This content has been generated for SALG by Dr Amy Dodd and Dr Linda Nel on behalf of the Perioperative Allergy Network

CASE 1

The patient undergoing a kidney transplant was given co-amoxiclav approximately an hour after induction of anaesthesia.  Within 2 to 4 minutes intra-arterial monitoring revealed profound hypotension. The patient had been haemodynamically stable without vasopressor support prior to this event. Anaphylaxis was suspected and treated with 100 mcg adrenaline administered IV peripherally, with the patient head-down. Initially, there was no rash or angioedema, but a sparse urticarial rash was later noted on the abdomen.

Following discussion between anaesthetic and surgical consultants, after 15–20 minutes of stability, surgery continued. A sample was obtained for serum tryptase, and the reaction was documented in the electronic record. The patient was monitored postoperatively in the critical care unit for less than 24 hours before stepping down.

CASE 2

The patient experienced severe anaphylactic reaction possibly related to teicoplanin (previously tolerated without incident) during general anaesthesia in a standalone treatment centre. Despite treatment with adrenaline, steroids, nebulisers, and oxygen, the patient suffered a period of hypoxia and hypotension. The patient was transferred to ICU, where fluid resuscitation, adrenaline, advanced ventilatory support, and nebulisers continued. Tryptase blood samples were taken.

CT brain later showed cerebral oedema due to hypoxic brain injury, which progressed to clinical evidence of brain stem death and formal brain stem testing.

CASE 3

During induction of anaesthesia for a knee arthroscopy, severe bronchospasm after administration of fentanyl, propofol, and rocuronium raised the suspicion of anaphylaxis. Despite administration of adrenaline, ketamine, aminophylline, salbutamol, and hydrocortisone, the patient remained in severe bronchospasm for several hours and required transfer to intensive care intubated. Extubation was achieved the following day.

CASE 4

The patient suffered a cardiac arrest shortly after induction of anaesthesia for elective subacromial decompression. A straightforward nerve block had been performed, followed 10 minutes later by general anaesthesia. Whilst in the anaesthetic room, the patient suddenly developed bronchospasm. Prolonged resuscitation followed, including CPR and use of a LUCAS device. Inotropic support was required, including adrenaline and dopamine. Intralipid was administered

The patient was stabilised sufficiently for transfer to ICU. Despite maximal support over the next 24 hours the patient deteriorated, and life-sustaining treatment was withdrawn.

Differential diagnoses include anaphylaxis (serum tryptase later returned at 30.7), local anaesthetic toxicity, and tension pneumothorax (although chest drain insertion showed no evidence of tension). This case will be referred directly to the Coroner and a post-mortem is anticipated.

Commentary:

Case 1 illustrates early recognition and prompt management of anaphylaxis. The presenting feature of rapid onset profound hypotension after intravenous exposure, is typical of perioperative anaphylaxis. Bronchospasm as a presenting sign is more common in patients with underlying airway disease or obesity. Skin changes such as urticaria or generalised erythema, often only appear once perfusion is restored or noted once the drapes are removed.¹ When physiological stability is achieved following treatment, it may be appropriate to continue with surgery, particularly if non-elective.

When signs and symptoms of anaphylaxis are refractory to boluses of adrenaline, a low dose adrenaline infusion should be initiated.  This should be administered peripherally in the absence of central venous access. Large volume fluid boluses should be given alongside adrenaline. If clinical signs persist despite adrenaline infusion and appropriate fluid resuscitation, a second line vasopressor should be added.²

In patients with severe, persistent bronchospasm, nebulised or intravenous β-2 agonists and ketamine may be effective. Volatile anaesthetics also have a bronchodilator effect. These agents must be used as an adjunct treatment and not as an alternative to an adrenaline infusion.²

Anaphylaxis should be considered whenever there is unexpected severe cardiac or respiratory compromise, however differential diagnoses must also be considered and managed, as described in case 4. Collection of timely serum samples for mast cell tryptase (MCT) can help to support a diagnosis of anaphylaxis and future management. Samples for MCT should also be taken in cases of fatal anaphylaxis.

Cardiac arrest secondary to anaphylaxis following intravenous exposure to a triggering agent typically occurs within 5-10 minutes, which is more rapid than other routes of exposure.¹ In cardiac arrest, intravenous adrenaline should be administered as per advanced life support protocols. Prolonged cardiopulmonary resuscitation (including extracorporeal life support) should be considered as this is a potentially reversible cause.³

Fatal anaphylaxis occurs in 1-4% of perioperative hypersensitivity reactions,⁴ a higher mortality rate than for anaphylaxis in other settings.  Fatal cases of anaphylaxis should be referred as soon as possible to the UK Fatal Anaphylaxis Registry (https://www.bsaci.org/workforce/bsaci-registries/ukfar/). This can provide support and guidance on peri-mortem sample collection. Local laboratories should be advised to retain all peri-mortem samples to allow for post-mortem investigation.

SALG welcomes information about all cases of suspected perioperative anaphylaxis.  In order to learn from such cases, a list of all drugs administered within the hour preceding the onset of anaphylaxis, MCT results and relevant patient comorbidities (eg obesity, respiratory disease, cardiac disease) are helpful.

References

1. Harper NJN, Cook TM, Garcez T, et al. Anaesthesia, surgery, and life-threatening allergic reactions: epidemiology and clinical features of perioperative anaphylaxis in the 6th National Audit Project (NAP6). BJA 2018; 121: 159–71.
2. Dodd A, Turner PJ, Soar J et al. Emergency treatment of peri-operative anaphylaxis: Resuscitation Council UK algorithm for anaesthetists. Anaes 2024; 79:535-541
3. Garvey LH, Dewachter P, Hepner DL, et al. Management of suspected immediate perioperative allergy reactions: an international overview and consensus recommendations. BJA 2019; 123: e50–64.
4. Mertes, PM; Ebo, DG; Garcez, T etal. Comparative epidemiology of suspected perioperative hypersensitivity reactions. BJA 2019; 123: e16–28.