Molecular mechanisms and pathophysiology of perioperative hypersensitivity and anaphylaxis: a narrative review

Relationship between perioperative anaphylaxis and history of allergies or allergic diseases: A systematic review and meta-analysis with meta-regression

STUDY OBJECTIVE

We conducted this meta-analysis to summarize the available evidence and evaluate the relationship between a history of allergies/allergic diseases and perioperative anaphylaxis to offer preventive decision support.

DESIGN

Systematic review and meta-analysis of observational studies.

SETTING

We searched the MEDLINE (OVID), EMBASE, and the Cochrane Central Register of Controlled Trials databases for observational studies. Two investigators independently performed the search, screened the articles, and collected the study details.

MEASUREMENTS

Several databases were systematically searched to evaluate the relationship between a history of allergies/allergic diseases and perioperative anaphylaxis using subgroup analysis, sensitivity analysis and meta-regression.

MAIN RESULTS

A total of 19 studies involving 672 anaphylaxis episodes, 5608 immune-mediated reactions, and 1126 severe episodes met the eligibility criteria and were included in this meta-analysis. Drug allergies, food allergies, a history of allergies, and atopy increased the incidence of perioperative anaphylaxis (Drug allergies, odds ratio [OR] 3.54, 95% confidence interval [CI] 1.07-11.69; Food allergies, OR 2.29, 95% CI 1.23-4.26; A history of allergies, OR 4.86, 95% CI 3.65-6.49; Atopy, OR 3.58, 95% CI 1.47-8.71), but not the presence of immune-mediated reactions and the severity of perioperative anaphylaxis.

CONCLUSIONS

Patients with previous drug allergies, food allergies, a history of allergies, or atopy are more likely to develop anaphylaxis during the perioperative period. Additional studies should be carried out to determine whether a history of allergies/allergic diseases is a major factor for perioperative anaphylaxis when confounders are controlled.

Epidemiology of perioperative anaphylaxis in France in 2017-2018: the 11th GERAP survey

BACKGROUND

Perioperative anaphylaxis is rare but is associated with significant morbidity. This complication has been well described in France by the GERAP (Groupe d'Etude des Réactions Anaphylactiques Périopératoires), a network focused on its study. The epidemiology of perioperative anaphylaxis is evolving, influenced by environmental factors and clinical practice. The aim of this study was to update the epidemiology of perioperative anaphylaxis in France.

METHODS

This multicentre retrospective study was performed in 26 allergy clinics of the GERAP network in 2017-8.

RESULTS

There were 765 patients with perioperative anaphylaxis included. Most cases were severe, with 428 (56%) reactions graded as 3 or 4 according to the Ring and Messmer classification. Skin test results were available for 676 patients, with a culprit agent identified in 471 cases (70%). Neuromuscular blocking agents were the main cause of perioperative anaphylaxis (n=281; 60%), followed by antibiotics (n=118; 25%) and patent blue dye (n=11; 2%). Cefazolin was the main antibiotic responsible for perioperative anaphylaxis (52% of antibiotic-related reactions). Suxamethonium and rocuronium were the main neuromuscular blocking agents responsible for perioperative anaphylaxis with 7.1 (6.1-8.4) and 5.6 (4.2-7.4) reactions per 100,000 vials sold, respectively, whereas cefazolin-related cases were estimated at 0.7 (0.5-0.9) reactions per 100,000 vials sold.

CONCLUSIONS

Our results confirm that most commonly identified triggering agents remain neuromuscular blocking agents. Reactions to antibiotics, particularly cefazolin, are becoming increasingly frequent. The origin of sensitisation to cefazolin is unknown, as no cross-sensitisation has been described, and it should be the subject of further study. Perioperative anaphylaxis should be followed over the years and understood given the changing triggers.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov (NCT04654923).

Management and treatment of perioperative hypersensitivity

PURPOSE OF REVIEW

Perioperative hypersensitivity reactions are rare but potentially catastrophic events. This review acts to summarize recent recommendations for both immediate and poststabilization management of suspected reactions, alongside practical advice for anaesthetists who may be faced with these events.

RECENT FINDINGS

Prompt treatment is essential but may be hampered by delay in recognition. This can occur because there are multiple differential diagnoses for the observed clinical signs as well as variations in clinical presentation. Resuscitation is dependent on the use of adrenaline and fluids. Adrenaline should be administered in small, titrated intravenous boluses. Low-dose infusions should be commenced early if the response to boluses is poor. Large volume fluid resuscitation may be required to maintain adequate circulating volume. Chest compressions are recommended when there is evidence of inadequate perfusion, rather than waiting until cardiac arrest is confirmed. Antihistamines and corticosteroids are no longer recommended in the immediate management phase. Once the patient has been stabilized, it is important to obtain serial tryptase concentrations to aid the subsequent clinic investigation. The decision to proceed or abandon surgery will be based on an individual risk-benefit analysis. All cases of suspected perioperative hypersensitivity, including fatal cases, must be referred for formal investigation.

SUMMARY

There have been recent updates to management guidelines in perioperative hypersensitivity. Treatment algorithms, treatment packs and referral packs can all help the anaesthetist manage these complex cases, aid the subsequent investigation and ensure patient safety in the future.

Perioperative anaphylaxis: updates on pathophysiology

PURPOSE OF REVIEW

Perioperative anaphylaxis has historically been attributed to IgE/FcεRI-mediated reactions; there is now recognition of allergic and nonallergic triggers encompassing various reactions beyond IgE-mediated responses. This review aims to present recent advancements in knowledge regarding the mechanisms and pathophysiology of perioperative anaphylaxis.

RECENT FINDINGS

Emerging evidence highlights the role of the mast-cell related G-coupled protein receptor X2 pathway in direct mast cell degranulation, shedding light on previously unknown mechanisms. This pathway, alongside traditional IgE/FcεRI-mediated reactions, contributes to the complex nature of anaphylactic reactions. Investigations into the microbiota-anaphylaxis connection are ongoing, with potential implications for future treatment strategies. While serum tryptase levels serve as mast cell activation indicators, identifying triggers remains challenging. A range of mediators have been associated with anaphylaxis, including vasoactive peptides, proteases, lipid molecules, cytokines, chemokines, interleukins, complement components, and coagulation factors.

SUMMARY

Further understanding of clinical endotypes and the microenvironment where anaphylactic reactions unfold is essential for standardizing mediator testing and characterization in perioperative anaphylaxis. Ongoing research aims to elucidate the mechanisms, pathways, and mediators involved across multiple organ systems, including the cardiovascular, respiratory, and integumentary systems, which will be crucial for improving patient outcomes.

Emergency treatment of peri-operative anaphylaxis: Resuscitation Council UK algorithm for anaesthetists

Peri-operative anaphylaxis is a rare but potentially catastrophic event which must be considered whenever unexpected and significant cardiovascular or respiratory compromise occurs during anaesthesia. The Resuscitation Council UK algorithm for peri-operative anaphylaxis highlights the importance of early intravenous adrenaline and fluid resuscitation and provides guidance on the treatment of refractory anaphylaxis and immediate follow-up. This algorithm is endorsed by the Royal College of Anaesthetists, Association of Anaesthetists, British Society of Allergy and Clinical Immunology and Clinical Immunology Professional Network of the British Society for Immunology. This document was produced by the Perioperative Allergy Network steering committee in collaboration with the Resuscitation Council UK.

Pholcodine and allergy to neuromuscular blocking agents: where are we and how did we get here?

Despite the purported link between pholcodine and neuromuscular blocking agent allergy, screening for prior pholcodine use offers no practical benefit to patients, and anaesthetists should continue to use a neuromuscular blocking agent where this is clinically indicated.

Paediatric perioperative hypersensitivity: the performance of the current consensus formula and the effect of uneventful anaesthesia on serum tryptase

Background

Paired sampling of acute (aST) and basal (bST) serum tryptase has been recommended when investigating patients with a suspected perioperative hypersensitivity (POH) reaction. In the current consensus formula, an aST value exceeding (1.2×bST+2) confirms mast cell activation. The current consensus formula has been validated in adults but not in children.

Methods

We prospectively included 96 children who underwent uneventful anaesthesia and sampled serum tryptase at baseline and 60-90 min after induction. Tryptase changes were then compared with those in 94 children with suspected POH who were retrospectively included from four reference centres in Belgium, France, and Denmark.

Results

We observed a median decrease in serum tryptase during uneventful anaesthesia of 0.41 μg L-1 (-15.9%; P<0.001). The current consensus formula identified mast cell activation in 31.9% of paediatric POH patients. After generating receiver operating characteristic curves through 100 repeated five-fold cross-validation, aST>bST+0.71 was identified as the optimal cut-off point to identify mast cell activation. This new paediatric formula has higher sensitivity than the current consensus formula (53.2% vs 31.9%, P<0.001) with a specificity of 96.9%. Analysis in the subpopulation where a culprit was identified and in grade 3-4 reactions similarly yielded higher sensitivity for the new paediatric formula when compared with the current consensus formula (85.3% vs 61.8%; P=0.008 and 78.0% vs 48.8%; P<0.001, respectively). Internally cross-validated sensitivity and specificity were 53.3% and 93.3%, respectively.

Conclusions

This is the first study suggesting the need for an adjusted formula in children to identify perioperative mast cell activation as tryptase is significantly lowered during uneventful anaesthesia. We propose a new formula (aST>bST+0.71) which performs significantly better than the current consensus formula in our multicentric paediatric population.

Experimental Evaluation of the Hypersensitivity Reactions of a New Glycopeptide Antibiotic Flavancin in Animal Models

Glycopeptide antibiotics are still in demand in clinical practice for treating infections caused by resistant gram-positive pathogens; however, their use is limited due to severe adverse reactions. Their predominant types of side effects are immunoglobulin E-mediated or nonmediated hypersensitivity reactions. Therefore, the development of new glycopeptide antibiotics with improved toxicity profiles remains an important objective in advancing modern antimicrobial agents. We investigated a new eremomycin aminoalkylamide flavancin, its anaphylactogenic properties, influence on histamine levels in blood plasma, pseudoallergic inflammatory reaction on concanavalin A and the change in the amount of flavancin in the blood plasma after administration. It has been shown that flavancin does not demonstrate anaphylactogenic properties. The injection of flavancin resulted in a level of histamine in the blood three times lower than that caused by vancomycin. The therapeutic dose of vancomycin led to a statistically significant increase in the concanavalin A response index compared to flavancin (54% versus 3.7%). Thus, flavancin does not cause a pseudo-allergic reaction. The rapid decrease in flavancin concentration in the blood and the low levels of histamine in the plasma lead us to assume that any pseudoallergic reactions resulting from flavancin application, if they do occur in clinical practice, will be significantly less compared to the use of vancomycin.

Delayed Nonimmune Anaphylaxis Caused by Ropivacaine for Preoperative Nerve Blocks: A Case Report

Ropivacaine is an amide local anesthetic with rare reports of anaphylaxis. To our knowledge, this is the first report of delayed nonimmune anaphylaxis induced by ropivacaine. A 70-year-old man underwent general anesthesia with a nerve block for a total knee arthroplasty. The patient developed symptoms of anaphylaxis 3.5 hours after receiving ropivacaine for femoral and tibial nerve blocks. A basophil activation test (BAT) revealed ropivacaine as the causative agent. Notably, anaphylaxis can be caused by medications even hours after their administration, and all administered drugs should be suspected of potentially causing anaphylaxis.

Perioperative anaphylaxis management and testing: a quaternary centre audit

BACKGROUND

Anaphylaxis is a severe, potentially life-threatening generalized or systemic hypersensitivity reaction. Sequential reports have cited anaphylaxis as the most common cause of anaesthesia-related deaths. We undertook an audit at a quaternary centre, examining the management of perioperative anaphylaxis and quality of referrals made to our anaesthesia allergy testing service.

METHODS

The data of 41 patients consulted at St Vincent's Hospital Melbourne for perioperative anaphylaxis between 17th of January 2020 and 20th of January 2022 were analysed. Intervention outcomes included total intravenous fluid administered, adrenaline administration, instigation of CPR and the collection and the timing of serum tryptase samples. We also assessed referral quality, provision of institutional allergy alert and time elapsed from the anaphylaxis event to allergy testing. Contemporaneous Australian and New Zealand Anaesthetic Allergy Group (ANZAAG) guidelines were used as the reference standard for most outcomes.

RESULTS

Our data reveals compliance of <80% with respect to intravenous fluid administration, referral quality and tryptase sampling, particularly at the 4-h timepoint.

CONCLUSION

Surgical leadership and patient advocacy in the post-acute phase would likely facilitate requisite testing and improve the quality of counselling. We recommend institutions adopt a case-by-case review of management compliance with recommendations. Additionally, we advocate for the inclusion of a prompt to the ANZAAG referral form, that encourages the operator to update their patient's institutional allergy alert while awaiting allergy testing.

Perioperative anaphylaxis: when the allergological work-up goes negative

PURPOSE OF REVIEW

Perioperative anaphylaxis (POA) is rare but is associated with significant morbidity and mortality. Patients are referred to the allergist to identify the mechanism of the reaction, the causative agent and make recommendations regarding subsequent anaesthesia. Despite a well conducted allergological evaluation, the causative agent is not found in 30-60% of these reactions, leaving patients without a well established diagnosis.

RECENT FINDINGS

Several mechanisms can induce POA. In addition to the well known IgE-mediated reactions, IgG-mediated reaction, MRGPR-X2-related reaction or nonspecific histamine release may be involved. These situations are not easily assessed by the allergological workup.

SUMMARY

When the allergological workup is negative, the situation should be reassessed with the team present at the time of the reaction to confirm the reality of the hypersensitivity reaction and to search for a possible differential diagnosis. If POA is confirmed, the allergological evaluation should be repeated, ensuring proper execution according to current guidelines and including the search for hidden allergens. Specific IgE assays or basophil activation tests may be of interest. In case of negative results, a closely monitored drug challenge test, in coordination with the anaesthesia teams, may be useful to avoid the exclusion of any drug injected during the reaction.

Suspected perioperative anaphylaxis: are we making the correct diagnosis?

We provide a commentary on aspects of a prospective study of the epidemiology of perioperative anaphylaxis in Japan (Japanese Epidemiologic Study for Perioperative Anaphylaxis [JESPA]). Accurate diagnosis of perioperative anaphylaxis is important for research but essential for clinical safety. We evaluate the diagnostic approach used in the JESPA study and caution against over-reliance on diagnostic tests that lack sensitivity and specificity when clinical data suggest an immediate perioperative hypersensitivity reaction is likely.

Retrospective review of diphenhydramine vs diphenhydramine plus glucocorticoid for the treatment of allergic reaction in cats

OBJECTIVES

The aims of the present study were to report the outcomes of treating allergic reactions in cats with diphenhydramine vs diphenhydramine plus glucocorticoid and to determine whether signs recurred or additional veterinary intervention was needed in the days after initial treatment.

METHODS

This retrospective study evaluated 73 cats treated for allergic reaction with diphenhydramine alone or in combination with a glucocorticoid at a 24 h emergency and specialty referral veterinary hospital between 1 January 2012 and 31 March 2021.

RESULTS

In total, 44 cats were treated with diphenhydramine alone, and 29 were treated with diphenhydramine plus dexamethasone sodium phosphate. The inciting cause was known or highly suspected in 50 patients. Vaccines were the most common (31 patients), followed by insect envenomation (17 cases). No cat in either group progressed to anaphylaxis. There was no difference in resolution of clinical signs between the groups. Follow-up contact was successfully made with 40/73 cat owners. All 40 cats were alive. Eight had persistent signs. There was no difference in the number of cats with persistent signs between groups. Five cats required additional treatment after the initial emergency visit. There was no difference between the two groups for persistent signs at follow-up.

CONCLUSIONS AND RELEVANCE

There was no difference in measured outcomes between cats treated with diphenhydramine alone vs those treated with a glucocorticoid in addition to diphenhydramine in this population. The ideal treatment for allergic reactions is unknown. Based on currently available data in human and veterinary literature, glucocorticoids are not indicated to treat acute allergic reactions. The role of antihistamines as part of a symptomatic supportive treatment plan to shorten the duration of signs is unclear at this time and may be considered.

Investigating the optimal diagnostic value of histamine for diagnosing perioperative hypersensitivity: a prospective, observational study

Although several guidelines recommend measuring blood tryptase and histamine concentrations to diagnose perioperative anaphylaxis (POA), tryptase measurement is more common. The appropriate timing of blood collection and the diagnostic threshold for histamine measurement are still controversial. To address these issues, histamine concentrations in patients with anaphylaxis and those with anaphylaxis-uncertain were compared in our previous study, the Japanese Epidemiologic Study for Perioperative Anaphylaxis (JESPA). However, because we could not rule out the possibility that the anaphylactic-uncertain group included anaphylactic patients, histamine concentrations were measured in patients who underwent general anesthesia with no complications as controls in the present study. Histamine levels were measured at anesthesia induction (baseline), 30 min (first point), and 2 h (second point) after the start of surgery in 30 control patients. Histamine concentrations in controls were lower than in patients with POA in JESPA at the first and second points. At the first point, a threshold of 1.5 ng/ml resulted in sensitivity of 77% and specificity of 100%. A threshold of 1.1 ng/ml at the second point resulted in sensitivity of 67% and specificity of 87%. Measurement of histamine concentrations within two hours after symptom onset might help diagnose POA.

A quarter of a century fundamental and translational research in perioperative hypersensitivity and anaphylaxis at the Antwerp university hospital, a Belgian Centre of Excellence of the World Allergy Organization

Perioperative hypersensitivity constitutes an important health issue, with potential dramatic consequences of diagnostic mistakes. However, safe and correct diagnosis is not always straightforward, mainly because of the application of incorrect nomenclature, absence of easy accessible in-vitro/ex-vivo tests and uncertainties associated with the non-irritating skin test concentrations. In this editorial we summarize the time line, seminal findings, and major realizations of 25 years of research on the mechanisms, diagnosis, and management of perioperative hypersensitivity.

Perioperative Hypersensitivity Evaluation and Management: A Practical Approach

Perioperative hypersensitivity (POH) is an uncommon, potentially life-threatening event. Identification of POH can be difficult given the lack of familiarity, physiological effects of anesthesia, draping of the patient during surgery, and potential nonimmunological factors contributing to signs and symptoms. Given the unique nature and large number of medications administered in the perioperative setting, evaluation of POH can be challenging. In this paper, we present a practical approach to management with an emphasis on understanding what happens in the operating room, the overlap of signs and symptoms between nonimmunological and immunological reactions, acute management, and subsequent evaluation. In addition, we provide a strategy for further review of an initially negative evaluation and emphasize the importance of establishing management plans for the patient as well as providing recommendations to the medical, anesthesia, and surgical teams for future surgeries. A critical factor for successful management at all points in the process is a close collaboration between the anesthesia and the allergy teams.

Perioperative Anaphylaxis

Anesthesiologists routinely manage patients receiving drugs and agents, all of which have the potential for anaphylaxis, the life-threatening presentation of an allergic reaction. Clinicians must be ready to diagnose and manage the acute cardiopulmonary dysfunction that occurs.

Management of Suspected Life-Threatening Perioperative Anaphylaxis and Risk Factors for Near-Fatal and Fatal Outcomes: A Retrospective Study in China

Purpose

Perioperative anaphylaxis (POA) is an acute severe systemic hypersensitivity reaction characterized by life-threatening respiratory and circulatory collapse. In our previous study, we reported the epidemiology of suspected POA in China. In the present study, we aimed to elucidate the management and outcomes of these cases and further verify the risk factors for near-fatal and fatal outcomes.

Patients and Methods

This was a retrospective study of 447 cases of suspected life-threatening POA encountered at 112 tertiary hospitals in mainland China between September 2018 and August 2019. Patient characteristics, symptoms, duration of hypotension, treatments, and clinical outcomes were documented. Bivariate logistic regression was used to identify risk factors for near-fatal and fatal outcomes.

Results

Most cases of suspected POA (89.9%) were recognized and treated within 5 min. Epinephrine was administered as the initial treatment in 232 (51.9%) cases. Corticosteroids (26.6%), other vasoactive drugs (18.3%), and bronchodilators (1.6%) were also administered as the initial treatment instead of epinephrine. The initial dosage of epinephrine (median, 35 µg) was insufficient according to the anaphylaxis guidelines. On multivariable analysis, age ≥65 years (odds ratio [OR] 7.48; 95% confidence interval [CI]: 1.33-41.87, P=0.022), ASA physical status IV (OR 17.68; 95% CI: 4.53-68.94; P<0.001), and hypotension duration ≥15 min (OR 3.63; 95% CI: 1.11-11.87; P=0.033) were risk factors for fatal and near-fatal outcomes.

Conclusion

Most cases in this study were managed in a timely manner, but the epinephrine application should be optimized according to the guidelines. Age ≥65 years, ASA physical status IV, and long-term hypotension were risk factors for near-fatal and fatal outcomes.

Genes involved in platelet aggregation and activation are downregulated during acute anaphylaxis in humans

Objective

Mechanisms underlying the anaphylactic reaction in humans are not fully understood. Here, we aimed at improving our understanding of anaphylaxis by investigating gene expression changes.

Methods

Microarray data set GSE69063 was analysed, describing emergency department (ED) patients with severe anaphylaxis (n = 12), moderate anaphylaxis (n = 6), sepsis (n = 20) and trauma (n = 11). Samples were taken at ED presentation (T0) and 1 h later (T1). Healthy controls were age and sex matched to ED patient groups. Gene expression changes were determined using limma, and pathway analysis applied. Differentially expressed genes were validated in an independent cohort of anaphylaxis patients (n = 31) and matched healthy controls (n = 10), using quantitative reverse transcription-polymerase chain reaction.

Results

Platelet aggregation was dysregulated in severe anaphylaxis at T0, but not in moderate anaphylaxis, sepsis or trauma. Dysregulation was not observed in patients who received adrenaline before T0. Seven genes (GATA1 (adjusted P-value = 5.57 × 10^-4), TLN1 (adjusted P-value = 9.40 × 10^-4), GP1BA (adjusted P-value = 2.15 × 10^-2), SELP (adjusted P-value = 2.29 × 10^-2), MPL (adjusted P-value = 1.20 × 10^-2), F13A1 (adjusted P-value = 1.39 × 10^-2) and SPARC (adjusted P-value = 4.06 × 10^-2)) were significantly downregulated in severe anaphylaxis patients who did not receive adrenaline before ED arrival, compared with healthy controls. One gene (TLN1 (adjusted P-value = 1.29 × 10^-2)) was significantly downregulated in moderate anaphylaxis patients who did not receive adrenaline before ED arrival, compared with healthy controls.

Conclusion

Downregulation of genes involved in platelet aggregation and activation is a unique feature of the early anaphylactic reaction not previously reported and may be associated with reaction severity.

Agreement of a clinical scoring system with allergic anaphylaxis in suspected perioperative hypersensitivity reactions: prospective validation of a new tool

BACKGROUND

A clinical scoring system to estimate the likelihood that a reaction represents a perioperative immediate hypersensitivity reaction has been devised using a Delphi consensus process. Agreement of this clinical scoring system with the outcome of allergological assessment would allow the use of this tool in post-resuscitation and subsequent management of suspected perioperative immediate hypersensitivity reaction and potentially as a new standard reference for clinical investigations.

METHODS

We prospectively scored 301 cases of suspected perioperative immediate hypersensitivity reaction according to the Hypersensitivity Clinical Scoring Scheme. Classification of cases was by allergological workup based on immediate and delayed investigations. The discrimination and calibration of the Hypersensitivity Clinical Scoring Scheme was compared with results from an expert panel of allergologists, skin testing, mast cell tryptase ratios, and specific IgE assays, as was agreement by Cohen's kappa coefficient.

RESULTS

The Hypersensitivity Clinical Scoring Scheme predicted cases of allergic perioperative immediate hypersensitivity reaction with comparable discrimination to an expert panel, mast cell tryptase formula, and specific IgE assays in anaphylaxis to neuromuscular blocking drugs. Using a score threshold of 15 or greater to indicate allergic perioperative immediate hypersensitivity reaction, the sensitivity was 88.9%, with a specificity of 79.4%. Prospectively, the Hypersensitivity Clinical Scoring Scheme correctly classified a greater number of subjects than the expert panel and the optimal post hoc binary logistic regression model (86% vs 85% vs 84%), however it was inferior to skin testing.

CONCLUSION

The Hypersensitivity Clinical Scoring Scheme predicts allergic perioperative immediate hypersensitivity using features of the acute syndrome. This approach could guide algorithms for the post-resuscitative management of suspected perioperative immediate hypersensitivity, and identify patients requiring drug provocation challenge.

Allergic Reactions to COVID-19 Vaccines: Risk Factors, Frequency, Mechanisms and Management

Conventional vaccines have been widely studied, along with their risk of causing allergic reactions. These generally consist of mild local reactions and only rarely severe anaphylaxis. Although all the current COVID-19 vaccines marketed in Europe have been shown to be safe overall in the general population, early post-marketing evidence has shown that mRNA-based vaccines using novel platforms (i.e., lipid nanoparticles) were associated with an increased risk of severe allergic reactions as compared to conventional vaccines. In this paper we performed an updated literature review on frequency, risk factors, and underlying mechanisms of COVID-19 vaccine-related allergies by searching MEDLINE and Google Scholar databases. We also conducted a qualitative search on VigiBase and EudraVigilance databases to identify reports of “Hypersensitivity” and “Anaphylactic reaction” potentially related to COVID-19 vaccines (Comirnaty, Spikevax, Vaxzevria and COVID-19 Janssen Vaccine), and in EudraVigilance to estimate the reporting rates of “Anaphylactic reaction” and “Anaphylactic shock” after COVID-19 vaccination in the European population. We also summarized the scientific societies’ and regulatory agencies’ recommendations for prevention and management of COVID-19 vaccine-related allergic reactions, especially in those with a history of allergy.

Pathophysiological, Cellular, and Molecular Events of the Vascular System in Anaphylaxis

Anaphylaxis is a systemic hypersensitivity reaction that can be life threatening. Mechanistically, it results from the immune activation and release of a variety of mediators that give rise to the signs and symptoms of this pathological event. For years, most of the research in anaphylaxis has focused on the contribution of the immune component. However, approaches that shed light on the participation of other cellular and molecular agents are necessary. Among them, the vascular niche receives the various signals (e.g., histamine) that elicit the range of anaphylactic events. Cardiovascular manifestations such as increased vascular permeability, vasodilation, hypotension, vasoconstriction, and cardiac alterations are crucial in the pathophysiology of anaphylaxis and are highly involved to the development of the most severe cases. Specifically, the endothelium, vascular smooth muscle cells, and their molecular signaling outcomes play an essential role downstream of the immune reaction. Therefore, in this review, we synthesized the vascular changes observed during anaphylaxis as well as its cellular and molecular components. As the risk of anaphylaxis exists both in clinical procedures and in routine life, increasing our knowledge of the vascular physiology and their molecular mechanism will enable us to improve the clinical management and how to treat or prevent anaphylaxis.

Key Message

Anaphylaxis, the most severe allergic reaction, involves a variety of immune and non-immune molecular signals that give rise to its pathophysiological manifestations. Importantly, the vascular system is engaged in processes relevant to anaphylactic events such as increased vascular permeability, vasodilation, hypotension, vasoconstriction, and decreased cardiac output. The novelty of this review focuses on the fact that new studies will greatly improve the understanding of anaphylaxis when viewed from a vascular molecular angle and specifically from the endothelium. This knowledge will improve therapeutic options to treat or prevent anaphylaxis.

Mas-Related G Protein–Coupled Receptor-X2 and Its Role in Non-immunoglobulin E–Mediated Drug Hypersensitivity

A diverse group of Food and Drug Administration-approved cationic drugs including antibiotics, neuromuscular blocking drugs, opioids, antidepressants, and radiocontrast media activate mast cells and cause hypersensitivity reactions by both an immunoglobulin E IgE-dependent and independent manner. The recent discovery that these drugs activate mast cells via the G protein-coupled receptor known as Mas-related GPCR-X2 (MRGPRX2) has represented a paradigm shift of how drug hypersensitivity reactions are viewed. This article provides an overview of the current status of the role of MRGPRX2 on non-IgE-mediated drug hypersensitivity. Potential risk factors and evaluation for suspected MRGPRX2-mediated drug reactions are also discussed.

Clinical characteristics and allergen detection of perioperative anaphylaxis: a 12-year retrospective analysis from an anesthesia clinic in China

Abstract

Background

Anaphylaxis during anesthesia is a rare but often a potentially life-threatening event for patients. Identifying culprit agents responsible for anaphylaxis is of great important for avoiding potential re-exposure to allergens, but it poses great challenge for anesthetists. This retrospective study aimed to analyze the culprits of patients with a history of perioperative anaphylaxis referred to an anesthesia allergy clinic in China, and to evaluate the role of allergy diagnostic tests in clinical practice.

Methods

A total of 145 patients (102 female/43 male) who attended the Anesthesia Allergy Clinic for allergen detection between 1 January 2009 and 31 December 2020 were reviewed retrospectively. Clinical characteristics, results of allergy diagnostic tests including skin, and/or basophil activation tests, and the incidence of repeat anaphylaxis after use of recommended alternative anesthetics were obtained.

Results

Of these 145 patients, 109 patients (75.2%, 74 females/35 males) were determined to experience perioperative anaphylaxis. The most common presenting clinical feature was cardiovascular manifestations (n = 63, 57.8%). According to diagnostic work up, the most common causative agents for perioperative anaphylaxis were neuromuscular blocking agents (n = 35, 32.1%). After diagnostic work up, 52 patients underwent repeat anesthesia. None of these patients experienced recurrent anaphylaxis.

Conclusions

This study suggests that neuromuscular blocking agents are the main cause of perioperative anaphylaxis. For patients with perioperative anaphylaxis, allergy diagnostic tests are essential to identify causative agents, and to find suitable alternative drugs for the future planning of subsequent anesthetics.

End-tidal Carbon Dioxide for Diagnosing Anaphylaxis in Patients with Severe Postinduction Hypotension

BACKGROUND

Perioperative hypersensitivity reactions may be difficult to diagnose during general anesthesia. Postinduction hypotension is the most common sign but is not specific. It was recently suggested that low end-tidal carbon dioxide (ETco2) might be a marker of anaphylaxis (Ring and Messmer grades III to IV immediate hypersensitivity reactions) in hypotensive patients under mechanical ventilation. To test this hypothesis, the authors compared ETco2 in patients with a diagnosis of anaphylaxis and in patients with severe hypotension from any other cause after the induction of anesthesia.

METHODS

This was a retrospective single-center case-control study in which two groups were formed from an anesthesia data warehouse. The anaphylaxis group was formed on the basis of tryptase/histamine assay data and allergy workup data recorded over the period 2010 to 2018. The control (hypotension) group consisted of all patients having experienced severe hypotension (mean arterial pressure less than 50 mmHg for 5 min or longer) with a cause other than anaphylaxis after anesthesia induction in 2017.

RESULTS

The anaphylaxis and hypotension groups comprised 49 patients (grade III: n = 38; grade IV: n = 11) and 555 patients, respectively. The minimum ETco2 value was significantly lower in the anaphylaxis group (median [interquartile range]: 17 [12 to 23] mmHg) than in the hypotension group (32 [29 to 34] mmHg; P < 0.001). The area under the receiver operating characteristic curve (95% CI) for ETco2 was 0.95 (0.91 to 0.99). The sensitivity and specificity (95% CI) for the optimal cutoff value were 0.92 (0.82 to 0.98) and 0.94 (0.92 to 0.99), respectively. In multivariable analysis, minimum ETco2 was associated with anaphylaxis after adjusting for confounders and competing predictors, including arterial pressure, heart rate, and peak airway pressure (odds ratio [95% CI] for ETco2: 0.51 [0.38 to 0.68]; P < 0.001).

CONCLUSIONS

In case of severe hypotension after anesthesia induction, a low ETco2 contributes to the diagnosis of anaphylaxis, in addition to the classical signs of perioperative immediate hypersensitivity.

EDITOR’S PERSPECTIVE

Antibody or Anybody? Considering the Role of MRGPRX2 in Acute Drug-Induced Anaphylaxis and as a Therapeutic Target

Acute anaphylaxis to small molecule drugs is largely considered to be antibody-mediated with immunogloblin E (IgE) and mast cell activation being key. More recently, a role for drug-reactive immunoglobulin G (IgG) with neutrophil activation has also been suggested, at least in reactions to neuromuscular blocking agents (NMBAs). However, the mast cell receptor MRGPRX2 has also been highlighted as a possible triggering mechanism in acute anaphylaxis to many clinically used drugs. Significantly, MRGPRX2 activation is not dependent upon the presence of drug-recognising antibody. Given the reasonable assumption that MRGPRX2 is expressed in all individuals, the corollary of this is that in theory, anybody could respond detrimentally to triggering drugs (recently suggested to be around 20% of a drug-like compound library). But this clearly is not the case, as the incidence of acute drug-induced anaphylaxis is very low. In this mini-review we consider antibody-dependent and -independent mechanisms of mast cell activation by small molecule drugs with a focus on the MRGPRX2 pathway. Moreover, as a juxtaposition to these adverse drug actions, we consider how increased understanding of the role of MRGPRX2 in anaphylaxis is important for future drug development and can complement exploration of this receptor as a drug target in broader clinical settings.

What do we know about perioperative hypersensitivity reactions and what can we do to improve perioperative safety?

Hypersensitivity reactions are an important aspect of perioperative care and are a crucial interdisciplinary issue in anaesthesiological practice, as well as allergological and laboratory diagnostics. This phenomenon was observed as early as the 1980s and 1990s in Western European countries, and knowledge on this subject has grown significantly over time. Although hypersensitivity reactions are not frequent events (the incidence of perioperative hypersensitivity reactions ranges from 1:386 to 1:13 000 procedures, with higher frequency - 1 per 6500 general anaesthesias with neuromuscular blocking agents administrations), their courses are unfortunately serious and life-threatening. It should also be noted that there is no information regarding the occurrence of perioperative hypersensitivity reactions in many countries. Hence, global assessment of the problem is underestimated. The primary source of actual knowledge comes from epidemiological studies, which indicate an increasing frequency of hypersensitivity reaction occurrence and changes in aetiological factors. The first report from France (1984 to 1989) described two main causes - neuromuscular blocking agents and hypnotic agents. The following years confirmed an increase in perioperative hypersensitivity reactions associated with latex and antibiotics. The most recent data from the National Audit Project 6 indicated increased participation of antibiotics, chlorhexidine, and contrast agents. The results of epidemiological analyses are the basis of medical management guidelines and practice modification. Thanks to the activity of many organisations monitoring the intensity and nature of perioperative hypersensitivity reactions, guidelines for diagnostics and management have been developed. This article presents the results of numerous studies, including the first and the most recent, from various geographical regions. The clinical significance, pathogenesis mechanisms are also discussed. This publication also presents important directions for further scientific and epidemiological research on perioperative hypersensitivity reactions.Key messagesThe incidence of perioperative hypersensitivity reactions ranges from 1:386 to 1:13 000 procedures, with higher frequency - 1 per 6500 general anaesthesias with neuromuscular blocking agents administrations.Reactions may occur during the first episode of anaesthesia, most frequently in the induction of general anaesthesia, and much less frequently during postoperative follow-up.The first reports of perioperative hypersensitivity reaction come from the 1990s, and knowledge on this subject has grown significantly over time.In many countries, multidisciplinary teams and organisations have been established to identify, monitor the occurrence of this phenomenon, and have set the directions of medical activities and have changed the rules and recommendations.There is no information about the occurrence of perioperative hypersensitivity reactions in many countries, and global assessment of the problem is underestimated. Additionally, there is a great need to develop a system to monitor their occurrence in other countries.The long-term epidemiologic studies have demonstrated variability in pharmacologic triggers. However, the main pharmacological substances (antibiotics, muscle relaxants, disinfectans, contrast agents) are related to aspects of patient safety during anaesthesia.

Perioperative Anaphylaxis

Perioperative anaphylaxis is a potentially life-threatening and under-recognized event most commonly caused by antibiotics, neuromuscular blocking agents, dyes, latex, and disinfectants. This review provides updates in the epidemiology and pathogenesis of perioperative anaphylaxis, discusses culprit agents, and highlights the tenets of management including a comprehensive allergy evaluation.

Epidemiology of suspected life-threatening perioperative anaphylaxis: a cross-sectional multicentre study in China

BACKGROUND

Perioperative anaphylaxis is relatively rare but can be life-threatening. The incidence in China is unknown and may differ from other global geographic regions. This study was therefore designed to understand the incidence of perioperative anaphylaxis in China.

METHODS

We enrolled 112 tertiary care hospitals from seven distinct geographic areas in mainland China. We collected information about Ring and Messmer III and IV reactions from September 2018 to August 2019. A collaborative educational learning network was used to reduce diagnostic errors. Information about patient characteristics, clinical features, treatment, and clinical outcomes were recorded and analysed.

RESULTS

A total of 447 cases of 5 078 118 surgical procedures met inclusion criteria. The incidence of suspected perioperative anaphylaxis throughout China was one in 11 360 anaesthetics (95% confidence interval [CI], with a range of 1:12 521 to 1:10 397). The incidence in South China was higher (one in 6050; 95% CI, from 1:8013 to 1:4859) than in Northeast China (one in 19 262; 95% CI, from 1:33 088 to 1:13 585) (P<0.01) with an increasing trend from the north to the south. The most common clinical manifestations were hypotension (91.1%) and tachycardia (65.3%). The majority of patients (83.4%) were given epinephrine. A total of 27 patients (6.0%) required cardiopulmonary resuscitation. Ultimately, nine patients died (2.0%).

CONCLUSIONS

This nationwide survey showed an incidence of perioperative anaphylaxis of one in 11 360, but this varied significantly by region. The underlying reason for this pattern remains unknown and could be attributable to environmental or genetic influences, which requires further investigation.

CLINICAL REGISTRY NUMBER

ChiCTR1900025956.

Clinical reasoning in anaphylactic shock: addressing the challenges faced by anaesthesiologists in real time: A clinical review and management algorithms

Acute hypersensitivity reactions to drugs occur infrequently during anaesthesia and the peri-operative period. When clinical presentation includes the classical triad, erythema, cardiovascular abnormalities and increased airway pressure, the diagnosis is evident and the challenge is to prescribe a therapeutic regimen according to guidelines and to manage refractory signs in a timely manner. In many situations, however, the initial clinical signs are isolated, such as increased airway pressure or arterial hypotension. Rendering a differential diagnosis with causes and mechanisms other than acute hypersensitivity reactions (AHRs) is difficult, delaying treatment with possible worsening of the clinical signs, and even death, in previously healthy individuals. In these difficult diagnostic situations, clinical reasoning is mandatory, and guidelines do not explicitly explain the elements on which clinical reasoning can be built. In this article, based on clinical evidence whenever available, experimental data and pathophysiology, we propose algorithms that have been evaluated by experts. The goal of these algorithms is to provide explicit elements on which the differential diagnosis of AHRs can be made, accelerating the implementation of adequate therapy.

Epidemiology of perioperative anaphylaxis in the United States: new insights but more to learn and do

Gonzalez-Estrada and colleagues report an estimated risk of severe or fatal perioperative anaphylaxis of one in 6,825 procedures during the period 2005-2014. This is slightly higher than that reported previously in France and England. Several predictors of near-fatal and fatal reactions are identified, such as increased age, cancer, and congestive cardiac failure.

Recent update on the management of anaphylaxis

Anaphylaxis is a life-threatening systemic allergic reaction presenting various clinical manifestations. Its prevalence has increased in almost all age groups and both sexes. Food, venom, and drugs are major causes in both children and adults; a higher prevalence of food-induced anaphylaxis is noted in children, while a higher prevalence of drug-induced anaphylaxis is noted in adults. The pathogenic mechanism is mediated by immunologic and nonimmunologic mechanisms, where mast cells and basophils are key cells that release mediators. A diagnosis of anaphylaxis is mainly based on clinical symptoms and physical findings; however, an increased serum tryptase level is a useful biomarker. Epinephrine is the first-line drug to treat acute symptoms, and an epinephrine auto-injector should be prescribed for each patient. Antihistamines and systemic corticosteroids are used to relieve symptoms. This review updates current issues in the management of anaphylaxis as well as the new guidelines for proper diagnosis and treatment.

Intraoperative anaphylaxis due to aprotinin after local application of fibrin sealant diagnosed by skin tests and basophil activation tests: a case report

Background

There are few cases of anaphylaxis after local application of fibrin sealant diagnosed by skin tests.

Case presentation

A 49-year-old woman underwent partial lung resection under general anesthesia. Anesthesia was induced uneventfully. Shortly after applying absorbable suture reinforcement felt that contained fibrin sealant, her systolic blood pressure fell to approximately 70 mmHg, along with facial flushing. Anaphylaxis was diagnosed based on the clinical symptoms and high serum tryptase levels. Three months after the event, skin tests were performed with all agents and were positive only for fibrin sealant vial no. 2, whose main component is aprotinin. Subsequently, basophil activation tests using fibrin sealant vial no. 2 and pure aprotinin demonstrated that the causative agent was likely aprotinin.

Conclusions

We diagnosed aprotinin-induced anaphylaxis using skin tests and basophil activation tests. The occurrence of anaphylaxis should be considered when changes in vital signs are observed after the use of fibrin sealant.

MRGPRX2 and Adverse Drug Reactions

Many adverse reactions to therapeutic drugs appear to be allergic in nature, and are thought to be triggered by patient-specific Immunoglobulin E (IgE) antibodies that recognize the drug molecules and form complexes with them that activate mast cells. However, in recent years another mechanism has been proposed, in which some drugs closely associated with allergic-type events can bypass the antibody-mediated pathway and trigger mast cell degranulation directly by activating a mast cell-specific receptor called Mas-related G protein-coupled receptor X2 (MRGPRX2). This would result in symptoms similar to IgE-mediated events, but would not require immune priming. This review will cover the frequency, severity, and dose-responsiveness of allergic-type events for several drugs shown to have MRGPRX2 agonist activity. Surprisingly, the analysis shows that mild-to-moderate events are far more common than currently appreciated. A comparison with plasma drug levels suggests that MRGPRX2 mediates many of these mild-to-moderate events. For some of these drugs, then, MRGPRX2 activation may be considered a regular and predictable feature after administration of high doses.

Mechanisms Governing Anaphylaxis: Inflammatory Cells, Mediators, Endothelial Gap Junctions and Beyond

Anaphylaxis is a severe, acute, life-threatening multisystem allergic reaction resulting from the release of a plethora of mediators from mast cells culminating in serious respiratory, cardiovascular and mucocutaneous manifestations that can be fatal. Medications, foods, latex, exercise, hormones (progesterone), and clonal mast cell disorders may be responsible. More recently, novel syndromes such as delayed reactions to red meat and hereditary alpha tryptasemia have been described. Anaphylaxis manifests as sudden onset urticaria, pruritus, flushing, erythema, angioedema (lips, tongue, airways, periphery), myocardial dysfunction (hypovolemia, distributive or mixed shock and arrhythmias), rhinitis, wheezing and stridor. Vomiting, diarrhea, scrotal edema, uterine cramps, vaginal bleeding, urinary incontinence, dizziness, seizures, confusion, and syncope may occur. The traditional (or classical) pathway is mediated via T cells, Th2 cytokines (such as IL-4 and 5), B cell production of IgE and subsequent crosslinking of the high affinity IgE receptor (FcεRI) on mast cells and basophils by IgE-antigen complexes, culminating in mast cell and basophil degranulation. Degranulation results in the release of preformed mediators (histamine, heparin, tryptase, chymase, carboxypeptidase, cathepsin G and tumor necrosis factor alpha (TNF-α), and of de novo synthesized ones such as lipid mediators (cysteinyl leukotrienes), platelet activating factor (PAF), cytokines and growth factors such as vascular endothelial growth factor (VEGF). Of these, histamine, tryptase, cathepsin G, TNF-α, LTC₄, PAF and VEGF can increase vascular permeability. Recent data suggest that mast cell-derived histamine and PAF can activate nitric oxide production from endothelium and set into motion a signaling cascade that leads to dilatation of blood vessels and dysfunction of the endothelial barrier. The latter, characterized by the opening of adherens junctions, leads to increased capillary permeability and fluid extravasation. These changes contribute to airway edema, hypovolemia, and distributive shock, with potentially fatal consequences. In this review, besides mechanisms (endotypes) underlying IgE-mediated anaphylaxis, we also provide a brief overview of IgG-, complement-, contact system-, cytokine- and mast cell-mediated reactions that can result in phenotypes resembling IgE-mediated anaphylaxis. Such classifications can lead the way to precision medicine approaches to the management of this complex disease.

Anaphylaxis after injecting a hemostatic agent containing gelatin into vertebral bone under pressure-a warning

STUDY DESIGN

Case series.

PURPOSE

The use of topical hemostatic agents is common in spinal deformity surgery. While beneficial, emerging case data shows gelatin-containing agents causing intra-operative complications. We present two patients who developed anaphylaxis after injection of these gelatin-containing hemostatic agents into the vertebral body using manual pressure. In the literature, while anaphylactic reactions associated with the use of animal-derived gelatin has been implicated; the risk of injecting these products into the closed vascular cavity of the vertebral body with subsequent embolization into systemic circulation bears emphasis. This report is to meant to make the surgical team aware of the risks of injecting hemostatic agents using manual pressure into the vertebral body and to highlight a plausible mechanism for the phenomenon.

METHODS

Two children with spinal deformity undergoing posterior spinal fusion procedures with the use of gelatin-containing hemostatic agents injected into the vertebral body through the pedicle are described.

RESULTS

Both patients had gelatin-containing hemostatic agent solution injected under manual pressure through the vertebral pedicle to prevent excessive bleeding. Anaphylaxis occurred soon thereafter, resulting in emergent cessation of the surgery and initiation of medical resuscitation. In both cases, tryptase levels obtained just after the event were elevated.

CONCLUSION

Patients with an allergy to or prior history of exposure to zoologic products undergoing spine surgery may be at risk of anaphylaxis if the gelatin-containing hemostatic agent is injected under manual pressure into the closed space of the vertebral body. This allows rapid entry into the venous circulation. We recommend that the surgeon perform a thorough history of a patient's allergies and use extreme caution when injecting these topical hemostatic products into the vertebral body.

LEVEL OF EVIDENCE

IV.

[Cardiac arrest under special circumstances]

These guidelines of the European Resuscitation Council (ERC) Cardiac Arrest under Special Circumstances are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required for basic and advanced life support for the prevention and treatment of cardiac arrest under special circumstances; in particular, specific causes (hypoxia, trauma, anaphylaxis, sepsis, hypo-/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), specific settings (operating room, cardiac surgery, cardiac catheterization laboratory, dialysis unit, dental clinics, transportation [in-flight, cruise ships], sport, drowning, mass casualty incidents), and specific patient groups (asthma and chronic obstructive pulmonary disease, neurological disease, morbid obesity, pregnancy).

Perioperative Anaphylaxis from a Perspective of Temperature

Perioperative anaphylaxis poses a special challenge due to its unique condition with the additive effects of surgery and anesthesia, which tends to be more difficult to recognize, diagnose, and manage, resulting in potentially fatal outcomes. Appropriate prevention and treatment benefits patients and reduces mortality and morbidity. Significant body temperature changes occur during anaphylaxis and/or anesthesia, which correlates with the outcomes. During the perioperative period, body temperature and anaphylaxis bidirectionally interact with each other, and anaphylaxis is generally deteriorated by hypothermia, which is usually required in cardiac surgeries. Perioperative factors, such as surgery and anesthesia, affect body temperature and anaphylaxis. The complicated role of body temperature and its application in the diagnosis of perioperative anaphylaxis and prediction of the outcomes are still unclear. To date, a profile of body temperature change during perioperative anaphylaxis is lacking, which requires further study. This literature review was conducted with updated data on perioperative anaphylaxis from the perspective of temperature as a component aiming to bring attention to and offer some cues for improving perioperative prevention and management for perioperative medical teams.Supplemental data for this article is available online at https://doi.org/10.1080/08941939.2021.1922553 .

Mast Cell Activation During Suspected Perioperative Hypersensitivity: A Need for Paired Samples Analysis

BACKGROUND

Perioperative hypersensitivity (POH) reactions constitute a significant clinical and diagnostic challenge. A transient increase in serum tryptase during POH reflects mast cell activation (MCA) and helps to recognize an underlying hypersensitivity mechanism.

OBJECTIVE

To determine the diagnostic performance of different tryptase decision thresholds based on single and paired measurements to document MCA in suspected POH.

METHODS

Acute serum tryptase (aST) and baseline serum tryptase (bST) samples were obtained from patients referred to our outpatients clinic because of clinical POH. Tryptase samples from controls were obtained before induction (Tt₀) and 1.5 hours after induction (Tt₁) in uneventful anesthesia. Different cutoff points for tryptase increase over bST and the percentage increase in tryptase (%T) were calculated and compared with existing thresholds: aST > [1.2 × (bST) + 2] (consensus formula), aST higher than 11.4 ng/mL, and aST higher than 14 ng/mL.

RESULTS

Patients with POH had higher bST and aST levels compared with controls (respectively 5.15 vs 2.28 ng/mL for bST and 20.30 vs 1.92 ng/mL for aST). The consensus formula and a tryptase increase over bST of greater than or equal to 3.2 ng/mL held the highest accuracies to document MCA in POH (respectively 81% and 82%). A bST of higher than 8 ng/mL was present in 4% of controls, 5% of patients with grade 1 POH, 24% of patients with grade 2 POH, 15% of patients with grade 3 POH, and 17% of patients with grade 4 POH.

CONCLUSIONS

Our data endorse the consensus formula for detection of MCA in POH. Furthermore, it shows that a bST of higher than 8 ng/mL was associated with occurrence of anaphylaxis.

Hypersensitivity and Chemotherapy Desensitization

OBJECTIVES

Hypersensitivity reactions (HSRs) are defined as reactions with reproducible signs and symptoms, triggered by an exposure to a stimulus at a dose tolerated by normal subjects. Although discontinuing the allergenic medication can eliminate the potential for HSRs, it can also lead to significant morbidity and mortality due to suboptimal treatment of the underlying disease. Therefore, desensitization protocols have been developed that offer a safe process that delivers full therapeutic doses in an incremental fashion without eliciting life-threatening reactions.

DATA SOURCES

This article uses a case study to discuss the process of chemotherapy desensitization, associated complications, and identify areas of improvement in the management of HSRs within an academic medical center.

CONCLUSION

HSRs are a complex pathophysiologic response that requires an experienced oncology nurse at the bedside to manage potentially life-threatening symptoms.

IMPLICATIONS FOR NURSING PRACTICE

Thorough education and training is needed among nursing staff to manage HSRs during the chemotherapy desensitization process.

European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances

These European Resuscitation Council (ERC) Cardiac Arrest in Special Circumstances guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the modifications required to basic and advanced life support for the prevention and treatment of cardiac arrest in special circumstances; specifically special causes (hypoxia, trauma, anaphylaxis, sepsis, hypo/hyperkalaemia and other electrolyte disorders, hypothermia, avalanche, hyperthermia and malignant hyperthermia, pulmonary embolism, coronary thrombosis, cardiac tamponade, tension pneumothorax, toxic agents), special settings (operating room, cardiac surgery, catheter laboratory, dialysis unit, dental clinics, transportation (in-flight, cruise ships), sport, drowning, mass casualty incidents), and special patient groups (asthma and COPD, neurological disease, obesity, pregnancy).

Use and Interpretation of Acute and Baseline Tryptase in Perioperative Hypersensitivity and Anaphylaxis

Paired acute and baseline serum or plasma tryptase sampling and determination have recently been included as a mechanistic approach in the diagnostic and management guidelines of perioperative immediate hypersensitivity and anaphylaxis. The timing of this paired sampling is clearly defined in international consensus statements, with the optimal window for acute tryptase sampling between 30 minutes and 2 hours after the initiation of symptoms, whereas baseline tryptase should be measured in a sample collected before the event (preop) or at least 24 hours after all signs and symptoms have resolved. A transient elevation of the acute tryptase level greater than [2 + (1.2 × baseline tryptase level)] supports the involvement and activation of mast cells. Here, we provide the clinical, pathophysiological, and technical rationale for the procedure and interpretation of paired acute and baseline tryptase. Clinical examples, up-to-date knowledge of hereditary α-tryptasemia as a frequent cause of baseline tryptase of 7 μg/L and higher, mastocytosis, other clonal myeloid disorders, cardiovascular or renal failure, and technical improvements resulting in continued lowering of the 95th percentile value are discussed. Clues for improved management of perioperative immediate hypersensitivity and anaphylaxis include (1) sustained dissemination and implementation of updated guidelines; (2) preoperative sample storage for deferred analysis; (3) referral for thorough allergy investigation, screening for mast cell-related disorders, and recommendations for future anesthetic procedures; and (4) sustained collaboration between anesthesiologists, immunologists, and allergists.

Critical Care Management of the Patient With Anaphylaxis: A Concise Definitive Review

OBJECTIVES

Anaphylaxis is a rapidly progressive life-threatening syndrome manifesting as pruritus, urticaria, angioedema, bronchospasm and shock. The goal of this synthetic review is to provide a practical, updated approach to the evaluation and management of this disorder and associated complications.

DATA SOURCES

A MEDLINE search was conducted with the MeSH of anaphylaxis, anaphylactic reaction, anaphylactic shock, refractory anaphylaxis and subheadings of diagnosis, classification, epidemiology, complications and pharmacology. The level of evidence supporting an intervention was evaluated based on the availability of randomized studies, expert opinion, case studies, reviews, practice parameters and other databases (including Cochrane).

STUDY SELECTION

Selected publications describing anaphylaxis, clinical trials, diagnosis, mechanisms, risk factors and management were retrieved (reviews, guidelines, clinical trials, case series) and their bibliographies were also reviewed to identify relevant publications.

DATA EXTRACTION

Data from the relevant publications were reviewed, summarized and the information synthesized.

DATA SYNTHESIS

This is a synthetic review and the data obtained from a literature review was utilized to describe current trends in the diagnosis and management of the patient with anaphylaxis with a special emphasis on newer evolving concepts of anaphylaxis endotypes and phenotypes, management of refractory anaphylaxis in the ICU setting and review of therapeutic options for the elderly patient, or the complicated patient with severe cardiorespiratory complications. Most of the recommendations come from practice parameters, case studies or expert opinions, with a dearth of randomized trials to support specific interventions.

CONCLUSION

Anaphylaxis is a rapidly progressive life-threatening disorder. The critical care physician needs to be familiar with the diagnosis, differential diagnosis, evaluation, and management of anaphylaxis. Skilled intervention in ICUs may be required for the patient with complicated, severe, or refractory anaphylaxis.

Minireview: Mas-related G protein-coupled receptor X2 activation by therapeutic drugs

Symptoms that resemble allergic reactions, such as pruritus, flushing, and hypotension, are common side effects of therapeutic drugs. In a true allergic reaction, Immunoglobulin E (IgE) antibodies recognize the drug and trigger mediator release from mast cells through cross-linking of IgE receptors. However, many drugs can bypass this pathway and can activate mast cells directly through MRGPRX2, a G protein-coupled receptor that responds to a wide range of small molecules, peptides, and proteins that have little in common except for a net positive charge. This review will provide an overview of MRGPRX2, including its expression pattern, studies of its pharmacology, and its orthologs. It also will review evidence for MRGPRX2 activation by many drugs closely associated with these reactions.

Human peripheral basophils extended phenotype shows a high expression of CD244 immuno-regulatory receptor

INTRODUCTION

Basophils play a major physio-pathological role in hypersensitivity related diseases. Basophils express high affinity Immunoglobulin (Ig) E receptors (FcεRI), IgG and complement regulatory. Basophils also have immunoregulatory activity through interaction with T cells. The aim of this study was to look for the expression of markers reflecting the activation status of peripheral Basophil in healthy donors.

METHOD

the study was performed on 29 healthy donors, 62% females with a mean age of 50.1 + 17.0 years. Basophils were identified on their expression of CD123 without HLA-DR and/or CD193 in two 8 colors panels including CD46, CD55, CD59, CD203c, CD32 (FcγRII), CD64 (FcγRIII), CD163, CD137L (4-1BBL), CD252 (OX40L), CD244 (2B4) and CD3 on whole blood. Basophil activation with anti IgE was performed on 14 donors.

RESULTS AND DISCUSSION

Our results confirmed the Basophil expression of CD123, CD193 and CD203 (the latter is strongly increased under stimulation). Complement regulatory proteins (CD46, CD55, CD59) were expressed at the same levels as on other leukocytes; CD46, CD59 expression being slightly increased under stimulation. CD32 and CD163 scavenger were slightly higher than on lympho and not influenced by activation. CD252 or CD137L were expressed at low levels and significantly induced by stimulation. Most of all, CD244 was highly expressed on Basophils as compared to any other leukocytes in fresh peripheral blood.

CONCLUSIONS

Our study shows that human resting Basophils express IgE and IgG Fc receptors and check point receptor CD244 that could potentially play a role in their previously reported immunoregulatory activity in sensitization and even in tumor immune escape.

Relationship of perioperative anaphylaxis to neuromuscular blocking agents, obesity, and pholcodine consumption: a case-control study

BACKGROUND

The observation that patients presenting for bariatric surgery had a high incidence of neuromuscular blocking agent (NMBA) anaphylaxis prompted this restricted case-control study to test the hypothesis that obesity is a risk factor for NMBA anaphylaxis, independent of differences in pholcodine consumption.

METHODS

We compared 145 patients diagnosed with intraoperative NMBA anaphylaxis in Western Australia between 2012 and 2020 with 61 patients with cefazolin anaphylaxis with respect to BMI grade, history of pholcodine consumption, sex, age, comorbid disease, and NMBA type and dose. Confounding was assessed by stratification and binomial logistic regression.

RESULTS

Obesity (odds ratio [OR]=2.96, χ²=11.7, P=0.001), 'definite' pholcodine consumption (OR=14.0, χ²=2.6, P<0.001), and female sex (OR=2.70, χ²=9.61, P=0.002) were statistically significant risk factors for NMBA anaphylaxis on univariate analysis. The risk of NMBA anaphylaxis increased with BMI grade. Confounding analysis indicated that both obesity and pholcodine consumption remained important risk factors after correction for confounding, but that sex did not. The relative rate of rocuronium anaphylaxis was estimated to be 3.0 times that of vecuronium using controls as an estimate of market share, and the risk of NMBA anaphylaxis in patients presenting for bariatric surgery was 8.8 times the expected rate (74.9 vs 8.5 per 100 000 anaesthetic procedures).

CONCLUSIONS

Obesity is a risk factor for NMBA anaphylaxis, the risk increasing with BMI grade. Pholcodine consumption is also a risk factor, and this is consistent with the pholcodine hypothesis. Rocuronium use is associated with an increased risk of anaphylaxis compared with vecuronium in this population.