How to manage hypotension (low blood pressure) during dialysis?

Management of Intradialytic Hypotension

For acute hypotension during dialysis, immediately reduce or stop ultrafiltration and administer an intravenous normal saline bolus while placing the patient in Trendelenburg position. 1, 2

Immediate Acute Management

When hypotension occurs during dialysis (systolic BP <90 mmHg or symptomatic drop ≥20 mmHg), take these sequential steps:

• Stop or reduce ultrafiltration immediately to prevent further blood pressure decline—this addresses the most common cause of intradialytic hypotension 1, 2
• Administer IV normal saline bolus to rapidly expand plasma volume and restore blood pressure 1, 2
• Place patient in Trendelenburg position (head down, legs elevated) to improve venous return 1
• Provide supplemental oxygen to improve tissue oxygenation and reduce symptoms 1

Reassessment After Acute Episode

Any symptomatic hypotension or systolic BP <90 mmHg requires immediate reassessment of multiple factors 2:

• Evaluate ultrafiltration parameters: Check if the ultrafiltration rate and total volume removed are excessive—rates as low as 6 mL/kg/hour can increase mortality risk 2, 3
• Reassess dry weight: Hypotension may indicate the target weight is set too low; gently probe the prescribed target weight upward in patients with recurrent hypotension 1, 2
• Review interdialytic weight gain: Excessive gains necessitate higher ultrafiltration rates that predispose to hypotension 2
• Audit all antihypertensive medications: These prevent compensatory vasoconstriction—consider holding or timing doses at night rather than before dialysis 2, 3

Pharmacological Prevention

Administer midodrine 2.5-25 mg orally within 30 minutes before dialysis initiation to prevent hypotension in susceptible patients 1. This selective α1-adrenergic agonist significantly increases intradialytic systolic pressure by 14 mmHg and is safe and effective 1, 4.

Critical medication considerations:

• Metoprolol is dialyzable and contributes to intradialytic hypotension when given before dialysis 2
• Hold or reduce beta-blockers if heart rate <60 bpm with concurrent hypotension 2
• Avoid administering multiple antihypertensives before dialysis 2

Dialysate Modifications (Highly Effective)

Sodium profiling is the most effective first-line intervention, starting with dialysate sodium at 152 mEq/L and gradually decreasing to 140 mEq/L in the last 30 minutes 1, 5. This maintains vascular stability better than other interventions 5.

Alternative dialysate strategies:

• Increase dialysate sodium to 144-148 mEq/L to prevent early-session hypotension 1, 5
• Reduce dialysate temperature to 34-35°C (from standard 37°C) to increase peripheral vasoconstriction and cardiac output—this is equally effective as sodium profiling 1, 5
• Switch from acetate to bicarbonate dialysate to prevent inappropriate decreases in total vascular resistance 1, 3

Important caveats: Increased dialysate sodium may cause increased thirst, interdialytic weight gain, and hypertension 1. Reduced temperature may cause uncomfortable hypothermia in some patients 1.

Ultrafiltration Strategy Modifications

Target ultrafiltration rate <13 mL/kg/hour when possible to minimize cardiovascular stress 2:

• Extend treatment time to reduce hourly ultrafiltration rate while achieving target volume removal 2
• Use ultrafiltration profiling with weight-based calculations 6
• Avoid isolated ultrafiltration followed by isovolemic dialysis—this approach causes significantly more hypotensive episodes than other strategies 5

Prevention Strategies for Recurrent Hypotension

Volume and dietary management:

• Limit sodium intake to 2-3 g/day through regular dietitian counseling to reduce interdialytic weight gain 2
• Avoid food intake immediately before or during dialysis—eating causes splanchnic vasodilation and decreased peripheral vascular resistance 1, 3

Anemia correction:

• Raise hemoglobin to 11 g/dL to improve oxygen-carrying capacity and reduce hypotension incidence 1, 2, 3

Critical Pitfalls to Avoid

• Do not use hypotension alone to define volume status—patients may be hypotensive yet volume overloaded 2
• Do not compromise dialysis adequacy in attempts to prevent hypotension; protracted hypotension can exaggerate urea rebound and compromise adequacy 2, 3
• Do not ignore the dialyzability of medications—dialyzable drugs like metoprolol cause variable blood pressure control throughout the dialysis cycle 2
• Do not set dry weight too low—this triggers compensatory mechanisms including increased thirst and paradoxically higher interdialytic weight gains 3

Algorithmic Approach Summary

1. Acute episode: Stop/reduce UF → IV saline → Trendelenburg → oxygen
2. Immediate reassessment: UF rate → dry weight → medications → interdialytic gains
3. First-line prevention: Sodium profiling OR cool dialysate (34-35°C)
4. Second-line prevention: Midodrine 30 minutes pre-dialysis
5. Ongoing management: Extend treatment time, limit dietary sodium, correct anemia to Hgb 11 g/dL, time antihypertensives at night