Measurement of the cutaneous blood flow reserve in normal humans by laser-Doppler flowmetry.

Aim: To assess the normality of the cutaneous blood flow reserve (CR).

Methods: To explore the feasibility and reproducibility of laser-Doppler flowmetry for CR measurement, we prospectively measured CR in 17 healthy subjects on the dorsum of the foot and pulp of the big toe. CR was defined as the sum of the venoarteriolar reflex (VAR), i.e. postural vasoconstriction, and postischemic reactive vasodilation (H), expressed as % of the resting supine flux and assessed by using laser-Doppler flowmetry.

Results: For the dorsal foot, VAR%+/-SEM was 61+/-14, H%, 752.5+/-214 and CR, 813.5+/-217. On the pulp of the big toe, VAR% was 61.6+/-4.7, H%, 588.2+/-174 and CR, 649.9+/-176. CR measurement variability was assessed by calculating the inter-individual coefficient of variation of CR, which was 1.1 for both the dorsal foot and pulp of the big toe. Reproducibility was assessed by calculating the CR intraclass correlation coefficient, which was 0.49 for the dorsal foot and 0.64 for the pulp of the big toe.

Conclusions: The CR is proposed as a new parameter for assessing the microvascular integrity and contractile reserve of the skin. Laser-Doppler flowmetry is suitable for this non-invasive evaluation. The method displayed large variability, and its reproducibility varied from moderate for the dorsal foot, to substantial for the toe. Further studies are necessary to demonstrate its clinical usefulness.