Using continuous renal replacement therapy to manage patients of shock and acute renal failure.

BACKGROUND: The incidence of acute renal failure (ARF) in the hospital setting is increasing. It portends excessive morbidity and mortality and a considerable burden on hospital resources. Extracorporeal therapies show promise in the management of patients with shock and ARF. It is said that the potential of such therapy goes beyond just providing renal support. The aim of our study was to analyze the clinical setting and outcomes of critically ill ARF patients managed with continuous renal replacement therapy (CRRT).

PATIENTS AND METHODS: Ours was a retrospective study of 50 patients treated between January 2004 and November 2005. These 50 patients were in clinical shock and had concomitant ARF. All of these patients underwent CVVHDF (continuous veno-venous hemodiafiltration) in the intensive care unit. For the purpose of this study, shock was defined as systolic BP < 100 mm Hg in spite of administration of one or more inotropic agents. SOFA (Sequential Organ Failure Assessment) score before initiation of dialysis support was recorded in all cases. CVVHDF was performed using the Diapact((R)) (Braun) CRRT machine. The vascular access used was as follows: femoral in 32, internal jugular in 8, arteriovenous fistula (AVF) in 4, and subclavian in 6 patients. We used 0.9% or 0.45% (half-normal) saline as a prefilter replacement, with addition of 10% calcium gluconate, magnesium sulphate, sodium bicarbonate, and potassium chloride in separate units, while maintaining careful monitoring of electrolytes. Anticoagulation of the extracorporeal circuit was achieved with systemic heparin in 26 patients; frequent saline flushes were used in the other 24 patients.

RESULTS: Of the 50 patients studied, 29 were males and 21 females (1.4:1). The average age was 52.88 years (range: 20-75 years). Causes of ARF included sepsis in 24 (48%), hemodynamically mediated renal failure (HMRF) in 18 (36%), and acute over chronic kidney disease in 8 (16%) patients. The overall mortality was 74%. The average SOFA score was 14.31. The variables influencing mortality on multivariate analysis were: age [odds ratio (OR):1.65; 95% CI: 1.35 to 1.92; P = 0.04], serum creatinine (OR:1.68; 95% CI: 1.44 to 1.86; P = 0.03), and serum bicarbonate (OR: 0.76; 95% CI: 0.55 to 0.94; P = 0.01). On univariate analysis the SOFA score was found to be a useful predictor of mortality.

CONCLUSIONS: Despite advances in treating critically ill patients with newer extracorporeal therapies, mortality is dismally high. Multiorgan dysfunction adversely affects outcome of CRRT. Older age, level of azotemia, and severity of metabolic acidosis are important predictors of adverse outcome.