Reproducibility of a local cooling test to assess microvascular function in human skin.

Abstract Objective In the present study we aimed to assess the reproducibility of skin microvascular reactivity while fast cooling locally with a custom-designed laser-Doppler flowmetry (LDF) probe. Methods Twenty-two healthy volunteers underwent local 15 °C cooling on the forearm during 5 (protocol 1, n  = 12) or 30 min (protocol 2, n  = 10). Skin blood flow was concomitantly assessed using LDF. Measurements were repeated after 30 min (protocol 1) or 7 days (protocols 1 and 2). Data were expressed as cutaneous vascular conductance (CVC) and percentage of baseline (%BL). Within subject coefficients of variation (CV) and intra-class correlation coefficients (ICC) were calculated. Results Immediate reproducibility of the 5-min cooling was very good, either expressed as CVC or %BL (CV were 8% and 18%; ICC were 0.85 and 0.78, respectively). However, the 30-min cooling was the most reproducible at 1 week, either as CVC or %BL (CV were 26% and 23%; ICC were 0.86 and 0.75, respectively). Local cooling was well tolerated by all volunteers. Conclusions We propose in the present work a reproducible 30-min LDF cooling test. Such a tool could be of great interest to assess microvascular reactivity to local cooling in diseases such as Raynaud's syndrome, and to further evaluate drugs for such diseases.