Thermographic analysis of skin test reaction using AGA thermovision.

The course of infrared thermography including isothermograms on the skin surface was investigated considering blood flow, redness of the skin and permeability of blood vessel, in the following skin reactions: 1. Intracutaneous injection of histamine and histamine liberator compound 48/80 increased the heat radiation. Local application of antihistamine externa which decreased the development of the urticarial histamine reaction, increased the infrared radiation of the skin surface. Combined injection of histamine or histamine liberators with antihistamines in a sufficient dosis (1:1 respectively 4:1) diminished also the heat radiation in addition to the urticarial reaction. 2. The Pyrexal reaction of the skin with early erythema and later papule development shows an equivalent picture in the AGA Thermovision. The pretreatment shows an equivalent picture in the AGA Thermovision. The pretreatment of the skin with corticosteroid ointments shows a corresponding lowering of the erythema, of papule development as well as of heat radiation. The blanching of corticosteroids after occlusive dressing is difficult to recognize by the isotherms of AGA Thermovision. 3. Allergic reactions of the immediate type show, corresponding to the wheal eruption, a marked increased of heat radiation combined with a projection of the enlarged veins on the skin surface. 4. Allergic reactions of the delayed type are combined with a definite elevation of heat radiation of the skin. The area of a positive skin test with allergic eczematous reaction shows a distinct elevation of ann infrared radiation. Although the allergic skin area which was substantiated by a positive skin test was no longer visible, a distinct infrared radiation could be detected. Preventive treatment of the test area of skin patch-testing with corticosteroids inhibits the heat radiation even if the allergic eczematous reaction occurs faintly. The thermographic analysis of the different skin test reactions complied with the morphological aspects of the reaction.