How to manage hypotension in a patient undergoing hemodialysis who is not on any antihypertensive medications?

Management of Hypotension in Hemodialysis Patients Not on Antihypertensives

In hemodialysis patients experiencing hypotension who are not on antihypertensive medications, immediately stop or reduce ultrafiltration, administer IV normal saline (100-250 mL bolus), place in Trendelenburg position, and provide supplemental oxygen, then systematically modify the dialysis prescription by keeping ultrafiltration rates below 6 mL/h/kg through extended treatment time (minimum 4 hours) or increased frequency (three times weekly), while reassessing the estimated dry weight upward as it is likely set too low. 1, 2, 3

Immediate Acute Interventions

When hypotension occurs during dialysis, execute these steps in rapid sequence:

• Stop or reduce ultrafiltration immediately to prevent further blood pressure decline and allow vascular refilling—this is the single most critical intervention 1, 2, 3
• Administer intravenous normal saline bolus of 100-250 mL to rapidly expand plasma volume, though avoid routine saline administration for every episode as this perpetuates volume overload and fails to address the underlying problem 1, 3
• Place patient in Trendelenburg position (head down, legs elevated) to improve venous return and increase blood pressure 1, 2
• Provide supplemental oxygen to improve tissue oxygenation and reduce symptoms 1, 2

Critical Dialysis Prescription Modifications

The most common cause of hypotension in dialysis patients not on antihypertensives is excessive ultrafiltration rate relative to vascular refilling capacity:

• Keep ultrafiltration rates below 6 mL/h/kg as rates exceeding this threshold are associated with higher mortality risk and increased hypotension 1, 3
• Extend treatment time to minimum 4 hours per session to slow the ultrafiltration rate and allow adequate vascular refilling 1, 3
• Increase dialysis frequency from twice to three times weekly when patients have excessive interdialytic weight gain requiring aggressive ultrafiltration that exceeds vascular refilling capacity 1, 3

Common pitfall: Continuing twice-weekly dialysis forces dangerously high ultrafiltration rates (often exceeding 10-13 mL/h/kg) and inadequate solute clearance—this must be avoided 3

Reassess Estimated Dry Weight

In patients not on antihypertensives, hypotension strongly suggests the target dry weight is set too low:

• Gradually probe the dry weight upward over 4-12 weeks without inducing hypotension, as the current target is likely underestimating true dry weight 3
• Look for signs of improving nutrition (increasing serum albumin, creatinine, or normalized protein catabolic rate) alongside hypotension, which indicates the dry weight needs upward adjustment 1
• Consider residual urine output as this commonly leads to underestimation of true dry weight—a frequent pitfall in these patients 1, 3

Dialysate Modifications

Modify the dialysate composition to enhance hemodynamic stability:

• Increase dialysate sodium concentration to 148 mEq/L, especially early in the dialysis session, or implement sodium profiling (starting higher at 148 mEq/L and gradually decreasing) to maintain vascular stability 1, 2
• Reduce dialysate temperature from 37°C to 34-35°C to increase peripheral vasoconstriction and cardiac output through increased sympathetic tone, which decreases symptomatic hypotension from 44% to 34% 1, 2
• Switch from acetate-containing to bicarbonate-containing dialysate to prevent inappropriate decreases in total vascular resistance and venous pooling 1, 2, 3

Caution: Increased dialysate sodium may lead to increased thirst, interdialytic weight gain, and subsequent hypertension; reduced dialysate temperature may cause uncomfortable hypothermia in some patients 2

Pharmacological Management with Midodrine

For patients with persistent hypotension despite dialysis prescription modifications:

• Administer midodrine (oral α1-adrenergic agonist) 30 minutes before dialysis initiation at a mean dose of 8 mg (range 2.5-25 mg) to increase peripheral vascular resistance and enhance venous return 1, 2, 4
• Midodrine significantly increases minimal systolic pressure from 93 mmHg to 107 mmHg during hemodialysis and post-dialysis pressures from 116/62 to 130/68 mmHg 5
• Monitor for supine hypertension as midodrine can cause elevated blood pressure when lying flat; patients should avoid taking their last daily dose within 3-4 hours of bedtime 4
• Note that midodrine is removed by dialysis, so timing of administration is critical 4

Contraindications and precautions: Use midodrine cautiously in patients with urinary retention, diabetes, visual problems, renal impairment (start at 2.5 mg), or hepatic impairment; avoid concomitant use with MAO inhibitors, and monitor carefully when used with cardiac glycosides or beta-blockers 4

Long-Term Prevention Strategies

Implement these measures to prevent recurrent hypotension:

• Limit sodium intake to <5.8 g/day to reduce thirst and interdialytic weight gain, as water intake adjusts to match salt intake 1, 3
• Restrict interdialytic weight gain to <3% of body weight between sessions to prevent excessive ultrafiltration requirements 1, 3
• Avoid food intake immediately before or during hemodialysis, as this causes decreased peripheral vascular resistance and may precipitate hypotension 1, 2
• Maintain hemoglobin at 11 g/dL per NKF-K/DOQI guidelines to improve oxygen-carrying capacity and cardiovascular compensation during ultrafiltration 1, 3

Special Consideration: Chronically Hypotensive Patients

For patients with persistent hypotension despite all interventions:

• Consider transition to peritoneal dialysis as these patients may tolerate continuous ambulatory peritoneal dialysis (CAPD) better than hemodialysis due to slower, continuous ultrafiltration 6, 3

Algorithm for Management

Step 1: During acute hypotensive episode → Stop/reduce UF + IV saline + Trendelenburg + O2 1, 2

Step 2: Reassess dry weight upward (likely too low) 1, 3

Step 3: Modify dialysis prescription → UF rate <6 mL/h/kg via longer sessions (≥4 hours) or increased frequency (3x/week) 1, 3

Step 4: Adjust dialysate → Increase sodium to 148 mEq/L + Reduce temperature to 34-35°C + Switch to bicarbonate 1, 2

Step 5: If hypotension persists → Add midodrine 30 minutes pre-dialysis (start 2.5-8 mg) 1, 2, 5

Step 6: Implement prevention → Sodium restriction <5.8 g/day + Interdialytic weight gain <3% + Avoid pre-dialysis meals + Maintain Hgb 11 g/dL 1, 3

Step 7: If refractory → Consider peritoneal dialysis 6, 3