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.

EAACI/ENDA position paper on drug provocation testing

In drug hypersensitivity, drug provocation testing (DPT), also called drug challenge, is the gold standard for investigation. In recent years, risk stratification has become an important tool for adjusting the diagnostic strategy to the perceived risk, whilst still maintaining a high level of safety for the patient. Skin tests are recommended before DPT but may be omitted in low-risk patients. The task force suggests a strict definition of such low-risk patients in children and adults. Based on experience and evidence from studies of allergy to beta-lactam antibiotics, an algorithm on how to adjust DPT to the risk, and when to omit skin tests before DPT, is presented. For other antibiotics, non-steroidal anti-inflammatory drugs and other drugs, skin tests are poorly validated and DPT is frequently necessary. We recommend performing DPT with chemotherapeutics and biologicals to avoid unnecessary desensitization procedures and DPT with skin tests negative contrast media. We suggest DPT with anesthetics only in highly specialized centers. Specifics of DPT to proton pump inhibitors, anticonvulsants and corticosteroids are discussed. This position paper provides general recommendations and guidance on optimizing use of DPT, whilst balancing benefits with patient safety and optimizing the use of the limited available resources.

Healthcare professionals' attitudes to penicillin allergy labels

INTRODUCTION

About 10% of hospital inpatients are labelled with penicillin allergy in their electronic medical record (EMR). However, allergy is confirmed in less than 10% of these records. Consequently, 90% of patients are treated with broad-spectrum antibiotics, contributing to antimicrobial resistance. We aimed to explore experiences and practices of healthcare professionals that may explain incorrect labelling of penicillin allergy in Denmark and elucidate any consequences hereof.

METHODS

An electronic survey was distributed to physicians and nurses in six hospital units in Copenhagen and via social media. The survey was active from 19 March to 1 May 2020. Data were assessed using descriptive statistics and by thematic analysis.

RESULTS

The response rate was 44.6%. The survey had 369 participants; 152 physicians and 217 nurses. Half of the physicians and one in every five nurses had experienced problems treating patients with a penicillin allergy label. Physicians reported limited trust in allergy labels, and labelling practices varied. The risk that patients may be truly allergic was the main reason for not removing labels (72%), and a precautionary principle was identified related to penicillin allergy labelling.

CONCLUSIONS

The penicillin allergy label is an independent factor of medication errors. Solutions to enhance patient safety may include education of physicians in allergy labelling, decision support, standardisation of the allergy registration in the various EMR systems used, and ideally also a national drug allergy register, which is accessible from all sectors.

FUNDING

None.

TRIAL REGISTRATION

Not relevant.

Topical eye medications causing allergic contact dermatitis

BACKGROUND

Allergic contact dermatitis (ACD) in the eye region caused by topical eye medications is difficult to diagnose and may be overlooked.

OBJECTIVE

To study the characteristics and causative agents in patients with ACD caused by topical eye medications in a Danish tertiary dermatology department.

METHODS

A retrospective study of 318 patients, patch tested between 2013 and 2021 due to suspected ACD to topical eye medications. All patients were tested with a locally developed eye medication series, some were additionally tested with suspected eye medications. Medical records were studied in patch test positive patients.

RESULTS

Contact allergy to a topical eye allergen/medication was found in 12.9% (n = 41) of 318 patients, and culprit allergens were phenylephrine (6.9%), timolol (2.5%) and ketotifen (1.6%). Patch test positive patients were often previously diagnosed with cataract (29.3%) or glaucoma (24.4%), and the majority reported more than one previous reaction. Initial symptoms were oedema (56.0%), erythema (48.8%) and dermatitis (31.7%) in the eye region, and facial dermatitis was also seen.

CONCLUSIONS

Patients with symptoms from the eye region who have been using topical eye medications should be patch tested with ingredients from commonly used eye medications supplemented by the products tested 'as is'.

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.

Allergies and COVID-19 vaccines: An ENDA/EAACI Position paper

BACKGROUND

Anaphylaxis, which is rare, has been reported after COVID-19 vaccination, but its management is not standardized.

METHOD

Members of the European Network for Drug Allergy and the European Academy of Allergy and Clinical Immunology interested in drug allergy participated in an online questionnaire on pre-vaccination screening and management of allergic reactions to COVID-19 vaccines, and literature was analysed.

RESULTS

No death due to anaphylaxis to COVID-19 vaccines has been confirmed in scientific literature. Potential allergens, polyethylene glycol (PEG), polysorbate and tromethamine are excipients. The authors propose allergy evaluation of persons with the following histories: 1-anaphylaxis to injectable drug or vaccine containing PEG or derivatives; 2-anaphylaxis to oral/topical PEG containing products; 3-recurrent anaphylaxis of unknown cause; 4-suspected or confirmed allergy to any mRNA vaccine; and 5-confirmed allergy to PEG or derivatives. We recommend a prick-to-prick skin test with the left-over solution in the suspected vaccine vial to avoid waste. Prick test panel should include PEG 4000 or 3500, PEG 2000 and polysorbate 80. The value of in vitro test is arguable.

CONCLUSIONS

These recommendations will lead to a better knowledge of the management and mechanisms involved in anaphylaxis to COVID-19 vaccines and enable more people with history of allergy to be vaccinated.

Successful Desensitization to mRNA COVID-19 Vaccine in a Case Series of Patients With a History of Anaphylaxis to the First Vaccine Dose

Background

Coronavirus disease 2109 (COVID-19) vaccines have recently been approved to curb the global pandemic. The risk of allergic reactions to the vaccine polyethylene glycol (PEG) component has raised significant public concern. Desensitization is suggested in cases of vaccine related hypersensitivity reactions. After comprehensive literature review on the topic, our aim was to establish a safe and effective desensitization protocol for patients with suspected or confirmed immediate type hypersensitivity reactions to the COVID-19 vaccine.

Methods

Participants were referred to the McGill University Health Center (MUHC) Allergy-Immunology department for clinical evaluation following a reported reaction to their first dose of Moderna® mRNA-1273 or Pfizer-BioNTech® BNT162b2 vaccines. They underwent skin prick testing (SPT) with higher and lower molecular weight (MW) PEG and polysorbate 80, as per published protocols. Their second dose was administered following a desensitization protocol consisting of multiple dose-administration steps followed by a 60-min observation period.

Results

Among a cohort of 142 patients with an increased risk for allergic reactions to the COVID-19 vaccines, six individuals were selected to undergo desensitization. All were female with allergic background including chronic spontaneous urticaria, anaphylaxis to medications, and/or vaccines. The main symptom after their first dose was difficulty swallowing with lightheadedness or immediate urticaria, angioedema, and/or dizziness. Two patients had positive skin testing. One patient was on chronic antihistamines which resulted in an inconclusive PEG skin test and the skin testing was negative for the three other patients. During the desensitization, two patients reported cutaneous symptoms of an immediate reaction and were managed with antihistamines. One of these patients also complained of ear pressure and had a drop in her systolic blood pressure, treated with intravenous fluids.

Conclusion

This study suggests that some individuals with an immediate-type hypersensitivity reaction to their first dose of mRNA COVID-19 vaccine may safely receive their second dose using a desensitization protocol. The success of this desensitization protocol is a step forward in the fight against COVID-19, allowing more individuals to be immunized.

EAACI guidelines: Anaphylaxis (2021 update)

Anaphylaxis is a clinical emergency which all healthcare professionals need to be able to recognize and manage. The European Academy of Allergy and Clinical Immunology Anaphylaxis multidisciplinary Task Force has updated the 2014 guideline. The guideline was developed using the AGREE II framework and the GRADE approach. The evidence was systematically reviewed and recommendations were created by weighing up benefits and harms. The guideline was peer-reviewed by external experts and reviewed in a public consultation. The use of clinical criteria to identify anaphylaxis is suggested with blood sampling for the later measurement of tryptase. The prompt use of intramuscular adrenaline as first-line management is recommended with the availability of adrenaline autoinjectors to patients in the community. Pharmacokinetic data should be provided for adrenaline autoinjector devices. Structured, comprehensive training for people at risk of anaphylaxis is recommended. Simulation training and visual prompts for healthcare professionals are suggested to improve the management of anaphylaxis. It is suggested that school policies reflect anaphylaxis guidelines. The evidence for the management of anaphylaxis remains mostly at a very low level. There is an urgent need to prioritize clinical trials with the potential to improve the management of patients at risk of anaphylaxis.

Allergy to polyethylene glycol and polysorbates in a patient cohort: Diagnostic work-up and decision points for vaccination during the COVID-19 pandemic

BACKGROUND

During the COVID-19 pandemic focus has been on polyethylene glycol (PEG) and polysorbate as these excipients are constituents in the first vaccines and possible elicitors of allergic reactions to the vaccines. We aimed to evaluate the possibility of vaccinating patients with PEG and/or polysorbate allergy against COVID-19.

METHODS

Twenty-five patients with a history of an allergic reaction to drugs, vaccines and mouth hygiene products containing PEG or polysorbate and sensitization (skin test or in vitro test) or a positive challenge were included. We re-evaluated 19 of 21 patients diagnosed before 2021 and four new patients by skin prick tests (SPT) and Basophil Histamine Release (BaHR) for PEGs, polysorbates and approved COVID-19 vaccines as well as measurement of specific IgE (PEG 2000, 10,000). Patients were offered vaccination based on decision points from the primary diagnosis and re-evaluation.

RESULTS

Most common primary elicitors were depot-steroids and laxatives. Most patients had experienced more than one reaction. SPT was superior to BaHR test although many SPTs became negative over time. After careful re-evaluation three patients were successfully vaccinated with the Pfizer/BioNTech vaccine. Three were vaccinated before referral. Eleven were offered the Johnson-Johnson vaccine; four were vaccinated successfully, seven abstained. Six patients could not be vaccinated with PEG or polysorbate containing vaccines.

CONCLUSION

Hypersensitivity to excipients in COVID-19 vaccines constitutes a risk to patients with allergy to PEG or polysorbates. After diagnostic evaluation, a safe COVID-19 vaccine could be offered to most patients, the remainders will await new vaccines containing different excipients.

Optimizing investigation of suspected allergy to polyethylene glycols

BACKGROUND

Polyethylene glycols (PEGs) are polymers of varying molecular weight (MW) used widely as excipients in drugs and other products, including the mRNA vaccines against coronavirus disease 2019. Allergy to PEGs is rare. Skin testing and graded challenge carries a high risk of inducing systemic reactions.

OBJECTIVE

We evaluated skin prick test (SPT) results and in vitro reactivity over time to different MW PEGs and assessed cross-sensitization patterns in PEG allergy.

METHODS

Ten patients with previously diagnosed PEG allergy underwent SPT twice with PEGs 26 months apart. Lower MW (PEG 300, 3000, 6000) were tested, followed by PEG 20,000, in stepwise, increasing concentrations. Cross-sensitization to polysorbate 80 and poloxamer 407 was assessed. SPT was performed in 16 healthy controls. In vitro basophil histamine release (HR) test and passive sensitization HR test were performed in patients and controls.

RESULTS

Patients previously testing positive on SPT to PEG 3000 and/or 6000 also tested positive to PEG 20,000. Patients with a longer interval since diagnosis tested negative to lower MW PEGs and positive mainly to higher concentrations of PEG 20,000. Three patients developed systemic urticaria during SPT. Eight patients showed cross-sensitization to poloxamer 407 and 3 to polysorbate 80. All controls tested negative. In vitro tests showed limited usefulness.

CONCLUSIONS

Skin test reactivity to PEG can decrease over time, but titrated SPT with increasing concentrations of PEG 20,000 can be diagnostic when lower MW PEGs test negative. To avoid systemic reactions, stepwise SPT is mandatory.

Diagnosing, managing and preventing anaphylaxis: Systematic review

BACKGROUND

This systematic review used the GRADE approach to compile evidence to inform the European Academy of Allergy and Clinical Immunology's (EAACI) anaphylaxis guideline.

METHODS

We searched five bibliographic databases from 1946 to 20 April 2020 for studies about the diagnosis, management and prevention of anaphylaxis. We included 50 studies with 18 449 participants: 29 randomized controlled trials, seven controlled clinical trials, seven consecutive case series and seven case-control studies. Findings were summarized narratively because studies were too heterogeneous to conduct meta-analysis.

RESULTS

It is unclear whether the NIAID/FAAN criteria or Brighton case definition are valid for immediately diagnosing anaphylaxis due to the very low certainty of evidence. There was also insufficient evidence about the impact of most anaphylaxis management and prevention strategies. Adrenaline is regularly used for first-line emergency management of anaphylaxis but little robust research has assessed its effectiveness. Newer models of adrenaline autoinjectors may slightly increase the proportion of people correctly using the devices and reduce time to administration. Face-to-face training for laypeople may slightly improve anaphylaxis knowledge and competence in using autoinjectors. We searched for but found little or no comparative effectiveness evidence about strategies such as fluid replacement, oxygen, glucocorticosteroids, methylxanthines, bronchodilators, management plans, food labels, drug labels and similar.

CONCLUSIONS

Anaphylaxis is a potentially life-threatening condition but, due to practical and ethical challenges, there is a paucity of robust evidence about how to diagnose and manage it.

[Anaphylaxis in children and adults]

In this review, we discuss anaphylaxis, which is a severe allergic condition with potentially life-threatening symptoms from airways or circulation and often associated with skin symptoms. First-line treatment is intramuscular adrenaline given by autoinjector for rapid administration. Initial dose for children less than 25 kg is 0.15 mg and for children ≥ 25 kg and adults 0.3 mg. Repeated smaller doses of adrenaline is to be preferred. Patients with severe anaphylaxis will need an IV access for fluid replacement and supplementary oxygen. Antihistamines and steroids are only second-line treatment after adrenaline administration.

[Work-up of penicillin allergy]

Up to 10% of hospitalised patients are registered as penicillin allergic. However, 80-90% will tolerate penicillin after evaluation. New Danish guidelines suggest criteria for evaluation of patients based on risk stratification according to the severity of the index reaction. The allergy label can be removed immediately, if allergy can be ruled out using the criteria presented in this review, but all other patients should be referred for evaluation in a specialist allergy department. Specific IgE measurement should only be done in adult patients with an immediate reaction (onset less-than 2 h after intake of a tablet) or urticaria.

Intradermal Tests With Drugs: An Approach to Standardization

Background: Intradermal tests (IDTs) are performed and interpreted differently in drug allergy centers making valid comparison of results difficult.

Objective: To reduce method-related and intercenter variability of IDTs by the introduction of a standardized method.

Materials and methods: In 11 centers of the European Network for Drug Allergy, IDTs were prospectively performed with saline and with amoxicillin (20 mg/ml) using (1) the local method and (2) the standardized European Network in Drug Allergy (ENDA) method (0.02 ml). The diameters of the initial injection wheal (Wi) for the different volumes and sites injected obtained from each center were analyzed.

Results: The most reproducible method was to fill a syringe with test solution, then expel the excess fluid to obtain exactly 0.02 ml. The median Wi diameter with 0.02 ml injection using the standardized method was 5 mm [range 2–10 mm; interquartile range (IQR) 5–5 mm; n = 1,096] for saline and 5 mm (range 2–9 mm; IQR = 4.5–5 mm; n = 240) for amoxicillin. IDT injection sites did not affect the Wi diameter. Training improved precision and reduced the variability of Wi diameters.

Conclusion: Using the standardized IDT method described in this multicenter study helped to reduce variability, enabling more reliable comparison of results between individuals and centers.

Perioperative anaphylaxis in children: Etiology, time sequence, and patterns of clinical reactivity

BACKGROUND

Perioperative anaphylaxis (PA) in children is an uncommon but potentially life-threatening complication associated with anesthesia. Early identification and management of PA is essential to optimize clinical outcomes.

METHODS

We performed a retrospective study of anesthesia records from pediatric patients with PA from centers in the United Kingdom, France, and the United States over a period of 10 years. Time sequence of clinical signs and physiological variables during PA were collected, along with results of allergy testing.

RESULTS

Twenty-nine children with PA were included. Median age was 11 years. Based on the modified Ring and Messmer Grading Scale, severe reactions were seen in 25 (86%) members of this cohort, with 4 (14%) experiencing cardiac arrest. Life-threatening hypotension was the first clinical sign of PA in 59% of cases, followed by tachycardia and bronchospasm. In 16 (55%) cases, the initial signs of PA involved multiple organ systems. When the initial signs of PA were cardiovascular and/or respiratory, more epinephrine doses were administered. Average time from initial sign of PA to treatment with epinephrine was 6 minutes (SD: 6, range: 1-25). The causative allergen was identified in 15 patients.

CONCLUSION

Severe hypotension is the most common presenting sign of PA in children. Initial cardiovascular and/or respiratory signs are associated with the need for increased epinephrine doses. Further studies should optimize the prediction, identification, and early management of PA in children.

An EAACI position paper on the investigation of perioperative immediate hypersensitivity reactions

Perioperative immediate hypersensitivity reactions are rare. Subsequent allergy investigation is complicated by multiple simultaneous drug exposures, the use of drugs with potent effects and the many differential diagnoses to hypersensitivity in the perioperative setting. The approach to the investigation of these complex reactions is not standardized, and it is becoming increasingly apparent that collaboration between experts in the field of allergy/immunology/dermatology and anaesthesiology is needed to provide the best possible care for these patients. The EAACI task force behind this position paper has therefore combined the expertise of allergists, immunologists and anaesthesiologists. The aims of this position paper were to provide recommendations for the investigation of immediate-type perioperative hypersensitivity reactions and to provide practical information that can assist clinicians in planning and carrying out investigations.

A EAACI drug allergy interest group survey on how European allergy specialists deal with β-lactam allergy

An accurate diagnosis of β-lactam (BL) allergy can reduce patient morbidity and mortality. Our aim was to investigate the availability of BL reagents, their use and test procedures in different parts of Europe, as well as any differences in the diagnostic workups for evaluating subjects with BL hypersensitivity. A survey was emailed to all members of the EAACI Drug Allergy Interest Group (DAIG) between February and April 2016, and the questionnaire was meant to study the management of suspected BL hypersensitivity. The questionnaire was emailed to 82 DAIG centres and answered by 57. Amoxicillin alone or combined to clavulanic acid were the most commonly involved BL except in the Danish centre, where penicillin V was the most frequently suspected BL. All centres performed an allergy workup in subjects with histories of hypersensitivity to BL: 53 centres (93%) followed DAIG guidelines, two national guidelines and two local guidelines. However, there were deviations from DAIG recommendations concerning allergy tests, especially drug provocation tests. A significant heterogeneity exists in current practice not only among countries, but also among centres within the same country. This suggests the need to re-evaluate, update and standardize protocols on the management of patients with suspected BL allergy.

Chlorhexidine Allergy: On the Rise and Often Overlooked

PURPOSE OF REVIEW

In recent years, the risk of allergy to chlorhexidine is increasingly recognised. In this review, we discuss why the allergy is so easily overlooked and point out several preventative initiatives that can minimise the risk of both chlorhexidine sensitisation and allergy development and accidental re-exposure in patients with chlorhexidine allergy. Testing for chlorhexidine allergy is also discussed.

RECENT FINDINGS

Numerous reports have been published from many different specialties. Symptoms range from mild skin symptoms to life-threatening anaphylaxis. Testing for chlorhexidine allergy is based on skin testing and in vitro testing. Recently, it was found that both skin prick testing and specific IgE have high sensitivities and specificities. This review gives an overview of chlorhexidine allergy with a special focus on preventative initiatives and testing.

Chlorhexidine Allergy: Mild Allergic Reactions Can Precede Anaphylaxis in the Healthcare Setting

Chlorhexidine can cause severe immediate-type allergic reactions such as urticaria, anaphylactic shock or, even, cardiac arrest. We report the case of a patient who developed perioperative anaphylactic shock caused by chlorhexidine 1 year after a postoperative urticarial reaction, which was assumed not to be significant at the time. This case highlights the importance of identifying mild allergy symptoms after exposure to chlorhexidine at the pre-anaesthetic assessment to prevent more severe allergic reactions in future.

Management of a surgical patient with a label of penicillin allergy: narrative review and consensus recommendations

Unsubstantiated penicillin-allergy labels are common in surgical patients, and can lead to significant harm through avoidance of best first-line prophylaxis of surgical site infections and increased infection with resistant bacterial strains. Up to 98% of penicillin-allergy labels are incorrect when tested. Because of the scarcity of trained allergists in all healthcare systems, only a minority of surgical patients have the opportunity to undergo testing and de-labelling before surgery. Testing pathways can be modified and shortened in selected patients. A variety of healthcare professionals can, with appropriate training and in collaboration with allergists, provide testing for selected patients. We review how patients might be assessed, the appropriate testing strategies that can be used, and the minimum standards of safe testing.

Immediate-type hypersensitivity to polyethylene glycols: a review

Polyethylene glycols (PEGs) or macrogols are polyether compounds widely used in medical and household products. Although generally considered biologically inert, cases of mild to life-threatening immediate-type PEG hypersensitivity are reported with increasing frequency. Nevertheless, awareness of PEG's allergenic potential remains low, due to a general lack of suspicion towards excipients and insufficient product labelling. Information on immediate-type reactions to PEG is limited to anecdotal reports, and the potential for PEG sensitization and cross-sensitization to PEGylated drugs and structurally related derivatives is likely underestimated. Most healthcare professionals have no knowledge of PEG and thus do not suspect PEG's as culprit agents in hypersensitivity reactions. In consequence, patients are at risk of misdiagnosis and commonly present with a history of repeated, severe reactions to a range of unrelated products in hospital and at home. Increased awareness of PEG prevalence, PEG hypersensitivity, and improved access to PEG allergy testing, should facilitate earlier diagnosis and reduce the risk of inadvertent re-exposure. This first comprehensive review provides practical information for allergists and other healthcare professionals by describing the clinical picture of 37 reported cases of PEG hypersensitivity since 1977, summarizing instances where PEG hypersensitivity should be considered and proposing an algorithm for diagnostic management.

Endothelial Regulator of Calcineurin 1 Promotes Barrier Integrity and Modulates Histamine-Induced Barrier Dysfunction in Anaphylaxis

Anaphylaxis, the most serious and life-threatening allergic reaction, produces the release of inflammatory mediators by mast cells and basophils. Regulator of calcineurin 1 (Rcan1) is a negative regulator of mast-cell degranulation. The action of mediators leads to vasodilation and an increase in vascular permeability, causing great loss of intravascular volume in a short time. Nevertheless, the molecular basis remains unexplored on the vascular level. We investigated Rcan1 expression induced by histamine, platelet-activating factor (PAF), and epinephrine in primary human vein (HV)-/artery (HA)-derived endothelial cells (ECs) and human dermal microvascular ECs (HMVEC-D). Vascular permeability was analyzed in vitro in human ECs with forced Rcan1 expression using Transwell migration assays and in vivo using Rcan1 knockout mice. Histamine, but neither PAF nor epinephrine, induced Rcan1-4 mRNA and protein expression in primary HV-ECs, HA-ECs, and HMVEC-D through histamine receptor 1 (H1R). These effects were prevented by pharmacological inhibition of calcineurin with cyclosporine A. Moreover, intravenous histamine administration increased Rcan1 expression in lung tissues of mice undergoing experimental anaphylaxis. Functional in vitro assays showed that overexpression of Rcan1 promotes barrier integrity, suggesting a role played by this molecule in vascular permeability. Consistent with these findings, in vivo models of subcutaneous and intravenous histamine-mediated fluid extravasation showed increased response in skin, aorta, and lungs of Rcan1-deficient mice compared with wild-type animals. These findings reveal that endothelial Rcan1 is synthesized in response to histamine through a calcineurin-sensitive pathway and may reduce barrier breakdown, thus contributing to the strengthening of the endothelium and resistance to anaphylaxis. These new insights underscore its potential role as a regulator of sensitivity to anaphylaxis in humans.

Beyond IgE-When Do IgE-Crosslinking and Effector Cell Activation Lead to Clinical Anaphylaxis?

Anaphylaxis in humans is inherently difficult to study due to the acuteness of symptoms and the lack of biomarkers serving as risk predictors. Most cases are related to IgE sensitizations to foods, insect venoms, and drugs with mastocytosis patients forming a smaller risk group. However, identifying the relatively small fraction of persons at risk has been exceedingly difficult. In this review, we propose to describe anaphylaxis in a broader context than defined by IgE sensitization alone. Exposure to a trigger, such as an allergen, may lead to anaphylaxis, but in particular, the internal dose sensed by the immune system needs to be established. Moreover, intrinsic patient factors as well as the specific circumstances of the exposure, i.e., the extrinsic factors, need to be thoroughly accounted for. More controversially, other triggers of anaphylaxis, such as increased sensitivity to or reduced catabolism of histamine (“histamine intolerance”) or mast cell activation syndrome also named mast cell activation disorder have been suggested, but still with very limited epidemiological evidence that a significant proportion of the observed reactions are caused by these alleged conditions. Thus, when all conditions are considered, it seems as if IgE-mediated reactions are responsible for the vast majority of anaphylactic conditions.

Anaphylaxis after disinfection with 2% chlorhexidine wand applicator

A 54-year-old man with end-stage renal failure attended for dialysis. Within seconds of applying 2% w/v chlorhexidine (ChloraPrep 3 mL Wand Applicator) to the skin surrounding the insertion point of his dialysis catheter (Tesio catheter), he developed pruritus, urticaria, shortness of breath, hypotension and reduced responsiveness. Treatment for anaphylaxis was initiated with rapid improvement of his symptoms, and he made a full recovery. Allergy to chlorhexidine was confirmed with skin testing, and the patient was warned against all future exposure to chlorhexidine. Subsequent dialysis without chlorhexidine was uneventful.

Mast Cells and Anaphylaxis

For half a century, it has been known that the mast cell is the cell responsible for the majority of anaphylactic events. Its mediators, taken as a whole, are capable of producing all of the clinical manifestations of these events. With the discovery of immunoglobulin E (IgE), it was originally felt that the vast majority of anaphylactic episodes were due to antigen coupling with two cell-bound IgE molecules. More recently it has been learned that many episodes are produced by direct activation of mast cells, not involving antigen binding to IgE, and that monomeric IgE under certain conditions can also cause degranulation. Of note--in regard to antigen independent degranulation--are recent reports that the human G-protein-coupled receptor, MRGPRX2, may be the receptor for many drugs and cationic proteins capable of producing direct mast cell degranulation and anaphylactic events.

Differences in hospital attendance for anaphylaxis between immigrants and non-immigrants: a cohort study

BACKGROUND

The impact of migration on the risk of anaphylaxis remains unknown. We hypothesized that non-Western immigrants have a lower incidence of anaphylaxis compared to Danish-born. We investigated variations in hospital attendance for anaphylaxis between immigrants and Danish-born including time- and age- trends.

METHODS

A register-based, historical prospective cohort design. Refugees or family reunified immigrants (n = 127 250) who, between January 1, 1994 and December 31, 2010, obtained residency permits in Denmark were included and matched in a 1 : 6 ratio on age and sex with Danish-born individuals (n = 740 600). Personal identification numbers were cross-linked to the Danish National Patient Registry identifying all first-time hospital attendances for anaphylaxis from January 1, 1994 and December 31, 2010. Incidence rate ratios were estimated, stratified for sex and region of birth, adjusting for age using a Cox regression model including the influence of duration of residence and age when residence was obtained.

RESULTS

In total 1053 hospital attendances for anaphylaxis were identified: 89 among non-Western immigrants, 9 among Western immigrants and 955 among Danish-born patients. Both male (RR = 0.65; 95%CI: 0.46;0.90) and female (RR = 0.64; 95%CI: 0.48;0.85) non-Western immigrants had a significantly lower risk ratio of hospital attendance for anaphylaxis compared to Danish-born. Compared to Danish-born, non-Western immigrants living in Denmark during the entire follow-up period also showed a decreased risk (RR = 0.65; 95%CI: 0.34;1.25). Compared to Danish-born, non-Western immigrants who obtained residence permission as children had a decreased risk of hospital attendance for anaphylaxis (RR = 0.48; 95%CI: 0.25;0.91).

CONCLUSION

This Danish register-based study using nationwide data revealed fewer hospital attendances for anaphylaxis among non-Western immigrants compared to Danish-born; however this protection was lost over time.

Dynamics of plasma levels of specific IgE in chlorhexidine allergic patients with and without accidental re-exposure

BACKGROUND

Chlorhexidine is an effective disinfectant, which may cause severe allergic reactions. Plasma level of specific IgE to chlorhexidine (ImmunoCAP(®) ) has high estimated sensitivity and specificity when measured within 6 months of allergic reaction, but knowledge of the dynamics over longer time periods is lacking and it is unknown whether levels fall below <0.35 kUA/L in patients with previously elevated levels. It is also unclear whether re-exposure influences levels of specific IgE.

OBJECTIVE

To investigate the dynamics of specific IgE in chlorhexidine allergic patients with and without re-exposure.

METHODS

All patients diagnosed with chlorhexidine allergy in the Danish Anaesthesia Allergy Centre January 1999 to March 2015 were invited to participate. The study included blood samples from the time of reaction and time of investigation and blood samples drawn prospectively over several years.

RESULTS

Overall, 23 patients were included. Specific IgE within hours of reaction was available in eight patients and was >0.35 kUA/L in six of these. During allergy investigations, usually 2-4 months later, specific IgE was >0.35 kUA/L in 22 of 23 patients. In the following months/years specific IgE declined <0.35 kUA/L in 17 of 23 patients (most rapidly within 4 months). Nine re-exposures in the healthcare setting were reported by seven patients (35%). Most re-exposures caused symptoms and were followed by an increase in specific IgE. Two patients with specific IgE <0.35 kUA/L reacted upon re-exposure.

CONCLUSIONS & CLINICAL RELEVANCE

Time from reaction should be considered when interpreting specific IgE results. Specific IgE is >0.35 kUA/L in most patients at time of reaction but should be repeated after a few weeks/months if negative. The optimal sampling time seems to be >1 month and <4 months. A value <0.35 kUA/L neither excludes allergy nor implies loss of reactivity in previously sensitized patients. Re-exposures are common, often iatrogenic, and can cause a rebound in specific IgE.

No evidence for contraindications to the use of propofol in adults allergic to egg, soy or peanut†

BACKGROUND

Propofol is thought to be a potential cause of allergic reactions in patients allergic to egg, soy or peanut, since current formulations contain an emulsion that includes egg lecithin and soybean oil. However, other than six case reports lacking in confirmatory evidence of an allergic reaction, there is no evidence linking the two types of allergies. The aim of this study was to examine the frequency of propofol allergy and to investigate if patients with specific immunoglobulin E (IgE) to egg, soy or peanut tolerated propofol.

METHODS

Study A examined the frequency of propofol allergy in 273 patients systematically investigated for suspected perioperative allergic reactions. Of these, 153 had been exposed to propofol and underwent skin tests and intravenous provocation. Study B retrospectively investigated propofol exposure and tolerance in 520 adult patients with a positive specific IgE to egg, soy or peanut.

RESULTS

Four of the 153 propofol-exposed patients (2.6%) investigated in study A were diagnosed with propofol allergy. Of these, three tested positive only on intravenous provocation. None of the four had allergic symptoms when eating egg, soy or peanut and none had detectable levels of specific IgE to egg or soy in their serum. In study B we found no signs of allergic reactions towards propofol in 171 retrieved anaesthetic charts from 99 patients with specific IgE to egg, soy or peanut.

CONCLUSION

No connection between allergy to propofol and allergy to egg, soy or peanut was found. The present practice of choosing alternatives to propofol in patients with this kind of food allergy is not evidence based and should be reconsidered.

Clinical and diagnostic features of perioperative hypersensitivity to cefuroxime

INTRODUCTION

The Danish Anaesthesia Allergy Centre (DAAC) investigated 89 adult patients with suspected perioperative cefuroxime-associated hypersensitivity reactions between 2004 and 2013. The goals were to determine whether the time to index reaction after cefuroxime exposure could be used to implicate cefuroxime as the cause of the reactions and explore different test modalities in diagnosing cefuroxime hypersensitivity.

METHOD

Skin tests, in vitro tests, and titrated provocations were used to determine cefuroxime hypersensitivity. Patients were deemed cefuroxime positive on the basis of at least two positive tests and/or a positive provocation.

RESULTS

One or more tests were positive for cefuroxime in 24 of 89 (27.0%) patients. One was only specific IgE positive and was deemed cefuroxime negative. Twenty-three (25.8%) were deemed cefuroxime positive. There were four specific IgE-, 4 histamine release test-, 13 skin test-, and 14 provocation positive patients. There were eight (34.8%) patients who were only provocation positive. Data on time to index reaction after cefuroxime exposure were available for 80 patients (22 in the positive group and 58 in the negative group), 22 of 22 (100%) of positive patients reacted in <15 min vs. only 38 of 58 (65.5%) of negative patients.

CONCLUSION

All patients with confirmed hypersensitivity to cefuroxime reacted within 15 min of administration, but so did 65.5% of Cefuroxime negative patients, making timing of administration an unreliable predictor of causation in the perioperative setting. Provocations were always positive when carried out in skin test positive patients; however, eight patients had positive provocations only, highlighting the need for provocation in skin test negative patients.

[Anaphylactic shock after intradermal injection of corticosteroid]

Carboxymethylcellulose (CMC) is a derivative of cellulose found in many food products, pharmaceuticals and cosmetics. Allergy to CMC in parenteral corticosteroid preparations leading to anaphylaxis is rare, but has previously been reported. We report a case of a 52-year-old woman with prurigo nodularis of Hyde, who reacted with anaphylaxis after intradermal injection of Kenalog 40 mg/ml. Allergy testing showed a positive skin prick test for CMC and the patient was advised to avoid future parenteral exposure to CMC. This case highlights the need to examine excipients in severe cases of drug allergy.

[Anaphylaxis]

Anaphylaxis is a potentially life-threatening systemic allergic reaction involving several organ systems. Recognition of the reaction leading to prompt treatment is essential for a good outcome. The lifesaving treatment is intramuscular injection of adrenaline (0.3-0.5 mg for adults and children > 40 kg, 0.3 mg for children 20-40 kg and 0.15 mg for infants < 20 kg). The patient must be placed on the back with elevated lower extremities to improve cerebral and cardiac circulation. High dose oxygen and crystalloid fluid load are needed to improve oxygenation and cardiac output.

Transfusion-associated anaphylaxis during anaesthesia and surgery--a retrospective study

BACKGROUND AND OBJECTIVES

Transfusion-associated anaphylaxis (TAA) is a severe adverse reaction reported to occur in 1:9000-90,000 transfusions. According to the Danish Registration of Transfusion Risks (DART), the frequency is 1:300,000 transfusions, which suggests insufficient reporting of TAA in Denmark. Our aims were to identify possible cases of TAA, to characterize their symptoms and tryptase levels and to investigate the reporting of TAA to the haemovigilance systems.

MATERIAL AND METHODS

We reviewed 245 patients with suspected allergic reactions during anaesthesia and surgery, investigated at the Danish Anaesthesia Allergy Centre (DAAC). Based on the outcome of this investigation, the patients were classified as DAAC positive (confirmed hypersensitivity to identified agent, n = 112), or DAAC negative (no confirmed hypersensitivity, n = 133). Data on case history, details of blood transfusion and results of laboratory and clinical investigations were collected. TAA cases were identified according to the recommendations of the International Society of Blood Transfusion (ISBT).

RESULTS

Ten possible TAA cases (30% of all transfused patients) were identified, all DAAC negative. The frequency of elevated serum tryptase, hypotension and male sex was significantly higher among these cases compared with the remaining DAAC negative (P < 0·05), but not different from the DAAC-positive patients. One case had been reported to the Blood Bank haemovigilance system and none to DART.

CONCLUSION

We identified unreported cases of possible TAA, which resembled the DAAC-positive patients with respect to elevated tryptase and symptoms. By applying the ISBT criteria of adverse transfusion reactions, we conclude that TAA during anaesthesia and surgery is likely to be underreported in Denmark.

[Pulmonary oedema subsequent to radiographic contrast in a computed tomography of the coronary arteries]

Adverse reactions to radiographic contrast media are relatively rare and occur with a frequency of 0.02-0.04%. We describe a case of isolated pulmonary oedema after computed tomography of the coronary arteries in a 51 year-old man. Initially anaphylaxis was suspected, but due to the clinical picture together with lack of response to treatment with adrenaline and lack of increase in the serum tryptase concentration an IgE mediated mechanism was less likely. The patient responded to non-invasive ventilation over three days. The mechanism behind the reaction is unknown.

[Suspected allergic reaction during anesthesia requires thorough postoperative investigation]

Allergic reactions during anaesthesia are rare and the cause is seldom immediately obvious. Incorrect guesses for the offending substance can lead to suboptimal management. Furthermore there is a risk of a serious reaction on subsequent exposure to the real allergen. We present a case of suspected allergy to fentanyl investigated at the Danish Anaesthesia Allergy Centre. Allergy to this drug could not be demonstrated by skin tests or challenge. The reaction was due to unspecific histamine release induced by several opioids given at the same time. Future pretreatment with antihistamine was recommended.

National pholcodine consumption and prevalence of IgE-sensitization: a multicentre study

BACKGROUND

The aim of this study was to test, on a multinational level, the pholcodine (PHO) hypothesis, i.e. that the consumption of PHO-containing cough mixtures could cause higher prevalence of IgE antibodies to PHO, morphine (MOR) and suxamethonium (SUX). As a consequence the risk of anaphylaxis to neuromuscular blocking agents (NMBA) will be increased.

METHODS

National PHO consumptions were derived from the United Nations International Narcotics Control Board (INCB) database. IgE and IgE antibodies to PHO, MOR, SUX and P-aminophenyl-phosphoryl choline (PAPPC) were measured in sera from atopic individuals, defined by a positive Phadiatop test (>0.35 kU(A)/l), collected in nine countries representing high and low PHO-consuming nations.

RESULTS

There was a significant positive association between PHO consumption and prevalences of IgE-sensitization to PHO and MOR, but not to SUX and PAPPC, as calculated both by exposure group comparisons and linear regression analysis. The Netherlands and the USA, did not have PHO-containing drugs on the markets, although the former had a considerable PHO consumption. Both countries had high figures of IgE-sensitization.

CONCLUSION

This international prevalence study lends additional support to the PHO hypothesis and, consequently, that continued use of drugs containing this substance should be seriously questioned. The results also indicate that other, yet unknown, substances may lead to IgE-sensitization towards NMBAs.

IgE-mediated chlorhexidine allergy: a new occupational hazard?

BACKGROUND

Chlorhexidine is an effective antimicrobial agent commonly used in UK hospitals, primarily for skin decontamination. Recent UK infection control guidelines recommend the use of 2% chlorhexidine solution in specific clinical settings, thus increasing chlorhexidine use by health care workers (HCWs). Chlorhexidine has been widely reported to cause IgE-mediated allergic reactions (from urticaria and angioedema to anaphylaxis) among patients undergoing surgery/invasive procedures. Despite its widespread use in health care settings, there are no reports of clinically confirmed occupational IgE-mediated chlorhexidine allergy.

AIMS

To identify cases of chlorhexidine allergy among health care workers.

METHODS

A questionnaire was distributed among HCWs in wards and operating theatres at a UK district general hospital to raise awareness of potential chlorhexidine allergy and to invite those with possible clinical allergy to come forward for further testing. Diagnosis was based on an appropriate clinical history with positive serum-specific IgE to chlorhexidine and/or positive skin prick testing.

RESULTS

Four cases of occupational IgE-mediated allergy to chlorhexidine were identified.

CONCLUSIONS

Despite its excellent antimicrobial properties, chlorhexidine is an occupational allergen. We suggest that chlorhexidine allergy be included in the differential diagnosis of HCWs presenting with work-related allergic symptoms. Increased awareness and easier access to chlorhexidine-specific IgE serological testing should facilitate early diagnosis of affected HCWs, allowing appropriate avoidance measures to be instigated--thus reducing the risk of potentially severe allergic reactions in the future.

The undesirable effects of neuromuscular blocking drugs

Neuromuscular blocking drugs are designed to bind to the nicotinic receptor at the neuromuscular junction. However, they also interact with other acetylcholine receptors in the body. Binding to these receptors causes adverse effects that vary with the specificity for the cholinergic receptor in question. Moreover, all neuromuscular blocking drugs may cause hypersensitivity reactions. Often the symptoms are mild and self-limiting but massive histamine release can cause systematic reactions with circulatory and respiratory symptoms and signs. At the end of anaesthesia, no residual effect of a neuromuscular blocking drug should be present. However, the huge variability in response to neuromuscular blocking drugs makes it impossible to predict which patient will suffer postoperative residual curarization. This article discusses the undesirable effects of the currently available neuromuscular blocking drugs including the definitions, diagnosis and causes of hypersensitivity reactions and postoperative residual curarisation.

IgE-mediated allergy to chlorhexidine

BACKGROUND

Investigations at the Danish Anesthesia Allergy Centre have included testing for allergy to chlorhexidine since 1999.

OBJECTIVE

To investigate whether measurement of IgE and histamine release confirm an IgE-mediated mechanism for chlorhexidine allergy.

METHODS

Twenty-two patients with clinical history suggestive of chlorhexidine allergy were included. Skin tests with chlorhexidine and tryptase measurements were performed during initial investigations. Sera were analyzed retrospectively for IgE and histamine release (passive sensitization) to chlorhexidine.

RESULTS

Twelve patients were skin test positive and 10 were skin test negative. Of the skin test-positive patients, 11 of 12 had IgE to chlorhexidine and 7 of 11 had a positive histamine release test. None of the skin test-negative patients had specific IgE or positive histamine release to chlorhexidine. Skin test-positive patients had higher median age (64 vs 49 y) and were mainly male (11/12 vs 6/10). In both groups, 8 patients had hypotension, but bronchospasm mainly appeared in skin test-negative patients (1/12 vs 6/10). Reactions occurred more often during urologic surgery in skin test-positive patients (5/12 vs 0/10). Baseline tryptase was higher in skin test-positive patients (median, 11.5 vs 3.7 microg/L), and 6 of 7 patients had elevated IgE to chlorhexidine in serum at the time of reaction.

CONCLUSION

This study confirms that chlorhexidine allergy is IgE-mediated and that measurement of specific IgE and histamine release are good adjuncts to skin testing in patients with clinical history suggesting chlorhexidine allergy.

CLINICAL IMPLICATIONS

IgE and histamine release can be used to support the diagnosis of allergy to chlorhexidine.

Scandinavian Clinical Practice Guidelines on the diagnosis, management and follow-up of anaphylaxis during anaesthesia

The present approach to the diagnosis, management and follow-up of anaphylaxis during anaesthesia varies in the Scandinavian countries. The main purpose of these Scandinavian Clinical Practice Guidelines is to increase the awareness about anaphylaxis during anaesthesia amongst anaesthesiologists. It is hoped that increased focus on the subject will lead to prompt diagnosis, rapid and correct treatment, and standardised management of patients with anaphylactic reactions during anaesthesia across Scandinavia. The recommendations are based on the best available evidence in the literature, which, owing to the rare and unforeseeable nature of anaphylaxis, mainly includes case series and expert opinion (grade of evidence IV and V). These guidelines include an overview of the epidemiology of anaphylactic reactions during anaesthesia. A treatment algorithm is suggested, with emphasis on the incremental titration of adrenaline (epinephrine) and fluid therapy as first-line treatment. Recommendations for primary and secondary follow-up are given, bearing in mind that there are variations in geography and resources in the different countries. A list of National Centres from which anaesthesiologists can seek advice concerning follow-up procedures is provided. In addition, an algorithm is included with advice on how to manage patients with previous suspected anaphylaxis during anaesthesia. Lastly, Appendix 2 provides an overview of the incidence, mechanisms and possibilities for follow-up for some common drug groups.

Allergic reactions in anaesthesia: are suspected causes confirmed on subsequent testing?

BACKGROUND

The aim of this retrospective survey of possible allergic reactions during anaesthesia was to investigate whether the cause suspected by anaesthetists involved corresponded with the cause found on subsequent investigation in the Danish Anaesthesia Allergy Centre (DAAC).

METHODS

Case notes and anaesthetic charts from 111 reactions in 107 patients investigated in the DAAC were scrutinized for either suspicions of or warnings against specific substances stated to be the cause of the supposed allergic reaction.

RESULTS

In 67 cases, one or more substances were suspected. In 49 of these (73%) the suspected cause did not match the results of subsequent investigation, either a different substance being the cause or no cause being found. Only five cases (7%) showed a complete match between suspected cause and investigation result. In the remaining 13 cases (19%) there was a partial match, the right substance being suspected, but investigations showed an additional allergen or several substances, including the right substance being suspected.

CONCLUSIONS

An informed guess is not a reliable way of determining the cause of a supposed allergic reaction during anaesthesia and may put a significant number of patients at unnecessary risk. Some patients may be labelled with a wrong allergy, leading to unnecessary warnings against harmless substances, and some patients may be put at risk of subsequent re-exposure to the real allergen. Patients with suspected allergic reactions during anaesthesia should be referred for investigation in specialist centres whenever possible.