Systemic sclerosis: blood rheometry and laser Doppler imaging of digital cutaneous microcirculation during local cold exposure.

A combined study of microcirculation hemodynamics in vivo and blood rheometry has been carried out in patients with scleroderma compared to primary Raynaud's phenomenon (PRP) and healthy controls (HC). Laser Doppler perfusion imaging was used to assess superficial skin blood flow in the fingers before, during and after local cold exposure. Blood viscosity was measured at 19 and 37 degrees C. Dynamic and transient flows were also investigated. The scleroderma group showed a significantly lower level of perfusion before the cold test, that was further decreased during and after cold exposure, the difference with PRP being maximal during the rewarming period. It also showed a significantly increased viscosity (p < 0.05) at low shear rates. Hemorheological behavior of the PRP group was similar to the HC group. A significant negative correlation between the LDI perfusion and the apparent blood viscosity at low shear rates was found for the whole population. These findings suggest that rheological factors may be involved in the abnormal cold reactivity of patients with scleroderma.