How to manage hypertension (high blood pressure) in a patient with impaired renal function undergoing dialysis, considering their underlying medical conditions such as diabetes and cardiovascular disease?

Management of High Blood Pressure During Dialysis

Prioritize achieving euvolemia through ultrafiltration and strict sodium restriction (2-3 g/day) before initiating or escalating antihypertensive medications, as volume overload is the primary driver of hypertension in dialysis patients. 1, 2

Understanding Intradialytic Hypertension

Intradialytic hypertension is defined as a systolic blood pressure increase >10 mm Hg from pre- to post-dialysis into the hypertensive range occurring in at least 4 of 6 consecutive dialysis treatments. 1 This phenomenon:

• Affects 5-15% of hemodialysis patients and is associated with increased hospitalization and mortality 1
• Results from sympathetic nervous system activation, renin-angiotensin system activation, endothelial stiffness, and most importantly, volume excess 1
• Should prompt extensive evaluation including out-of-unit blood pressure measurements and critical reassessment of dry weight 1, 2

Step 1: Volume Management (First-Line Strategy)

Before considering any medication adjustments, implement aggressive volume control measures: 1, 2

• Achieve true dry weight through gradual ultrafiltration adjustments (0.1 kg per 10 kg body weight over 4-12 weeks), which reduces ambulatory blood pressure by approximately 7 mmHg 2
• Enforce strict dietary sodium restriction to 2-3 g/day with intensive dietitian counseling 2, 3
• Consider extended dialysis time or increased frequency (>3 treatments per week), as the Tassin experience demonstrated that 89% of hypertensive patients no longer required antihypertensive medications after 3 months of long, slow dialysis combined with sodium restriction 2
• Use lower dialysate sodium concentrations (around 135 mmol/L rather than 140 mmol/L) to achieve proper volume control 2

Common pitfall: Initiating or escalating antihypertensive medications without first optimizing volume status will likely fail and increase risk of intradialytic hypotension. 1, 3

Step 2: Blood Pressure Targets

Target predialysis blood pressure <140/90 mmHg and postdialysis blood pressure <130/80 mmHg. 2, 3 However:

• Avoid targets that cause substantial orthostatic hypotension or symptomatic intradialytic hypotension 2, 3
• Maintain mean arterial pressure (MAP) ≥65 mmHg during hemodialysis sessions to ensure adequate tissue perfusion 2
• Be cautious with excessive blood pressure reduction as a U-shaped relationship exists between blood pressure and mortality in dialysis patients 2

Step 3: Accurate Blood Pressure Assessment

Use home blood pressure monitoring or ambulatory blood pressure monitoring rather than relying solely on in-center measurements, as they correlate poorly with interdialytic ambulatory blood pressure. 2

• Measure blood pressure with the patient seated quietly for at least 5 minutes, feet on floor, arm supported at heart level 2
• In patients with bilateral vascular access procedures, measure blood pressure in the thighs or legs using appropriate cuff size in the supine position 2

Step 4: Pharmacological Management (Only After Volume Optimization)

If blood pressure remains above target after 4-12 weeks of optimized ultrafiltration and sodium restriction, initiate antihypertensive medications in the following order: 1, 2, 3

First-Line Agents (Choose Based on Comorbidities):

For patients with coronary artery disease, prior myocardial infarction, or heart failure:

• Beta-blockers are first-line as they demonstrate the strongest evidence for reducing cardiovascular mortality and heart failure hospitalizations 2, 3
• Prefer non-dialyzable beta-blockers (propranolol, carvedilol) over highly dialyzable ones (atenolol, metoprolol) for preserved intradialytic protection against arrhythmias 1, 4
• However, use dialyzable beta-blockers (atenolol) in patients with frequent intradialytic hypotension, administered after the dialysis session 3, 4
• Carvedilol reduces cardiovascular mortality in hemodialysis patients with dilated cardiomyopathy but increases intradialytic hypotension risk 3, 4

For patients without specific cardiovascular indications:

• Calcium channel blockers (amlodipine) are first-line as they reduced cardiovascular events compared with placebo in randomized controlled trials of hemodialysis patients 3
• Calcium channel blockers are associated with decreased total and cardiovascular mortality in observational studies 3

Second-Line Agents:

ACE inhibitors or ARBs should be added if blood pressure remains uncontrolled: 1, 2, 3

• They cause greater regression of left ventricular hypertrophy, reduce sympathetic nerve activity, improve endothelial function, and are associated with decreased mortality 2, 3
• They may preserve residual kidney function, especially in peritoneal dialysis patients 3
• Critical warning: ACE inhibitors can cause sudden and potentially life-threatening anaphylactoid reactions in patients dialyzed with high-flux membranes; dialysis must be stopped immediately if this occurs 5

Step 5: Medication Timing Considerations

Administer antihypertensive medications preferentially at night to reduce nocturnal blood pressure surge and minimize intradialytic hypotension. 2, 3

For patients with frequent intradialytic hypotension (systolic BP drops >20 mmHg or symptomatic hypotension): 3

• Hold carvedilol and other non-dialyzable agents before dialysis
• Administer these medications after the dialysis session
• Consider switching to dialyzable agents like atenolol administered post-dialysis

Special Considerations for Diabetes and Cardiovascular Disease

In patients with both diabetes and cardiovascular disease on dialysis: 2, 3

• Beta-blockers remain first-line for cardiovascular protection 2, 3
• ACE inhibitors/ARBs provide additional benefits through left ventricular mass reduction 3
• Monitor serum potassium periodically as ACE inhibitors/ARBs can cause hyperkalemia, especially with concurrent diabetes and renal insufficiency 5
• Erythropoietin therapy can worsen hypertension, particularly in patients with pre-existing hypertension or rapid anemia correction 2

Critical Pitfalls to Avoid

• Never initiate or escalate antihypertensive medications without first assessing and optimizing volume status 1, 2, 3
• Do not rely solely on predialysis or postdialysis blood pressure measurements as they correlate poorly with interdialytic ambulatory blood pressure 2
• Avoid high dialysate sodium concentration and sodium profiling as these aggravate thirst, fluid gain, and hypertension 2
• Do not use ACE inhibitors with high-flux dialysis membranes without awareness of anaphylactoid reaction risk 5
• Failing to consider medication dialyzability when selecting agents and dosing schedules leads to suboptimal outcomes 1, 3

Monitoring and Reassessment

• Monitor for orthostatic hypotension, particularly in elderly patients 2
• Evaluate for secondary causes of resistant hypertension if blood pressure remains uncontrolled despite optimal therapy 2
• Preserve residual kidney function when possible through appropriate medication selection and volume management 2
• Large doses of loop diuretics (furosemide) can be administered to promote sodium and water loss in patients with residual kidney function, though use should be approached with caution 2