Hyertension in patients on regular hemodialysis

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  • HYPERTENSION IN PATIENTS

    ON REGULAR HEMODIALYSIS

    Prepared by

    Dr/ Ehab Ashoor M.B.B.Ch. Alex. University

    M.Sc. Internal Medicine, Cairo University

  • TALK OUTLINE

    General view

    Pathogenesis

    Blood pressure measurement in dialysis patients

    Management of high blood pressure in hemodialysis patients:

    Target blood pressure of hypertensive dialysis patients

    Algorithm for blood pressure control in dialysis patients

    Intradialytic hypertension

    Hemodialysis patients admitted with hypertensive urgency

  • General view Hypertension is common in dialysed patients

    - at pre-dialysis state >80%,

    - in patients with haemodialysis >60%,

    - in those with peritoneal dialysis >30 %

    The leading cause of death in dialysed patients

    is cardiovascular!

    Rahman M, Smith MC. Hypertension in hemodialysis patients. Current Hypertension Reports 2001; 3: 496-502.

  • General view But:

    in dialysed patients the relationship between

    hypertension and cardiovascular mortality/morbidity

    is controversial because of

    - the high prevalence of co-morbid conditions,

    - by the underlying vascular pathology and

    - by the effects of

    - dialysis on blood pressure

    - age

    - left ventricular hypertrophy/dysfunction (also

    more prevalent in patients with hypertension)

    - poor nutrition .

  • General view In patients on hemodialysis, hypertension has been

    associated with:

    - stroke,

    - MI,

    - CHF,

    - ventricular arrhythmias and

    - progression of atherosclerosis

  • General view Characteristics of cardiovascular

    complications in patients on dialysis

    Hypertension present in 60-90%

    LVH: 90%

    Total mortality: 12-25% - CV mortality: 60-70%

    CHD: 17x mortality

    Risk factors 1 mm Hg icrease in MAP = 35% increase in CV morbidity

    5 mm Hg increase in MAP = 3% increase in the risk of LVH

  • PATHOGENESIS

    Putative Pathogenetic Mechanisms of Hypertension in ESRD Patients

    Expanded extracellular fluid volume

    Renin angiotension aldosterone stimulation

    Increased sympathetic activity

    Endogenous digitalis-like factors

    Prostaglandins/bradykinins

    Altered function of endothelium-derived factors

    Erythropoietin administration

    Nephron number

    Parathyroid hormone secretion

    Calcified arterial tree

    Worsening of pre-existing essential hypertension

    Renal vascular disease

  • EXPANDED EXTRACELLULAR FLUID VOLUME

    Volume expansion is perhaps the most important factor in the development and maintenance of hypertension in dialyzed patients

    It leads to an elevation in BP through the combination of an increased in cardiac output and an inappropriately high systemic resistance

  • INCREASED SYMPATHETIC ACTIVITY

    Sympathetic overactivity is a common finding in ESRD

    The afferent signal may arise within the kidney because sympathetic activation is not seen in aphrenic patients

    Chemoreceptors within the kidney by uremic metabolites may be important in generation of these signals

  • ENDOGENOUS DIGITALIS-LIKE SUBSTANCE

    It is believed to be produced in either the hypothalamus or adrenal cortex

    Because it inhibits Na+-K+ ATPase activity, cytosolic sodium increases, inhibiting calcium outflux, and causing increased smooth muscle calcium content leading to increased smooth muscle tone

  • ENDOTHELIUM-DERIVED FACTORS

    The abnormal endothelial release of hemodynamically active compounds

    Elevated plasma levels of endothelin-1, the potent vasoconstrictor, had been found in uremic patients

    Uremic plasma contains a higher level of an endogenous compound, asymmetrical dimethylarginine, that is an inhibitor of NO synthesis

  • ERYTHROPOIETIN

    An increase in BP of 10mmHg or more occurs in approximately one third of the patients with renal failure who are treated with erythropoietin

    Through increased total peripheral resistance related to increased viscosity and decreased hypoxic vasodilatation

  • HYPERPARATHYROIDISM

    Increase in intracellular calcium induced by parathyroid hormone excess cause vasoconstriction and hypertension

    Either vitamin D administration or parathyroidectomy has been shown to lower blood pressure

  • Blood pressure measurement

    in dialysis patients

    Pre- or post-dialysis blood pressure measurements

    in patients with hemodialysis may be misleading for

    the diagnosis of hypertension:

    - the pre-dialysis systolic blood pressure may

    overestimate by an average of 10 mmHg

    - the post-dialysis systolic blood pressure may

    underestimate by an average of 7 mmHg

    Blood pressure readings over a period of 1 to 2 weeks rather than

    isolated readings should be used

    Luik AJ, Kooman JP, Leunissen ML. Hypertension in hemodialysis patients: Is it only hypervolaemia?

    Nephrol Dial Transplant 1997; 12: 1557-60.

  • Blood pressure measurement

    in dialysis patients

    Ambulatory blood pressure monitoring (ABPM) appears to be reproducible in pts. on hemodialysis.

    Blood pressure is frequently

    - high in pre-dialysis state,

    - it falls immediately after dialysis, and then

    - it gradually increases during the inter-dialytic period.

    ABPM may be useful in determining systolic blood pressure load(the amount of time that the patients systolic Bp exceeds normal values) which is an important factor in the development of left ventricular hypertrophy.

  • - Pre-dialysis blood pressure correlates better with

    LVH than post-dialysis blood pressure.

    - The dialyzed patients usually lose the diurnal variation

    in blood pressure and consequently these patients develop

    nocturnal hypertension.

    - Home blood pressure measurement, an increasingly popular

    method, may be useful to estimate the blood pressure control

    also in dialysed patients

    Conion PJ, Walshe JJ, Heinle SK et al. Predialysis systolic blood pressure correlates strongly with mean 24-hour systolic blood pressure

    and left ventricular mass in stable hemodialysis patients. J Am Soc Nephrol 1996; 7: 2658-63.

    Agarwal R. Role of home blood pressure monitoring in hemodialysis patients. Am J Kidney Dis 1999; 33: 682-7.

  • Management of high blood pressure in

    hemodialysis patients

    Improved survival due to adequate blood pressure

    control of dialysed patients has been clearly demonstrated,

    stressing the importance of adequate antihypertensive treatment.

    Salem MM, Bower J. Hypertension int he hemodialysis population: any relation to one-year survival? Am J Kidney Dis 1996; 28: 737-40.

  • Target blood pressure of hypertensive

    dialysed patients

    The pre-dialysis & post-dialysis Bp goals should be

  • Algorithm for blood pressure control

    in dialysis patients

    1. Estimate dry weight

    2. Initiate non-pharmacological treatment

    3. Attain dry weight

    4. Start or increase the dose of antihypertensives

    to maintain BP below 140/90 mmHg

    Fishbane S, Maseka JK, Goreja MA et al. Hypertension in Dialysis Patients . In Cardiovascular Disease in End-stage Renal Failure.

    Loscalzo J, London GM. Oxford University Press, New York, USA, 2000. pp 471-484.

  • Clinical definitions of stable dry weight - either the blood pressure has normalized or - symptoms of hypervolemia disappear (not merely the absence

    of edema);

    - after dialysis seated blood pressure is optimal, and

    - symptomatic orthostatic hypotension and clinical signs of

    fluid overload are not present;

    - at the end of dialysis patients remain normotensive until the

    next dialysis without antihypertensive medication.

    - No HTN (pre-dialysis Bp at the beginning of the week < 140/90 mmHg)

    - No peripheral edema

    - CXR; no pulmonary congestion & cardiothoracic ratio 50% ( 53% in females)

    - Absence of edema does not exclude the hypervolemia

  • DRY WEIGHT

    Not merely the absence of edema, but the body sodium content and volume of body water below which further reduction results in hypotension

    Volume removal to correct clinical fluid overload and optimized seated BP without symptomatic orthostatic hypotension after dialysis

    Body weight at the end of dialysis at which the patient can remain normotensive until the next dialysis without antihypertensive medication

    Salt & water balance: Patient compliance is often suboptimal & so, heavy reliance is placed on dialysis UF capacity to remove this excess fluid

  • LAG PHENOMENON

    In new patients starting dialysis, some period of time passes before volume is controlled, dry weight is achieved, and BP is controlled; this period has been called the lag phenomenon

    This is the time required to convert the patient from a catabolic to an anabolic state while the extracellular fluid space slowly stabilized

  • Algorithm for blood pressure control

    in dialysis patients

    5. If BP is not controlled or dry weight not attained in 30 days,

    consider:

    - 24-48 hours ABPM

    - increasing the duration of dialysis to facilitate removal

    of fluid and attainment of dry weight