Sunday 3 June, 0900-1030H, Auditorium 15
This session on Sunday morning will cover definitions, clinical classifications, clinical diagnosis, epidemiology and specialist investigation of anaesthetic drug allergy.
In the first talk, Professor Paul Michel Mertes (University Hospitals of Strasbourg, France) will explain that perioperative anaphylaxis is often a dramatic event demanding prompt recognition and action by anaesthesiologists to ensure the best immediate outcome for the patient, but also to facilitate subsequent identification of the responsible agent and of safe anaesthetics that can be used for future anaesthesia.
“Perioperative immediate hypersensitivity reactions are clinically and functionally heterogeneous. The mode of action of drugs leading to effector cells stimulation responsible for the clinical symptoms observed is a decisive factor in understanding and managing drug hypersensitivity reactions,” says Professor Mertes. “Different subclassifications based on timing of symptom appearance or type of immune mechanism have been proposed. These will be of importance to define appropriate investigations to identify the responsible drug and the risk of cross-reactivity.”
Professor Mertes will also highlight how clinical classification, depending on the diagnosis criteria used, will be helpful for epidemiologic studies and evaluation of the risk of reactions depending on the drug used.
He concludes: “The severity of anaphylactic reactions can vary from minor to death. The use of clinical grading systems or of diagnostic and treatment pathway checklist for anaphylaxis are very useful and practical tools to guide titrated epinephrine administration and volume expanding fluid administration.”
Dr Nigel J N Harper, Consultant in Anaesthesia and Intensive Care, Anaesthetic Reaction Clinic, Manchester Royal Infirmary, UK, will then address the epidemiology of drug allergy in anaesthesia. He will discuss the report of the Royal College of Anaesthetists’ 6th National Audit Project (NAP 6): Perioperative Anaphylaxis, which was launched in May 2018. Dr Harper was the clinical lead on the report.
“A panel of anaesthetists, allergists, clinical immunologists and patient groups audited the clinical management, investigation and outcomes of life-threatening (Grade 3-5) perioperative anaphylaxis,” says Dr Harper. “Using published guidelines and methods designed to minimise bias, the panel identified the causative agent where possible and attributed a mechanism and probability.”
Dr Harper will outline key parts NAP6:
NAP6 main case-reporting phase
- Local co-ordinator anaesthetists in every NHS hospital reported anonymised cases over a one-year period to November 2016.
- Services provided by UK specialist adult and paediatric allergy clinics.
- UK anaesthetic workload, patient demographics and anaesthetic techniques.
- Exposure to potentially-allergenic drugs and other substances during the perioperative period, providing denominator data for incidence estimation.
- Anaesthetists’ perceptions of perioperative anaphylaxis and avoidance behaviours.
Dr Harper will outline that, of 541 cases submitted, 266 had complete data and were analysed. The estimated incidence of perioperative anaphylaxis was 1:11,752. This is likely an under-estimate. Ten patients died.
He says: “Antibiotics were responsible for 46% of reactions, neuromuscular blocking agents (NMBA) for 33% and chlorhexidine almost 10%. The incidence for teicoplanin (16.4:100,000 administrations) was higher than for any other drug. Co-amoxiclav (8.7:100,000) was the second most prominent antibiotic, while patent Blue dye (14.6:100,000) had the overall second highest rate.”
He adds: “The incidences for suxamethonium, rocuronium and atracurium were 11.1; 5.9 and 4.2: 100,000 respectively. Ten per cent of NMBA anaphylaxis was non-allergic.”
The full NAP6 report can be accessed at http://www.nationalauditprojects.org.uk/NAP6Report
The third talk in this session, investigating suspected anaesthetic drug allergy, will be given by Lene Heise Garvey, Associate Professor, Department of Clinical Medicine, University of Copenhagen and Head of the Danish Anaesthesia Allergy Centre (DAAC), Allergy Clinic Gentofte Hospital. DAAC is a National reference centre based on close collaboration between anaesthesiologists and allergists.
As perioperative anaphylaxis is rare, and investigation is extremely complex, only a few countries have standardised systems for investigation of these patients. Dr Garvey is leading a European task force on the investigation of perioperative hypersensitivity reactions under the European Academy for Allergy and Clinical immunology (EAACI) and a position paper from this group will be published later this year. “My talk will be based on the experiences from 20 years of investigation of perioperative anaphylaxis in DAAC and recommendations from the EAACI position paper,” says Dr Garvey.
The talk will cover the many differential diagnoses to perioperative anaphylaxis and how referral for allergy investigation is necessary to confirm or rule out specific allergy and prevent potentially life-threatening reactions in the future. Investigations start with a blood test for serum tryptase that should be taken in the first hour after the reaction and subsequent referral to a specialised allergy clinic is needed.
Dr Garvey says: “A referral containing detailed information about the events during the reaction is important to enable identification of all potential allergens as there are many hidden, and often undocumented, exposures in the perioperative setting. To achieve the best results of investigation close collaboration between anaesthesiologists and allergists is extremely important.”
Different investigations will be outlined in the presentation. Traditionally investigations comprise blood-tests and skin-testing with suspected culprits. In DAAC, intravenous challenge/provocation has been carried out routinely since 2004 for most drugs including anaesthetic drugs and since 2016 also with NMBAs. Drug provocation is still not routine in perioperative anaphylaxis in other parts of the world and is therefore still controversial.
Dr Garvey concludes: “Some preliminary results on NMBA provocation will be presented in a poster session later on Sunday.”
Title of Dr Garvey’s poster: Intravenous provocation with Neuromuscular Blocking Agents in the investigation of perioperative anaphylaxis –preliminary findings from the Danish Anaesthesia Allergy Centre (DAAC). (Abstract 1349)