Skip to Main Content


This 25-year-old black woman presents to the emergency department (ED) 2 hours after the onset of lip swelling that has progressed to difficulty in breathing. With the exception of newly diagnosed hypertension, she is otherwise well. Last week, her primary care physician began a course of a new antihypertensive medication, lisinopril. She has had no history of swelling and there is no family history of disorders characterized by swelling. Her vital signs are temperature 37°C, heart rate (HR) 100 beats per minute (bpm), respiratory rate (RR) 22 breaths per minute, blood pressure (bp) 165/90 mm Hg, and SpO2 is 99% on 2 L·min−1 of O2 by nasal prongs.


The patient is seated (Figure 24-1) with markedly edematous lips. She has a muffled voice (hot potato voice) and is unable to swallow her own secretions due to the swelling. There is no stridor. The remainder of the physical examination is unremarkable.

Figure 24-1.
Graphic Jump Location

Patient with angioedema.


24.2.1 What Is the Pathophysiology of Angioedema?


Angioedema is defined as the abrupt onset of non-pitting swelling of the skin, mucous membranes, and deep subcutaneous tissues, including the linings of the upper respiratory and intestinal tracts.1 Angioedema develops because of a local increase in permeability of the submucosal or subcutaneous capillary vessels, causing local plasma extravasation. This is exacerbated by the release of vasoactive substances such as histamines, prostaglandins, bradykinins, and cytokines.2 Angioedema can be divided into hereditary angioedema (HAE) and acquired angioedema.


Hereditary angioedema is extremely rare, affecting 1 in 50,000 people.2 It develops due to a C1 esterase inhibitor deficiency, which is inherited in an autosomal dominant pattern. This deficiency results in an abnormal increase in the activation of C1 and subsequently excessive formation of the enzyme kallikrein. The excess kallikrein transforms kininogen into kinins, including bradykinin. Bradykinin is highly vasoactive and produces the characteristic tissue swelling.2 HAE is commonly precipitated by trauma and stress, and can recur. If the patient has known HAE, then treatment with fresh frozen plasma (FFP) is beneficial, as it contains C1 esterase inhibitor. In some centers, vapor-heated C1 inhibitor concentrate is available and is proving beneficial in recurrent attacks of HAE.2


Acquired angioedema is due to faulty activation of the complement and kallikrein–kinin systems. It comprises several types, including the traditional IgE-mediated allergic response, precipitated by exposure to an allergen (such as peanuts, antibiotics, and shellfish). Anaphylaxis is characterized by an acute onset and not only causes angioedema of the upper airways but also has a more systemic effect causing wheeze secondary to bronchoconstriction and hypotension secondary to vasodilation and third spacing.3 Anaphylaxis (or anaphylactoid) reactions can cause angioedema through other mechanisms such as direct mast cell degranulation (opiates, radio-contrast media) or by altering arachidonic acid metabolism (benzoates, angiotensin-converting enzyme inhibitors ...

Want remote access to your institution's subscription?

Sign in to your MyAccess profile while you are actively authenticated on this site via your institution (you will be able to verify this by looking at the top right corner of the screen - if you see your institution's name, you are authenticated). Once logged in to your MyAccess profile, you will be able to access your institution's subscription for 90 days from any location. You must be logged in while authenticated at least once every 90 days to maintain this remote access.


About MyAccess

If your institution subscribes to this resource, and you don't have a MyAccess profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus.

Subscription Options

AccessAnesthesiology Full Site: One-Year Subscription

Connect to the full suite of AccessAnesthesiology content and resources including procedural videos, interactive self-assessment, real-life cases, 20+ textbooks, and more

$995 USD
Buy Now

Pay Per View: Timed Access to all of AccessAnesthesiology

24 Hour Subscription $34.95

Buy Now

48 Hour Subscription $54.95

Buy Now

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.