What causes sudden onset of dyspnea (shortness of breath) during hemodialysis?

Causes of Sudden Onset of Dyspnea During Hemodialysis

The most common causes of sudden onset of dyspnea during hemodialysis include myocardial ischemia, fluid overload, pulmonary embolism, hemolysis, dialyzer bio-incompatibility reactions, and air embolism. 1

Cardiovascular Causes

• Myocardial ischemia/Acute Coronary Syndrome: The most frequent serious cause of dyspnea during hemodialysis, often induced by hypotension or tachyarrhythmias in patients with coronary artery disease 1
• Fluid overload/Heart failure: Inadequate ultrafiltration or incorrect dry weight assessment can lead to pulmonary congestion and dyspnea 1
• Arrhythmias: Electrolyte shifts during dialysis can trigger arrhythmias causing dyspnea 1
• Pericarditis: A potential complication in dialysis patients that can present with dyspnea 1

Dialysis-Related Causes

• Hemolysis: Mechanical destruction of red blood cells due to kinked blood lines, excessive pump speeds, or other technical issues can cause acute dyspnea, often accompanied by chest/abdominal pain and darkening of blood in the circuit 2
• Dialyzer bio-incompatibility reactions: Ethylene oxide or other sterilants used in dialyzer manufacturing can trigger allergic reactions with dyspnea within minutes of starting dialysis 3
• Air embolism: Accidental introduction of air into the circuit can cause pulmonary air embolism with sudden dyspnea 4
• Rapid ultrafiltration: Excessive or too rapid fluid removal can cause hypotension and compensatory dyspnea 1, 5

Pulmonary Causes

• Pulmonary embolism: Blood clots can form and embolize during dialysis, particularly with inadequate anticoagulation 1
• Hypoxemia: Dialysis-induced leukocyte sequestration in pulmonary circulation can cause transient hypoxemia 4
• Pulmonary hypertension: Pre-existing pulmonary hypertension can worsen during dialysis due to fluid shifts 1

Other Causes

• Electrolyte imbalances: Rapid shifts in potassium, calcium, or magnesium can trigger respiratory muscle dysfunction and dyspnea 1
• Anemia: Severe anemia reduces oxygen-carrying capacity and can worsen during dialysis 5
• Infection: Fever and sepsis can present with dyspnea during dialysis 6

Diagnostic Approach

1. Immediate assessment:

   • Check vital signs including oxygen saturation 1
   • Examine dialysis circuit for abnormalities (blood color, kinks in tubing) 2
   • Assess for signs of fluid overload (crackles, elevated jugular venous pressure) 1

2. Urgent investigations:

   • 12-lead ECG to evaluate for ischemia or arrhythmias 1
   • Chest X-ray for pulmonary edema, infiltrates, or pneumothorax 1
   • Blood tests including complete blood count, cardiac enzymes, and electrolytes 2

Management Principles

• For suspected cardiac ischemia: Obtain ECG immediately and transfer to acute care setting by EMS 1
• For fluid overload: Adjust ultrafiltration goals and reassess dry weight 1
• For hemolysis: Stop dialysis immediately without blood restitution, check for mechanical causes, and consider blood transfusion if severe 2
• For bio-incompatibility reactions: Stop dialysis, consider steroid administration, and use alternative dialyzer materials in subsequent sessions 3

Prevention Strategies

• Regular assessment of dry weight and cardiovascular status 1
• Appropriate anticoagulation during dialysis 1
• Regular maintenance of dialysis equipment 2
• Proper rinsing of dialyzers before use if ethylene oxide sensitivity is suspected 3
• Slower ultrafiltration rates in patients with cardiovascular instability 1, 5

Important Considerations

• Dyspnea is often multifactorial in dialysis patients and may persist despite adequate ultrafiltration, suggesting multiple underlying mechanisms 4, 7
• Neuromechanical dissociation (mismatch between respiratory effort and ventilatory output) is a major pathophysiologic mechanism of dyspnea in chronic kidney disease patients 7
• Patients with end-stage renal disease have a high prevalence of underlying cardiopulmonary disease that may be unmasked during the hemodynamic stress of dialysis 1