Temperature-dependent laser Doppler fluxmetry in healthy and patients with peripheral arterial occlusive disease

Laser Doppler flux (LDF) was determined at the forefoot in 17 healthy volunteers and 16 patients with mild peripheral arterial occlusive disease. LDF was assessed simultaneously by two probes, one was unheated and the other was run with a probe holder temperature of 37 degrees C. During occlusion of the venous circulation a decrease between 43 and 61% was recorded in both groups and at both temperatures. When the leg was elevated there was an increase of about 60% in unheated skin; at 37 degrees C LDF was impaired significantly in patients. During leg dependency LDF decreased in 15 of the volunteers by 44 and 50% which is the result of the physiological vasoconstrictor response. In patients there was a decrease in unheated skin in 12 cases, in heated skin only in 8 cases. When pure oxygen was inhaled, LDF was unchanged in probands, but increased in patients when measured at 37 degrees C. Reactive hyperaemia flow was about three times higher in unheated skin than in heated skin. Reproducibility was best during leg elevation and was more reliable for measurements at 37 degrees C. Rhythmical variations had a frequency of about 4 cycles/min in healthy subjects and 2.6 cycles/min in patients. As a rule, in both groups frequencies at 37 degrees C were higher as compared with unheated skin. Patients had lower frequencies than probands at both temperatures. During intraarterial application of two differently acting drugs quite different reactions of LDF could be recorded. Measurements of LDF at 37 degrees C made differences between patients with PAOD and healthy volunteers more obvious. Moreover, vasomotional changes in skin blood flow could better be studied at this temperature.