Laser doppler flowmetry at unheated skin and at 37 C in patients with arterial occlusive disease

Laser Doppler Flowmetry (LDF) as diagnostic tool in patients with peripheral arterial occlusive disease (PAOD) is still under discussion. As we know from transcutaneous oxygen pressure measurements skin temperatures play an important role on results of pathophysiological experiments. We investigated LDF flow at unheated skin (temperature 29.8 - 31.4 degrees C) and at constant heating to 37 degrees C on forefoot of patients with PAOD simultaneously. The results were expressed in % of initial values. During venous occlusion (5 min 40 mmg Hg cuff pressure at distal calf) there was a decrease of LDF signal of about 30% at both temperatures. When the leg was depending LDF signal increased or was unchanged in about 40% of cases and decreased in 60% at both temperatures. The decrease of unheated LDF signal was more pronounced. During arterial occlusion LDF (37 degrees C) decreased down to about 20% and LDF (unheated) to about 50% of initial values. Reactive hyperemia was more pronounced at th e unheated skin. During intraarterial infusion of prostaglandin E sub 1 and energy rich phosphates there was a decrease of LDF (37 degrees C) of 15%, but an increase of LDF (unheated) up to 25%. The results show that modest heating skin up to 37 degrees C may influence reaction of LDF signal to some extent, but has the advantage of measuring under identical temperature conditions. (ITA)