Acute Management, Diagnosis, and Follow-Up of Suspected Perioperative Hypersensitivity Reactions in Flanders 2001-2018

Mast cell versus basophil activation test in allergy: Current status

In the past two decades, we witnessed the evolution of the basophil activation test (BAT) from mainly research applications to a potential complementary diagnostic tool to document IgE-dependent allergies. However, BAT presents some technical weaknesses. Around 10%-15% of tested patients are non-responders, BAT can be negative immediately post-reaction and the use of fresh basophils, ideally analysed within 4 h of collection, restricts the number of tests that can be performed per sample. The need for fresh basophils is especially limiting when conducting batch analyses and interlaboratory comparisons to harmonize BAT methodology. These limitations significantly hinder the wider application of BAT and urge the development of alternative testing, such as the mast cell activation test (MAT). The essential difference between BAT and MAT is the heterogeneity of the starting material used to perform the assays. Mast cells are tissue-resident, so cannot be easily accessed. Current alternative sources for functional studies are generating primary human mast cells, differentiated from donor progenitor cells, or using immortalized mast cell lines. Hence, the methodological approaches for MAT are not only vastly different from BAT, but also different among MAT protocols. This review summarizes the advantages and disadvantages of BAT and MAT assays, dedicating special attention to elucidating the key differences between the cellular sources used and provides an overview of studies hitherto performed comparing BAT and MAT in the diagnosis of IgE-mediated food and drug allergies.

A US-Based Multicenter Retrospective Report of Perioperative Anaphylaxis, 2010-2021

BACKGROUND

US-based perioperative anaphylaxis (POA) studies are limited to single-center experiences. A recent report found that a serum acute tryptase (sAT) >9.8 ng/mL or mast cell activation (MCA) can predict POA causal agent identification. Urinary mast cell mediator metabolites (uMC) have not been studied in POA.

OBJECTIVE

To analyze the epidemiologic data of POA, to determine if sAT or MCA can predict suspected causal agent identification, and to evaluate uMC utility in POA.

METHODS

This study is a retrospective multicenter review of POA cases that were subcategorized by suspected causal agent identification status. sAT, MCA (defined as sAT >2 + 1.2 × serum baseline tryptase), and uMC (N-methylhistamine [N-MH], 11β-prostaglandin-F2α [11β-PGF2α], leukotriene E4 [LTE4]) were recorded.

RESULTS

Of 100 patients (mean age 52 [standard deviation 17] years, 94% adult, 50% female, 90% White, and 2% Hispanic) with POA, 73% had an sAT available, 41% had MCA, 16% had uMC available, and 50% had an identifiable suspected cause. POA cases with an identifiable suspected cause had a positive MCA status (100% vs 78%; P = .01) compared with POA with an unidentifiable cause. An elevated median sAT did not predict causal agent identification. Positive uMC were not associated with suspected causal agent identification during POA. Patients with positive uMC had a higher median sAT (30 vs 6.45 ng/mL; P = .001) and MCA status (96% vs 12%; P = .001) compared with negative uMC patients. Patients with POA had an elevated acute/baseline uMC ratios: 11β-PGF2α ratio > 1.6, N-MH ratio >1.7, and LTE4 ratio >1.8.

CONCLUSIONS

The presence of MCA in POA is associated with suspected causal agent identification. Positive uMC possibly correlate with a higher sAT level and MCA status but require further study. The authors suggest applying an acute/baseline uMC ratio (11β-PGF2α ratio >1.6, N-MH ratio >1.7, and LTE4 ratio >1.87) in patients with POA for MCA when a tryptase level is inconclusive during POA evaluations.

Biomarkers of immediate drug hypersensitivity

Immediate drug hypersensitivity reactions (IDHRs) are a burden for patients and the health systems. This problem increases when taking into account that only a small proportion of patients initially labelled as allergic are finally confirmed after an allergological workup. The diverse nature of drugs involved will imply different interactions with the immunological system. Therefore, IDHRs can be produced by a wide array of mechanisms mediated by the drug interaction with specific antibodies or directly on effector target cells. These heterogeneous mechanisms imply an enhanced complexity for an accurate diagnosis and the identification of the phenotype and endotype at early stages of the reaction is of vital importance. Currently, several endophenotypic categories (type I IgE/non-IgE, cytokine release, Mast-related G-protein coupled receptor X2 (MRGPRX2) or Cyclooxygenase-1 (COX-1) inhibition and their associated biomarkers have been proposed. A precise knowledge of endotypes will permit to discriminate patients within the same phenotype, which is crucial in order to personalise diagnosis, future treatment and prevention to improve the patient's quality of life.

Flow-based basophil activation test in immediate drug hypersensitivity. An EAACI task force position paper

Diagnosing immediate drug hypersensitivity reactions (IDHRs) can pose a significant challenge and there is an urgent need for safe and reliable tests. Evidence has emerged that the basophil activation test (BAT), an in vitro assay that mirrors the in vivo response, can be a complementary test for many drugs. In this position paper, members of Task Force (TF) "Basophil activation test in the evaluation of Drug Hypersensitivity Reactions" from the European Academy of Allergy and Clinical Immunology (EAACI) present the data from a survey about the use and utility of BAT in IDHRs in Europe. The survey results indicate that there is a great interest for using BAT especially for diagnosing IDHRs. However, there are still main needs, mainly in the standardization of the protocols. Subsequently consensus-based recommendations were formulated for: (i) Technical aspects of BAT in IDHRs including type of sample, management of drugs, flow cytometry protocols, interpretation of the results; and (ii) Drug-specific aspects that should be taken into account when performing BAT in relation to betalactams, neuromuscular blocking agents, fluoroquinolones, chlorhexidine, opioids, radio contrast media, chemotherapeutics, biological agents, nonsteroidal anti-inflammatory drugs, COVID vaccine, and excipients. Moreover, aspects in the evaluation of pediatric population have also been considered. All this indicates that BAT offers the clinician and laboratory a complementary tool for a safe diagnostic for IDHRs, although its place in the diagnostic algorithm depends on the drug class and patient population (phenotype, geography, and age). The standardization of BAT is important for generalizing this method beyond the individual laboratory.

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.

Comparison of the passive mast cell activation test with the basophil activation test for diagnosis of perioperative rocuronium hypersensitivity

BACKGROUND

Rocuronium is a major cause of perioperative hypersensitivity (POH). Skin tests (STs) and quantification of specific immunoglobulin E antibodies (sIgEs) can yield incongruent results. In such difficult cases, the basophil activation test (BAT) can be helpful. Here, we evaluated the passive mast cell activation test (pMAT) as a substitute of BAT as part of the diagnostic tests for rocuronium allergy.

METHODS

Sera from patients with a suspected POH reaction potentially related to rocuronium were included. All patients had a complete diagnostic investigation, including STs, quantification of sIgEs to morphine and rocuronium, and BAT. For execution of pMAT, human mast cells were generated from healthy donor peripheral blood CD34+ progenitor cells and sensitised overnight with patient sera.

RESULTS

In total, 90 sera were studied: 41 from ST+sIgE+ patients, 13 from ST-sIgE- patients, 20 from ST+sIgE- patients, and 16 from ST-sIgE+ patients. According to BAT results, patients were further allocated into subgroups. Of the 38 BAT+ patients, 25 (66%) showed a positive pMAT as well. Of the 44 BAT- patients, 43 (98%) also showed a negative pMAT. Mast cells that were not passively sensitised did not respond to rocuronium.

CONCLUSIONS

We show that the pMAT, in many cases, can substitute for BAT in the diagnosis of rocuronium hypersensitivity and advance diagnosis in difficult cases with uncertain ST or sIgE results when BAT is not locally available.

United States Drug Allergy Registry (USDAR) grading scale for immediate drug reactions

BACKGROUND

There is no accepted grading system classifying the severity of immediate reactions to drugs.

OBJECTIVE

The purpose of this article is to present a proposed grading system developed through the consensus of drug allergy experts from the United States Drug Allergy Registry (USDAR) Consortium.

METHODS

The USDAR investigators sought to develop a consensus severity grading system for immediate drug reactions that is applicable to clinical care and research.

RESULTS

The USDAR grading scale scores severity levels on a scale of 0 to 4. A grade of no reaction (NR) is used for patients who undergo challenge without any symptoms or signs, and it would confirm a negative challenge result. A grade 0 reaction is indicative of primarily subjective complaints that are commonly seen with both historical drug reactions and during drug challenges, and it would suggest a low likelihood of a true drug allergic reaction. Grades 1 to 4 meet the criteria for a positive challenge result and may be considered indicative of a drug allergy. Grade 1 reactions are suggestive of a potential immediate drug reaction with mild symptoms. Grade 2 reactions are more likely to be immediate drug reactions of moderate severity. Grade 3 reactions have features suggestive of a severe allergic reaction, whereas grade 4 reactions are life-threatening reactions such as anaphylactic shock and fatal anaphylaxis.

CONCLUSION

This proposed grading schema for immediate drug reactions improves on prior schemata by being developed specifically for immediate drug reactions and being easy to implement in clinical and research practice.

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.

Treatment of perioperative anaphylaxis: room for improvement?

Perioperative anaphylaxis is associated with significant morbidity and mortality. Prompt and appropriate treatment is required for optimal outcome. Despite general knowledge of this condition, delays occur in the administration of epinephrine and in particular the use of i.v. route of administration in the perioperative setting. Barriers should be addressed to allow prompt utilisation of i.v. epinephrine in perioperative anaphylaxis.

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.

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.

Could Artificial Intelligence Prevent Intraoperative Anaphylaxis? Reference Review and Proof of Concept

Drugs and various medical substances have been used for many decades to diagnose or treat diseases. Procedures like surgery and anesthesia (either local or general) use different pharmacological products during these events. In most of the cases, the procedure is safe and the physician performs the technique without incidents. Although they are safe for use, these substances (including drugs) may have adverse effects, varying from mild ones to life-threatening reactions in a minority of patients. Artificial intelligence may be a useful tool in approximating the risk of anaphylaxis before undertaking a medical procedure. This material presents these undesirable responses produced by medical products from a multidisciplinary point of view. Moreover, we present a proof of concept for using artificial intelligence as a possible guardship against intraoperative anaphylaxis.

Reliability of Early and Late Testing for Suspected Perioperative Hypersensitivity

BACKGROUND

The optimal timing of diagnostic testing for perioperative hypersensitivity (POH) remains unknown. It has been recommended that investigation is best carried out at least 4 to 6 weeks after the event. On the other hand, guidelines discourage the use of in vitro tests later than 3 years after the index reaction.

OBJECTIVE

This retrospective study aimed to assess the reliability of early and late skin tests (STs). It also attempted to verify whether discouraging late ex vivo and in vitro tests is substantiated.

METHODS

For the first aim, patients were stratified over three epochs: an early timing group, with investigations performed within 6 weeks; a recommended timing group, with tests performed between 6 weeks and 6 months; and a late timing group, tested later than 6 months after the event. For the second study purpose, we studied the reliability of specific IgE quantification and basophil activation test rocuronium within 6 weeks and after 3 years in patients who experienced an ST-proven POH to rocuronium.

RESULTS

A total of 677 patients were included. Based on a positive ST result, a causative agent was found in 74.2% of the early timing group, 62.6% of the recommended timing group, and 50% of the late timing group. A positive specific IgE for rocuronium or morphine was found in 80% of patients tested within 6 weeks, 63% of patients tested between 6 weeks and 3 years, and 50% of patients tested more than 3 years after the event. A positive basophil activation test was found in 83.3%, 51%, and 20%, respectively, of patients.

CONCLUSIONS

Our data confirm that evaluation of drug allergy for suspected POH can be performed before 6 weeks after the event, and there is no maximal upper time limit disclosing ex vivo and in vitro testing.

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.

Investigation of perioperative hypersensitivity reactions: an update

PURPOSE OF REVIEW

The purpose of this review is to provide an update on how best to manage the investigation of suspected perioperative hypersensitivity reactions based on recent literature and key publications.

RECENT FINDINGS

In the past two years, several very important initiatives have been taken in the field of perioperative hypersensitivity. The 6th national audit project in the United Kingdom has provided new knowledge through a series of studies, including a nationwide prospective study, and the European Academy of Allergy and Clinical Immunology has commissioned a position paper with updated recommendations for investigations. Lastly, a large international working group comprising experts in anesthesiology, allergology, and immunology, the International Suspected Perioperative Allergic Reactions group, has published a series of articles providing updates and new insights into several different key areas of perioperative hypersensitivity.

SUMMARY

The investigation of perioperative hypersensitivity reactions is highly complex and aims to identify the correct culprit to ensure future avoidance but also to disprove allergy to other suspected culprits, making them available for subsequent anesthesia. To achieve this, close collaboration between anesthesiologists and allergists is called upon to ensure the best possible outcome for the patient.

Diagnostic Approach of Hypersensitivity Reactions to Cefazolin in a Large Prospective Cohort

BACKGROUND

Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial because the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated.

OBJECTIVE

We aimed to characterize a large number of patients reporting cefazolin allergic reactions and to analyze the diagnostic role of in vivo and in vitro tests.

METHODS

We prospectively evaluated patients with suspicion for allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients, basophil activation test (BAT) and radioallergosorbent test were done before allergologic workup was performed and the final diagnosis was achieved.

RESULTS

We evaluated 184 patients, 76 of whom were confirmed as allergic (41.3%), 90 were nonallergic (48.9%), and 18 were nonconfirmed (9.8%). All patients reporting anaphylactic shock and most reporting anaphylaxis were confirmed to be allergic (P < .001). Forty allergic patients (52.6%) were confirmed by STs, 22 by DPT (28.9%), and 14 by clinical history (18.4%). All subjects manifesting exanthemas and pruritus were nonallergic. The BAT sensitivity was 66.7% when CD63 and CD203c were combined as activation markers. Six of 8 patients with negative STs and positive DPT had a positive BAT.

CONCLUSIONS

Patients allergic to cefazolin often reported severe immediate-type reactions. Skin tests enabled a diagnosis in half of patients when using cefazolin at 20 mg/mL. Unfortunately, DPT could not be performed in all patients owing to reaction severity, which makes BAT a promising diagnostic tool. Further research is needed to clarify the underlying mechanisms, especially in severe reactions.

Perioperative Anaphylaxis: Evaluation and Management

Perioperative anaphylaxis (PA) is a rare but life-threatening condition that poses diagnostic and management challenges in the operating room. The incidence of severe perioperative reactions is estimated to be approximately 1:7000-10,000. Management involves both immediate stabilization of the patient and identifying the culprit agent. Identification is essential to prevent recurrence of the event in subsequent surgeries and to avoid unnecessary labeling of drug allergy. Identifying all possible exposures including medications, disinfectants, latex, and dyes and choosing the appropriate tests are essential for proper evaluation. To identify the culprit, primary testing modalities include tryptase at the time of the reaction with subsequent levels and skin testing with nonirritating concentrations to the medications and substances utilized during the procedure and those potentially used as alternates. This strategy provides guidance for future surgeries and procedures. Close collaboration between the allergy, anesthesiology, and surgery teams is essential for appropriate management of these patients at the time of the reaction, during the post event evaluation and in preparation for subsequent surgeries.

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.

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.

Approach to Perioperative Anaphylaxis in 2020: Updates in Diagnosis and Management

PURPOSE OF REVIEW

The goal of the paper is to review the epidemiology, pathogenesis, diagnosis, and manifestations of perioperative anaphylaxis (POA). We seek to review the most common culprits of POA and different diagnostic modalities for evaluation.

RECENT FINDINGS

Specific IgE testing has a limited role in POA evaluation due to lack of widespread availability and low sensitivity. Basophil activation testing is complementary to skin tests and can assist NMBA sensitivity diagnosis in complex cases. In the past years, there has been an exponential increase in suspected teicoplanin allergic reactions in the European Union. Chlorhexidine is also being increasingly implicated as a culprit in POA. Multiple classes of perioperative medications cause POA. Diagnostic modalities available include skin testing with nonirritating concentrations, basophil activation tests, specific IgE, and drug provocation testing. An accurate record and critical analysis of perioperative events is more important than isolated test results. Future studies evaluating the pathophysiology of these reactions and other therapeutic strategies, such as targeting the MRGPRX2 receptor, are needed.

IgE-mediated chlorhexidine allergy-Cross-reactivity with other biguanide disinfectants

BACKGROUND

Chlorhexidine (CHX) is a widely utilized disinfectant that can cause IgE-mediated urticaria/anaphylaxis. The cross-reactivity of patients with IgE-mediated CHX allergy with other disinfectants, which share structural similarities with CHX like polyhexanide (polyhexamethylene biguanide; PHMB), alexidine (ALX), or octenidine (OCT), is unknown.

METHODS

Forty-four patients with anaphylaxis or urticaria upon CHX exposure and positive skin prick test (SPT) and/or positive CHX ImmunoCAP test (Phadia TFS, Uppsala, Sweden) were recruited. IgE to the biguanide and/or hexamethylene structure was investigated with PHMB ImmunoCAP (n = 32) and by basophil activation tests (BAT) with CHX and ALX (n = 37). Inhibition tests of CHX and PHMB ImmunoCAPs by CHX, ALX, PHMB, and OCT were performed.

RESULTS

IgE reactivity to PHMB as surrogate marker for biguanide/hexamethylene reactivity was detected in 5/32 sera. Seven of 37 patients showed a positive BAT with ALX, but only under optimized conditions. Binding to CHX ImmunoCAP was inhibited by ALX in 1/32 sera, and binding to PHMB was blocked by ALX (1/5) and by OCT in another (1/5). In SPT, 9/10 patients were positive for CHX and 3 of them with ALX (only at highest concentration at 5 mg/mL). A further patient reacted primarily with OCT and showed IgE cross-reactivity with CHX, ALX, and PHMB.

CONCLUSION

The IgE response to CHX seems polyclonal. The chloroguanide ending of CHX is the main epitope for the IgE and is suitable as screening assay to detect CHX reactivity. IgE-reactivities with the biguanide or hexamethylene components of other disinfectants (ALX, PHMB) can be detected by SPT, PHMB ImmunoCAP, and ALX-BAT in 15%-33% of CHX-allergic patients.

Advances and novel developments in drug hypersensitivity diagnosis

A correct diagnosis of drug hypersensitivity reactions (DHRs) is very important for both the patient and health system. However, DHRs diagnosis is complex, time consuming, requires trained personnel, is not standardized for many drugs, involves procedures not exempt of risk, and in most cases lacks standardized in vivo and in vitro tests. Thus, there is an urgent need for improving the different approaches to diagnose patients with suspected DHRs. In this review, we have analyzed the advances performed in immediate and nonimmediate DHRs diagnosis during the last two years and obtained several conclusions: the significant heterogeneity in current practice among centers illustrates the need to re-evaluate, update, and standardize in vivo tests and protocols for the diagnosis and management of patients with suspected drug allergy. Regarding in vitro tests, the latest studies have focused on increasing their sensitivity or on establishing the sensitivity and specificity for the tests performed with new drugs. There seems to be a consensus about combining in vivo and in vitro tests as the best way to increase the diagnostic accuracy.

Perioperative Allergic Reactions: Allergy Assessment and Subsequent Anesthesia

BACKGROUND

Evidence-based guidelines are needed in the United States to improve evaluation of perioperative allergic reactions including recommendations for subsequent anesthesia.

OBJECTIVE

To identify causative agent(s) and evaluate patients' tolerability of subsequent anesthesia in patients evaluated by Allergy/Immunology (A/I) at Massachusetts General Hospital.

METHODS

We performed a retrospective review of patients referred to the outpatient A/I clinic for perioperative allergic reactions between October 2003 and May 2017. Patient demographics, atopic history, and prior adverse drug reactions were reviewed. Patients underwent a comprehensive evaluation with testing including skin testing (ST), drug challenges (when appropriate), tryptase level measurement, and specific IgE to latex measurement. Tolerance of subsequent procedures requiring anesthesia was assessed.

RESULTS

Of 123 patients referred, 74 (60%) were female and the mean age was 46 (±18) years. At least 1 causative agent was identified in 28 patients (24%, n = 28 of 118). Seventeen of 28 (61%) patients were ST positive to an antibiotic, including 13 (46%) positive to cefazolin; 3 patients (11%) had a positive latex specific IgE. Of 85 patients who had subsequent anesthesia with a known outcome, 78 (91%) did not have another perioperative allergic reaction. Two of 5 patients with an elevated baseline tryptase level did not tolerate subsequent anesthesia.

CONCLUSION

The majority of patients safely received subsequent anesthesia after comprehensive A/I evaluation for their perioperative allergic reactions; however, improved algorithmic care is needed in the United States. Among ST-positive patients (24%), antibiotics (especially cefazolin) were the most common culprits. An elevated baseline tryptase level was associated with an increased risk of recurrent perioperative allergic reactions.

Incidence of and risk factors for perioperative or periprocedural anaphylaxis in the United States from 2005 to 2014

BACKGROUND

The estimated worldwide incidence of perioperative or periprocedural anaphylaxis (PA) is between 1 in 1250 and 1 in 20,000 procedures.

OBJECTIVE

To evaluate the incidence of PA in the United States and compare patient characteristics and underlying risk factors using a large national database.

METHODS

Using deidentified data from the nationwide inpatient sample from 2005 to 2014, we identified cases of PA through the International Classification of Diseases, Ninth Revision, Clinical Modification codes and conducted a retrospective analysis.

RESULTS

Among 35,647,347 surgeries and procedures, there were 5458 (0.015%) PA cases identified. The incidence of PA was 15.3 cases per 100,000 procedures. When compared with controls, PA cases had an increased mortality (3.4% vs 1.4%; P < .001), median length of stay (5 vs 3 days; P < .001), and median hospital cost ($45,155 vs $24,734; P < .001). The age group between 18 and 34 years (odds ratio [OR], 1.34; 95% confidence interval [CI], 1.13-1.58; P < .001) and female sex (OR, 1.40; 95% CI, 1.31-1.49; P < .001) were associated with increased odds of PA. Transplant (OR, 3.35; 95% CI, 2.59-4.34; P < .001), hematologic (OR, 1.63; 95% CI, 1.30-2.05; P < .001), vascular (OR, 1.49; 95% CI, 1.30-1.67; P < .001), and cardiac (OR, 1.47; 95% CI, 1.30-1.67; P < .001) procedures were at increased risk for PA. Several comorbidities were associated with PA including chronic pulmonary disease (OR, 1.41; 95% CI, 1.31-1.51; P < .001).

CONCLUSION

The incidence of PA is 1 in 6531 procedures, with a mortality of 1 in 191,652 procedures. PA has worsening outcomes compared with controls. The risk factors of PA include age, sex, procedure type, and comorbidities.

Hevea latex-associated allergies: piecing together the puzzle of the latex IgE reactivity profile

Introduction: IgE-mediated Hevea latex allergy and associated food-allergies constitute a significant health issue with serious consequences of diagnostic error. Hence, there is a need for more reliable confirmatory diagnostics.Areas covered: Here, we summarize the major limitations of conventional tests using native extracts and describe how piecing together the IgE reactivity profile can benefit correct diagnosis in difficult cases in whom conventional tests yield equivocal or negative results. A diagnostic algorithm integrating traditional sIgE and component-resolved diagnosis (CRD) is presented.Expert opinion: Moreover, it is clear that the discoveries in the field of the Hevea latex proteome will contribute to our understandings and accurate approach of sometimes complex cross-reactivity phenomena that extend beyond the 'latex-fruit syndrome.'