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BP Thresholds for Antihypertensive Therapy in CKD on Maintenance Hemodialysis (MHD)

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1. Intradialytic / During-Dialysis Hypertension

Systolic BP > 180 mm Hg during a dialysis session requires drug intervention.

• First-line: Captopril (oral, short-acting ACE inhibitor) - given sublingually or orally during the session.
• This is "fire-fighting" therapy; the definitive treatment is dry-weight reduction, not escalating medications.
• Comprehensive Clinical Nephrology, 7th Edition (Ch. 100, p. 1302-1303) explicitly states: "Increasing hypertension during a dialysis session requires intervention if systolic BP is greater than 180 mm Hg. This is best treated with a short-acting agent, such as the ACE inhibitor captopril."

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2. Interdialytic BP Target (Between Sessions)

Systolic BP 125-145 mm Hg is the reasonable goal for patients on RRT (renal replacement therapy).

• Goldman-Cecil Medicine states: "The ideal or goal interdialytic blood pressure for the patient with end-stage renal disease is probably 125 to 145 mm Hg systolic."
• The approach to antihypertensive therapy is similar to the general population, except diuretics are not helpful in anuric/oliguric dialysis patients.

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3. Pre-Dialysis BP: When to Start / Adjust Medications

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4. Intradialytic Hypotension (IDH) - When to Treat

1. Place patient in Trendelenburg position (head-down tilt)
2. Reduce or stop ultrafiltration
3. IV normal saline bolus (100-200 mL) or hypertonic saline (3%)
4. Reduce blood flow rate
5. If refractory: consider dialysate temperature reduction to 35.5-36°C, or switch to hemodiafiltration (HDF)

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5. Drug Choices in MHD - Key Points

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Summary Table: BP Thresholds at a Glance

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Key Clinical Principle

Volume control (dry weight optimization) is the primary treatment for hypertension in MHD patients - not escalating antihypertensive medications. A common clinical error is adding more BP drugs instead of reducing dry weight. Evidence from the DRIP trial supports that optimal BP control in HD patients is via extracellular fluid volume control.

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IV Medications for Acute Intradialytic Hypertension - Specific Indications & Dosing

When to Use IV (vs. Oral) Agents

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IV Drug Protocols: Acute/Emergency Setting in CKD-MHD

1. Nicardipine (Calcium Channel Blocker) - Drug of Choice in Renal Failure

• Indication: Hypertensive emergency in CKD/dialysis; excellent renal perfusion profile; preferred when IV drip is needed
• Starting dose: 5 mg/h IV infusion
• Titration: Increase by 2.5 mg/h every 5-15 min
• Maximum: 30 mg/h
• Dialysis removal: Unknown/minimal - safe to use
• Advantage: 92% of patients reached target SBP within 30 min (vs. 78% with labetalol) in an ED series with renal dysfunction patients
• Caution: Avoid in severe aortic stenosis

2. Labetalol (Alpha + Beta Blocker) - First-line IV Beta-blocker

• Indication: Hypertensive emergency; also useful when tachycardia is present
• Dialysis removal: < 1% - not removed by dialysis, making it ideal
• Bolus dosing: 20 mg IV over 2 min initially; repeat 40-80 mg boluses every 10 min as needed
• Infusion dosing: 0.4-1.0 mg/kg/h IV; maximum 3 mg/kg/h
• Cumulative maximum: 300 mg per 4-6 hour period
• Contraindications: Acute decompensated heart failure, significant bronchospasm, severe bradycardia, heart block

3. Hydralazine (Direct Vasodilator)

• Indication: Useful in acute setting; not removed by dialysis (see table below)
• IV dose: 5-10 mg slow IV over 2 min
• Repeat: Every 4-6 hours if needed; maximum initial dose 20 mg
• Caution in MHD: Can worsen volume retention and fluid overload; use with caution. Vasodilators as a drug class should generally be avoided in dialysis patients for long-term use
• Onset: 10-20 min; Duration: 3-8 hours (unpredictable, risk of prolonged hypotension)

4. Fenoldopam (Dopamine D1 Agonist) - Nephrology-Specific

• Indication: Hypertensive emergency with renal involvement; improves renal blood flow
• Dose: Start 0.1-0.3 mcg/kg/min IV; maximum 1.6 mcg/kg/min
• Advantage: Selectively vasodilates renal vasculature - preserves/improves renal perfusion
• Note: Primarily used in pre-dialysis or perioperative CKD; evidence in MHD is limited

5. Esmolol (Ultra-short Beta-1 Blocker) - For Rate Control + BP

• Indication: Acute BP elevation with tachycardia; aortic dissection
• Loading dose: 500 mcg/kg IV over 1 min
• Maintenance infusion: 50-200 mcg/kg/min
• Half-life: ~9 min - extremely titratable
• Note: Metabolized by red blood cell esterases, not renal excretion - safe in dialysis

6. Sodium Nitroprusside (SNP) - Use with Caution / Mostly AVOID in MHD

• Indication: Rarely, severe emergency when other agents fail
• Dose: 0.3-0.5 mcg/kg/min; max 10 mcg/kg/min
• Major Concern in dialysis: Metabolized to thiocyanate and cyanide - these accumulate in renal failure and cause cyanide toxicity (lactic acidosis, altered consciousness)
• Rule: If SNP must be used in dialysis >30 min or at doses >4-10 mcg/kg/min, co-administer sodium thiosulfate
• Practical advice: Best avoided - use nicardipine or labetalol instead

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Drug Removal by Dialysis - Quick Reference

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BP Reduction Goals During Emergency Treatment

• Reduce MAP by no more than 20-25% in the first 1-2 hours
• Then to approximately 160/100-110 mmHg within 2-6 hours
• Normalize to < 140/90 mmHg over the next 24-48 hours
• Do not lower BP too rapidly - risks cerebral, coronary, or mesenteric ischemia

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Practical Algorithm for the Dialysis Unit

SBP > 180 mmHg during HD
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        ├── No symptoms / no end-organ signs
        |       → Oral Captopril 25-50 mg (sublingual)
        |       → Continue dialysis, reassess in 20-30 min
        |       → Consider reducing UF rate
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        └── Symptoms present (headache, chest pain, visual Δ, neuro signs)
                → STOP dialysis
                → IV Labetalol 20 mg over 2 min (first-line)
                   or IV Nicardipine 5 mg/h infusion (preferred in pure renal failure)
                → Target: reduce MAP by 20-25% in 1-2 hours
                → Emergency consult if refractory

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Key Drugs to AVOID in MHD

• Nitroprusside - thiocyanate/cyanide accumulation (if used, add thiosulfate)
• Diuretics (for anuric patients) - no effect
• Minoxidil - pericardial and pleural effusions; fluid retention
• Hydralazine long-term - volume retention worsens overload
• Nifedipine (short-acting) - reflex tachycardia, hypotension, unpredictable; oral nifedipine/clonidine have no role in acute hypertensive emergency per current guidelines

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Oral vs IV Antihypertensives in Maintenance Hemodialysis (MHD) Patients

Full Comparison Table

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Summary by Clinical Scenario

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Key Principles at a Glance

• Choose non-dialyzable drugs for maintenance - ARBs (all), Amlodipine, Carvedilol, Fosinopril, Clonidine
• Oral captopril SL is the go-to for acute IDH without end-organ involvement
• IV Nicardipine is the preferred IV infusion drug when a drip is needed in renal failure
• IV Labetalol is the preferred IV bolus drug - < 1% removed by dialysis
• Never use nitroprusside without thiosulfate cover in dialysis patients; best avoided entirely
• Dry weight optimization remains the most effective BP intervention - drugs are adjuncts, not substitutes