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Blood pressure changes during

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Blood pressure changes during

  1. 1. CHANGES IN BLOOD PRESSURE AFTER HEMODIALYSIS Magdy El-Masry Prof. of Cardiology Tanta University
  2. 2. Hemodialysis Removal of Fluid and Solutes with the Goal to Achieve “Dry Weight” What the cardiologist should know ?
  3. 3. Hemodialysis Basics
  4. 4. Diffusion
  5. 5. Convection
  6. 6. Goals of Dialysis –Solute clearance • Diffusive transport (based on countercurrent flow of blood and dialysate) • Convective transport (solvent drag with ultrafiltration) –Fluid removal
  7. 7. 11
  8. 8. Body Fluid Compartments Figure 3-2
  9. 9. Extravascular Fluid Removal by Ultrafiltration (UFR) illicits compensatory mechanisms, termed plasma or intravascular refill, aimed at minimizing this reduction Appropriate Removal Rate setting the fluid removal rate to not exceed the plasma refill rate (PRR) will minimize risk of hypovolemia, hypotension “Never too fast, never too much” UFR ≤ PRR Plasma Refill Rate Intravascular Vascular Space Hemodialysis UF rate
  10. 10. Dialysate Buffer • • Acetate: in the early 1960s became the standard dialysate buffer used to correct uremic acidosis In the mid 1980s some reported the linking between acetate and cardiovascular instability and hypotension during HD Bicarbonate: emerged the buffer of choice
  11. 11. Dialysis Solution Sodium Level Plus Minus Low dialysate sodium Less weight-gain, thirst &hypertension More hypotension, cramps High dialysate sodium Less hypotension, More weight gain, cramps thirst & hypertension
  12. 12. CONCEPT of DRY WEIGHT EXCESS FLUID WEIGHT Body weight at which composition of body fluid compartments is normal. DRY WEIGHT (euvolemia) At higher weights there is expansion of compartments At lower weights there is depletion of compartments. Both these states have adverse clincal consequences.
  13. 13. In short, among all these elements, the 2 essential clues are the BP and the weight
  14. 14. Intradialytic Hypotension
  15. 15. Acute complications of dialysis HHCCBNF • • • • • • • • Hypotension — 25 to 55 % Cramps — 5 to 20 % Nausea and vomiting — 5 to 15 % Headache — 5% Chest pain — 2 to 5 % Back pain — 2 to 5 % Itching — 5 % Fever and chills — Less than 1 %
  16. 16. Intradialytic Hypotension K/DOQI • ↓SBP≥20mmHg or ↓MAP 10mmHg with symptoms: abdominal discomfort, yawning, sighing, N/V, cramps, restlessness, anxiety, fainting
  17. 17. Arterial Blood Pressure Cardiac output Heart rate / rhythm Diastolic filling Atrial kick Systemic vascular resistance Stroke volume preload afterload contractility
  18. 18. PATHOGENESIS Ultrafiltration Osmolality Fall Warm Dialysate Bio-incompatibility Endotoxin Acetate Infusion MEDIATORS Volume PATHOPHYSIOLOGY CARDIAC OUTPUT PATIENT Heart Disease Vasopressors Vascular Disease Vasodilatator Autonomic Dysfunction PERIPHERAL RESISTANCE Cell Dysfunction Hormonal Dysfunction Medications Complement Activation, Sepsis Infection Cytokine release HYPOTENSION Hypoxemia Vasovagal stim.
  19. 19. Acute management of low blood pressure associated with hemodialysis  Ultrafiltration should either be stopped or the rate decreased.  The patient should be placed in the Trendelenburg position.  The blood flow rate should be reduced.  Intravascular volume may be replaced with mannitol or saline. Currently the use of an intravenous bolus of saline is the first-line therapy for hypotension.
  20. 20. PREVENTION • Accurate setting of the "dry weight" • Steady, constant ultrafiltration • Increased dialysate sodium concentration and sodium modeling • Bicarbonate dialysate buffer • Decrease dialysate temperature from 37C to 34-35C
  21. 21. Prevention – Con’t  Improvement in cardiovascular Performance in cardiac patients.  Midodrine (the selective alpha-1 adrenergic agonist) in patients with autonomic neuropathy and perhaps others with severe hemodialysis hypotension not responsive to the above measures.  Avoidance of food.  Avoid large interdialytic weight gain  No antihypertensive before dialysis
  22. 22. Intradialytic Hypertension The growing problem of intradialytic hypertension (5 – 15 % of HD patients )
  23. 23. Intradialytic Hypertension Clinical Definitions • ↑MAP of ≥ 15 mmHg during or immediately post dialysis • Hypertension during 2nd or 3rd hr of HD after significant UF removed • ↑BP that is resistant to UF
  24. 24. The Etiopathogenesis of Intradialytic Hypertension Hypervolemia Sodium balance positive and extracellular volume expand Increased systemic vascular resistance Increased sympathetic activity Renin-angiotensin system hyperactivity Endothelial cell dysfunction Elevated concentration of endothelin 1 Nitric oxide deficiency Increased vascular stiffness Calcification of the arterial tree Increased hematocrit Erythropoietin Therapy
  25. 25. Hypertension in dialysis (Another World • There are limited studies on controlling blood pressure in patients on dialysis. • No consistent guidelines available due to the fact that no one knows what blood pressure to target. – Pre, Post, intradialytic, non-dialysis day.
  26. 26. Blood pressure measurement in dialysis patients  Majority of Uremic patients lack diurnal variation in BP  Immediate pre‐dialysis and post‐dialysis are misleading and not reflective of true interdialytic BP However, a post dialytic BP is more reflective of interdialytic BP *Continuous monitoring is warranted in poor control patients (those with large interdialytic weight gain) *“Systolic load “ ‐‐ > amount of time SBP exceeds 140 mmHg per day as correlates to incidence of LVH
  27. 27. K/DOQI Blood Pressure Goals in Hypertensive ESRD Patients • Target BP ≤ 140/90 mmHg (predialysis) • ≤ 130/80 mmHg (postdialysis)
  28. 28. Treatment of hypertension in patients on hemodialysis Treatment of hypertension is often a multiple-step, multidisciplinary process to reach KDOQI guidelines of predialysis BP values of <140/90 mm Hg. The key to successful treatment is patience; it often takes 4-6 weeks to achieve results. (This represents the lag phenomenon )
  29. 29. Lag period between normalisation of ECF and optimal control of BP DLIS etc Chronic volume expansion LAG BP ADMA Vascular Na/K ATPase NO Synthetase iCa++ NO DLIS etc ADMA ECV Vasoconstriction Sustained UF & Na restriction DLIS:digoxin-like immunoreactive substance ADMA:asymmetric-dimethyl arginine
  30. 30. Treatment of Intradialytic Hypertension The step-by-step approach
  31. 31. Choice of antihypertensive drugs All classes of antihypertensive drugs can be used in dialysis patients, with the sole exception of diuretics, which are not commonly used because of their lack of efficacy. Therefore, with the exceptions of diuretics, the criteria for drug selection are quite similar to those used in non-dialysis patients.
  32. 32. Dialysis Clearance of Drugs In general, removal of drugs on HD has NOT been tested and is based on theoretical considerations of molecular size and chemical makeup of the drug Drugs with low MW, limited volume of distribution (Vd) , and that are water-soluble are most likely to be removed by HD and will require extra dosing
  33. 33. Postdialysis dosing or extra doses after HD may be necessary for certain antihypertensive agents: •Angiotensin converting enzyme inhibitors (ACE-I): all are dialyzable except fosinopril •Angiotensin receptor blockers (ARB): none are dialyzed •B-blockers: atenolol and metoprolol are dialyzable but labetolol and carvedilol are not •Calcium channel blocker: amlodipine is not dialyzable
  34. 34. Conclusions The fluctuations in BP with every dialysis is complex “We can do better”
  35. 35. Intradialytic Blood Pressure Fluctuations • Current State Clinically significant alteration in blood pressures is one of the biggest challenges encountered in the dialysis unit • Ideal State Clinicians understand the physiological changes in blood pressures during hemodialysis and prevent and manage these changes effectively to ensure patient’s safety
  36. 36. Thank you for your attention Gracias por su atención Danke für Ihre Aufmerksamkeit Go raibh maith agat Grazie per l´Attenzione AAp sAAb kA shukriyA… Merci pour votre attention

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