Improved cardiovascular stability during continuous modes of renal replacement therapy in critically ill patients with acute hepatic and renal failure
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A Davenport1, E J Will, A M Davidson
1Department of Renal Medicine, St. James's University Hospital, Leeds, UK.
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.