Management of anaphylactic shock in the operating room

Hymenoptera Venom Immunotherapy in Dogs: Safety and Clinical Efficacy

Hymenoptera allergens are the main triggers for anaphylaxis in susceptible dogs and humans. Hymenoptera venom specific immunotherapy (VIT), the only disease-modifying treatment, has the potential to prevent future life-threatening reactions in human patients. Prospective clinical data on VIT efficacy in dogs are currently lacking. Therefore, the aim of this study was to show that VIT is not only safe but also efficacious in preventing anaphylaxis in dogs allergic to Hymenoptera. This uncontrolled prospective clinical trial included 10 client-owned dogs with a history of anaphylaxis following repeated Hymenoptera stings. The sensitization to bee and wasp allergens was demonstrated by intradermal testing (IDT) and allergen-specific IgE serology. For VIT induction (induction phase), dogs received a shortened rush immunotherapy protocol with aqueous allergens, which was then followed by monthly injections of 100 µg of alum-precipitated allergen (maintenance phase). VIT efficacy was determined by observing patients' clinical reactions to re-stings. No systemic adverse events were seen during the induction and maintenance phases. From the seven re-stung dogs, only one developed a mild angioedema at the site of the sting; the remaining dogs were asymptomatic. These results show that VIT represents a safe and effective treatment option for Hymenoptera-allergic dogs.

Multifactorial Shock: A Neglected Situation in Polytrauma Patients

Background: Shock after traumatic injury is likely to be hypovolemic, but different types of shock (distributive shock, obstructive shock, or cardiogenic shock) can occur in combination, known as multifactorial shock. Multifactorial shock is a neglected area of study, and is only reported sporadically. Little is known about the incidence, characteristics, and outcomes of multifactorial shock after polytrauma. Methods: A retrospective, observational, multicenter study was conducted in four Level I trauma centers involving 1051 polytrauma patients from June 2020 to April 2022. Results: The mean Injury Severity Score (ISS) was 31.1, indicating a severely injured population. The most common type of shock in the early phase after polytrauma (≤48 h) is hypovolemic shock (83.2%), followed by distributive shock (14.4%), obstructive shock (8.7%), and cardiogenic shock (3.8%). In the middle phase after polytrauma (>48 h or ≤14 days), the most common type of shock is distributive shock (70.7%), followed by hypovolemic shock (27.2%), obstructive shock (9.9%), and cardiogenic shock (7.2%). Multifactorial shock accounted for 9.7% of the entire shock population in the early phase and 15.2% in the middle phase. In total, seven combinations of multifactorial shock were described. Patients with multifactorial shock have a significantly higher complication rate and mortality than those with single-factor shock. Conclusions: This study characterizes the incidence of various types of shock in different phases after polytrauma and emphasizes that different types of shock can occur simultaneously or sequentially in polytrauma patients. Multifactorial shock has a relatively high incidence and mortality in polytrauma patients, and trauma specialists should be alert to the possibility of their occurrence.

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

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

Proteomic and Biological Analysis of an In Vitro Human Endothelial System in Response to Drug Anaphylaxis

Anaphylaxis is a life-threatening systemic hypersensitivity reaction. During anaphylaxis, mediator release by effector cells causes endothelial barrier breakdown, increasing vascular permeability and leakage of fluids, which may lead to tissue edema. Although endothelial cells (ECs) are key players in this context, scant attention has been paid to the molecular analysis of the vascular system, and further analyses of this cell type are necessary, especially in humans. The protein expression pattern of human microvascular ECs was analyzed in response to sera from anaphylactic patients (EC-anaphylaxis) and sera from non-allergic subjects (EC-control) after 2 hours of contact. Firstly, a differential quantitative proteomic analysis of the protein extracts was performed by mass spectrometry using an isobaric labeling method. Second, the coordinated behavior of the identified proteins was analyzed using systems biology analysis (SBA). The proteome of the EC-anaphylaxis system showed 7,707 proteins, of which 1,069 were found to be significantly altered between the EC-control and EC-anaphylaxis groups (p-value < 0.05). Among them, a subproteome of 47 proteins presented a high rate of change (|ΔZq| ≥ 3). This panel offers an endothelial snapshot of the anaphylactic reaction. Those proteins with the highest individual changes in abundance were hemoglobin subunits and structural support proteins. The interacting network analysis of this altered subproteome revealed that the coagulation and complement systems are the main biological processes altered in the EC-anaphylactic system. The comprehensive SBA resulted in 5,512 functional subcategories (biological processes), 57 of which were significantly altered between EC-control and EC-anaphylaxis. The complement system, once again, was observed as the main process altered in the EC system created with serum from anaphylactic patients. Findings of the current study further our understanding of the underlying pathophysiological mechanisms operating in anaphylactic reactions. New target proteins and relevant signaling pathways operating in the in vitro endothelial-serum system have been identified. Interestingly, our results offer a protein overview of the micro-EC-anaphylaxis environment. The relevance of the coagulation, fibrinolytic, contact and complement systems in human anaphylaxis is described. Additionally, the untargeted high-throughput analysis used here is a novel approach that reveals new pathways in the study of the endothelial niche in anaphylaxis.

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

OBJECTIVES

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

DATA SOURCES

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

STUDY SELECTION

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

DATA EXTRACTION

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

DATA SYNTHESIS

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

CONCLUSION

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

[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]

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.

Platelets expressing IgG receptor FcγRIIA/CD32A determine the severity of experimental anaphylaxis

Platelets are key regulators of vascular integrity; however, their role in anaphylaxis, a life-threatening systemic allergic reaction characterized by the loss of vascular integrity and vascular leakage, remains unknown. Anaphylaxis is a consequence of inappropriate cellular responses triggered by antibodies to generally harmless antigens, resulting in a massive mediator release and rapidly occurring organ dysfunction. Human platelets express receptors for immunoglobulin G (IgG) antibodies and can release potent mediators, yet their contribution to anaphylaxis has not been previously addressed in mouse models, probably because mice do not express IgG receptors on platelets. We investigated the contribution of platelets to IgG-dependent anaphylaxis in human IgG receptor-expressing mouse models and a cohort of patients suffering from drug-induced anaphylaxis. Platelet counts dropped immediately and markedly upon anaphylaxis induction only when they expressed the human IgG receptor FcγRIIA/CD32A. Platelet depletion attenuated anaphylaxis, whereas thrombocythemia substantially worsened its severity. FcγRIIA-expressing platelets were directly activated by IgG immune complexes in vivo and were sufficient to restore susceptibility to anaphylaxis in resistant mice. Serotonin released by activated platelets contributed to anaphylaxis severity. Data from a cohort of patients suffering from drug-induced anaphylaxis indicated that platelet activation was associated with anaphylaxis severity and was accompanied by a reduction in circulating platelet numbers. Our findings identify platelets as critical players in IgG-dependent anaphylaxis and provide a rationale for the design of platelet-targeting strategies to attenuate the severity of anaphylactic reactions.

Risk factors and treatment of refractory anaphylaxis - a review of case reports

INTRODUCTION

Patients experiencing anaphylaxis who do not recover after treatment with intramuscular adrenaline are regarded as suffering from refractory anaphylaxis. The incidence of refractory anaphylaxis is estimated to range between 3-5% of anaphylaxis cases. The risk factors for refractory anaphylaxis are unknown. Areas covered: In the present analysis, we aimed to evaluate the management and risk factors of refractory anaphylaxis to highlight possible clinical implications for updating current management algorithms. Expert commentary: According to international guidelines, adrenaline given through the intramuscular (i.m.) route is a rapid and safe treatment but may be insufficient. Therefore, defined standardized treatment protocols for such cases of refractory anaphylaxis are needed to optimize the treatment. Point-of-care diagnostics may enable doctors to identify patients experiencing severe, refractory anaphylaxis early in order to initiate intensified critical care treatment.

Anaphylaxis

Anaphylaxis is a systemic, life-threatening disorder triggered by mediators released by mast cells and basophils activated via allergic (IgE-mediated) or nonallergic (non-IgE-mediated) mechanisms. It is a rapidly evolving, multisystem process involving the integumentary, pulmonary, gastrointestinal, and cardiovascular systems. Anaphylaxis and angioedema are serious disorders that can lead to fatal airway obstruction and culminate in cardiorespiratory arrest, resulting in hypoxemia and/or shock. Often, these disorders can be appropriately managed in an outpatient setting; however, these conditions can be severe enough to warrant evaluation of the patient in the ED and in some cases, hospitalization, and management in an ICU. Reports suggest that underdiagnosis and undertreatment of anaphylaxis are common. Several new syndromes have been described recently including bird-egg, pork-cat, delayed allergy to mammalian meat and a diverse group of mast cell activation disorders. Conditions such as postural orthostatic tachycardia syndrome, carcinoid syndrome, Munchausen stridor, and factitious anaphylaxis can present similarly and need to be included in the differential diagnosis. Anaphylaxis is a clinical diagnosis, but plasma tryptase and urinary histamine levels are often elevated, allowing diagnostic confirmation; however, diagnostic testing should not delay treatment as results may not be immediately available. The sine qua non of treatment is avoidance of any known triggers and epinephrine, which should never be delayed if this disorder is suspected. Secondary treatments include fluids, bronchodilators, antihistamines, and glucocorticoids. Patients with cardiopulmonary arrest or airway or vascular compromise require mechanical ventilation, vasopressors, and other advanced life support in the ICU.