Laser Doppler flowmetry, transcutaneous oxygen pressure and thermal clearance in patients with vascular intermittent...

In the present study, heat thermal clearance (HTC) was compared to laser Doppler flowmetry (LDF) and transcutaneous oxygen pressure (tcPO2), measured on the forefoot of 17 patients with vascular intermittent claudication and 10 controls in various positions at rest and after a treadmill exercise test. The mean ankle brachial systolic pressure ratio (ABSP) of the patients, measured using ultrasonic Doppler velocimetry, was 0.53 +/- 0.05. Their walking distance was 480 +/- 100 meters, the treadmill exercise being stopped as soon as pain sensation. No statistically significant difference was found between patients and controls for HTC, LDF, tc P02, forefoot and ankle skin temperatures. Statistically significant differences between patients and controls occurred in the sitting position for tcPO2, in standing position for HTC and after treadmill exercise for tcPO2 and LDF. When assuming the sitting position HTC did not vary significantly in patients and decreased in controls, LDF decreased and tcPO2 increased in both groups. After treadmill exercise, HTC in patients did not vary compared to supine values and HTC decreased in controls, tcPO2 remained unchanged in controls and decreased in patients, LDF increased in controls and decreased in patients. No significant correlations were found between the different techniques measured at rest in patients and controls. However in patients, after the treadmill test, LDF correlated with the walking distance (r = 0.667) and with ABSP (r = 0.641), HTC inversely correlated with the walking distance (r = -0.680) and ABSP (r = -0.577). Laser Doppler, tcPO2 and HTC are useful as tools to understand the alterations of cutaneous microcirculation of the lower limbs in patients with V.I.C.. However their results need to be interpreted with caution because these methods do not measure directly blood flow.