Laser Doppler skin perfusion pressure in normal and vascular subjects with rest pain: An universal measurement?

Laser-Doppler (LDF) skin perfusion pressure was measured and compared with Doppler ankle pressure measurements in 40 normal subjects and 20 patients with rest pain and ankle/foot Doppler pressure lower than 70 mmHg. Six different, commercially available LDF instruments were used. To obtain perfusion pressure a standard blood pressure cuff was used measuring the pressure at which the skin flux reading reached the biological zero level when inflating the cuff (P1) and the pressure at which the LDF tracing reappeared after deflating the cuff from sovrasistolic pressure level (P2). Perfusion pressure (PP) was considered to be the average [P1 + P2]/2. No differences in PP amongs the 6 instruments both in normal and vascular subjects were observed. These results indicate that PP is an universal LDF measurement which can be easily obtained with different LDF instruments.