Assessment of cutaneous microcirculation in unaffected skin regions by transcutaneous oxygen saturation monitoring and Laser Doppler flowmetry in systemic sclerosis

We assessed the cutaneous microcirculatory reactivity of a clinically unaffected skin region in patients with systemic sclerosis (SSc) compared to healthy controls by measuring transcutaneous oxygen saturation (TcPO2) and Laser Doppler flowmetry (LDF).Twelve consecutive patients with SSc and twelve healthy controls were subjected to TcPO2 monitoring and LDF during cuff-induced ischemia and reactive hyperemia in order to measure the skin oxygen tension and the microcirculatory blood flow. Mean minimal and maximal values of oxygen tension and blood flow, time to peak (TTP), and declining slopes after peaking (slope) were compared between patients with SSc and controls.Compared to the controls, TcPO2 values in SSc were similar during ischemia and diminished during reactive hyperemia, with longer TTP, and a slower return to baseline (-60% vs. -58% , p = 1.000, +76% vs. +210% , p = 0.047, 137 s vs. 108 s, p = 0.028, -0.009% /s vs. -0.019% /s, p = 0.021, respectively). LDF values, however, did not differ significantly between patients with SSc and controls.Unaffected skin regions of SSc patients showed a significantly diminished postischemic vasodilatory reactivity when assessed by TcPO2 monitoring, but not by LDF, indicating that vasculopathy may represent an early mechanism in the onset of skin sclerosis. TcPO2 measurement may help to detect changes in the microcirculation in SSc with no skin affection.