Angioedema Causes and Treatment

Angioedema, is the rapid swelling (edema) of the dermis, subcutaneous tissue submucosal tissues, or mucous membranes as a result of vascular leakage. It is also known by the terms giant urticaria, Quincke edema, and angioneurotic edema. It is a nonpitting and nonpruritic edema. There without any color changes on the involved skin.

The lips and periorbital edema are most common manifestations. Face, hands, feet, and genitalia are other common sites.

Swelling that involves the tongue and upper airways are life-threatening and are medical emergencies.

Angioedema can affect people of all ages.

Approximately 10-20% of the population may experience at least 1 episode of angioedema during their lifetime.

Pathophysiology

Angioedema is a result of a sudden increase in local vascular permeability in subcutaneous or submucosal tissue often mediated by histamine and bradykinin.

Mast cells and basophils are the primary sources of histamine. The activation of mast cells or basophils with subsequent histamine release may be either mediated or unmediated by immunoglobulin E (IgE). IgE-mediated mast cell activation and degranulation, key elements of an allergic reaction, often manifest as urticaria and angioedema.

Hereditary angioedema (HAE), angiotensin-converting enzyme (ACE) inhibitor–induced angioedema, and certain idiopathic angioedemas are examples of bradykinin-mediated angioedema; bradykinin levels are elevated during an episode of angioedema.

Leukotriene may play an important role in the NSAIDs induced angioedema .

Urticaria and Angioedema

Two conditions are remarkably similar but the angioedema is also quite different from urticaria, in that it usually involves a deeper layer of skin (reticular dermis) whereas urticaria affects a more superficial layer of skin (papillary dermis and mid-dermis).

Mucosal involvement is observed only in angioedema but not in urticaria.

Itching is the most prominent complaint in urticaria, but it is less troublesome or absent in angioedema. Pain or tenderness is not common in urticaria but frequent or even severe in angioedema.

Classification of Angioedema

Angioedema with urticaria

Acute (< 6 weeks) or chronic (>6 weeks)
Allergic
- Food
- Insect sting
- Latex)
Pseudoallergic
- NSAIDs [aspirin most common]
- IV contrast material

Physical
- Cold
- Vibration
- Pressure
- Physical exercise
Autoimmune disease
Idiopathic

Angioedema without urticaria

Acquired Angioedema (AAE)

Idiopathic (no identifiable causes)
- Idiopathic histaminergic – Responds to antihistamines
- Idiopathic nonhistaminergic – No response to antihistamines
Acquired angioedema related to ACE Inhibitors
- Seen on On ACE inhibitor therapy
- Interfere with the degradation of bradykinin
- No other identifiable causes

C1 INH deficiency
- No family history of angioedema
- Onset > 40 years of age
- Low C1q levels
- No genetic mutation in C1 INH gene
- Secondary reduction of C1 INH function.

Hereditary Angioedema

Hereditary angioedema with C1 INH deficiency
- Impaired normal C1 INH production and/or function
- Mutation in 25% of cases
- Family history in others
Normal C1 INH
- Hereditary angioedema with FXII mutations
- Hereditary angioedema of unknown origin

Causes

Idiopathic [40%]
- Nonspecific triggers present
  - Trauma
  - Surgical procedures
  - Stress
Hypersensitivity
- Food
- Drugs
- Insect stings
- Preservatives
- Food colorants

Physical stimuli
- Cold
- Vibrations
Autoimmune disease
Infection
ACE inhibitors
NSAIDs
C1-INH deficiency

Angioedema has also been associated with certain conditions

Cytokine-associated angioedema syndrome
- Gleich syndrome or episodic angioedema with eosinophilia
Well syndrome or eosinophilic cellulitis (ie, granulomatous dermatitis with eosinophilia
Helicobacter pylori infection
Systemic viral, bacterial, or parasitic infections
Thyroid autoantibodies

Clinical Presentation

When a patient presents with angioedema, presence or absence of urticaria should be looked into. Those with urticaria are further evaluated and treated on the line of urticaria. Otherwise, the following approach is used.

The patient presents with subcutaneous swelling. Face, tongue, hands, and feet; the genitalia can be affected, and rarely, edema of the soft palate may occur.

Abdominal pain occurs from intestinal involvement. Nausea, vomiting, and ascites could be seen and sometimes presenting symptom of angioedema. Throat tightness, voice changes, and breathing problems may suggest airway involvement.

Angioedema can be acute or chronic, and each episode may last a few hours to a few days. Burning sensation and pain can be present. .

In hereditary acquired edema, idiopathic angioedema, and drug-induced angioedema, there would be of relapsing, self-limiting edema lasting for 1-7 days and are followed by a disease-free interval.

The history may reveal triggers of the attack [, such as local trauma or surgery]

On examination, the affected areas show edema of distensible tissues, often with ill-defined margins.

In severe abdominal involvement, abdominal distention and signs consistent with bowel obstruction may be present.

Patients may have only changes in bowel sounds and diffuse or localized tenderness.

Oral cavity can be visualized directly for tongue or uvula but laryngoscopy is indicated to assess laryngeal or vocal cord involvement. Family history and history about possible triggers like food, medicine etc [see causes] should be asked.

Angioedema can be life-threatening when it involves the larynx and upper airway. Throat pain or discomfort, dysphonia, and dysphasia may indicate laryngeal involvement. In severe attacks, dyspnea can indicate the onset of systemic anaphylaxis.

Differential Diagnoses

Acute Urticaria
Anaphylaxis
Cellulitis
Delayed Hypersensitivity Reactions
Allergies

Lab Studies

Mild cases of angioedema do not require any laboratory tests.

For recurrent angioedema without a clear trigger, the following tests may be considered

Complete blood count
Erythrocyte sedimentation rate
C-reactive protein (CRP) levels
D-dimer level
Urinalysis
Metabolic profile
Antinuclear antibody testing
Complement activity [CH50 level]
- If low consider C1-INH function and C1q levels
Thyroid function tests
- Thyroid-stimulating hormone
- Free T4
Thyroid autoantibody
Tests for allergy
- Food
- Stinging insects
- Latex
- Antibiotics

Other studies

Further tests are based on the initial laboratory results or to probe a specific medical condition

These include

Stool analysis for ova and parasites
H pylori workup
Hepatitis B and C workup
Rheumatoid factor
Cryoglobulin levels

In patients with recurrent angioedema without urticaria following tests should be performed establish or rule out C1-INH deficiency–associated angioedema

C1 INH levels to know the deficiency
C4 level

C1 esterase inhibitor measurements
C1q level

Imaging

Most angioedema patients do not need any imaging studies.

Abdominal imaging [x-rays or CT] reveal findings consistent with small bowel wall edema during angioedema attacks. Ascites may be seen.

Treatment of Angioedema

Emergency Care

Patients with moderate to severe angioedema often present to the emergency. Supportive care should also be provided.

Epinephrine should be used in suspected laryngeal angioedema.

For patients with a known history of hereditary angioedema, a suitable agent should be administered as soon as an angioedema attack is recognized. These agents could be any of the following

C1 esterase inhibitor [C1-INH] concentrate
Ecallantide
- Reversible inhibitor of plasma kallikrein
- Blocks its binding site and inhibits kininogen conversion to bradykinin.
Icatibant
- Inhibits the binding of bradykinin
- Treats the clinical symptoms
- Recommended dose is 30 mg subcutaneously in the abdominal area.

Airway protection is the most important consideration with laryngeal involvement.

Early intubation may be preferred. When intubation is required, the patient should be sent to intensive care unit.

Non-emergency care

Without urticaria, clinicians must rule out hereditary angioedema, acquired C1-INH deficiency, and ACE inhibitor−induced angioedema. Following triggers may be confirmed or excluded. If present and possible [like use of drugs] the triggers should be removed.

Food allergies
Drugs
Physical factors (eg, vibrations, cold or heat, or pressure)
Nonsteroidal anti-inflammatory drugs
Angiotensin-converting enzyme inhibitors

Depending on the etiology of the angioedema, management can vary. Angioedema with unidentifiable causes can be regarded as histaminergic or nonhistaminergic.

Treatment of Histaminergic Angioedema

Histaminergic angioedema could be is either immunoglobulin E (IgE)-dependent (eg, an allergic reaction to a food or drug) or IgE-independent (eg, a reaction to radiocontrast medium). NSAID-related angioedema and most cases of idiopathic angioedema are treated with the same measures.

These patients can mostly be managed well with outpatient treatment alone. Treatment includes following

Antihistamines, usually second-generation agents
- Cetirizine
- Desloratadine
- Exofenadine
- Levocetirizine
- Loratadine
Monitoring esp. in moderate to severe cases is often necessary
First-generation antihistamines as add-on therapy when a second-generation antihistamine fails
Doxepin is used in recalcitrant forms[One that does not respond to histamines]
- Tricyclic antidepressant
- Has potent H1-blocking activity.
Corticosteroid use in severe cases

Nonhistaminergic

This includes bradykinin-mediated angioedema like Ace inhibitor, hereditary, acquired, estrogen-dependent and certain types of idiopathic angioedema

Antihistamines have no role in these. Following agents are used in their treatment

In C1-INH deficiency treatment of the underlying disorder usually results in correction of the abnormality.
C1-INH deficiency can be helped by fresh frozen plasma transfusion [contains C1-INH]
Antifibrinolytic agents
- Aminocaproic acid
- Tranexamic acid
- Mechaism not known
- Not effective in histamernergic form