Acute kidney injury in critically ill burn patients. Risk factors, progression and impact on mortality

Abstract

Introduction: The aim of this study was to apply the RIFLE [risk (R), injury (I), failure (F), loss (L) and end-stage kidney disease (E)] criteria in burn ICU patients, to identify the risk factors for occurrence of acute kidney injury (AKI), as well as to analyze the progression between stages (classes) of RIFLE classification, and the impact of progression of AKI on morbidity and mortality.

Design: Retrospective, descriptive cohort study.

Setting: Single-center, 8 bed burn ICU facility.

Patients: All consecutive patients aged >18 years with a burn injury of 20% or more of a total body surface area percent (TBSA%) admitted during a 2-year-period were included in the study.

Interventions: None.

Measurements and results: Data of 60 patients were studied. AKI occurred in 32 (53.3%) of patients with severe burns with the maximum RIFLE category: Risk in 9 (28.1%), Injury in 6 (18.8%) and Failure 17 (53.1%). Patients with AKI had a mortality rate of 34.4%. None of patients who did not develop AKI during ICU stay died. Thirteen patients progressed to higher RIFLE I class of AKI. Patients who progressed to higher RIFLE class had higher mortality rate (46%) compared to those who remained at the same (Risk or Injury) RIFLE class (7.7%). The progression to higher RIFLE class was associated with the higher extrarenal SOFA and the higher SOFA at maximum RIFLE class, the use of nephrotoxic drugs, the number of operations, the cumulative fluid balance prior the maximum RIFLE and the presence of sepsis. Logistic regression analysis indicated that maximum SOFA score, presence of sepsis and Failure class of AKI (p=0.033) were the independent risk factors for mortality.

Conclusion: This study demonstrated (a) the high incidence of AKI in patients with severe burns; (b) the number of predisposing to progression of AKI factors (severity of organ failure, presence of sepsis, use of nephrotoxic drugs, number of previous surgical operations, cumulative fluid balance); (c) the association of Failure class of acute kidney injury with high mortality.