Microvascular reactivity during sympathetic stimulations in Raynaud's phenomenon.

Background: The objective of the study was to assess skin autonomic microvascular reactivity to sympathetic stimulations and its association with primary and secondary Raynaud's phenomenon (RP).

Methods: Laser-Doppler recorded finger pulp skin blood flow was monitored during orthostatic and deep breathing tests of 4 subjects groups, each of them composed of 20 subjects: group 1, healthy controls; group 2, vibration-induced secondary RP (vRP); group 3, primary RP (pRP); group 4, systemic sclerosis-related secondary RP (sclRP). Within groups comparisons by Wilcoxon matched pairs rank test and between groups by Bonferroni's multiple test for unpaired data were done using SPSS Statistics software.

Results: Reliably lower initial perfusion values were established in all the RP patients. The local sympathetic axon-reflex mediated responses to orthostasis were reduced in all RP groups with increased perfusions in upright posture instead of decreased. The vasoconstrictor responses to deep breathing tended to increase instead of decreasing in the vRP and pRP groups, while in the sclRP group the perfusions decreased. Strong correlations between the initial finger pulp perfusions and the orthostatic and deep breathing perfusion responses were found in the control, pRP and vRP groups (P<0.0001) and a modest correlation between the initial perfusions and the deep breathing perfusion responses in the sclRP group.

Conclusions: Abnormal cutaneous microvascular reactivity to central and local axon-reflex sympathetic stimulations was established in RP patients reflecting self-regulatory dysfunctions which might contribute to the manifestations of the ischemic microcirculatory paroxysms. Laser Doppler flowmetry with functional orthostatic and deep breathing tests contribute to the diagnosis of RP.