Overview of Allergy and Anaphylaxis.

Allergic reactions and anaphylaxis occur on a severity continuum from mild and self-limited to potentially life-threatening or fatal reactions. Anaphylaxis is typically a multiorgan phenomenon involving a broad range of effector cells and mediators. Emergency department visits for anaphylaxis are increasing, especially among children. There is a broad differential diagnosis for anaphylaxis, and the diagnosis of anaphylaxis can be aided by the use of the National Institutes of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network clinical diagnostic criteria. Risk factors for severe anaphylaxis include older age, delayed epinephrine administration, and cardiopulmonary comorbidities.

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.

Anaphylaxis: Mediators, Biomarkers, and Microenvironments

The life-threatening nature of anaphylactic reactions has increased interest in discovering new biomarkers that could improve diagnosis and prevention. However, the diverse nature of the clinical features and the etiology and pathogenesis of anaphylaxis hinder the identification of valuable molecular indicators of disease. Most studies on anaphylaxis focus on the immune system. Anaphylactic reactions are characterized primarily by IgE-mediated activation of mast cells and basophils and release of mediators. Determination of serum tryptase levels is the main in vitro test used to confirm the reaction, although there are no biomarkers that can predict it. Nevertheless, recent research has postulated that alternative pathways, cell types, and systems are involved. Consequently, various molecular products have been explored and considered potential biomarkers, although none of them are yet used in clinical practice. The products that are altered in patients with anaphylaxis include vasoactive agents, proteases, proteoglycans, lipids, interleukins, cytokines, products of the complement-contact and coagulation systems, circulating proteins, extracellular vesicles, microRNAs, and metabolites. The recognition of biological processes and molecular pathways affecting the microenvironments involved in anaphylaxis will considerably improve clinical practice and the identification of better molecular markers. We offer a broad review of the various mediators described in anaphylaxis, consider their usefulness as potential biomarkers of this pathological event, and examine their role in the molecular basis of the reaction (AU)

Clinical significance of plasma PAF acetylhydrolase activity measurements as a biomarker of anaphylaxis: Cross-sectional study.

INTRODUCTION: Platelet-activating factor (PAF) has a direct role as a mediator in the pathogenesis of various disorders with an inflammatory component, including those with allergic aetiology. The peripheral blood concentration of PAF is dynamically regulated by plasma PAF acetylhydrolase (PAF-AH). Previous research suggest that low activity of plasma PAF-AH could be a predictive marker for increased severity of some types of allergic hypersensitivity reactions-especially anaphylaxis. The purpose of the study was to evaluate the association between plasma PAF-AH activity and severity in patients with anaphylactic reactions following a wasp or bee sting. MATERIALS AND METHODS: The study group of 89 patients was divided into two subgroups depending on the increasing severity of the most severe anaphylactic reaction in the past, which was assessed according to the Müller's scale. The first subgroup included participants with a history of hypersensitivity reactions up to grade II. The second subgroup consisted of patients who have experienced at least one grade III or IV reactions in the past. A control group of 20 people was established. Plasma PAF-AH activity was measured using a colorimetric method. RESULTS: It has been observed that plasma activity of platelet-activating factor acetylhydrolase was significantly lower in patients with anaphylaxis history compared to the control group with negative atopic history (on average 21.38 nmol/min/ml for the control group, 9.47 nmol/min/ml for the first subgroup and 10.16 nmol/min/ml for the second subgroup, in both cases p < 0.0001). CONCLUSION: The plasma activity of PAF-AH is a promising parameter that can help to distinguish a group of patients not threatened with development of anaphylaxis and not requiring laborious or expensive prophylactic procedures.

Comparative study between conventional and new methods in defining the cause of death from anaphylactic shock.

ABSTRACT: Anaphylaxis is defined as a rapid systemic reaction that develops in individuals previously exposed to specific allergens. The new exposure causes systemic cellular degranulation, which in turn leads to cardiovascular and respiratory changes that are fatal if not treated immediately. One of the main problems of this scenario in the forensic field is the determination of a correct post-mortem diagnosis. Traditional methods, such as histopathological examination of the respiratory tract and the use of specific antibodies used in immunohistochemistry, are sensitive but not always specific and therefore do not guarantee a high degree of probability in the diagnosis of anaphylaxis. For this reason, a new and promising research frontier in this field of forensic pathology could be represented by the application of miRNAs as biomarkers, as has been done in other areas of medicine.

Naturally occurring hypothermia promotes survival in severe anaphylaxis.

Although hypothermia has received substantial attention as an indicator of severity in anaphylaxis, it has been neglected from the perspective of whether it could act as a disease-modifying factor in this condition. Here, the impact of naturally occurring (spontaneous) hypothermia on anaphylaxis was evaluated in a murine model of ovalbumin (OVA)-induced allergy. Nonextreme changes in the ambient temperature (Ta) were used to modulate the magnitude of spontaneous hypothermia. At a Ta of 24°C, challenge with OVA intraperitoneally or intravenously resulted in a rapid, transient fall in body core temperature, which reached its nadir 4-6°C below baseline in 30 min. This hypothermic response was largely attenuated when the mice were kept at a Ta of 34°C. The Ta-dependent attenuation of hypothermia resulted in a survival rate of only 30%, as opposed to survival of 100% in the condition that favored the development of hypothermia. The protective effect of hypothermia did not involve changes in the rate of mast cell degranulation, as assessed by the concentration of mast cell protease-1 in bodily fluids. On the other hand, hypothermia improved oxygenation of the brain and kidneys, as indicated by higher NAD+/NADH ratios. Therefore, it is plausible to propose that naturally occurring hypothermia makes organs more resistant to the anaphylactic insult.

Emergency medicine updates: Anaphylaxis.

INTRODUCTION: Anaphylaxis is a potentially deadly condition that requires emergent therapy. While frequently treated in the emergency department (ED), recent evidence updates may improve the diagnosis and management of this condition. OBJECTIVE: This paper evaluates key evidence-based updates concerning the diagnosis and management of anaphylaxis for the emergency clinician. DISCUSSION: The presentation of anaphylaxis can vary. Current diagnostic criteria can be helpful when evaluating patients for anaphylaxis, though multiple criteria exist. While the most common causes of anaphylaxis include medications, insect venom, and foods, recent literature has identified an IgE antibody response to mammalian galactose alpha-1,3-galactose, known as alpha-gal anaphylaxis. Epinephrine is the first-line therapy and is given in doses of 0.01 mg/kg (up to 0.5 mg in adults) intramuscularly (IM) in the anterolateral thigh. Intravenous (IV) epinephrine administration is recommended in patients refractory to IM epinephrine and IV fluids, or those with cardiovascular collapse. Antihistamines and glucocorticoids should not delay administration of epinephrine and do not demonstrate a significant reduction in risk of biphasic reactions. Biphasic reactions may affect 1-7% of patients with anaphylaxis. Risk factors for biphasic reaction include severe initial presentation and repeated doses of epinephrine. Disposition of patients with anaphylaxis requires consideration of several factors. CONCLUSIONS: Emergency clinicians must be aware of current updates in the evaluation and management of this disease.

Delayed symptoms and orthostatic intolerance following peanut challenge.

BACKGROUND: Clinical reactions to Oral Food Challenge (OFC) in peanut-allergic individuals have been well-characterised, but rates and phenotypes of symptom recurrence beyond the first hour after objective symptoms are less well-characterised. OBJECTIVE: To evaluate the rate of new-onset symptoms occurring at least 1 h after stopping OFC in peanut-allergic children and adults undergoing peanut-OFC. METHODS: We prospectively collected data relating to adverse events following positive reactions at double-blind, placebo-controlled food challenges (DBPCFC) to peanut in children and adults evaluated for eligibility to participate in two clinical trials (NCT02149719, NCT02665793). The trials included people aged 8 to 45 with primary, IgE-mediated peanut allergy at DBPCFC. The challenge protocol included consumption of a light meal 1 h after reaction. RESULTS: A total of 121 participants (64 children, 57 adults) had immediate, objective symptoms at DBPCFC, 25 (17 children, 8 adults) with anaphylaxis. Thirty-three (27%) had progression or recurrence of symptoms ≥ 1 h after objective clinical reaction, of whom 8 developed anaphylaxis. In 23 cases, the onset of new symptoms was associated with consumption of a light meal. In eight cases, symptoms were limited to a symptomatic postural fall in blood pressure noted in preparation for discharge, without any other new features of an allergic reaction. CONCLUSIONS & CLINICAL RELEVANCE: Progressive or new-onset symptoms ≥1 h following initial allergic reaction at OFC are common and can include orthostatic hypotension. Recurrent symptoms may be temporally associated with food consumption.

Cardiovascular changes during peanut-induced allergic reactions in human subjects.

BACKGROUND: Food allergy is the most common cause of anaphylaxis. Changes in posture during acute reactions can trigger fatal outcomes, but the impact of allergic reactions on the cardiovascular system in nonfatal reactions remains poorly understood. OBJECTIVE: Our aim was to systematically evaluate changes in cardiovascular function during acute allergic reactions to peanut. METHODS: Participants underwent double-blind placebo-controlled food challenge to peanut as part of a clinical trial. Changes in hemodynamic parameters (heart rate, stroke volume, blood pressure, and peripheral blood flow) and electrocardiogram findings during food challenges were assessed using noninvasive continuous monitoring. RESULTS: A total of 57 adults (median age 24 years [interquartile range = 20-29]), 53% of whom were female, participated; 22 (39%) had anaphylaxis. Acute reactions were associated with significant changes in stroke volume (mean decrease of 4.2% [95% CI = 0.8-7.6; P = .03]), heart rate (mean increase 11.6% [95% CI = 8.4-14.8; P < .0001]), and peripheral blood flow (mean increase 19.7% [95% CI = 10.8-28.6; P < .0001]), irrespective of reaction severity. These changes were reproduced at a subsequent repeat peanut challenge in 26 participants, and could be reversed with administration of intravenous fluids which resulted in faster resolution of abdominal symptoms. CONCLUSIONS: In this first detailed human study of cardiovascular changes during food-induced allergic reactions, we found evidence for significant fluid redistribution, independent of reaction severity. This provides a sound rationale for optimizing venous return during significant allergic reactions to food. Finally, these data provide a new paradigm for understanding severity in anaphylaxis, in which poor outcomes may occur as a result of a failure in compensatory mechanisms.

Phenotype and risk factors of venom-induced anaphylaxis: A case-control study of the European Anaphylaxis Registry.

BACKGROUND: Venom-induced anaphylaxis (VIA) is a common, potentially life-threatening hypersensitivity reaction associated with (1) a specific symptom profile, 2) specific cofactors, and 3) specific management. Identifying the differences in phenotypes of anaphylaxis is crucial for future management guidelines and development of a personalized medicine approach. OBJECTIVE: This study aimed to evaluate the phenotype and risk factors of VIA. METHODS: Using data from the European Anaphylaxis Registry (12,874 cases), we identified 3,612 patients with VIA and analyzed their cases in comparison with sex- and age-matched anaphylaxis cases triggered by other elicitors (non-VIA cases [n = 3,605]). RESULTS: VIA more frequently involved more than 3 organ systems and was associated with cardiovascular symptoms. The absence of skin symptoms during anaphylaxis was correlated with baseline serum tryptase level and was associated with an increased risk of a severe reaction. Intramuscular or intravenous epinephrine was administered significantly less often in VIA, in particular, in patients without a history of anaphylaxis. A baseline serum tryptase level within the upper normal range (8-11.5 ng/mL) was more frequently associated with severe anaphylaxis. CONCLUSION: Using a large cohort of VIA cases, we have validated that patients with intermediate baseline serum tryptase levels (8-11 ng/mL) and without skin involvement have a higher risk of severe VIA. Patients receiving ß-blockers or angiotensin-converting enzyme inhibitors had a higher risk of developing severe cardiovascular symptoms (including cardiac arrest) in VIA and non-VIA cases. Patients experiencing VIA received epinephrine less frequently than did cases with non-VIA.

Assessment of ED triage of anaphylaxis patients based on the Emergency Severity Index.

OBJECTIVES: To describe the emergency department (ED) triage of anaphylaxis patients based on the Emergency Severity Index (ESI), assess the association between ESI triage level and ED epinephrine administration, and determine characteristics associated with lower acuity triage ESI assignment (levels 3 and 4). METHODS: We conducted a cohort study of adult and pediatric anaphylaxis patients between September 2010 and September 2018 at an academic ED. Patient characteristics and management were compared between Emergency Severity Index (ESI) triage level 1 or 2 versus levels 3 or 4 using logistic regression analysis. We adhered to STROBE reporting guidelines. RESULTS: A total of 1090 patient visits were included. There were 26 (2%), 515 (47%), 489 (45%), and 60 (6%) visits that were assigned an ESI triage level of 1, 2, 3, and 4, respectively. Epinephrine was administered in the ED to 53% of patients triaged ESI level 1 or 2 and to 40% of patients triaged ESI level 3 or 4. Patients who were assigned a lower acuity ESI level of 3 or 4 had a longer median time from ED arrival to epinephrine administration compared to those with a higher acuity ESI level of 1 or 2 (28 min compared to 13 min, p < .001). A lower acuity ESI level was more likely to be assigned to visits with a chief concern of hives, rash, or pruritus (OR 2.33 [95% CI, 1.20-4.53]) and less likely to be assigned to visits among adults (OR, 0.43 [0.31-0.60]), patients who received epinephrine from emergency medical services (OR 0.56 [0.38-0.82]), presented with posterior pharyngeal or uvular angioedema (OR, 0.56 [0.38-0.82]), hypoxemia (OR, 0.34 [0.18-0.64]), or increased heart (OR 0.83 [0.73-0.95]) or respiratory (OR 0.70 [0.60-0.82]) rates. CONCLUSION: Patients triaged to lower acuity ESI levels experienced delays in ED epinephrine administration. Adult and pediatric patients with skin-related chief concerns were more likely to be to be assigned lower acuity ESI levels. Further studies are needed to identify interventions that will improve ED anaphylaxis triage.

Severe Bronchoconstriction Caused by Administration of Rocuronium in a 3-Month-Old Infant: Case Report.

We present the case of a 3-month-old infant with severe, persistent bronchoconstriction following administration of rocuronium. This observation raises awareness of a rare but potentially life-threatening reaction to neuromuscular blocking agents.

[Update on perioperative hypersensitivity reactions: joint document from the Brazilian Society of Anesthesiology (SBA) and Brazilian Association of Allergy and Immunology (ASBAI) - Part II: etiology and diagnosis]. / Atualização sobre reações de hipersensibilidade perioperatória: documento conjunto da Sociedade Brasileira de Anestesiologia (SBA) e Associação Brasileira de Alergia e Imunologia (ASBAI) ­ Parte II: etiologia e diagnóstico.

This second joint document, written by experts from the Brazilian Association of Allergy and Immunology (ASBAI) and Brazilian Society of Anesthesiology (SBA) concerned with perioperative anaphylaxis, aims to review the pathophysiological reaction mechanisms, triggering agents (in adults and children), and the approach for diagnosis during and after an episode of anaphylaxis. As anaphylaxis assessment is extensive, the identification of medications, antiseptics and other substances used at each setting, the comprehensive data documentation, and the use of standardized nomenclature are key points for obtaining more consistent epidemiological information on perioperative anaphylaxis.

Update on perioperative hypersensitivity reactions: joint document from the Brazilian Society of Anesthesiology (SBA) and Brazilian Association of Allergy and Immunology (ASBAI) - Part II: etiology and diagnosis / Atualização sobre reações de hipersensibilidade perioperatória: documento conjunto da Sociedade Brasileira de Anestesiologia (SBA) e Associação Brasileira de Alergia e Imunologia (ASBAI) - Parte II: etiologia e diagnóstico

Abstract This second joint document, written by experts from the Brazilian Association of Allergy and Immunology (ASBAI) and Brazilian Society of Anesthesiology (SBA) concerned with perioperative anaphylaxis, aims to review the pathophysiological reaction mechanisms, triggering agents (in adults and children), and the approach for diagnosis during and after an episode of anaphylaxis. As anaphylaxis assessment is extensive, the identification of medications, antiseptics and other substances used at each setting, the comprehensive data documentation, and the use of standardized nomenclature are key points for obtaining more consistent epidemiological information on perioperative anaphylaxis.

Resumo Este segundo documento, escrito por especialistas da Associação Brasileira de Alergia e Imunologia (ASBAI) e da Sociedade Brasileira de Anestesiologia (SBA) interessados no tema anafilaxia perioperatória, tem por objetivo revisar os mecanismos fisiopatológicos, agentes desencadeantes (em adultos e crianças), assim como a abordagem diagnóstica durante e após o episódio. Por se tratar de uma avaliação abrangente, a identificação das medicações, antissépticos e outras substâncias usadas em cada região, registros detalhados, e nomenclatura padronizada são pontos fundamentais para a obtenção de dados epidemiológicos mais fidedignos sobre a anafilaxia perioperatória.

Update on perioperative hypersensitivity reactions: joint document of the Brazilian Society of Anesthesiology (SBA) and Brazilian Association of Allergy and Immunology (ASBAI) - Part I: post-crisis guidelines and treatment / Atualização sobre reações de hipersensibilidade perioperatória: documento conjunto da Sociedade Brasileira de Anestesiologia (SBA) e Associação Brasileira de Alergia e Imunologia (ASBAI) - Parte I: tratamento e orientação pós-crise

Abstract Experts from the Brazilian Association of Allergy and Immunology (ASBAI) and the Brazilian Society of Anesthesiology (SBA) interested in the issue of perioperative anaphylaxis, and aiming to strengthen the collaboration between the two societies, combined efforts to study the topic and to prepare a joint document to guide specialists in both areas. The purpose of the present series of two articles was to report the most recent evidence based on the collaborative assessment between both societies. This first article will consider the updated definitions, treatment and guidelines after a perioperative crisis. The following article will discuss the major etiologic agents, how to proceed with the investigation, and the appropriate tests.

Resumo Especialistas da Associação Brasileira de Alergia e Imunologia (ASBAI) e da Sociedade Brasileira de Anestesiologia (SBA) interessados no tema anafilaxia perioperatória reuniram-se com o objetivo de intensificar a colaboração entre as duas sociedades no estudo desse tema e elaborar um documento conjunto que possa guiar os especialistas de ambas as áreas. O objetivo desta série de dois artigos foi mostrar as evidências mais recentes alicerçadas na visão colaborativa entre as sociedades. Este primeiro artigo versará sobre as definições mais atuais, formas de tratamento e as orientações após a crise no perioperatório. No próximo artigo serão discutidos os principais agentes causais e a condução da investigação com testes apropriados.

Early Skin Test after Anaphylaxis during Induction of Anesthesia: A Case Report.

BACKGROUND: It is recommended that a skin test be performed 4-6 weeks after anaphylaxis. However, there is little evidence about the timing of the skin test when there is a need to identify the cause within 4-6 weeks. CASE REPORT: A 57-year-old woman was scheduled to undergo surgery via a sphenoidal approach to remove a pituitary macroadenoma. Immediately after the administration of rocuronium, pulse rate increased to 120 beats/min and blood pressure dropped to 77/36 mmHg. At the same time, generalized urticaria and tongue edema were observed. Epinephrine was administered and the surgery was postponed. Reoperation was planned two weeks after the event. Four days after the anaphylactic episode, rocuronium was confirmed to be the cause by the skin prick test. Cisatracurium, which showed a negative reaction, was selected as an alternative agent for future procedures. Two weeks later, the patient underwent reoperation without any adverse events. CONCLUSIONS: The early skin test can be performed if there is a need even earlier than 4-6 weeks after anaphylaxis.

[Management of perioperative anaphylaxis]. / Management der Anaphylaxie im OP.

The term anaphylaxis describes a severe, potentially life-threatening allergic reaction. It is caused by an acute, systemic immune response to substances against which in most cases a previous sensitization has taken place. An anaphylactic reaction can affect every organ system of the human body. The first signs of an allergic shock are symptoms such as hypotension, tachycardia, exanthema and dyspnea. The complete expression of anaphylactic shock can occur very quickly. A perioperative anaphylaxis, in particular, is not always easy to recognize. Therefore, it is important to know the possible perioperative triggers of anaphylaxis, for instance neuromuscular blocking agents and antibiotics. The treatment has to be initiated quickly to save the life of the patient. The rapid injection of epinephrine and intravenous fluid administration are most important.