What are the symptoms of anaphylaxis in a patient undergoing hemodialysis?

Symptoms of Anaphylaxis in Hemodialysis

Anaphylaxis during hemodialysis presents with the same multisystem manifestations as anaphylaxis in other settings, but typically occurs within 5-30 minutes of dialysis initiation and requires immediate recognition to prevent fatal outcomes. 1, 2

Core Clinical Manifestations

Cutaneous and Mucosal Symptoms

• Urticaria (hives) is the most common physical finding in anaphylaxis, though it may be delayed or completely absent in rapidly progressive cases 3
• Diffuse or localized erythema, pruritus (itching), and angioedema (swelling of lips, tongue, uvula) 3
• Cutaneous flushing or pallor, with patients appearing either flushed or pale 3

Respiratory Compromise

• Upper airway involvement: dysphonia (voice changes), stridor, hoarseness, lingual edema, and oropharyngeal swelling 3
• Lower airway involvement: cough, wheezing, bronchospasm, shortness of breath, and hypoxemia 3, 1
• Rhinitis is often an early sign of respiratory involvement 3
• Tachypnea and respiratory distress requiring oxygen support 4

Cardiovascular Manifestations

• Hypotension with or without syncope is a hallmark of severe anaphylaxis 3
• Tachycardia is the rule in anaphylaxis (though bradycardia may occur in patients with conduction defects or on sympatholytic medications) 3
• Cardiac arrhythmias and potential cardiovascular collapse 3
• Hemodynamic collapse can occur rapidly—up to 50% of intravascular fluid can shift into extravascular space within 10 minutes 3, 5
• In dialysis-specific cases: acute hypotension, undetectable blood pressure, and cardiopulmonary arrest have been reported 1, 6, 4

Gastrointestinal Symptoms

• Nausea, vomiting, crampy abdominal pain, and diarrhea 3
• Diarrhea occurring during or immediately after dialysis initiation 1

Neurological and Systemic Symptoms

• Altered level of consciousness or impaired mentation (reflecting hypoxia and end-organ dysfunction) 3, 5
• Lightheadedness, headache, and sensation of impending doom 3
• Agitation or anxiety 3
• Unconsciousness or syncope in severe cases 3
• Uterine cramps in female patients 3

Hematologic Findings (Dialysis-Specific)

• Thrombocytopenia (platelet count below 100,000/μL) may occur, particularly with heparin-induced reactions 4
• Partial platelet recovery between episodes 4

Critical Timing Considerations

• Symptoms typically begin within 5-30 minutes after dialysis initiation in hemodialysis-associated anaphylaxis 1, 2
• Reactions generally last 15-20 minutes but can be protracted 1
• The more rapidly symptoms develop after exposure, the more severe and life-threatening the reaction 3, 7
• Late-phase or biphasic reactions can occur 8-12 hours after the initial attack 3
• Severe anaphylaxis may last up to 32 hours despite aggressive treatment 3

Important Diagnostic Pitfalls

Distinguishing from Vasovagal Reactions

Vasovagal reactions are the most common condition confused with anaphylaxis but have key differences 3, 7:

• Vasovagal: urticaria is absent, heart rate is bradycardic, blood pressure is normal or increased, skin is cool and pale 3
• Anaphylaxis: urticaria is present, heart rate is tachycardic, blood pressure is decreased, skin may be flushed 3

Critical Warning Signs

• Hemodynamic collapse can occur rapidly with little or no cutaneous or respiratory manifestations 3
• Loss of consciousness reflects severe hypoxia and potential hypoxic-ischemic encephalopathy 5
• Respiratory arrest and cardiorespiratory arrest are terminal events if not immediately treated 1, 6

Dialysis-Specific Triggers to Consider

When anaphylaxis occurs during hemodialysis, potential triggers include 2, 8, 4:

• Dialyzer membranes (particularly polyacrylonitrile AN69, ethylene oxide-sterilized membranes) 2
• Heparin or low-molecular-weight heparin (enoxaparin) 4
• Citric acid solutions used for machine disinfection 8
• Intravenous iron preparations 2
• ACE inhibitors in combination with certain membranes 2

Repeated episodes during dialysis despite changing dialyzers or heparin should prompt investigation of alternative allergens in the dialysis circuit 8.