What are the common intradialytic complications in patients undergoing hemodialysis and how should they be prevented and managed?

Intradialytic Complications in Hemodialysis

The most critical intradialytic complication is hypotension, occurring in 25-30% of all hemodialysis sessions, and should be prevented through dialysate temperature reduction to 34-35°C, increased dialysate sodium to 148 mEq/L, and slowed ultrafiltration rates, with acute episodes managed by stopping ultrafiltration, Trendelenburg positioning, and supplemental oxygen. 1, 2

Primary Complications and Their Frequencies

Hypotension (Most Common)

• Intradialytic hypotension (IDH) is defined as a systolic blood pressure decrease ≥20 mmHg or mean arterial pressure decrease ≥10 mmHg with associated symptoms including abdominal discomfort, yawning, nausea, vomiting, muscle cramps, dizziness, or anxiety. 1
• Occurs in approximately 25-30% of all hemodialysis sessions, with rates ranging from 15-50% depending on patient population. 1, 3, 4
• Carries significant mortality risk through ischemic cardiac or neurological events, vascular access thrombosis, dysrhythmias, and mesenteric venous infarction. 1

Other Common Complications

• Nausea and vomiting occur in 11-26% of sessions. 3, 4
• Fever and chills occur in 14-19% of sessions. 4
• Muscle cramps occur in 2-3% of sessions but account for 70% of premature dialysis terminations due to medical reasons. 5, 4
• Headache occurs in 10-16% of sessions. 6, 4
• Hypertension occurs in 10-17% of sessions. 3, 4

High-Risk Patient Identification

Patients at highest risk for intradialytic hypotension include those with:

• Age ≥65 years 1
• Diabetes mellitus with autonomic dysfunction 1
• Pre-dialysis systolic blood pressure <100 mmHg 1
• Cardiovascular disease 1
• Poor nutritional status and hypoalbuminemia 1
• Severe anemia 1
• Use of nitrates before dialysis 1

Prevention Strategies (Prioritized by Evidence Strength)

Dialysate Temperature Modification (Highest Priority)

• Reduce dialysate temperature from 37°C to 34-35°C to increase peripheral vasoconstriction and cardiac output, decreasing symptomatic hypotension incidence from 44% to 34%. 2, 5, 6
• This intervention has the strongest evidence for reducing multiple complications including hypotension, headache, and muscle cramps. 2, 6

Dialysate Sodium Optimization

• Increase dialysate sodium concentration to 148 mEq/L, particularly early in the session, to maintain vascular stability and prevent rapid osmotic shifts. 2, 5, 6
• Consider sodium profiling with higher sodium early and gradual reduction throughout the session. 5

Dialysate Buffer Selection

• Switch from acetate-containing to bicarbonate-containing dialysate to minimize nausea, vomiting, and headache, as acetate inappropriately decreases vascular resistance and increases myocardial oxygen consumption. 2, 6

Ultrafiltration Rate Management

• Slow the ultrafiltration rate by extending treatment time when patients have large interdialytic weight gains, as excessive ultrafiltration causes 70% of premature terminations. 5, 6
• Reassess estimated dry weight if complications are recurrent, as the target may be set too low. 5, 6

Pharmacological Prevention

• Administer midodrine (oral α1-adrenergic agonist) within 30 minutes before dialysis initiation to increase peripheral vascular resistance and enhance venous return. 2, 5, 6
• Maintain hemoglobin at 11 g/dL per NKF-K/DOQI guidelines to improve oxygen-carrying capacity and cardiovascular compensation. 2, 5

Patient Education and Behavioral Modification

• Limit fluid and salt intake between dialysis sessions to reduce interdialytic weight gain, emphasizing salt restriction specifically since water intake adjusts to match salt intake. 5, 6

Acute Management Protocols

For Hypotension During Dialysis

1. Immediately stop or reduce ultrafiltration. 2
2. Place patient in Trendelenburg position. 2
3. Administer supplemental oxygen. 2, 5
4. Consider hypertonic saline bolus (50-100 mL of 23.4% NaCl) if symptoms persist. 5

For Muscle Cramps During Dialysis

1. Administer hypertonic saline bolus (50-100 mL of 23.4% NaCl) intravenously—this is the most effective acute treatment with 87% response rate versus 13% for placebo. 5
2. Reduce or temporarily stop ultrafiltration. 5
3. Provide supplemental oxygen. 5

For Nausea/Vomiting During Dialysis

1. Reduce dialysate temperature to 34-35°C. 2
2. Switch to bicarbonate-containing dialysate if not already in use. 2

For Headache During Dialysis

1. Reduce or temporarily stop ultrafiltration. 6
2. Administer supplemental oxygen. 6
3. Ensure dialysate temperature is already optimized to 34-35°C. 6

Critical Pitfalls to Avoid

• Do not reduce blood flow or ultrafiltration rate as the primary response without first optimizing dialysate parameters (temperature, sodium, buffer), as this compromises delivered dialysis dose. 6
• Do not overlook medication review, particularly antihypertensive medications taken before dialysis, as these may require adjustment. 6
• Do not ignore recurrent complications—they indicate need for prescription modification rather than repeated acute interventions. 2
• Do not rely on patient symptom reporting alone, as patients often under-report symptoms retrospectively. 5

Monitoring Parameters for Quality Improvement

• Review extracorporeal pressures on hemodialysis log, particularly prepump arterial pressure for values ≥200 mmHg indicating access problems. 2
• Assess for dialyzer clotting which may indicate inadequate anticoagulation or access dysfunction. 2
• Monitor interdialytic weight gain patterns to identify patients requiring enhanced dietary counseling. 6
• Track frequency of premature session terminations, as 55% are due to medical reasons with 70% being cramp-related. 5

Long-Term Consequences of Unmanaged Complications

Chronic intradialytic hypotension leads to:

• Volume overload due to suboptimal ultrafiltration and use of fluid boluses for resuscitation 1
• Left ventricular hypertrophy with associated morbidity and mortality 1
• Interdialytic hypertension 1
• Inadequate dialysis delivery (suboptimal Kt/V) due to compartment effect 1