[Development of erythema in thermographic images]

The intensity of erythema does not show a linear correlation with convective and conductive heat transport. In erythema induced by various means such as dermographism, the application of nicotinic acid benzylester, UV-B-irradiation, or dithranol, the mediators follow the direction of blood and lymph defluxion. As a result heat reflection occurs not only from the erythemic region, but also from the surrounding unaffected skin area. Venous blood vessel texture is increased within areas of blood defluxion. Erythemous flushing after alcohol uptake is characterized by an increase in skin temperature. This increase in temperature occurs prior to the appearance of erythema compared to exogenous skin irritation which first shows erythema and later on an increased temperature. An even further increment can be measured in the flushed area. An increase in acral temperature (hands, feet, nose) is an indication of the systemic effect of the resorbed alcohol.