Maher Fouad Ramzy; MD, FACP Professor of Renal Medicine, Cairo University

Transcription

1 Hypertension in Hemodialysis Patient Maher Fouad Ramzy; MD, FACP Professor of Renal Medicine, Cairo University Mechanism of HTN in HD patients Volume-dependent HTN ECV expansion. Volume-independent HTN Renal-dependent factors. Vascular factors. Medications and toxins. Am J Kidney Dis 2004; 43:739-51

2 Mechanism of HTN in HD patients ECV expansion: Blood volume-related vasoactive substances. Dietary salt non compliance. Hemodialysis prescription: Dialysate Na+ and K+ concentrations. Shorter dialysis sessions. Overestimation of dry weight. Renal-dependent factors: Dysregulation of renin-angiotensin system. Sympathetic hyperactivity. Loss of inherent renal vasodilatory factors. Vascular factors: Elevatted calcium/phosphate product. Secondary hyperparathyroidism. Vascular calcification and stiffening. Medications and toxins: Recombinant human erythropoietin. Cigarette smoking. Am J Kidney Dis 2004; 43: Deleterious effects of extra- cellular volume overload Congestive heart failure in 25 to 46% in Europe and US HD patients according to DOPPS. Goodkin, JASN 2003;14:3270 Role of inadequate coorection of ECV overload highly probable. It contributes to left ventricular hypertrophy. Fagugli, Nephron 2002; 91:79 Konings, PDI 2002; 22:477 It leads to HTN that decreases patient long-term survival. Charra, KI 1992; 41: Stidley, JASN 2006; 17:513 It exposes the patients to acute pulmonary oedema especially during catabolic events.

3 Blood Pressure and Outcomes Am J Nephrol 2001; 21:280-8; JAMA 2002; 287: General population: SBP is linearly linked with increased CDV morbidity and mortality. TT is associated with reduction in both. In HD patients: High SBP: a major predictor of mortality in HD p ts pts A Ushaped relationship between post-dialysis SBP and mortality has been described Reverse causality. Measurement of blood pressure in HD HD patients should have their BP assessed by home or ABP, and reliance on in-center measurements of BP should be discouraged. Home blood pressure recording agrees well with ABP and correlates with left ventricular hypertrophy and may serve well for managing HTN.

4 Control of ECV Evaluation of blood volume. Hemodialysis prescription. Ultrafiltration. Interdialytic weight gain. Diuretics. Evaluation of blood volume Clinical assessment of volume status Jugular vein Peripheral edema CXR Noninvasive evaluation of volume status Ultrasound measurement of IVC diameter Multifrequency bioimpedance Biochemical markers: Adrenomedullin levels may reflect systemic blood volume. "dry weight" is an inadequate surrogate for volume status of dialysis patients, and the reference standard remains to be defined.

5 Dry Weight A consensus definition of dry weight notoriously complicated The lowest weight pt p t can tolerate before hypotension or symptoms From Tassin: The postdialysis weight at which the p t remains normotensive w/o anti-htn and despite interdialytic weight gain Dry weight will constantly change based on nutritional status Subtle loss of true dry weight! Overestimation will contribute to HTN Only 2% BW difference between normotensive and HTN Nephron Physiol 2003; 93: Hemodialysis prescription Nephrol Dial Transplant 1999; 14:919-22; Am J Kidney Dis 1998; 31: Tight control of ECV prevents HTN in HD p ts: Long, slow HD (18 hrs per week). Ultrafiltration. High-flux or high-efficiency HD. No improvement in BP control or anti-htn medications. Minor interdialytic weight gain: lower frequency of HTN less anti-htn drugs higher 10-yr survival rate opposed to conventional HD (12 hrs per week)

6 Ultrafiltration Ultrafiltration initiated, probing for true dry weight Early ultrafiltration phase: tapering of anti- HTN medications Anti-HTN medications Don t allow vascular system to properly adapt to ongoing ultrafiltration Result in repeated hypotension Lag Phenomenon Once dry weight is achieved, BP often does normalize but may take weeks to months Anti-HTN medications should not be reinstituted MAP mmhg 94.4 mmhg after reduction to dry weight over the first 6 months Only a sustained normalization of ECV will result in perfect BP control Nephrol Dial Transplant 1999; 14:121-4

7 Reinstitution of Medication A minority remain hypertensive despite aggressive UF volume-independent HTN require reinstitution of anti-htn medications Classes of antihypertensive agents Various drugs are effective in controlling BP, but the comorbidities, pharmacokinetics, and the tolerability has to be taken into account. Patients often require more than one class. Choice of medication: concomitant disease CAD beta-blocker blocker

8 Evidence for survival advantage with beta blockers in dialysed patients DOPPS study: 13 % less mortality in pat. on β blockers Bragg, JASN abstract 2001 Improved survival and ejection fraction in dialysed pat. on carvedilol vs placebo (controlled prospective trial) Cice J Am Coll Card (2003)41:1438

9 RAAS Blockade Many studies focused on the role of RAAS blockade in mitigating CV complications in HD pts. ACEI cause regression of LVH in hypertensive ESRD, no such an effect in normotensive HD. ACEI preferable: fewer hypertensive episodes regression of LVH? favorable survival synergy with UF Larger prospective studies are necessary to clarify further the unanswered questions. Less mortality of dialysis patients on ACE inhibitors Efrati, Am.J.Kid.Dis(2002)40:1023.

10 Comparison of ACE inhibitors and Angiotensin II Antagonists Advantages Decreases angiotensin II level. Regression of LVH. May reduce thirst. Lipid neutral. Disadvantages Anaphylactic reaction. Cough as a side effect. Hyperkalemia. Dose adjustment needed. ACE Angiotensin i II Antagonists t inhibitors Maybe No, Decreases response to angiotensin II. Not studied in dialysis patients. Reduces L VH in non-dialysis patients Not studied.. Not reported. No. Not studied. No Blood pressure measurement Timing and targets Recommendations [JASN 17: S1-S27; 2006] Use predialysis BP to guide therapy. (Grade C) Systolic HTN should be the target of therapy. Target predialysis BP to be <140/90 (Grade C); optimal BP is unknown. Home measurement or ambulatory recording devices should be applied to patients where difficulty occurs in reaching target BP levels. (Grade D, opinion)

11 Management of hypertension Recommendations [JASN 17: S1-S27; 2006] Limit dietary sodium intake to meq/d. (Grade C) Reduce patient weight gradually by ultrafiltration, targeting for the dry weight, as antihypertensive medications are withdrawn. (Grade C) Paradoxical rises in BP during individual dialysis/ultrafiltration i lt ti sessions should be corrected by further gradual volume removal. (Grade D) Reinstitution of Medication when needed. Am J Kidney Dis 2004; 43:739-51