Evidence
BMJ Open
Organ failure type in fatal and near-fatal anaphylaxis: a systematic review
McKenzie B, Marshall SD, Sanci L, et al
First published March 9, 2026.
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Clinical and Experimental Allergy
Mechanism of cardiac arrest in fatal anaphylaxis
McKenzie B, Marshall SD, Sanci L, et al
First published May, 2026.
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IV adrenaline rescue bolus while awaiting infusion in an unconscious patient
Intramuscular adrenaline peak is 5 minutes or more in healthy patients - too long for sick decompensated patients. In addition to treating asthma/anaphylaxis, the rescue bolus serves as physiologic optimisation for RSI. All sick decompensated patients will end up on adrenaline infusion but it takes 10 minutes or more to prepare one, start the infusion, await for dead space to be transited and for it to circulate in the systemic circulation.
The pharmacokinetics of epinephrine/adrenaline autoinjectors - Allergy, Asthma and Clin Immunology
Pharmacokinetics of adrenaline autoinjectors - Clinical and Experimental Allergy
Adrenaline IV bolus dosing amount examples for patients with impending cardiac arrest:
Ambulance Victoria - Adrenaline 10mcg as required, 50-100mcg as required if poor response
Royal Childrens Hospital Melbourne - 1mg/kg for peri-arrest scenarios
Australian New Zealand College of Anaesthetists - Perioperative anaphylaxis
Initial adult bolus: moderate 10-20mcg, life threatening 50-100mcg
Initial paediatric bolus moderate 1-2mcg/kg, life threatening 4-10mcg/kg
St Johns Ambulance Western Australia - 10mcg every minute and consult for higher dosing
Pressures are too high for an LMA or BVM
The inspiratory pressures required to deliver oxygen in an unconscious asthma/bronchospasm are high, frequently above 80cmH20. The best evidence for this is the multiple works of David Tuxen, an intensivist who helped pioneer ventilation strategies in obstructive airway disease to prevent barotrauma. He progressed the concept of intubated patients being managed with permissive hypercapnoea, small tidal volumes, long expiratory times and high inspiratory flow (the latter increases Peak Inspiratory Pressures but not plateau pressures). These strategies reduce the risk of breath stacking (gas trapping), and hyperinflation which can cause decreased blood pressure and pneumothoraces.
The effects of ventilatory pattern on hyperinflation - abstract only, need library access
A classical case report of difficult asthma ventilation in a retrieval patient - Aeromedical Journal
LMAs have seal pressure that is too low to adequately deliver oxygen in severe bronchospasm
Igels have a mean seal pressure of 32 cmH20 and 5% are <25cmH20 - Anaesthesia 2024
Earlier Igel assessment showed a mean leak pressure of 25 cmH20 - BJA 2012
BVMs leak/inflate the stomach at lower pressures than LMAs. Good practice statements for asthma resuscitation in arrest situations from the Australian New Zealand Resuscitation Council include:
Ventilation will be difficult because of increased airway resistance; try to avoid gastric inflation [Good Practice Statement].
Intubate the trachea early. There is a significant risk of gastric inflation and hypoventilation of the lungs when attempting to ventilate a severe asthmatic without a tracheal tube [Good Practice Statement].