In order to investigate skin vasomotor response to local cooling in humans, we made a new local cooling/heating laser Doppler flowmetry probe. Using this probe, we tested the skin response to local cooling, down to 15°C, and its reproducibility.

The cooling/heating probe is made of paired optic fibres and a Peltier element as a thermoelectric cooler (TEC). The polarity of the voltage influences the direction of the heat flow, allowing either heating or cooling. We performed local cooling on the forearm of 11 healthy volunteers, from 33°C to 24°C, and then to 15°C, twice, and repeated the measurement seven days later. Skin blood flow was simultaneously recorded at two control sites (5 cm and contralateral). We also assessed the effect of a prolonged (30minute) 15°C local cooling.

Local cooling decreased cutaneous vascular conductance (CVC) between 33°C, 24° and 15°C (p<0.05, Friedman test), whereas we observed no -or mild- effect on control sites. Short term reproducibility of the CVC was very good at 24 and 15°C (intrasubject CV were 13 and 8 %, respectively). Seven day reproducibility was good when expressed as a percentage of baseline. Local cooling was well tolerated by all the volunteers.

This prototype was safe and able to perform local cooling, leading to a temperature-dependant, local, reproducible vasoconstriction. This new tool could be of great interest to assess skin microvascular function in diseases such as Raynaud’s phenomenon.