CLASSIFICATION OF ALLERGIC REACTIONS
Allergic reactions can be classified using the Coombs and Gell Classification System into one of four immunopathologic categories (types I through IV). The following table summarizes the key characteristics of each type of reaction.
|
Type |
Characteristics |
Usual Onset |
Examples |
|
I - Anaphylactic (IgE mediated) |
Requires the presence of IgE specific for drug antigen or other allergen; allergen binds to IgE on basophils and mast cells resulting in release of inflammatory mediators (eg, histamine, serotonin, proteases, bradykinin generating factor, eosinophil chemotactic factors, neutrophil chemotactic factor, leukotrienes, prostaglandins, thromboxanes) |
Within 30 minutes |
Immediate penicillin reaction Immediate latex reaction Blood products Vaccines Dextran Polypeptide hormones |
|
II - Cytotoxic |
Destruction of host cells; cell-associated antigen initiates cytolysis by antigen-specific antibody (IgG or IgM); most often involves blood elements (eg, erythrocytes, leukocytes, platelets) |
Usually 5-12 hours |
Penicillin, quinidine, phenylbutazone, thiouracils, sulfonamides, methyldopa |
|
III - Immune complex |
Antigen-antibody complexes form and deposit on blood vessel walls and activate complement. Result is a serum-sickness-like syndrome. |
3-8 hours |
Serum sickness; may be caused by penicillins, sulfonamides, I.V. contrast media, hydantoins |
|
IV - Cell mediated (delayed) |
Antigens cause activation of lymphocytes (T cells), which release inflammatory mediators |
24-48 hours |
Graft rejection Latex contact dermatitis Tuberculin reaction |
|
Modified from DiPiro JT and Stafford CT, "Allergic and Pseudoallergic Drug Reactions,"Pharmacotherapy: A Pathophysiologic Approach, 3rd ed, Stamford CT: Appleton and Lange, 1997, 1675-88. |
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SIGNS/SYMPTOMS OF ANAPHYLACTIC REACTION
The following table lists the signs and symptoms that may indicate an anaphylactic reaction during anesthesia.
|
Systems |
Symptoms |
Signs |
|
Cutaneous |
Itching, burning |
Urticaria (hives), flushing, periorbital edema, perioral edema |
|
Respiratory |
Dyspnea, chest tightness |
Coughing, wheezing, sneezing, laryngeal edema, decreased pulmonary compliance, pulmonary edema, acute respiratory distress, bronchospasm |
|
Cardiovascular |
Dizziness, malaise, retrosternal oppression |
Disorientation, diaphoresis, loss of consciousness, hypotension, tachycardia, dysrhythmias, decreased systemic vascular resistance, pulmonary hypertension, cardiovascular collapse |
|
Modified from Levy JH, Anaphylactic Reactions in Anesthesia and Intensive Care, Stoneham, Butterworth-Heinemann, 1992. |
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TREATMENT OF ANAPHYLACTIC REACTION
Treatment of a severe, life-threatening anaphylactic reaction must be immediate. Initial therapy should consist of: 1) stop administration of precipitating drug; 2) maintain airway with 100% oxygen; 3) discontinue all anesthetic agents; 4) intravascular volume expansion with crystalloid solution; and 5) epinephrine administration. Secondary therapy consists of administration of antihistamines (eg, diphenhydramine ), catecholamine infusions (eg, norepinephrine , epinephrine, inhaled bronchodilators (eg, albuterol ) for bronchospasm, corticosteroids (eg, hydrocortisone , methylprednisolone , dexamethasone ), and sodium bicarbonate . Patients should be admitted to an ICU for 24 hours following an anaphylactic reaction because of the possibility of recurrent "late-phase" reactions.