A reasonable and prompt cardiovascular evaluation of the cardiovascular system including cardiac risk factors, may help control of this complication.
Hypertension in dialysis patients
There
is no enough data concerned with the management of hypertension in dialysis
patients, however, certain recommendations may be admitted in this concept. A
reasonable and prompt cardiovascular evaluation of the cardiovascular system
including cardiac risk factors in particular, may help control of this serious
complication. Two important techniques may have crucial role in this concept, ambulatory
blood pressure monitoring as well as cardiac echocardiography.
Volume overload
Volume
expansion is probably the fundamental factor that help in the evolution of high
blood pressure (Hypertension) in patients on dialysis. Volume overload can
induce hypertension in two mechanisms, first, elevation of cardiac output as
well as elevation of the systemic vascular resistance. The latter effect may be
induced due to activation of the RAS (renin-angiotensin system) or due to ouabain-like
inhibitors secretion, that result in elevation in intra-cellular sodium and
calcium. Rise in intra-cellular calcium can induce vascular smooth muscle vasoconstriction
and elevation of blood pressure. However, whatever the mechanism, removing excess
sodium and establishment of the "dry weight" (see below) may induce
normalization of BP in > 60 % of hemodialysis patients and almost ALL
patients on peritoneal dialysis. The
magnitude of extracellular volume expansion may be not severe enough to induce peripheral
edema; so, lack of edema may not exclude the presence of hypervolemia.
Prolonged and/or more frequent hemodialysis
In Tassin,
France, patients have commenced a protocol of prolonged and slow hemodialysis
in the form of thrice weekly eight hourly dialysis. Surprisingly, almost all
patients became normotensive with no medications at all. In addition to
optimizing fluid overload, other factors may be also included like removal of
uremic toxins and decline of sympathetic nervous activity. Moreover, patients
with fluid overload still normotensive. Fortunately, this protocol of dialysis
that is not widely applied, is associated with a better patient survival.
Nocturnal hemodialysis
This
mode of dialysis can be performed 6-7 nights per week while the patient is
sleeping (usually 6-12 hours) according to the duration of sleep and results in
perfect BP control. Surprisingly, almost ALL patients commencing nocturnal dialysis
became normotensive with no medications. They have achieved this goal via
progressive decline of their target weight until they omit all their
anti-hypertensive medications. Moreover, certain trials have reached normal
blood pressure without medications and correction of the left ventricle enlargement
via commencing short daily dialysis. A recent recommendation by the European
Best Practice Guidelines that increasing the timing and/or frequency of dialysis
should be augmented in hypertensive patients despite optimizing volume
deloading. Target blood pressure (BP) should be individualized in every patient
situation. The lowest tolerable BP should be consistent with the general
feeling of sense of well-being without any hypotensive episodes between dialysis
sessions. Whilst the ideal suggested BP before dialysis should be less than 140/90 mmHg, the
ideal BP after dialysis should be less than 130/80 mmHg. However, with strict clinical supervision, the
normal BP can be defined as a mean BP of less than 135/85 mmHg
per day time and less than 120/80 mmHg per night.
To achieve
this goal of control, the following maneuvers may be applied:
1]
Gradual
withdrawal of the anti-hypertensive medications should be instituted unless
there are medications with cardiac background until the “dry weight” could be
recognized.
2]
This
trial, however, should be attempted through 3-4 weeks in young patients, whilst
this trial should be prolonged up to 12-14 weeks in old patients or those with
vessel disease.
3]
If
BP still high despite the establishment of the patient’ dry weight, the
antihypertensive medications should be resumed.
4]
Preference
of certain groups of antihypertensive medications depends to a great extent
upon patient’s experience of these agents in regard to its side effects and
their tolerance. A single daily dose, preferably at night is usually advised.
5]
A well-known
international guideline (The K/DOQI) suggest the use of
ACE inhibitors (ACEi) or angiotensin II receptor blockers (ARBs) due to
the observed cardiac beneficial effects.
6]
Adequate
dialysis should be the underlying base of therapy for all patients.
7]
Patient’s
weight between dialysis sessions (interdialytic weight gain) should be properly
adjusted according to K/DOQI guidelines (1-2
kilograms), a supervision of a dietitian is warranted in this concept to
regulate: low sodium consumption, augment ultrafiltration (fluid withdrawal), and/or increased daily dialysis dose.
8]
To
avoid the antihypertensive adverse effect of “erythropoietin”-hormone used to
treat anemia-its dosage should be kept at its lower limits with a slow progress
in anemia correction.
N.B. This Blogger is created to declare how can HT developed in HDX patients.
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