Changes in skin perfusion after sympathetic block with guanethidine. Laser Doppler flowmetry in human volunteers.

Total forearm blood flow and skin microcirculation have been measured by occlusion plethysmography and by laser Doppler flowmetry (skin blood cell flux) before and after the induction of regional sympathetic block with Guanethidine. Total forearm blood flow more than doubled while the skin blood cell flux increased by 50% comparing simultaneous flows of blocked and control arms. The increase lasted for 3 days during which period the flux pattern registered by the laser Doppler flowmeter in the blocked extremities showed regular variations oscillating around the mean flux in an almost sinus wave fashion. In non-blocked arms the flux pattern registered by the laser Doppler flowmeter was highly irregular. We conclude that regional sympathetic block with Guanethidine results in an increased skin microcirculation in healthy human volunteers and that the increase lasts for 3 days. No valid conclusions can be made from this study concerning the nutritive benefit of the microcirculatory change.