Emerging concepts in the diagnosis and treatment of patients with undifferentiated angioedema

Management of angioedema without urticaria in the emergency department

Angioedema refers to a localized, transient swelling of the deep skin layers or the upper respiratory or gastrointestinal mucosa. It develops as a result of mainly two different vasoactive peptides, histamine or bradykinin. Pathophysiology, as well as treatment, is different in each case; nevertheless, the resulting signs and symptoms may be similar and difficult to distinguish. Angioedema may occur at any location. When the affected area involves the upper respiratory tract, both forms of angioedema can lead to an imminent upper airway obstruction and a life-threatening emergency. Emergency physicians must have a basic understanding of the pathophysiology underlying this process. Angioedema evaluation in the emergency department (ED) should aim to distinguish between histamine- and bradykinin-induced angioedema, in order to provide appropriate treatment to patients. However, diagnostic methods are not available at the ED setting, neither to confirm one mechanism or the other, nor to identify a cause. For this reason, the management of angioedema should rely on clinical data depending on the particular features of the episode and the patient in each case. The history-taking should be addressed to identify a possible etiology or triggering agent, recording complete information for an ulterior diagnostic study in the outpatient clinic. It is mandatory quickly to recognize and treat a potential life-threatening upper airway obstruction or anaphylaxis. This review focuses on the underlying mechanisms and management of histamine- and bradykinin-induced angioedema at the emergency department and provides an update on the currently available treatments.

Angioedema in the neurointerventional suite

A 68-year-old woman with acute ischemic stroke presented for mechanical thrombectomy, after failed thrombolysis with intravenous recombinant tissue plasminogen activator. The procedure was completed successfully with dexmedetomidine infusion. However, she developed acute angioedema toward the end of the procedure requiring emergent fiberoptic-guided endotracheal intubation. Angioedema has been reported to occur after administering intravenous recombinant tissue plasminogen activator with an incidence of 1.3%-5.1% in patients with acute stroke.

Bradykinin B2 Receptor Antagonist off Label Use in Short-Term Prophylaxis in Hereditary Angioedema

Hereditary angioedema type I (HAE-C1-INH) is an inherited disorder characterized by repeated severe angioedema attacks mostly triggered by traumas, emotional stress, increased estrogen levels or surgical procedures, in particular, odontostomatological interventions. Icatibant, a bradykinin B2 receptor antagonist, has been approved for treatment of HAE attacks. In this paper we describe the “off label” administration of icatibant as short-term prophylaxis of dental extraction in a patient with HAE with the aim of preventing perioperative angioedema attacks. The drug showed an effective and safe profile. Thus, a short-term prophylaxis of angioedema attacks in patients with HAE may be arranged on a multidisciplinary basis, according to the clinical history of each single patients.

A consensus parameter for the evaluation and management of angioedema in the emergency department

Despite its relatively common occurrence and life-threatening potential, the management of angioedema in the emergency department (ED) is lacking in terms of a structured approach. It is paramount to distinguish the different etiologies of angioedema from one another and more specifically differentiate histaminergic-mediated angioedema from bradykinin-mediated angioedema, especially in lieu of the more novel treatments that have recently become available for bradykinin-mediated angioedema. With this background in mind, this consensus parameter for the evaluation and management of angioedema attempts to provide a working framework for emergency physicians (EPs) in approaching the patient with angioedema in terms of diagnosis and management in the ED. This consensus parameter was developed from a collaborative effort among a group of EPs and leading allergists with expertise in angioedema. After rigorous debate, review of the literature, and expert opinion, the following consensus guideline document was created. The document has been endorsed by the American College of Allergy, Asthma & Immunology (ACAAI) and the Society for Academic Emergency Medicine (SAEM).

Guidance for diagnosis and treatment of acute angioedema in the emergency department: consensus statement by a panel of Italian experts

Angioedema attacks, characterized by the transient swelling of the skin and mucosae, are a frequent cause of visits to the emergency department. Swellings of the oral cavity, tongue, or larynx can result in life-threatening airway obstruction, while abdominal attacks can cause severe pain and often lead to unnecessary surgery. The underlying pathophysiologic process resulting in increased vascular permeability and plasma extravasation is mediated by vasoactive molecules, most commonly histamine and bradykinin. Based on the mediator involved, distinct angioedema forms can be recognized, calling for distinct therapeutic approaches. Prompt recognition is challenging for the emergency physician. The low awareness among physicians of the existence of rare forms of angioedema with different aetiologies and pathogenesis, considerably adds to the problem. Also poorly appreciated by emergency personnel may be the recently introduced bradykinin-targeted treatments. The main objective of this consensus statement is to provide guidance for the management of acute angioedema in the emergency department, from presentation to discharge or hospital admission, with a focus on identifying patients in whom new treatments may prevent invasive intervention.

ACE inhibitor-induced angioedema

Angiotensin-converting enzyme inhibitors (ACEI) are commonly prescribed for blood pressure control and renal protection. ACEI angioedema is a common problem in patients who are taking ACEI, although, in most cases, the disorder is self-limited, and spontaneous episodes of apparently unprovoked angioedema stop with the discontinuation of the medication. In a subset of patients, hospitalization and even intubation are required for airway protection. The diagnosis is made clinically. There are no laboratory studies that establish the diagnosis. However, such investigations help exclude alternative diagnoses as the cause for the patient's presentation. Conventional treatment with regimens used to control allergic angioedema is ineffective in this condition. The mechanism of ACEI-induced angioedema is thought to be related to its effect on the kallikrein-kinin system. Kallikrein is a protease that converts high-molecular-weight kininogens into kinins, primarily bradykinin. Medications recently developed, primarily icatibant and ecallantide, to control hereditary angioedema, a disorder also associated with kallikrein-kinin activation, have been used to treat ACEI angioedema with some success. The efficacy of these agents and their optimal use remains to be established by randomized and placebo controlled trials.

Targeting the 'Janus face' of the B2-bradykinin receptor

INTRODUCTION

Kinins are main active mediators of the kallikrein-kinin system (KKS) via bradykinin type 1 inducible (B1R) and type 2 constitutive (B2R) receptors. B2R mediates most physiological bradykinin (BK) responses, including vasodilation, natriuresis, NO, prostaglandins release.

AREAS COVERED

The article summarizes knowledge on kinins, B2R signaling and biological functions; highlights crosstalks between B2R and renin-angiotensin system (RAS). The double role (Janus face) in physiopathology, namely the beneficial protection of the endothelium, which forms the basis for the therapeutical utilization of B2 receptor agonists, on the one side, and the involvement of B2R in inflammation or infection diseases and in pain mechanisms, which justifies the use of B2R antagonists, on the other side, is extensively analyzed.

EXPERT OPINION

For decades, the B2R has been unconsciously activated during angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) treatments. Whether direct B2R targeting with stable agonists could bring additional therapeutic benefit to RAS inhibition should be investigated. Efficacy, established in experimental models, should be confirmed by translational studies in cardiovascular pathologies, glaucoma, Duchenne cardiopathy and during brain cancer therapy. The other face of B2R is targeted by antagonists already approved to treat hereditary angioedema. The use of antagonists could be extended to other angioedema and efficacy tested against acute pain and inflammatory diseases.