Sweating response to moderate thermal stress in atopic dermatitis.

The local sweating response to thermal stress (mean ambient temperature 33 degrees C) was assessed under resting conditions on the non-eczematous back skin of 26 young men with atopic dermatitis (AD) and in 22 non-atopic controls with other dermatoses. The baseline (transepidermal) water loss was separately determined at room temperature (mean 23.6 degrees C) to calculate the pure sweat loss. A gravimetric collecting method was used for the measurements at 40, 60 and 80 min. In the heated room the sweat loss in AD patients was significantly lower at all time intervals. The cumulative sweat loss was 50-60% lower in AD patients than in the controls (P less than 0.02). Subjects with dry AD skin had a lower sweat loss than subjects with normal-looking skin. Compared with controls the sweat loss in AD patients was lowest at 40 min, suggesting a retarded sweating response. Half of the patients with AD and half of the controls had active participation in sports, and showed a greater sweat loss compared to the non-sporting subjects in the same group.

Local cholinergic sweat stimulation in atopic dermatitis. An evaporimetric study.

In atopic dermatitis the nature of potential sweating disturbances is still obscure. Using an evaporimeter, local sweating response to a supra-threshold concentration of methacholine and baseline water loss were measured from non-eczematous back skin of 167 young males in five main groups (pure atopic dermatitis, atopic dermatitis with rhinitis/asthma, rhinitis/asthma, non-atopic dermatosis, and non-atopic healthy). Subjects with atopic dermatitis were further divided into two subgroups: dry-looking and normal-looking back skin. Compared with non-atopic healthy individuals, the sweat loss was significantly depressed (p less than 0.01) and the baseline water loss significantly increased (p less than 0.001) in the main groups with atopic dermatitis. Both these trends were most distinct in atopic dry-looking skin, whereas in normal-looking atopic skin only the sweat loss was depressed (p less than 0.05). Respiratory atopy had no effect on the sweating response. No significant correlation was found between the individual baseline water loss and the sweating response.

Baseline water loss and cholinergic sweat stimulation in atopic dermatitis: a gravimetric measurement of local skin water loss.

The sweat gland function in atopic dermatitis (AD) and in respiratory atopy is a matter of controversy. We examined the baseline water loss and local sweating response in non-eczematous back skin of 146 young men: pure AD, AD with rhinitis/asthma, rhinitis/asthma alone, non-atopic dermatosis and non-atopic healthy. All AD subjects were further divided into the subgroups AD dry and AD normal skin. Following injections of saline and a high concentration of methacholine (5 x 10(4) mol/l) into separate sites the moisture losses were collected into closed pads over a period of 40 min. The baseline water loss was significantly increased (P less than 0.001) and median pure sweat loss was significantly decreased (P less than 0.01) in AD compared with nonatopic healthy individuals. These trends were accentuated in AD dry skin. Respiratory symptoms had no appreciable influence on results. A depressed sweating response occurred in 30% of AD subjects and 9% of non-AD subjects. An elevated baseline water loss value and a depressed sweat loss value coexisted in 22% of subjects with AD dry skin compared with 3% of the non-atopics.

Local sweat stimulation with the skin prick technique.

Intracutaneous injections of cholinergic agonists are usually employed for induction of local sweating. The possibility to apply a less painful skin prick technique as a sweat test was examined. Pricks were made on the forearm skin of 25 young men by puncturing the skin through drops of methacholine (MCH) and control saline solutions with lancets having a point length of 1 mm. The drops were kept on skin for 10 min and were then wiped off. Using an evaporimeter the measurements of water loss (WL) were started 5 min later and continued at 5 min intervals. Sweat loss (SL) was calculated from the difference of rates of evaporative WL recorded at the MCH and saline pricks. Ten, 1, 0.1, and 0.01% solutions of MCH elicited the following average peak evaporative sweat losses: 107.1, 77.5, 32.4 and 5.4 g m-2h-1. Both the degree and duration of the sweat responses were dependent on concentration. The prick technique is well tolerated and may serve for comparative studies of local sweating.