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

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.