A method of measuring the interaction between skin temperature and humidity on skin vascular endothelial function in people with diabetes

Abstract

Background: A core defect in people with Type 2 Diabetes is endothelial dysfunction. This defect permeates all organ systems in the body including the ability of the skin to protect itself from thermal injuries by an appropriate increase in skin circulation. Most studies on the local response to heating have been done with dry heat sources. Recent data show that endothelial function is improved in people with diabetes with moist heat. Little is known about ‘how’ moist heat must be or the mechanisms on why moist heat triggers a better blood flow response than dry heat. Methods: In the present investigation, a device was developed to provide variable temperature air and variable humidity as an aid to study the dynamics of the skin circulatory response to heat in people with diabetes. The device consisted of a water bath used to heat air and an air dryer and air bubbler to generate dry and moist air, respectively, at a fixed temperature. The air could then be mixed and the temperature stabilized to produce a variable temperature and humidity air source to expose the skin to in people with diabetes. Results: The device was validated at different air temperatures and humidities and tested on four subjects to assess operation. The air flows, temperatures and humilities were stable with less than a 5% coefficient of variation. Conclusions: Testing on humans showed that there appeared to be a linear relationship between air humidity and blood flow at a given air temperature exposed to the skin.

Keywords::

• Diabetes
• endothelial function
• circulation