Cardiac arrest due to anaphylaxis
Anaphylactic cardiac arrest
Predominant causes of anaphylactic cardiac arrest include food allergies, insect stings, and drug-induced reactions. Approximately 90% of anaphylactic cardiac arrests present with pulseless electrical activity (PEA) as the initial rhythm, while the remainder manifest ventricular fibrillation (VF) or asystole (Ebo et al).
Clinical manifestations of anaphylaxis
- Nervousness, anxiety.
- Bronchospasm, stridor, wheezing
- Life-threatening edema involving the lips, tongue, and uvula causing airway obstruction
- Circulatory collapse culminating in cardiac arrest
Anaphylaxis can develop without dermatological or upper airway manifestations. Anaphylactic cardiac arrest should be suspected among younger patients, in case of known allergy, when exposed to potent allergens (e.g. wasp stings, peanuts, etc.) and in case of swollen airways or dermatological symptoms suggestive of anaphylaxis. Dyspnea, wheezing, or coughing before cardiac arrest also speak for anaphylaxis (airway obstruction caused by a foreign body is an important differential).
Treatment of anaphylaxis and cardiac arrest
- Administer CPR as per guidelines. Most patients require an immediate intravenous dose of 1 mg epinephrine.
- For anaphylaxis without cardiac arrest:
- Administer 0.5 mg epinephrine intramuscularly in the anterolateral thigh. If ineffective, repeat after 3-5 minutes.
- If intramuscular epinephrine is inadequate, consider an intravenous bolus of epinephrine (20-50 μg) or an epinephrine infusion (0.01 to 0.10 μg/kg/min).
- Pediatric dosage: 0.01 mg/kg.
- Administer 100% oxygen promptly and ensure oxygen saturation remains > 94%.
- Provide an intravenous or intraosseous fluid bolus, beginning with 500 ml of normal saline over 5-10 minutes, adjusting based on response.
- If hypotension persists despite fluid and epinephrine administration, consider alternative vasopressors:
- Eliminate the causative allergen: discontinue any suspected medications and remove any remnants of allergens (e.g., insect residues).
- For patients on beta-blocker therapy, consider administering 1-2 mg of glucagon intravenously.
- Currently, there is insufficient evidence to support the use of steroids and antihistamines during cardiac arrest due to anaphylaxis.