Case

A multi-co-morbid patient underwent general anaesthesia and regional nerve blocks for reverse shoulder replacement. Induction of anaesthesia was uneventful and the patient was placed into beach chair position in the anaesthetic room. The patient remained stable and was transfered into theatre. Following administration of antibiotics a rise in heart rate was noted. This also coincided with the surgeons moving and prepping the upper limb, as such, morphine was administered.  High airway pressures were noted along with angioedema and a red rash, on removing the drapes. Pulse oximetry and blood pressure recordings were lost. The patient was flattened from the beach chair position. Anaphylaxis was suspected and adrenaline 0.5mg was administered intravenously (I.V.). An anaesthetic emergency was declared, defibrillation pads were placed on the patient and a further 0.5mg adrenaline I.V. dose was given, 5 minutes after the initial dose. A metaraminol infusion was started. Arterial and central lines were sited, and a noradrenaline infusion commenced. The patient was transferred to critical care, intubated and ventilated with ongoing noradrenaline support. Blood samples to measure Mast Cell Tryptase were taken.

Commentary

This content has been developed for SALG by the Perioperative Allergy Network

Perioperative anaphylaxis is a difficult diagnosis due to the wide range of differential diagnoses, including exaggerated physiological responses to induction agents; airway manipulation; and surgical interventions.

The emergency treatment of peri-operative anaphylaxis: Resuscitation Council UK algorithm for anaesthetists¹ recommends:

1. Anaphylaxis is considered whenever unexpected and significant cardiovascular or respiratory compromise occurs.
2. First-line treatment of peri-operative anaphylaxis is intravenous adrenaline (epinephrine). An initial dose of 50 micrograms (0.5 ml of 1 mg.10 ml-1 [1:10,000]) is recommended in adults and children aged 12 years and over. 0.5mg adrenaline (0.5ml of 1mg.ml^-1 [1:1000]) may be administered intramuscularly if venous access is not available. Care must be taken with correct dosing due to the risk of cardiovascular complications with excessive doses of adrenaline.
3. Adrenaline must be supported by intravenous crystalloid fluid. Multiple large volume fluid boluses may be required. Patient positioning is important to aid venous return. Head-down table tilt or leg elevation should be considered.
4. If signs of anaphylaxis persist despite adrenaline boluses, an adrenaline infusion should be initiated. A low-dose adrenaline infusion, given via a peripheral venous line, is an effective alternative if central venous access is unavailable. Where the clinical response is suboptimal despite an adrenaline infusion and appropriate fluid resuscitation, a second-line vasopressor should be started (in addition to adrenaline).
5. Cardiopulmonary resuscitation should be started if systolic blood pressure is < 50 mmHg despite initial adrenaline and intravenous fluid boluses.
6. Appropriately timed tryptase measurements can help to determine whether anaphylaxis might have occurred. However, anaphylaxis is fundamentally a clinical diagnosis. All patients with suspected peri-operative hypersensitivity reactions, should be referred to a specialist allergy service for formal allergy testing, irrespective of tryptase results. Guidance on who should be referred has been outlined by the Perioperative Allergy Network (PAN).²

Perioperative anaphylaxis is likely to be under-reported and investigated. PAN has developed a digital referral process for suspected perioperative allergy which would facilitate central data collection and help ensure patient safety (PASS system). PASS is currently being piloted at two large NHS Trusts, and has onboarding at 2 further NHS Trusts. Anyone interested in piloting PASS within their site can complete an expression of interest form via the PAN website.²

 References

[1] Dodd A, Turner PJ, Soar J, Savic L; representing the UK Perioperative Allergy Network. Emergency treatment of peri-operative anaphylaxis: Resuscitation Council UK algorithm for anaesthetists. Anaesthesia. 2024 May;79(5):535-541. doi:10.1111/anae.16206. 

[2] https://www.bsaci.org/about-bsaci/bsaci-council-and-executive/bsaci-subcommittees/perioperative-allergy-network/