FRIDAY, Oct. 29, 2004 (HealthDayNews) -- Kidney patients who undergo dialysis at home during nighttime sleep have improved cardiovascular health compared to patients on standard three-times-a-week daytime dialysis, Canadian researchers report.
The sleep-time regimen also frees patients from being hooked up to machines during waking hours -- allowing them to spend their days doing the things they love.
"We are very encouraged by the results of this study," said lead researcher Dr. Christopher Chan, medical director of home hemodialysis at Toronto General Hospital. "The quality of life of someone who can perform their own dialysis at home at night is much better."
The findings were presented Friday at the annual meeting of the American Society of Nephrology in St. Louis.
When kidneys fail to keep up with the body's demands, patients enter a state known as end-stage renal disease (ESRD). For most of these patients, this means multiple, hours-long sessions per week of artificial kidney dialysis just to stay alive.
One of the kidney's major functions is its role in maintaining proper levels of calcium in the blood. But as kidneys fail, this calcium balance goes awry, resulting in a gradual buildup of potentially dangerous calcium phosphate within arteries.
"With standard three-times-a-week daytime dialysis, the usual natural history is that there's a progression of calcium buildup," Chan said. "Even within one year, it ranges from a 10 percent to 90-to-100 percent increase in calcium [deposition]."
Chan and his team wondered if this trend could be slowed with nighttime dialysis, which offers patients six to eight hours of dialysis five or six nights per week -- a much higher frequency of sessions.
"The whole notion is that three-times-a-week -- the current standard of care -- just doesn't provide enough dialysis to adequately adjust for all the bodily functions that the kidneys used to do," he said.
In its study, the Toronto team compared the coronary artery CT scans of 14 end-stage kidney disease patients before they began nighttime dialysis, and then one year after beginning the at-home treatment.
Unlike the steady accumulation of calcium phosphate seen in the arteries of patients on daytime dialysis, "we did not find a significant worsening of calcium buildup in the coronary arteries" of patients on nighttime dialysis, Chan said.
While a larger, controlled trial is needed, the findings "are yet another piece of the puzzle that strongly suggest that these forms of therapy are, in the future, going to alter outcomes," said Dr. Robert Lindsay, an expert in nighttime hemodialysis and professor of medicine at the University of Western Ontario. He and Chan are collaborating on a textbook introducing clinicians to the nighttime procedure.
Lindsay said other small studies have suggested that nocturnal dialysis improves other cardiovascular risk factors, resulting in lower blood pressure and a shrinking of enlarged heart muscle in kidney patients.
While-you-sleep dialysis may also reduce patient levels of sleep apnea -- breathing difficulties causing multiple nighttime awakenings, according to Chan. Correcting sleep apnea is important for cardiovascular health, since the condition seems to upset the autonomic nervous system that controls heart rate.
"When we're asleep, we shouldn't have a high heart rate. It should be relaxed," he explained. "But in patients with kidney failure and sleep apnea, they actually have a heightened heart rate during sleep, so their heart never really rests."
Patients on nighttime dialysis make important gains in terms of lifestyle as well, with more time for leisure-time activities and reductions in clinic visits. "We train patients to administer the therapy at home -- it's essentially the same machine used in our clinic," Chan said.
The procedure may even help vary patient's diets. Because of the dangers of excess calcium in the blood, ESRD patients are usually told to keep away from calcium-rich dairy products. But, according to Lindsay, nighttime dialysis has proven so successful for some patients they even develop slight calcium deficiencies.
"In some cases," he said, "we tell them, 'Go drink milk, go and get a cheeseburger or something.' They'll say, 'Oh, really? For all of my time in dialysis before, this was forbidden.' They love it."
Although the study didn't look at patient survival, Chan noted that the Toronto team was the first in the world to institute a nighttime dialysis regimen, beginning in 1994. The program now includes 110 long-term patients and, "so far, we've seen remarkable survival statistics, with less than 10 patients passing away during that 10-year span," he said.
But Lindsay stressed that longer, larger better-controlled studies are necessary to confirm that nighttime dialysis does increase patient life span.
While nocturnal dialysis has yet to make significant inroads in the United States, Chan said that it's beginning to gain more acceptance among American clinicians.
"In fact," he said, "the U.S. National Institutes of Health is sponsoring a trial looking at nocturnal dialysis vs. three-times-per week."
For more on preventing and treating kidney disease, go to the National Kidney Disease Education Program.