Sugammadex-Induced Anaphylaxis

Sugammadex induced anaphylaxis is a severe hypersensitivity reaction after sugammadex reversal of neuromuscular block. It can follow within minutes of the injection, even on first exposure.

Epidemiology. Reported incidence is about 1 in 2,500 to 1 in 20,000 (a rate of 0.3% in some studies), with higher reporting at 16 mg/kg doses and in Japanese cohorts. Hypersensitivity (rash, flushing) is more common than anaphylaxis.

Risk factors. Previous sugammadex exposure (the reaction can happen on second dose), high dose, and drug allergic history. Cross-reactivity with cyclodextrin in foods and drugs has been suggested.

Pathophysiology.

The mechanism may be IgE-mediated against the cyclodextrin ring or its complex with rocuronium, or non-immune mast cell activation. Evidence is limited.

Onset within 1 to 5 minutes (and sometimes up to 30 minutes) of injection: hypotension, bronchospasm, flushing, urticaria, angioedema, tachycardia, collapse. Coronary spasm with bradycardia and arrest have been reported.

Red flags.

• Hypotension after extubation or reversal.
• Bronchospasm in a patient who was stable.
• Cardiac arrest.

Clinical. Measure serial tryptase (1 hour, 3 to 6 hours, baseline). Allergy testing at 4 to 6 weeks (skin prick 100 mg/mL, intradermal 1 mg/mL dilution and basophil activation test); false negatives and positives occur.

Differential diagnosis.

• Residual neuromuscular block with airway obstruction.
• Anaphylaxis to other agents given at the same time.
• Pulmonary embolism.
• Cardiac event.
• Bradycardia from sugammadex alone.

Begin the full anaphylaxis response: stop the drug, call for help, give 100% oxygen, secure the airway.

• Adrenaline: 50 microgram IV titrated every 1 to 2 minutes, then infusion 0.05 to 0.1 microgram/kg/min; 0.5 mg IM if no IV access; 1 mg IV every 3 to 5 minutes in arrest; monitor ECG and blood pressure; avoid excess in ischaemia.
• Crystalloid: 20 mL/kg IV, repeated as needed.
• Salbutamol: 5 mg nebulised for bronchospasm.
• Hydrocortisone 200 mg IV once and chlorphenamine 10 mg slow IV; maximum hydrocortisone 400 mg and chlorphenamine 20 mg in 24 hours.

Since sugammadex has been given, residual block may persist; keep sedated and ventilated, and monitor train-of-four. Neostigmine reversal is limited by the need for deeper recovery, so ventilatory support until recovery is the usual approach.

Follow up. Allergy testing and record. Avoid sugammadex until tested; use neostigmine with glycopyrronium or allow spontaneous recovery with quantitative monitoring.

Monitoring. ECG, blood pressure, saturation and train-of-four.

Referral and escalation. Critical care and allergy service. Report the event.