Do Corticosteroids Prevent Biphasic Anaphylaxis?

Very rare adverse reactions to intravascular contrast media: From Kounis to sweet syndrome

Intravascular administration of contrast media may inadvertently result in adverse drug reactions (ADR) including selected hypersensitivity reactions. This review highlights some very rare ADR, aiming to alert imaging physicians to these conditions and to prompt adequate management. This is particularly relevant for Kounis syndrome, an immediate hypersensitivity reaction involving the coronary arteries. The acute management of Kounis syndrome can be challenging, as it requires continued contrast media administration, while balancing the simultaneous coronary reperfusion that requires vasodilatation with anti-allergic treatment that may involve vasoconstrictor agents. For other adverse reactions, referral to a drug allergy specialist is highly recommended to assess causality and identify safe alternatives. CLINICAL RELEVANCE STATEMENT: Cardiologists and radiologists must recognize the key symptoms of these very rare adverse reactions to contrast media to promptly initiate the appropriate therapy and refer patients for allergological evaluation, ideally within 1-6 months after the reaction.

Hypersensitivity reactions to contrast media: Part 1. Management of immediate and non-immediate hypersensitivity reactions in adults. Updated guidelines by the ESUR Contrast Media Safety Committee

Hypersensitivity reactions to iodine-based, gadolinium-based and ultrasound contrast agents are a heterogeneous group that occur infrequently and can be classified as either immediate or non-immediate. In imaging, most are mild or moderate, while severe reactions are very rare. A standardized risk assessment and close patient monitoring are crucial. In addition to liberal use of supportive treatment by oxygen and volume expansion, the main drugs for treatment of individual reactions include intramuscular adrenaline and H1-antihistamines, with limited indications for short-acting β2-agonists (SABA) like salbutamol or albuterol. As these reactions occur infrequently, these situations often create stress and confusion. During treatment, the stability or progression of the reaction should be constantly assessed, assigning a specific task to each team member. In addition, detailed documentation and correct classification of the severity of such reactions will help improve the risk management in future imaging studies. Regular hands-on training for all personnel involved in managing these reactions is mandatory. To help, the ESUR Contrast Media Safety Committee has reviewed the literature on hypersensitivity reactions and updated its guidance on how to appropriately manage, treat, and document immediate and non-immediate hypersensitivity reactions to contrast media in adults. KEY POINTS: Question Hypersensitivity reactions to contrast media may require immediate action to prevent further damage to the patient. Guidance on management would help improving preparedness. Findings Clear treatment protocols with cards or flowcharts are mandatory. Intramuscular adrenaline is the most important drug for treatment. Documentation should be agent-specific and standardized. Clinical relevance The ESUR Contrast Media Safety Committee has updated its guidance on how to appropriately manage, treat, and document immediate and non-immediate hypersensitivity reactions to contrast media in adults.

Anaphylaxis in children: Latest insights

Background: The diagnosis and management of anaphylaxis in pediatric populations can be a particularly formidable challenge due to its variable definitions and atypical symptom presentation, which can often masquerade as other conditions. This complexity often leads to delays in early recognition and timely intervention. Most pediatric anaphylaxis guidelines emphasize the importance of identifying and avoiding triggers, ensuring accurate dosing and prompt administration of epinephrine to prevent severe complications. There is also growing scientific interest in strategies to intervene early in food allergy development to prevent allergies and protect infants and children from severe allergic reactions. Objective: This report aimed to review key aspects of the pathophysiology, epidemiology, management, and prevention of anaphylaxis in the pediatric population. Also, approved treatment modalities and future research to treat and prevent anaphylactic reactions are discussed. Methods: A review of the medical literature was conducted by using terms that included anaphylaxis, severe allergic reaction, pediatric, prevalence, desensitization, and immunotherapy. Results: Food allergies remain the leading trigger of pediatric anaphylaxis, followed by Hymenoptera venom, whereas drug allergies are less common in children compared with adults. A review of the literature underscores the importance of recognizing early signs and symptoms of anaphylaxis, particularly in preverbal infants, of identifying and eliminating key triggers and of prompt epinephrine administration in the immediate management of pediatric anaphylaxis. Advances in oral immunotherapy and other treatments (e.g., biologics) provide new management options. Notably, anti-immunoglobulin E therapy with omalizumab has shown substantial protection against reactions to accidental food exposure in children as young as 1 year old and with food allergy. Conclusion: This report explores critical aspects of anaphylaxis that affect allergic diseases in infants and children. Gaining a deeper understanding of age-specific triggers and the diverse symptoms of anaphylaxis will significantly enhance diagnosis, treatment, and prevention strategies, ultimately improving the timeliness of interventions. Recent approvals of novel therapies for food allergies, along with promising developments for future treatment and prevention of anaphylaxis in pediatric populations, hold exciting potential for better management of these conditions.

Exploring the anti-anaphylaxis potential of natural products: A Review

Allergies are a common health issue affecting many people around the world, especially in developed countries. They occur when the immune system overreacts to substances that are usually harmless. Some common allergic conditions include asthma, sinus infections, skin rashes, food allergies, hay fever, severe allergic reactions, eczema, swelling, and reactions to medications or insect stings. The causes of these allergies are complex and often linked to genetics, which can lead to heightened immune responses known as atopy. Throughout history, plant extracts have been used for various purposes, including medicine and food. In addition, their bioactive compounds show a wide range of beneficial effects, such as reducing allergic reactions, fighting oxidative stress, mast cell stabilizers, and lowering inflammation, highlighting their potential for treating various health conditions. Flavonoids and phenolic compounds are commonly used in anaphylaxis for their potent anti-inflammatory action. This review aims to promote the use of natural products as potential treatments for anaphylaxis. In addition, the discovery of new drugs derived from natural sources holds significant promise for the management of anaphylaxis.

[Anaphylactic shock]

Anaphylactic shock is a severe, potentially life-threatening systemic allergic reaction. It can involve multiple organ systems and is triggered by medication, food, or insect stings. Epidemiological data vary due to differing definitions, but studies estimate that 0,26% of hospital admissions are due to anaphylaxis, with 1-3 deaths per million annually. The incidence of allergic reactions has increased, though anaphylaxis-related mortality remains stable. Triggers vary by age, with food allergies being common in children, and insect stings and medication predominant in adults.An initial allergen exposure sensitizes the immune system, resulting in IgE production and binding to mast cells and basophils. Upon re-exposure, allergen-IgE binding triggers the release of mediators like histamine, prostaglandins, and cytokines, causing vasodilation, bronchospasm, and capillary leakage. Risk factors include asthma, cardiac or thyroid conditions, and elevated IgE levels. Symptoms usually affect 4 organ systems: skin, gastrointestinal tract, respiratory tract, and cardiovascular system. Grading is based on the severeness of symptoms, ranging from mild skin reactions (grade 1) to respiratory or circulatory arrest (grade 4). A reliable diagnostic marker is elevated serum tryptase.The cornerstone of treatment is adrenaline, administered intramuscularly for rapid action. Fluid resuscitation with balanced electrolyte solutions and high-flow oxygen are also fundamental. Antihistamines and corticosteroids are used a bit later to prevent recurrence but have delayed onset. Adrenaline can also be nebulized or given intravenously in severe cases.Post-crisis management includes patient education, allergy identification, and an emergency kit with an adrenaline auto-injector.

Cost-effectiveness of watchful waiting versus immediate emergency department transfer after epinephrine autoinjector use in Canada

BACKGROUND

Until recently, immediate emergency department (ED) transfer after food-related anaphylactic reactions was recommended regardless of symptom resolution following use of an epinephrine autoinjector (EAI). We evaluated the cost-effectiveness of delayed ED transfer after EAI use in non-medical settings (watchful waiting) compared to immediate ED transfer among pediatric patients with food allergies in Canada.

METHODS

We developed a probabilistic Markov model of individuals starting at age of one year who are at risk of severe food-related allergic reactions requiring epinephrine. We evaluated medical costs (in 2022 Canadian dollars) and quality-adjusted life years (QALY) of each strategy over a 20-year horizon. In the base case, we assumed a tenfold increase in food allergy fatality for patients under watchful waiting, which we increased to 100- to 1,000-fold in sensitivity analysis. The analysis was conducted from the Canadian healthcare system perspective with a 1.5% annual discount rate and a willingness-to-pay (WTP) threshold of $50,000 per QALY.

RESULTS

Immediate ED transfer following EAI use resulted in a decreased risk of food allergy fatality of 9.2 × 10- 5 over 20 years, which is equivalent to < 1 fatality per 200,000 patient-years. Watchful waiting resulted in cost savings of $1,157 per patient and a QALY loss of 7.28 × 10- 4; an incremental cost per QALY saved of $1,589,854. The incremental cost per death prevented with immediate ED transfer was $12,586,613. Watchful waiting remained cost-effective in all sensitivity and scenario analyses, except under extreme increases in fatality risk of 500-fold and 1,000-fold.

CONCLUSIONS

Watchful waiting for symptom re-occurrence following EAI administration in non-medical settings is cost-effective.

Anaphylaxis

Anaphylaxis is an acute, potentially fatal systemic hypersensitivity reaction with varied mechanisms and clinical presentations. Although prompt recognition and treatment of anaphylaxis are imperative, both patients and healthcare professionals often fail to recognize and diagnose its early signs. Clinical manifestations vary widely, however, the most common signs are cutaneous symptoms, including urticaria and angioedema. Immediate intramuscular administration of epinephrine into the anterolateral thigh is first-line therapy, and is always safe even if the diagnosis is uncertain. The mainstays of long-term management include specialist assessment, allergen avoidance measures, and the provision of an epinephrine auto-injector with an individualized anaphylaxis emergency plan. This article provides an overview of the causes, clinical features, diagnosis, and acute as well as long-term management of anaphylaxis.

Epidemiology, Risk Factors, and Management of Biphasic Anaphylaxis

PURPOSE OF REVIEW

Biphasic anaphylaxis is a variant of anaphylaxis characterized by recurrence of symptoms after initial resolution of anaphylaxis. It was first described in the mid 1990s by Popa and Lerner. Our understanding of the pathophysiology and epidemiology of the condition has advanced considerably since then. The purpose of this manuscript is to review the literature surrounding biphasic anaphylaxis while highlighting key works and recent advances.

RECENT FINDINGS

Prior studies have estimated biphasic anaphylaxis occurs in 0.4-20% of anaphylaxis episodes. The wide range may be related to differences in anaphylaxis diagnostic criteria which was inconsistent across studies. Recently identified risk factors for occurrence of biphasic anaphylaxis include severe initial symptoms including hypotension or hypoxia, delay in epinephrine use, and greater than one dose of epinephrine required to treat symptoms. Despite our progress to better understand biphasic anaphylaxis, there remain gaps in the literature. This article aims to review the recent literature including, epidemiology, risk factors, and management of biphasic anaphylaxis.

Applying the dissemination and implementation sciences to allergy and immunology: A Work Group Report from the AAAAI Quality, Adherence, and Outcomes Committee

Translating evidence-based practice (EBP) into real-world clinical settings often takes a considerable amount of time and resources. In allergy and immunology, the dissemination and implementation (D&I) sciences facilitate the study of how variations in knowledge, resources, patient populations, and staffing models lead to differences in the clinical care of asthma, allergic disease, and primary immunodeficiency. Despite the need for validated approaches to study how to best apply EBP in the real world, the D&I sciences are underutilized. To address this gap, an American Academy of Allergy, Asthma & Immunology (AAAAI) work group was convened to provide an overview for the role of the D&I sciences in clinical care and future research within the field. For the D&I sciences to be leveraged effectively, teams should be multidisciplinary and inclusive of community and clinical partners, and multimethods approaches to data collection and analyses should be used. Used appropriately, the D&I sciences provide important tools to promote EBP and health equity as well as optimization of clinical practice in allergy and immunology.

Venom Hypersensitivity

Stinging insects are a frequent cause of local and systemic hypersensitivity reactions, including anaphylaxis. For those with a history of life-threatening anaphylaxis, venom immunotherapy is effective, safe, and can be life-saving. Arachnids are a much less common source of envenomation through bites or stings and are less likely to cause a hypersensitivity reaction. However, recognizing the clinical manifestations when they do present is important for accurate diagnosis and treatment, and, when indicated, consideration of other diagnoses.

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

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

Anaphylaxis: A 2023 practice parameter update

This practice parameter update focuses on 7 areas in which there are new evidence and new recommendations. Diagnostic criteria for anaphylaxis have been revised, and patterns of anaphylaxis are defined. Measurement of serum tryptase is important for diagnosis of anaphylaxis and to identify underlying mast cell disorders. In infants and toddlers, age-specific symptoms may differ from older children and adults, patient age is not correlated with reaction severity, and anaphylaxis is unlikely to be the initial reaction to an allergen on first exposure. Different community settings for anaphylaxis require specific measures for prevention and treatment of anaphylaxis. Optimal prescribing and use of epinephrine autoinjector devices require specific counseling and training of patients and caregivers, including when and how to administer the epinephrine autoinjector and whether and when to call 911. If epinephrine is used promptly, immediate activation of emergency medical services may not be required if the patient experiences a prompt, complete, and durable response. For most medical indications, the risk of stopping or changing beta-blocker or angiotensin-converting enzyme inhibitor medication may exceed the risk of more severe anaphylaxis if the medication is continued, especially in patients with insect sting anaphylaxis. Evaluation for mastocytosis, including a bone marrow biopsy, should be considered for adult patients with severe insect sting anaphylaxis or recurrent idiopathic anaphylaxis. After perioperative anaphylaxis, repeat anesthesia may proceed in the context of shared decision-making and based on the history and results of diagnostic evaluation with skin tests or in vitro tests when available, and supervised challenge when necessary.

Anaphylactic reaction as an etiology of ischemic stroke: A case report

A 28-year-old man was brought to the emergency room (ER) with a history of decrease of consciousness 30 minutes before admission. In the previous 1 hour, the patient felt bitten or stabbed in the left temple area. Physical examination showed signs of N VII paresis, upper extremity motoric 3/2 (right/left) and lower extremity 3/2 (right/left), positive left extremity hypesthesia. Noncontrast MRI brain examination showed increased DWI signal intensity, suggesting diffusion restriction in bilateral centrum semiovale, bilateral posterior crus internal capsule, and bilateral corpus callosum leading to suspicion of acute-hyperacute ischemia. The therapy given while in the emergency room was IVFD asering, IV dexamethasone 5 mg, IV diphenhydramine 10 mg, oral paracetamol 500 mg, oral aspirin 80 mg, oral clopidogrel 75 mg, and oral atorvastatin 40 mg. We report a case of stroke due to an anaphylactic reaction in an effort to add to the point of view if the same case occurs.

Managing anaphylaxis: Epinephrine, antihistamines, and corticosteroids: More than 10 years of Cross-Canada Anaphylaxis REgistry data

BACKGROUND

Epinephrine is the first-line treatment for anaphylaxis but is often replaced with antihistamines or corticosteroids. Delayed epinephrine administration is a risk factor for fatal anaphylaxis. Convincing data on the role of antihistamines and corticosteroids in anaphylaxis management are sparse.

OBJECTIVE

To establish the impact of prehospital treatment with epinephrine, antihistamines, and/or corticosteroids on anaphylaxis management.

METHODS

Patients presenting with anaphylaxis were recruited prospectively and retrospectively in 10 Canadian and 1 Israeli emergency departments (EDs) between April 2011 and August 2022, as part of the Cross-Canada Anaphylaxis REgistry. Data on anaphylaxis cases were collected using a standardized form. Primary outcomes were uncontrolled reactions (>2 doses of epinephrine in ED), no prehospital epinephrine use, use of intravenous fluids in ED, and hospital admission. Multivariate regression was used to identify factors associated with primary outcomes.

RESULTS

Among 5364 reactions recorded, median age was 8.8 years (IQR, 3.78-16.9); 54.9% of the patients were males, and 52.5% had a known food allergy. In the prehospital setting, 37.9% received epinephrine; 44.3% received antihistamines, and 3.15% received corticosteroids. Uncontrolled reactions happened in 250 reactions. Patients treated with prehospital epinephrine were less likely to have uncontrolled reactions (adjusted odds ratio [aOR], 0.955 [95% CI, 0.943-0.967]), receive intravenous fluids in ED (aOR, 0.976 [95% CI, 0.959-0.992]), and to be admitted after the reaction (aOR, 0.964 [95% CI, 0.949-0.980]). Patients treated with prehospital antihistamines were less likely to have uncontrolled reactions (aOR, 0.978 [95% CI, 0.967-0.989]) and to be admitted after the reaction (aOR, 0.963 [95% CI, 0.949-0.977]). Patients who received prehospital corticosteroids were more likely to require intravenous fluids in ED (aOR, 1.059 [95% CI, 1.013-1.107]) and be admitted (aOR, 1.232 [95% CI, 1.181-1.286]).

CONCLUSION

Our findings in this predominantly pediatric population support the early use of epinephrine and suggest a beneficial effect of antihistamines. Corticosteroid use in anaphylaxis should be revisited.

Biologics to treat anaphylaxis

PURPOSE OF REVIEW

The purpose of this literature review was to review the latest use of biologics in the management of anaphylaxis. The methodology was to highlight both the nonbiologic management of anaphylaxis and the biologic management and how they can be used in conjunction with each other.

RECENT FINDINGS

As the phenotypes and endotypes of anaphylaxis are better portrayed, it furthers our understanding of the mechanisms of anaphylaxis. New applications of existing biologics to the prevention of anaphylaxis are described.

SUMMARY

Anaphylaxis is a potentially life-threatening acute hypersensitivity reaction affecting up to 16.8% of the U.S. population. Acute management entails swift identification, removal of the causative agent, and the prevention of cardiovascular collapse, firstly with epinephrine. Adjunctive treatments such as antihistamines work to prevent anaphylaxis from recurring. Biologic management of anaphylaxis involves the use of large-molecule drugs such as monoclonal antibodies. Omalizumab, an IgG1 monoclonal antibody targeting unbound IgE, is the most prevalent and widely studied biologic in the prevention of anaphylaxis. Other monoclonal antibodies in development or approved for other indications, such as ligelizumab, quilizumab, MEDI4212, and dupilumab, may also have potential for preventing anaphylaxis through various mechanisms.

Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are a diverse group of reactions mediated by the immune system after exposure to a drug. The Gell and Coombs classification divides immunologic DHRs into 4 major pathophysiologic categories based on immunologic mechanism. Anaphylaxis is a Type I hypersensitivity reaction that requires immediate recognition and treatment. Severe cutaneous adverse reactions (SCARs) are a group of dermatologic diseases that result from a Type IV hypersensitivity process and include drug reaction with eosinophilia and systemic symptom (DRESS) syndrome, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Other types of reactions are slow to develop and do not always require rapid treatment. Emergency physicians should have a good understanding of these various types of drug hypersensitivity reactions and how to approach the patient regarding evaluation and treatment.

Anaphylaxis: Emergency Department Treatment

Anaphylaxis is a potentially life-threatening, multisystem allergic reaction that can cause airway, breathing, or circulatory compromise. Intramuscular epinephrine is the immediate treatment of all patients. Intravenous epinephrine should be used in patients in shock, either as a bolus or infusion, along with fluid resuscitation. Airway obstruction must be recognized, and early intubation may be necessary. For shock that is refractory to epinephrine, additional vasopressors may be needed. Disposition depends on patient presentation and response to treatment. Mandatory observation periods are not necessary, because biphasic reactions are difficult to predict and may occur outside of typical observation periods.

Allergic Acute Coronary Syndrome-Kounis Syndrome

Acute coronary syndrome (ACS) in the setting of an allergic/immunologic reaction is known as Kounis syndrome. It is an underdiagnosed and underrecognized disease entity. One must keep a high index of suspicions when managing a patient presenting with cardiac as well as allergic symptoms. There are 3 main variants to the syndrome. Treating the allergic reaction may alleviate the pain; however, ACS guidelines should be followed if cardiac ischemia is present.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS AND RELEVANCE

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

Drug-Induced Kounis Syndrome: Latest Novelties

Kounis syndrome (KS) is defined by an acute coronary syndrome associated with hypersensitivity reactions, an under-diagnosed life-threatening medical emergency. Although multiple causes have been described, drugs constitute the most frequent cause. The purpose of this review is to update knowledge about drug-induced KS, to give guidelines on the correct diagnosis and treatment. This article reviews the literature on drug-induced KS from the last 5 years. Antibiotics and NSAIDs are the most frequently implicated drugs. In addition, data on pathophysiology, clinical presentation, diagnosis, and management are reviewed in detail. Highlight that there is a great deal of variability in the diagnosis and especially in the treatment of KS. This review provides a valuable selection of practical resources for all stakeholders to support effective care for KS, from a cardiologic and allergologic point of view. Future research should focus on developing validated, evidence-based, and patient-centered tools to improve the management of KS.

Trends and Variation in Pediatric Anaphylaxis Care From 2016 to 2022

BACKGROUND

Variation in the use of treatments and hospitalization for anaphylaxis would suggest a lack of consensus in therapeutic approach.

OBJECTIVE

To evaluate trends and practice variation in the emergency department (ED) care of children with anaphylaxis in a large US cohort.

METHODS

We conducted a 48-site retrospective cohort study using the Pediatric Health Information System from January 2016 through September 2022. Children younger than 18 years with a primary diagnosis of anaphylaxis were included. Care trends were assessed using negative binomial regression modeling. Rates of medication use, hospitalizations, and revisits were reported as medians with interquartile ranges (IQRs).

RESULTS

There were 42,909 ED visits for anaphylaxis, with a 4.2% per-year increase in visit incidence (95% CI, 1.8-6.7) during the study period. The median hospitalization rate was 3.5% (IQR, 2.2-6.0), and the 3-day ED revisit rate was 0.6% (IQR, 0.4-0.9). The hospital-level median use of therapies included intramuscular epinephrine (55.3%; IQR, 50.1-59.9), systemic steroids (73.8%; IQR, 63.9-81.4), antihistamines (59.9%; IQR, 53.5-65.5), H2-receptor antagonists (56.8%; IQR, 42.3-66.2), bronchodilators (15.1%; IQR, 12.5-17.0), inhaled epinephrine (1.1%; IQR, 0.6-1.9), and fluid boluses (19.8%; IQR, 11.3-29.3). Severe reactions requiring intensive care unit admission (1.5%; IQR, 0.8-2.2), vasopressors (0.3%; IQR, 0.0-0.6), and intubation (0.2%; IQR, 0.0-0.3) were rare.

CONCLUSIONS

ED visits for anaphylaxis increased during the study period, but hospitalization rates were low. Substantial variation exists between EDs regarding the use of anaphylaxis therapies, supporting the need for future research to evaluate the efficacy of these medications.

Venom Hypersensitivity

Stinging insects are a frequent cause of local and systemic hypersensitivity reactions, including anaphylaxis. For those with a history of life-threatening anaphylaxis, venom immunotherapy is effective, safe, and can be life-saving. Arachnids are a much less common source of envenomation through bites or stings and are less likely to cause a hypersensitivity reaction. However, recognizing the clinical manifestations when they do present is important for accurate diagnosis and treatment, and, when indicated, consideration of other diagnoses.

Canada’s First Joint Oncology-Allergy Clinic: Successful Desensitization to Trastuzumab Following Severe Anaphylactic Reaction in Which Epinephrine Was Inappropriately Withheld

Background: Recognition of anaphylaxis and differentiation from other infusion reactions in an oncology setting is imperative; epinephrine is the recommended treatment for anaphylaxis and should be administered immediately to patients in whom anaphylaxis is suspected. Trastuzumab has a potentially tremendous oncological benefit, and when hypersensitivity reactions occur, rechallenge with desensitization protocols has become more common. Oncology presents a unique situation in which repeat drug exposure after a serious adverse reaction is often warranted due to the mortality risk of untreated cancer—allergists can assist with both symptom assessment and risk mitigation. Case presentation: This case showcases successful desensitization in a 43-year-old female with locally advanced HER2-positive breast cancer following a severe anaphylactic reaction to trastuzumab, in which epinephrine was not administered. We report the establishment of the Medical Oncology and Allergy Clinic: Canada’s first multidisciplinary clinic aimed at expediting the assessment and management of oncology patients with adverse drug reactions (including chemotherapy, contrast media, antimicrobials) and those with primary and acquired immunodeficiency. Conclusions: We propose this multidisciplinary clinic model as a treatment framework moving forward, with the goal of continuing first-line therapies in cancer patients who develop drug-hypersensitivity (i.e., through desensitization). This case highlights the unmet need for a multidisciplinary approach to the management of oncology patients who experience hypersensitivity reactions.

Spread of stinging ants to oceanic islands, and the need to raise awareness of prevention and treatment of ant stings

OBJECTIVE

Venomous invasive ants are rapidly dispersing throughout oceanic islands. Medics unfamiliar with envenomation or venom-induced anaphylaxis may be unprepared for the range of possible reactions and corresponding treatments. We detail the suboptimal treatment of a patient suffering anaphylaxis from an ant sting on a remote island and describe what treatment should have been provided.

METHODS

The patient experienced stings on his feet from an ant later identified as tropical fire ant, Solenopsis geminata. Clinical examination revealed throat swelling without obstruction of the airway or pharynx.

RESULTS

The patient was provided the following suboptimal treatment: intravenously-administered antihistamine and saline perfusion. Injected epinephrine should be the standard first line of treatment for anaphylaxis, even when not all symptoms are present.

CONCLUSION

A rise in invasive hymenopteran stings on oceanic islands is inevitable, and proactively improving public awareness and medical training could save lives.

Biphasic Allergic Reactions at a Dutch Emergency Department: A 5-Year Retrospective Cohort Study

BACKGROUND

A biphasic allergic reaction develops in 0.4-20% of patients with an allergic reaction, but the incidence of severe biphasic reactions is unknown OBJECTIVE: Our objective was to assess the incidence and time of onset of clinically relevant biphasic reactions in a Dutch emergency department (ED) cohort. Furthermore, the characteristics of patients with a biphasic reaction and the mean observation time after an allergy-related ED visit were assessed.

METHODS

This was a single-center retrospective cohort study. We collected data from clinical records of adult patients presenting with an allergic reaction to the ED between January 2015 and December 2019. We defined clinically relevant biphasic reactions as biphasic reactions in which the criteria for anaphylaxis were met.

RESULTS

Five hundred fifty-seven patients were included. Eight patients (1.4%) developed a biphasic reaction, of which 1 (0.2% of the total inclusions) was clinically relevant. In the subgroup of patients with an anaphylactic reaction (n = 258), those percentages were 2.3% and 0.4%, respectively. The mean time between the initial allergic reaction and the biphasic allergic reaction was 25.4 h (95% CI 13.2-37.6 h). The single clinically relevant biphasic reaction occurred 30 h after the initial reaction.

CONCLUSIONS

The incidence of clinically relevant biphasic reactions in our cohort was low, with a mean time between the initial allergic reaction and the biphasic reaction of > 24 h. Based on these single-center retrospective data, routine inpatient monitoring for several hours does not seem warranted for all patients.

Variation in diagnosis and management of allergic reactions among emergency medicine and allergy immunology providers

Background: Children with anaphylaxis often emergently present for treatment. Providers' adherence to the principles of optimal management according to the most recent national guidelines is unknown. Objective: To assess the variation in management approaches for allergic reactions and anaphylaxis between allergy/immunology (AI) and emergency medicine (EM) providers. Methods: This was a cross-sectional survey study of AI and EM providers in the University of Colorado affiliated hospitals and Colorado Asthma and Allergy Society. The survey consisted of six cases of patients with allergic reactions, with four cases that represented patients with anaphylaxis that resolved by the time of discharge. For each vignette, the participants were asked about preferred initial therapy, adjunctive therapies, monitoring, outpatient prescription medications, and discharge instructions provided. Survey derivation and validation was accomplished by a multidisciplinary team of experts by using a modified Delphi process. Results: A total of 413 clinicians were contacted, of whom 194, (47%) responded, including 69 pediatric EM, 50 general EM, and 49 AI providers, and 26 did not identify a provider type. There were no statistically significant differences in correct recognition of anaphylaxis between the AI and EM providers. For each case, statistically significant differences were noted in the use of corticosteroids during and after resolution of anaphylaxis: AI providers reported giving fewer prescriptions than did the EM providers for corticosteroids in all cases of anaphylaxis (p < 0.001). The AI providers were less likely to prescribe scheduled antihistamines than were the EM providers in half of the cases (p < 0.02). Conclusion: Across the specialties, there were high rates of recognition of epinephrine as first-line treatment for anaphylaxis. The majority of the EM providers prescribed scheduled corticosteroids and antihistamines after resolution of anaphylaxis, whereas most of the AI providers did not prescribe scheduled corticosteroids. Analysis of the current data suggests against the routine use of corticosteroids in the management of anaphylaxis, particularly continued use after resolution of symptoms. AI involvement in the creation of EM and hospital protocols for allergic reactions could improve overall care.

Triage Grading and Correct Diagnosis Are Critical for the Emergency Treatment of Anaphylaxis

Introduction: Anaphylaxis is one of the most frequent and misdiagnosed emergencies in the pediatric emergency department (PED). We aimed to assess which factors play a major role for a correct diagnosis and an appropriate therapy. Methods: We reviewed the records of children discharged with a diagnosis of anaphylaxis or an allergic reaction over 11 years from 3 hospitals in the Bologna city area. Results: One hundred and sixteen cases matched the criteria (0.03% of the total admittances) and were divided according to the patients’ symptoms at arrival: active acute patients [AP], n = 50, or non-acute patients ([NAP], n = 66). At the patients’ discharge, anaphylaxis was diagnosed in 39 patients (33.6%). Some features seemed to favor a correct diagnosis: active symptoms at arrival (AP vs. NAP, p < 0.01), high-priority triage code (p < 0.01), and upper airway involvement (p < 0.01). Only 14 patients (12.1%), all in the AP group, received epinephrine, that was more likely administered to patients recognized to have anaphylaxis (p < 0.01) and with cardiovascular, respiratory, or persistent gastrointestinal symptoms (p < 0.02), as confirmed by logistic regression analysis. Conclusions: Anaphylaxis is still under-recognized and under-treated. Correct triage coding and a proper diagnosis seem to foster an appropriate treatment. Physicians often prefer third-line interventions. Specific training for nurses and physicians might improve the management of this disease.

Canadian Anaphylaxis Network-Predicting Recurrence after Emergency Presentation for Allergic REaction (CAN-PREPARE): a prospective, cohort study protocol

INTRODUCTION

Anaphylaxis is a severe, potentially fatal multiorgan system manifestation of an allergic reaction. The highest incidence of anaphylaxis is in children and adolescents. Biphasic anaphylaxis (BA) is defined as the recurrence of allergic symptoms after resolution of an initial reaction. It has been reported to occur in 10%-20% of cases within 1-48 hours from the onset of the initial reaction. The dilemma for physicians is determining which patients with resolved anaphylaxis should be observed for BA and for how long. Guidelines for duration of postanaphylaxis monitoring vary, are based on limited evidence and can have unintended negative impacts on patient safety, quality of life and healthcare resources. The objectives of this study are to derive a prognostic model for BA and to develop a risk-scoring system that informs disposition decisions of children who present to emergency departments (ED) with anaphylaxis.

METHODS AND ANALYSIS

This prospective multicentre cohort study will enrol 1682 patients from seven paediatric EDs that are members of the Paediatric Emergency Research Canada network. We will enrol patients younger than 18 years of age with an allergic reaction meeting anaphylaxis diagnostic criteria. Trained ED research assistants will screen, obtain consent and prospectively collect study data. Research assistants will follow patients during their ED visit and ascertain, in conjunction with the medical team, if the patient develops BA. A standardised follow-up survey conducted following study enrolment will determine if a biphasic reaction occurred after ED disposition. Model development will conform to the broad principles of the PROGRESS (Prognosis Research Strategy) framework and reporting will follow the Transparent Reporting of a multivariable prediction model for Individual Prognosis or Diagnosis Statement.

ETHICS AND DISSEMINATION

Ethics approval has been received from all participating centres. Our dissemination plan focuses on informing clinicians, policy makers and parents of the results through publication in peer-reviewed journals and broadcasting on multiple media platforms.

TRIAL REGISTRATION NUMBER

NCT05135377.

Emergency treatment of anaphylaxis: concise clinical guidance

Anaphylaxis is a serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death. It is characterised by the rapid development of airway and/or breathing and/or circulation problems. Intramuscular adrenaline is the most important treatment, although, even in healthcare settings, many patients do not receive this intervention contrary to guidelines. The Resuscitation Council UK published an updated guideline in 2021 with some significant changes in recognition, management, observation and follow-up of patients with anaphylaxis. This is a concise version of the updated guideline.

Safely Reducing Hospitalizations for Anaphylaxis in Children Through an Evidence-Based Guideline

BACKGROUND

Emergency department visits for anaphylaxis have increased considerably over the past few decades, especially among children. Despite this, anaphylaxis management remains highly variable and contributes to significant health care spending. On the basis of emerging evidence, in this quality improvement project we aimed to safely decrease hospitalization rates, increase the use of cetirizine, and decrease use of corticosteroids for children with anaphylaxis by December 31, 2019.

METHODS

A multipronged intervention strategy including a revised evidence-based guideline was implemented at a tertiary children's teaching hospital by using the Model for Improvement. Statistical process control was used to evaluate for changes in key measures. Length of stay and unplanned return visits within 72 hours were monitored as process and balancing measures, respectively. As a national comparison, hospitalization rates were compared with other hospitals' data from the Pediatric Health Information System.

RESULTS

Hospitalizations decreased significantly from 28.5% to 11.2% from preimplementation to implementation, and the balancing measure of 72-hour revisits was stable. The proportion of patients receiving cetirizine increased significantly from 4.2% to 59.7% and use of corticosteroids decreased significantly from 72.6% to 32.4% in patients without asthma. The proportion of patients meeting length of stay criteria increased from 53.3% to 59.9%. Hospitalization rates decreased nationally over time.

CONCLUSIONS

We reduced hospitalizations for anaphylaxis by 17.3% without concomitant increases in revisits, demonstrating that unnecessary hospitalizations can be safely avoided. The use of a local evidence-based guideline paired with close outcome monitoring and sustained messaging and feedback to clinicians can effectively improve anaphylaxis management.

Outcomes and Factors Associated With Prehospital Treatment of Pediatric Anaphylaxis

OBJECTIVE

Anaphylaxis is a potentially life-threatening reaction requiring prompt treatment with intramuscular epinephrine (EPI). We sought to describe presenting features of pediatric anaphylaxis and compare patient characteristics and outcomes of children treated with prehospital EPI with those untreated.

METHODS

We abstracted data from emergency department (ED) records for children meeting the National Institute of Allergy & Infectious Disease criteria for anaphylaxis (2015-2017) in one tertiary care children's hospital. We analyzed associations between patient characteristics and outcomes and receipt of prehospital EPI using descriptive statistics and multivariate logistic regression.

RESULTS

Of 414 children presenting with anaphylaxis, 39.4% received IM EPI and 62.1% received antihistamines before hospital arrival. Children with Medicaid received pre-emergency department EPI less frequently than did children with private insurance (24.5% vs 43.8%, P = 0.001). Factors positively associated with prehospital EPI administration were history of food allergy (odds ratio [OR], 4.4 [95% confidence interval {CI}, 2.4-8.2]) or arrival by emergency medical services (OR, 8.0 [95% CI, 4.2-15.0]). Medicaid insurance was associated with decreased odds of prehospital EPI (OR, 0.33 [95% CI, 0.16-0.66]) and prehospital H1-antihistamine use (OR, 0.30 [95% CI, 0.17-0.56]). Prehospital EPI treatment was also associated with decreased rates of observation (37% vs 63%), inpatient admission (38% vs 62%), and intensive care unit admission (20% vs 80%) compared with no pretreatment (P = 0.03).

CONCLUSIONS

Prehospital treatment with EPI remains low, and barriers to optimal treatment are more pronounced in children with public insurance. Prehospital treatment with EPI was associated with decreased morbidity including hospitalization and intensive care unit admission.

Physicians' knowledge and practice concerning diagnosis and management of anaphylaxis: The situation in Egypt

Introduction

Early recognition of an anaphylaxis event is crucial for instituting lifesaving management. We sought to explore knowledge and practice towards anaphylaxis in a sample of physicians from ten Egyptian governorates.

Methods

An eighteen question-based questionnaire was developed by expert allergists to evaluate the knowledge and practice towards anaphylaxis, based on the World Allergy Organization guidelines for the assessment and management of anaphylaxis. The questionnaires were distributed, and the answered forms collected via emails, and data were tabulated, and analysed.

Results

In this cross-sectional study, a total of 242 physicians completed the survey (183 (75.6%) paediatricians, 32 (13.2%) internists, 22 (9.1%) intensivists and five (2.1%) anaesthetists). Only 91 participants (37.6%) identified all the four proposed anaphylaxis clinical scenarios while 70, 45 and 36 identified three, two and one scenario, respectively. Loss of consciousness and abdominal symptoms were not recognised as possible presentations of anaphylaxis by 64.5% and 80.2% of the participants, respectively. Epinephrine was considered the first line treatment by 98 (40.5%), corticosteroids by 77 (31.8%) and antihistamines by 25 (10.3%). 75 (31%) responders identified the right dose of epinephrine while 119 (49.2%) identified the proper route. Concerning practice, 83 physicians (39.2%) used epinephrine for all cases of anaphylaxis, 88 (41.5%) used it for refractory cases only whereas 41 (19.3%) did not use epinephrine at all.

Discussion

Our survey shows that the knowledge of Egyptian physicians and their practice towards anaphylaxis are still inadequate. The current situation reinforces the need to disseminate and encourage the adoption of the international guidelines for anaphylaxis diagnosis and treatment.

Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are a diverse group of reactions mediated by the immune system after exposure to a drug. The Gell and Coombs classification divides immunologic DHRs into 4 major pathophysiologic categories based on immunologic mechanism. Anaphylaxis is a Type I hypersensitivity reaction that requires immediate recognition and treatment. Severe cutaneous adverse reactions (SCARs) are a group of dermatologic diseases that result from a Type IV hypersensitivity process and include drug reaction with eosinophilia and systemic symptom (DRESS) syndrome, Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). Other types of reactions are slow to develop and do not always require rapid treatment. Emergency physicians should have a good understanding of these various types of drug hypersensitivity reactions and how to approach the patient regarding evaluation and treatment.

Allergic Acute Coronary Syndrome-Kounis Syndrome

Acute coronary syndrome (ACS) in the setting of an allergic/immunologic reaction is known as Kounis syndrome. It is an underdiagnosed and underrecognized disease entity. One must keep a high index of suspicions when managing a patient presenting with cardiac as well as allergic symptoms. There are 3 main variants to the syndrome. Treating the allergic reaction may alleviate the pain; however, ACS guidelines should be followed if cardiac ischemia is present.

Anaphylaxis: Emergency Department Treatment

Anaphylaxis is a potentially life-threatening, multisystem allergic reaction that can cause airway, breathing, or circulatory compromise. Intramuscular epinephrine is the immediate treatment of all patients. Intravenous epinephrine should be used in patients in shock, either as a bolus or infusion, along with fluid resuscitation. Airway obstruction must be recognized, and early intubation may be necessary. For shock that is refractory to epinephrine, additional vasopressors may be needed. Disposition depends on patient presentation and response to treatment. Mandatory observation periods are not necessary, because biphasic reactions are difficult to predict and may occur outside of typical observation periods.

Recent update on the management of anaphylaxis

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

Biphasic anaphylaxis after exposure to the first dose of Pfizer-BioNTech COVID-19 mRNA vaccine

In the setting of a coronavirus disease 2019 (COVID-19) global pandemic and increased disease burden, vaccination has become one of the major solutions. With the increase in vaccination numbers worldwide, it is important to stay vigilant to the potential side effects and life-threatening complications of such vaccines. We report the case of a 30-year-old male with a biphasic allergic reaction post messenger (mRNA) Pfizer-BioNTech COVID-19 vaccination. Several reports of allergic reactions have been cited in the literature after the administration of the mRNA Pfizer-BioNTech COVID-19 vaccine. It is important to keep a high index of suspicion in severe anaphylactic cases as some patients may have a recurrence of symptoms after discharge. It is crucial to acknowledge the potential risk of anaphylaxis in select individuals and have the appropriate measures in place to deal with adverse events. In case of severe symptoms, the administration of epinephrine is advised to prevent the development of a delayed biphasic anaphylactic reaction.

State-of-the-Art on Biomarkers for Anaphylaxis in Obstetrics

Anaphylaxis is an unpredictable systemic hypersensitivity reaction and constitutes a high risk of maternal and fetal morbidity and mortality when occurring during pregnancy. Currently, the acute management of anaphylaxis is based on clinical parameters. A total serum tryptase is only used to support an accurate diagnosis. There is a need to detect other biomarkers to further assess high-risk patients in obstetrics. Our objective is to present biomarkers in this complex interdisciplinary approach beyond obstetrician and anaesthetic management. Candidate biomarkers derive either from mediators involved in immunopathogenesis or upcoming molecules from systems biology and proteomics. Serum tryptase is determined by singleplex immunoassay method and is important in the evaluation of anaphylactic mast cell degranulation but also in the assessment of other risk factors for anaphylaxis such as systemic mastocytosis. Another category of biomarkers investigates the IgE-mediated sensitization to triggers potentially involved in the etiology of anaphylaxis in pregnant women, using singleplex or multiplex immunoassays. These in vitro tests with natural extracts from foods, venoms, latex or drugs, as well as with molecular allergen components, are useful because in vivo allergy tests cannot be performed on pregnant women in such a major medical emergency due to their additional potential risk of anaphylaxis.

Management of pediatric allergic reaction: Practice patterns of Canadian pediatric emergency physicians

OBJECTIVES

Anaphylaxis is a severe allergic reaction that can be life-threatening. The literature indicates that the incidence of anaphylaxis is increasing and that there are deficiencies in both recognition and management. We aimed to examine the magnitude of these gaps in Canadian pediatric emergency medicine (PEM).

METHODS

We conducted a self-administered survey of the Pediatric Emergency Research Canada (PERC) physician database. The survey tool was developed through a literature review to identify recurring themes of gaps in anaphylaxis diagnosis and management. The final tool contained four scenarios; three scenarios featured each of the National Institute of Allergy and Infectious Diseases (NIAID) anaphylaxis criteria, separately, and a fourth case of non-anaphylactic allergy. Multiple-choice questions associated with each scenario addressed diagnosis, management, and disposition. Additional questions focused on epinephrine prescribing, observation durations, and respondent demographics.

RESULTS

Of the 214 members invited to participate in the survey, 152 (71%) responded. Anaphylaxis was accurately recognized 93%, 82%, and 99% of the time for the NIAID criteria one through three, respectively. When anaphylaxis was recognized, epinephrine was prescribed for each case 96%, 95%, and 72% of the time, respectively. Of all respondents, 115 (76%) accurately diagnosed all three cases of anaphylaxis and 82 (54%) treated anaphylaxis with epinephrine each time it was indicated.

CONCLUSION

Most respondents recognized cases of anaphylaxis; however, a substantial number demonstrated gaps in management that may adversely impact this vulnerable population. The recognition of anaphylaxis without urticaria or pulmonary findings and treatment of anaphylaxis with epinephrine, where indicated, were the main gaps identified.

The complexities of insulin allergy: a case and approach

Background

Insulin hypersensitivity is rare, but challenging for individuals with diabetes. The prevalence of insulin allergy has decreased since the introduction of human recombinant insulin preparations. Hypersensitivity reactions range from injection site erythema and swelling, to anaphylaxis. While some reactions are to excipients (zinc, protamine, metacresol), many are to recombinant insulin itself. We present a case of type 1 hypersensitivity to various preparations of insulin in a patient with insulin-dependent type 2 diabetes mellitus (T2DM).

Case presentation

A 61-year-old woman with a 30-year history of insulin-dependent T2DM was referred for evaluation of reactions to insulin. She had two episodes over 5-months; both required Emergency Department visits and epinephrine administration. The first episode entailed a burning sensation of the extremities and nausea, immediately after injecting NovoRapid^® insulin. The second event entailed a similar reaction but this time there was also angioedema of the upper airway with difficulty breathing and hypotension, immediately after injecting Levemir^® and NovoRapid^®, and taking metformin. There were no cofactors such as exercise, infectious illness, or NSAIDs use. Skin testing was performed with metformin, Lantus^®, Humalog^®, NovoRapid^®, glulisine, insulin regular, NPH, Levemir^® and the excipient protamine, as per published testing concentrations. Metacresol was not tested as its use was restricted by the hospital pharmacy. Insulin preparations with and without metacresol were included in testing however. A clinic staff served as a negative control. The patent had negative testing with protamine, but sensitization to all insulin preparations. Metformin skin testing and challenge along with latex IgE were negative. Subsequently, she underwent intentional weight loss of 70 lb, and was started on oral hypoglycemics with good effect.

Conclusions

Our case highlights the importance of diagnosing insulin allergy through a detailed history and focused testing. Therapeutic strategies include avoidance and insulin alternatives, alternate insulin preparations, or desensitization. In severe recurrent hypersensitivity reactions, Omalizumab or pancreatic transplantation have been effective.

Factors influencing emergency department observation time following anaphylaxis: a systematic review

OBJECTIVE

Anaphylaxis is a condition that warrants an observation period after symptoms resolution to detect rare but life-threatening delayed complications. There is a need for evidence to identify patients who would benefit from prolonged observation time. The purpose of this review was to identify factors that may influence the need for longer observation in the emergency department.

METHODS

PubMed, Embase, EBM Review, and Cochrane Library were searched using controlled vocabulary and keywords to cover all relevant data. Titles, abstract, and full text were reviewed for inclusion and exclusion criteria. Data were extracted from the included articles regarding case definitions, prognosis, treatment and time factors, and recommended observation time. Factors linked to observation time or complications were tabulated and compared between studies.

RESULTS

The search retrieved 2443 citations of which 49 were included. Twenty-one were primary studies and were used to identify factors influencing observation time or complications. Biphasic anaphylaxis was the only adverse event that warranted prolonged observation. The five risk factors often associated with biphasic reactions were time to first epinephrine, history of anaphylaxis, symptom severity, number of epinephrine doses, and unknown trigger. Biphasic reactions happened mostly within the first 72 h with most severe reactions occurring earlier than the milder ones. Heterogeneity in the definition of biphasic anaphylaxis made comparisons challenging.

CONCLUSIONS

Observation time should be based on the provider's best estimation of the risk of biphasic anaphylaxis, although no single factor can predict their occurrence. The identified factors will allow the development of an early discharge screening tool.

The Revenge of Unintended Consequences of Anaphylaxis-Risk Overdiagnosis: How Far We Have Come and How Far We Have to Go

Overdiagnosis of anaphylaxis risk is an underappreciated aspect of anaphylaxis prevention. Whereas the benefits of anaphylaxis-risk prevention are well known, potential harms resulting from preemptive approaches to mitigate anaphylaxis-risk are not insignificant. Still, great progress has been made in recent years to avoid the unintended consequences of anaphylaxis-risk overdiagnosis. Reflection on recent advances in the use of diagnostic testing, as well as the application of diagnostic labels, provides an important perspective to understand how far the specialty of allergy and immunology has come in improving the lives of patients and families. Examples of recent paradigm shifts in anaphylaxis-risk management include approaches to peanut allergy prevention without screening, deferral of corticosteroids to prevent biphasic anaphylaxis reactions, reevaluation of reflex use of emergency medical services for resolved community anaphylaxis, and an approach to penicillin allergy delabeling with direct oral challenge. Routine medical practices to decrease anaphylaxis risk can have lifelong impacts for patients-beyond just preventing anaphylaxis. As our understanding of these trade-offs evolves, it becomes necessary to weigh both the benefits and the harms of past management approaches. Because medicine remains a science of uncertainty and an art of probability, a critical approach to risk mitigation remains necessary to find the often-elusive balance in anaphylaxis prevention.

[Cardiac arrest under special circumstances]

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