Continuous versus Occasional Kidney Dialysis
Comparison of Continuous versus Occasional Kidney Dialysis and Organ Failure
What is the problem and what is known about it so far?
Patients with multiple-organ failure typically have impairment of kidney function and reduced urine production. These patients may require treatment with the artificial kidney (dialysis) to prevent the build up of toxic waste products and to reduce side effects associated with these toxins. Some researchers believe that continuous dialysis (24-hour continuous blood filtering) is better at removing wastes and preventing low blood pressure, compared with intermittent hemodialysis (blood filtering over a few hours). It is thought that continuous dialysis may improve survival compared to intermittent dialysis because it eliminates waste uninterruptedly in a manner similar to normally functioning kidneys.
Why did the researchers do this particular study?
To compare the effect of intermittent hemodialysis and continuous dialysis on 60-day survival in critically ill patients with acute kidney failure as part of multiple-organ failure.
Who was studied?
360 critically ill patients (72% male) 63 to 67 years of age in 21 medical or multidisciplinary intensive-care units in France.
How was the study done?
The researchers compared continuous hemodialysis (CHD) and intermittent hemodialysis (IHD) using the same type of dialysis membrane. A switch between therapies was allowed when multiple-organ failure had resolved or after 3 weeks of CHD to allow easier management (planned switch). Additionally, if the patient could not tolerate the treatment type, due to low blood pressure or other reasons, they were allowed to switch therapies (unplanned switch). The treatment endpoint of CHD was to achieve a certain waste product level and the goal of IHD was to yield a specific waste product reduction during each treatment time. Patients were followed until end of hospital stay, until kidney function recovered, or until 90 days, whichever was longest.
What did the researchers find?
There were no differences between the two treatments in 60-day survival, duration of dialysis, length of intensive care unit and hospital stay. More hypothermia (low body temperature) was seen in the CHD group, otherwise there were no differences in side effects. Three patients in the IHD group had to change to CHD due to low blood pressure.
What were the limitations of the study?
The treatment doses (blood flow rates for dialysis) were not specified and may have been less than optimal for determining survival differences between groups. There may not have been enough people in the study to show small effects.
What are the implications of the study?
There appears to be no difference in survival when treating impairment of kidney function from multiple-organ failure with either CHD or IHD. More research is needed to determine if maximal treatment in both groups leads to a survival difference. Also, researchers need to determine when to switch between treatments to maximize outcome and reduce treatment costs.
Summarized by Wesley D. Mcmillian, Pharm D. Resident in Pharmacy, Fletcher Allen Health Care.
Continuous venovenous haemodiafiltration versus intermittent haemodialysis for acute renal failure in patients with multiple-organ dysfunction syndrome: a multicentre randomised trial. Vinsonneau C. et. al. Lancet, July 29, 2006, Volume 368, Pages 379-385.
