Improved cardiovascular stability during continuous modes of renal replacement therapy in critically ill patients with acute hepatic and renal failure

Abstract

OBJECTIVE: To determine whether continuous modes of renal replacement therapy result in improved cardiovascular stability compared with standard daily intermittent treatment in critically ill patients. DESIGN: Prospective, randomized controlled trial. SETTING: Intensive care unit in a quaternary referral center for liver failure/transplantation. PATIENTS: Thirty-two consecutive, critically ill, mechanically ventilated patients with combined acute hepatic and renal failure. INTERVENTIONS: Patients were randomized to treatment with either intermittent machine hemofiltration or continuous modes of renal replacement therapy; continuous arteriovenous hemofiltration (CAVH) or arteriovenous hemofiltration with dialysis (CAVHD), provided intracranial pressure was controlled. MEASUREMENTS AND MAIN RESULTS: Cardiac output, tissue oxygen delivery (DO2), and uptake were assessed during 32 treatments with intermittent machine hemofiltration (4 hrs) and during the first 5 hrs of 25 continuous treatments (CAVH and CAVHD). During the first hour of treatment, there was a reduction in cardiac index of 15 +/- 2% during intermittent machine hemofiltration compared with no significant change during the continuous modes of treatment (CAVH/CAVHD) (3 +/- 3%; p < .05). This reduction in cardiac output during intermittent machine hemofiltration was associated with a maximum reduction in mean arterial pressure from 82 +/- 2 to 66 +/- 2 mm Hg (p < .001), a reduction in pulmonary artery occlusion pressure of 27 +/- 4%, tissue DO2 of 15 +/- 3%, and tissue oxygen uptake of 12 +/- 5%, with no significant change in systemic vascular resistance and an increase in pulmonary vascular resistance of 50 +/- 12%. In addition, there was a maximum increase in intracranial pressure of 45 +/- 5% during the first hour of intermittent machine hemofiltration. There were no significant changes during the same time period during the continuous modes of renal replacement therapy. CONCLUSIONS: In critically ill patients, in whom DO2 is impaired, the use of continuous forms of renal replacement therapy is preferred for its improved cardiovascular tolerance compared with daily intermittent machine treatments.