Acute kidney injury in patients with severe traumatic brain injury: implementation of the acute kidney injury network stage system.

BACKGROUND: There is limited information on the incidence and effect of acute kidney injury (AKI) in patients with severe traumatic brain injury (TBI), although AKI may affect outcome. Recently, acute kidney injury network (AKIN) classification has been widely accepted as a consensus definition for AKI. The aim of this study is to estimate the frequency and level of severity of AKI in patients with severe TBI by using AKIN criteria and to study whether AKI affects outcome. METHODS: The authors retrospectively identified a total of 136 patients with severe TBI admitted to the neurosurgical center during a 3-year period ending May 2010. Demographic data, severity of TBI, serum creatinine, urine output, outcome at 6 month, and death were collected. Renal function was assessed by using AKIN criteria. RESULTS: Thirty-one patients (23%) were classified as having AKI by using AKIN criteria during their hospitalization. Of them, 21 patients (68%) were stratified as stage 1, 7 patients (22%) as stage 2, and 3 patients (10%) as stage 3. Patients who developed AKI were older, had lower Glasgow coma scale at admission, and had higher level of admission serum creatinine and blood urea nitrogen. Patients with AKI had higher mortality and worse outcome when compared with patients with normal renal function. Furthermore, patients with mild renal dysfunction (stage 1 AKI) are also found having increased mortality and worse long-term outcome, compared with patients without renal dysfunction. CONCLUSION: It is demonstrated using the newly defined AKIN criteria for renal dysfunction that AKI is a relatively common feature in patients with severe TBI, and even seemingly insignificant decrease in renal function may be associated with worse outcome. This study highlights the importance of close surveillance of renal function and stresses the value of renal hygiene in the severe TBI population.