Anaphylaxis Management During Anaesthesia

Immediate Recognition and Response

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

The American Heart Association recommends intravenous adrenaline (epinephrine) as the first-line treatment for anaphylaxis, with a dose of 50 mcg (0.5 mL of 1:10,000 solution) for adults, repeated as needed 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 2, 3
Alternative infusion: 1 mg in 100 mL saline (1:100,000), infuse at 30-100 mL/h (5-15 mcg/min) 2, 3
Pediatric dosing: IV: 1 mcg/kg (0.1 mL/kg of 1:10,000 solution), titrated to response 4
Prepare 1 mL of 1:10,000 per 10 kg body weight; start with one-tenth of syringe contents 4
IM (if IV access unavailable): >12 years: 500 mcg (0.5 mL of 1:1000) 5
6-12 years: 300 mcg (0.3 mL of 1:1000) 5
<6 years: 150 mcg (0.15 mL of 1:1000) 5

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 2, 3
Children: up to 30 mL/kg in first hour 2, 3
Increased vascular permeability can transfer 50% of intravascular fluid to extravascular space within 10 minutes 2, 3
Avoid dextrose solutions (rapidly extravasated); use normal saline preferentially 2, 3

Adjunctive medications: Chlorphenamine 10 mg IV (adult dose) 1, 6
Hydrocortisone 200 mg IV (adult dose) 1, 6
Alternative vasopressors (metaraminol) if blood pressure does not recover despite adrenaline infusion 1, 6
For persistent bronchospasm: IV salbutamol infusion 1, 6
Metered-dose inhaler if appropriate connector available 1, 6
Consider IV aminophylline or magnesium sulphate 1, 6

Mast cell tryptase sampling: First sample: As soon as feasible after resuscitation starts (do not delay resuscitation) 1, 6, 5
Second sample: 1-2 hours after symptom onset 1, 6, 5
Third sample: At 24 hours or in convalescence (establishes baseline, as some individuals have elevated baseline) 1, 5
Collect 5-10 mL clotted blood, label with time and date 1, 6

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, 6
Neuraxial blockade exaggerates hypotension in anaphylaxis 1
Tourniquet deflation may trigger anaphylaxis if allergen sequestered in limb 1, 6
Patients with pre-existing asthma may have more prominent bronchospasm 1