Urticaria And Angio-Edema: Pathology, Treatment And Prophylaxis
Treatment Of Angio Edema
Acute urticaria is less than two months duration. Urticaria of longer duration are called chronic urticarias. These tend to be recurrent. Acute form is generally due to allergic causes and it is often associated with atopy. Several allergens including drugs, injections, foods, drinks and inhaled particles can be identified in many cases but no cause is detectable in 75% of cases.
Mechanism: Urticaria is the result of capillary dilatation and exudation of serum in the corium. This is a type I antigen antibody reaction brought about by the activation of mast cells by IgE and other activators, resulting in the release of vasoactive substances like histamine, serotonin, bradykinin, etc.
Emergency treatment: Since angio-edema affecting the tongue may be fatal if it leads to obstruction of the glottis, this possibility should be kept in mind in all cases of severe urticarias, especially those arising from inhaled and ingested allergens and caused by insect bites over the head and neck. In such cases, administration of 0.5 ml of 1/1000 adrenaline subcutaneously or intramuscularly repeated 20 to 30 minutes later helps in resolving the edema and to save life. The airway should be maintained by intubation or tracheostomy if airway obstruction progresses. Oral antihistamines have to be continued after subsidence of the acute symptoms. If the patient is in shock, intravenous hydrocortisone 100 mg or betamethason, 8 mg has to be administered in a drip or as bolus doses.
Specific Drugs: Antihistamines are useful in bringing down the urticaria, provide mild sedation and relief of pruritus. Depending on the urgency of the condition, they may be given parenterally or orally. Hydroxyzine in a dose of 25 mg orally may be given at 4 to 6 hours intervals. Along with this, measures to eliminate the offending agent are also adopted. In the case of contact allergens, washing may be helpful. In the case of ingested allergens, a purgative helps in more rapid elimination. Acute urticarias respond promptly to antihistamines. Chronic urticarias do nto show complete responses to antihistamines, but they respond satisfactorily to terbutaline and ketotifen. In hereditary angio-edema, treatment with danazol in a dose of 50 to 100 mg/day is often effective. Patients with food allergy may benefit by oral therapy with disodium cromoglycate.
Treatment Of Urticaria
The offending agent should be identified and avoided. Prick tests, patch tests, and provocation tests are used to identify the allergens. These are useful in trained hands. If infective causes or parasites are demonstrable, their eradication helps in achieving cure.
Urticaria may be one of the manifestations of systemic diseases like rheumatic fever, systemic lupus erythematosus, lymphomas, other malignancies and hypogammaglobulinemia and hence should not be treated and taken likely as a mere skin disorder or dermatological ailment. Urticarias are huge and very significant to our health as they affect man and his diversity.
© 2014 Funom Theophilus Makama