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Night versus daytime dialysis
The main difference between
nocturnal and normal dialysis is that the night-time
patients undergo dialysis more often and do it
at home while they sleep. Dialysing more frequently
means blood is filtered at a gentler rate, which
spares patients side effects like high blood pressure
and thickening of the walls of the heart.
But Dr Manns says not everyone's
suited to this approach. "It takes about 45 minutes
to set up, and almost half an hour to clean the
machine in the morning, and it means you have
to put a needle in your own vein," he says. "But
there's definitely a subgroup of patients suited
for this — approximately 15 or 20%, we think."
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Giving kidney patients dialysis
while they sleep significantly improves their cardiac
outcomes and quality of life, according to a Canadian
study in the September 19 JAMA.
University of Calgary nephrologist
Dr Braden Manns compared nocturnal hemodialysis (NH)
with conventional hemodalysis (CH) in a group of end-stage
renal disease (ESRD) patients. NH greatly reduced left
ventricular hypertrophy (LVH) — a common problem
for dialysis patients which often leads to cardiovascular
disease — by bringing their blood pressure back
to normal. It also boosted patients' quality of life
(QoL) scores by freeing them from spending their days
chained to the hospital dialysis machine three days
a week.
"Some of the patients absolutely
love it," beams Dr Manns. "They tend to have been on
dialysis a long time, and this offers them some hope
to return to normal during the day."
A
LOAD OFF
Dr Manns' study is the first to compare NH with CH in
a randomized study. Twenty-six patients were trained
over several weeks to use the at-home dialysis machines,
before proceeding to a treatment course of do-it-yourself
NH six times per week for six months. Another 26 patients
randomized to the control group received CH three times
a week in hospital for the same time period. Dialysis
rates were 250 ml/minute for NH patients, compared with
the 350-400 ml/minute norm.
The investigators looked for changes
of left ventricular (LV) mass, which often results from
the wilder blood pressure swings of less-frequent CH
schedules. LVH, which predicts cardiovascular (CV) events
in the general population, affects as many as 75% of
ESRD patients. "Patients on dialysis die of CV disease
due to the increased load on the heart," says Dr Manns.
"And people with the thickest hearts survive the least."
Between baseline measures and follow-up,
a difference between treatments in LV mass, quantified
by cardiac MRI, became apparent. Following NH, LV mass
decreased by an impressive 13.8g after six months, compared
with an average increase of 1.5g after CH. Systolic
blood pressure, too, showed a significant 7 mm Hg decrease
in NH patients, compared with a 4 mm Hg increase in
CH patients.
With improved blood pressure, 16
NH patients, compared with just three CH patients, were
able to reduce or go off their blood pressure medications.
Nineteen NH patients also reduced or discontinued oral
phosphate binders due to lowered serum phosphate and
calcium-phosphate product, again compared with just
three CH patients.
NH patients also scored higher
in the "effects of kidney disease" and "burden of kidney
disease" portions of a survey measuring kidney disease-specific
QoL issues. Intriguingly, there were no significant
differences on a portion of the test measuring sleep
quality. Despite these positive changes, a general health-related
QoL survey didn't detect significant differences between
treatment groups, although Dr Manns says the study lacked
statistical power to detect such a change.
"I hope that ESRD patients see
NH as an option to choose from," says Dr Manns. He suggests
that NH would probably be more common, if it weren't
for the treatment's high up-front costs. "In the long
run, the price would probably be comparable to hospital
hemodialysis, although we need more studies of the costs
to confirm this."
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