A comparison of continuous renal replacement therapy to intermittent dialysis in the management of renal insufficiency in the acutely ill surgical patient

Acute renal failure (ARF) occurs in 10 per cent to 23 per cent of intensive care unit patients with mortality ranging from 50 per cent to 90 per cent. ARF is characterized by an acute decline in renal function as measured by urine output (UOP), serum creatinine, and blood urea nitrogen (BUN). Causes may be prerenal, intrarenal, or postrenal. Treatment consists of renal replacement therapy (RRT), either intermittent (ID) or continuous (CRRT). Indications for initiation of dialysis include oliguria, acidemia, azotemia, hyperkalemia, uremic complications, or significant edema. Overall, the literature comparing CRRT to ID is poor. No studies of only surgical/trauma patients have been published. We hypothesize that renal function and hemodynamic stability in trauma/ surgical critical care patients are better preserved by CRRT than by ID. We performed a retrospective review of trauma/surgical critical care patients requiring renal supportive therapy. Thirty patients received CRRT and 27 patients received ID. The study was controlled for severity of illness and demographics. Outcomes assessed were survival, renal function, acid-base balance, hemodynamic stability, and oxygenation/ventilation parameters. Populations were similar across demographics and severity of illness. Renal function, measured by creatinine clearance, was statistically greater with CRRT (P = 0.035). There was better control of azotemia with CRRT: BUN was lower (P = 0.000) and creatinine was lower (P = 0.000). Mean arterial blood pressure was greater (P = 0.021) with CRRT. No difference in oxygenation/ventilation parameters or pH was found between groups. CRRT results in an enhancement of renal function with improved creatinine clearance at the time of dialysis discontinuation. CRRT provides better control of azotemia while preserving hemodynamic stability in patients undergoing renal replacement therapy. Prospective randomized controlled studies and larger sample sizes are needed to further evaluate these modalities.