Cannot Miss Diagnosis

Email Comment bookmark
Font : A-A+

Anaphylaxis
Cannot Miss Diagnosis No.5

-
Section Editor: Prof. T.K. Partha Sarathy

Anaphylaxis refers to a severe allergic reaction in which there are prominent dermal and systemic signs and symptoms. The full-blown syndrome includes urticaria (hives) and/or angioedema with hypotension and bronchospasm. The former involves prior sensitization with later re-exposure, producing symptoms via an immunologic mechanism. An anaphylactoid reaction produces a very similar clinical syndrome, but it is not immune-mediated. Treatment for both conditions is similar.


Pathophysiology: Rapid onset of increased secretion from mucous membranes, increased bronchial smooth muscle tone, decreased vascular smooth muscle tone, and increased capillary permeability occurs after exposure to an inciting substance. These effects are produced by the release of mediators, which include histamine, leukotriene C4, prostaglandin D2, and tryptase.
In the classic form, mediator release occurs when the antigen (allergen) binds to antigen-specific immunoglobulin E (IgE) attached to previously sensitized basophils and mast cells. The mediators are released almost immediately when the antigen binds. In an anaphylactoid reaction, exposure to an inciting substance causes direct release of mediators, a process that is not mediated by IgE. Increased mucous secretion and increased bronchial smooth muscle tone, as well as airway edema, contribute to the respiratory symptoms observed in anaphylaxis. Cardiovascular effects result from decreased vascular tone and capillary leakage. Histamine release in skin causes urticarial skin lesions.
The most common inciting agents in anaphylaxis are parenteral antibiotics (especially penicillins), IV contrast materials, Hymenoptera stings, and certain foods (most notably peanuts). Oral medications and many other types of exposures also have been implicated. Anaphylaxis also may be idiopathic.
Approximately 1 in 5000 exposures to a parenteral dose of a penicillin or cephalosporin antibiotic causes anaphylaxis. Between 1-2% of people receiving IV radiocontrast experience some sort of reaction. The majority of these reactions are minor, and fatalities are rare.


Clinical
History
  • Anaphylactic reactions almost always involve the skin. More than 90% of patients have some combination of urticaria, erythema, and pruritus.

  • Upper respiratory tract is commonly involved, with complaints of nasal congestion, sneezing, or coryza. Cough, hoarseness, or a sensation of tightness in the throat may presage significant airway obstruction.

  • Eyes may itch, and tearing may be noted. Conjunctival injection may occur.

  • Dyspnea will be present when patients have bronchospasm or upper airway edema. Hypoxia and hypotension may cause weakness, dizziness, or syncope. Chest pain may occur due to bronchospasm or myocardial ischemia (secondary to hypotension and hypoxia).

  • Gastrointestinal symptoms of cramp like abdominal pain with nausea, vomiting, or diarrhea also occur but are less common (except in the case of food allergy).

  • In a classic case of anaphylaxis, the patient or a bystander will provide a history of possible exposures that may have caused the rapid onset of skin and other manifestations. However, this history is often lacking.

The exposure may not be recalled, or it may not be considered as significant by the patient or physician.


Physical
General
  • Physical examination of patients with anaphylaxis is dependent upon the organ systems affected and the severity of the attack. Vital signs may be normal or significantly disordered with tachypnea, tachycardia, and/or hypotension.

  • Emphasis is placed on determining the patientís respiratory and cardiovascular status.

  • Frank cardiovascular collapse or respiratory arrest may occur in severe cases. Anxiety is common unless hypotension or hypoxia causes obtundation. Shock may occur without prominent skin manifestations or history of exposure; therefore, anaphylaxis is part of the differential diagnosis for patients who present with shock and no obvious cause.

  • General appearance and vital signs vary according to the severity of the attack and the organ system(s) affected. Commonly, patients are restless due to severe pruritus from urticaria. Anxiety, tremor, and a sensation of cold may result from compensatory endogenous catecholamine release.

Severe air hunger may occur when the respiratory tract is involved. If there is hypoperfusion or hypoxia, the patient may be agitated, may be combative, or may exhibit a depressed level of consciousness. Tachycardia is usually present, but bradycardia may occur in very severe reactions.

Post a Comment

Comments should be on the topic and should not be abusive. The editorial team reserves the right to review and moderate the comments posted on the site.
Notify me when reply is posted
I agree to the terms and conditions
Monte 

probably i m also facing the same problem since yesterday, so can you tell me about the duration until which such torsions in testes are reversible. please reply me quickly. here also the swelling is observed first time in my 19 years & is a bit painful too.

soroush 

it was better if you mentioned that his pain was acute onset or not

CME Lessons

Medindia Newsletters

Subscribe to our Free Newsletters!

Terms & Conditions and Privacy Policy.

Find a Doctor