How is intradialytic hypotension managed?

Management of Intradialytic Hypotension

Prioritize non-pharmacological interventions first—specifically reducing ultrafiltration rates below 6 ml/h/kg, lowering dialysate temperature to 34-35°C, and using bicarbonate-buffered dialysate—before considering midodrine administration 30 minutes pre-dialysis for refractory cases. 1, 2

Initial Assessment and Target Weight Optimization

Reassess the estimated dry weight (EDW) as the first step in patients with recurrent intradialytic hypotension, looking specifically for:

• Increased dietary intake with rising serum albumin, creatinine, or normalized protein catabolic rate (NPCR) occurring alongside hypotensive episodes 1, 2
• Signs that EDW may be set too low, causing inappropriate volume depletion 1, 2

The target weight should be adjusted treatment-by-treatment based on clinical status, recognizing the narrow therapeutic window between volume depletion and overload 1, 2

Ultrafiltration Management (Primary Strategy)

Reduce ultrafiltration rates to minimize hemodynamic stress:

• Keep ultrafiltration rates below 6 ml/h/kg, as higher rates associate with increased mortality and end-organ ischemia (heart, brain, liver, gut, kidneys) 1, 2
• Extend dialysis treatment time rather than accepting high ultrafiltration rates for patients with large interdialytic weight gains 1, 2
• Consider sequential ultrafiltration followed by diffusive clearance, which improves hemodynamic stability by separating fluid removal from solute clearance 1
• Counsel patients with excessive interdialytic weight gain to restrict fluid intake 1, 2

Dialysate Modifications (Highly Effective)

Implement these dialysate changes systematically:

Temperature Reduction

• Lower dialysate temperature from 37°C to 34-35°C to increase peripheral vasoconstriction and cardiac output 1, 2
• This intervention reduced symptomatic hypotension from 44% to 34% in clinical studies, with greatest benefit in patients with frequent hypotensive episodes 1
• Cold dialysis does not compromise urea clearance but may cause mild hypothermia symptoms in some patients 1

Buffer Composition

• Switch from acetate-containing to bicarbonate-containing dialysate, as acetate inappropriately decreases total vascular resistance and increases venous pooling 1, 2
• Bicarbonate dialysate also reduces headaches, nausea, and vomiting 1

Sodium Profiling

• Increase dialysate sodium concentration to 148 mEq/L early in the session, followed by continuous or stepwise decrease ("sodium ramping") 1, 2
• Caveat: This may increase interdialytic weight gain and blood pressure variability 1, 2

Pharmacological Intervention: Midodrine

For refractory cases after optimizing non-pharmacological measures:

• Administer midodrine 5-10 mg orally 30 minutes before hemodialysis initiation 1, 2, 3, 4
• Midodrine increases peripheral vascular resistance through alpha-1 adrenergic receptor activation and enhances venous return 1, 3
• Clinical studies demonstrate significant increases in lowest intradialytic systolic blood pressure (from 69 to 85 mm Hg) and reduced need for intravenous fluid interventions 5, 6
• Midodrine is effectively cleared during dialysis with a reduced half-life of 1.4 hours 3

Important monitoring considerations:

• Watch for reflex bradycardia due to baroreceptor-mediated vagal stimulation from increased blood pressure 3
• Monitor for supine hypertension (occurs in up to 25% of patients); avoid dosing within several hours of bedtime 3
• Use caution when combining with beta-blockers or non-dihydropyridine calcium channel blockers 3

Additional Supportive Measures

Consider these adjunctive strategies:

• Raise hemoglobin to 11 g/dL per anemia guidelines, particularly for patients with cardiovascular or respiratory disease 1, 2
• Administer supplemental inhaled oxygen during dialysis for high-risk patients 1, 2
• Avoid food intake immediately before or during hemodialysis, as it decreases peripheral vascular resistance 1, 2
• Review timing of antihypertensive medications, considering withholding doses before dialysis in patients with frequent intradialytic hypotension 1, 2

Alternative Pharmacological Options (Limited Evidence)

For patients who cannot tolerate or fail midodrine therapy, consider:

• Arginine-vasopressin, sertraline, droxidopa, amezinium metilsulfate, fludrocortisone, or carnitine 1
• Note: The evidence base for these alternatives is relatively weak with small, short-duration studies 1

Critical Pitfalls to Avoid

• Do not decrease blood flow or ultrafiltration rate reactively during hypotensive episodes without adjusting the overall prescription, as this compromises dialysis adequacy and may worsen urea rebound 1
• Do not use hypotension alone to define intravascular volume status when setting target weight 1
• Do not ignore the ultrafiltration rate as a modifiable risk factor—patient and clinician awareness of this parameter is critically important 1
• Do not apply a single UF rate threshold universally—consider intradialytic hemodynamics, comorbidities, symptoms, and current clinical conditions on a treatment-by-treatment basis 1

Patient Education Component

Engage patients actively in their hemodialysis care, emphasizing:

• The value of limiting interdialytic fluid intake 1, 2
• Avoiding food immediately before or during dialysis 1, 2
• Understanding that failure to adhere to the hemodialysis prescription compromises all other interventions 1