What is the management of anaphylaxis during anesthesia?

Management of Anaphylaxis During Anaesthesia

Administer intravenous adrenaline (epinephrine) immediately at 50 mcg (0.5 mL of 1:10,000 solution) for adults, repeated as needed, while simultaneously securing the airway, administering 100% oxygen, and providing aggressive fluid resuscitation with normal saline. 1

Immediate Recognition and Response

Clinical Presentation

• Cardiovascular collapse occurs in 50.8% of cases and is the most common presentation during anaesthesia, often without cutaneous signs 1
• Hypotension may be the sole clinical feature in approximately 10% of patients 1
• Bradycardia occurs in ~10% of cases, not just tachycardia 1
• Cutaneous signs (flushing, urticaria) are present in 72% of cases but their absence does not exclude anaphylaxis 1
• Bronchospasm occurs in 39.8% of allergic anaphylaxis cases 1
• Symptoms typically develop within minutes but may be delayed up to one hour (latex, antibiotics, IV colloids, Cidex OPA can cause delayed reactions) 1

Critical First Actions (ABC Approach)

1. Call for help immediately and note the time 1
2. Stop all potential causative agents (IV colloids, latex, chlorhexidine, antibiotics) and maintain anaesthesia with inhalational agent only if needed 1
3. Secure airway and administer 100% oxygen - intubate if necessary and ventilate 1
4. Elevate legs if hypotension present to prevent orthostatic hypotension and improve venous return 1
5. Start CPR immediately if indicated according to Advanced Life Support Guidelines 1

Pharmacological Management

Adrenaline (First-Line Treatment)

Intravenous Route (Preferred in Anaesthesia Setting):

• Adults: 50 mcg IV (0.5 mL of 1:10,000 solution) initially 1
• Repeat doses every few minutes as needed for severe hypotension or bronchospasm 1
• Start continuous IV infusion if multiple boluses required (adrenaline has short half-life) 1
• Infusion preparation: 1 mg (1 mL of 1:1000) in 250 mL D5W = 4 mcg/mL, infuse at 1-4 mcg/min initially, titrate up to 10 mcg/min 1
• Alternative infusion: 1 mg in 100 mL saline (1:100,000), infuse at 30-100 mL/h (5-15 mcg/min) 1

Pediatric Dosing:

• IV: 1 mcg/kg (0.1 mL/kg of 1:10,000 solution), titrated to response 1
• Prepare 1 mL of 1:10,000 per 10 kg body weight; start with one-tenth of syringe contents 1
• IM (if IV access unavailable):

  • 12 years: 500 mcg (0.5 mL of 1:1000) 1

  • 6-12 years: 300 mcg (0.3 mL of 1:1000) 1
  • <6 years: 150 mcg (0.15 mL of 1:1000) 1

Fluid Resuscitation

• Administer normal saline 0.9% or lactated Ringer's at high rate through large-bore IV 1
• Adults: 1-2 L at 5-10 mL/kg in first 5 minutes, up to 7 L may be required 1
• Children: up to 30 mL/kg in first hour 1
• Increased vascular permeability can transfer 50% of intravascular fluid to extravascular space within 10 minutes 1
• Avoid dextrose solutions (rapidly extravasated); use normal saline preferentially 1

Secondary Management

Adjunctive Medications

1. Chlorphenamine 10 mg IV (adult dose) 1
2. Hydrocortisone 200 mg IV (adult dose) 1
3. Alternative vasopressors (metaraminol) if blood pressure does not recover despite adrenaline infusion 1
4. For persistent bronchospasm:
   • IV salbutamol infusion 1
   • Metered-dose inhaler if appropriate connector available 1
   • Consider IV aminophylline or magnesium sulphate 1

Diagnostic Workup

Mast Cell Tryptase Sampling

Critical for confirming diagnosis and medicolegal documentation:

• First sample: As soon as feasible after resuscitation starts (do not delay resuscitation) 1
• Second sample: 1-2 hours after symptom onset 1
• Third sample: At 24 hours or in convalescence (establishes baseline, as some individuals have elevated baseline) 1
• Collect 5-10 mL clotted blood, label with time and date 1

Post-Resuscitation Care

Transfer and Monitoring

• Arrange immediate transfer to Critical Care area for continued monitoring 1
• Monitor for biphasic reactions, though mandatory observation periods are not evidence-based 2
• Continue hemodynamic monitoring and wean adrenaline incrementally over 12-24 hours once stabilized 3

Documentation Requirements

• Record exact timing of reaction onset 4
• Document all anaesthetic agents administered 4
• Note vital signs throughout event 4
• Detail all treatments given and patient response 4

Common Pitfalls and Caveats

Critical Errors to Avoid

• Do not delay adrenaline administration - it is the definitive treatment with alpha-agonist (vasoconstriction), beta-agonist (inotropy, bronchodilation), and mediator release inhibition properties 1
• Do not exclude anaphylaxis based on absence of cutaneous signs - 28% of cases lack skin manifestations 1
• Do not assume tachycardia will be present - bradycardia occurs in 10% of cases 1
• Do not use IM route when IV access is available in the anaesthesia setting - IV allows for precise titration 1
• Exclude equipment failure (misplaced tracheal tube) before attributing symptoms solely to anaphylaxis 1

Special Considerations

• Neuraxial blockade exaggerates hypotension in anaphylaxis 1
• Tourniquet deflation may trigger anaphylaxis if allergen sequestered in limb 1
• Neuromuscular blocking agents are the most common cause (65% of cases), followed by antibiotics and latex 5
• Patients with pre-existing asthma may have more prominent bronchospasm 1

Monitoring for Complications

• Watch for pulmonary edema from increased cardiac output and peripheral vasoconstriction 3
• Monitor for cardiac arrhythmias and ischemia, especially in patients with coronary artery disease 3
• Check IV site frequently to prevent extravasation and tissue necrosis 3
• If extravasation occurs, infiltrate area with 10-15 mL saline containing 5-10 mg phentolamine within 12 hours 3