIFLE criteria. Patients undergoing nephrectomy are also at an increased risk for this morbid complication. Future studies examining the safety and efficacy of renal salvage versus nephrectomy on the development and severity of AKI are required in patients with renal injuries identified at the time of operation.