Microcirculation in the diabetic foot as measured by a multichannel laser Doppler instrument.

Background: The purpose of this study was to investigate microvascular perfusion in insulin-dependent diabetic patients at various locations on the foot, and to determine which part of the foot is most sensitive to microangiopathic changes. All the parameters of postocclusive reactive hyperemia calculated from multichannel laser Doppler recordings were also evaluated to find the most valuable measure for diabetes examination.

Material/methods: Our study involved 65 subjects divided into four subgroups: male and female controls, and male and female IDDM patients without overt complications. The measurements were performed with a multichannel laser Doppler perfusion monitor using surface probes located in the distal parts of the lower limbs. The occlusion test was performed using a cuff located on the limb above the knee. Multivariate discriminatory analysis was used to evaluate the data.

Results: The most valuable data were obtained by recordings from the laser-Doppler probes located on the hallex and the base of the little toe. The maximum hyperemic response for both sex subgroups was significantly lower in the diabetic patients. The time to peak flow was higher in male diabetics. The half-time for hyperemia was significantly longer in the male diabetic patients.

Conclusions: The females showed smaller changes in foot perfusion than the males, probably due to protection by estrogens. The best locations for perfusion measurement are the most distal, especially the hallex and the base of the little toe. The most valuable parameters of postocclusive hyperemia were maximum response, time to peak flow, and half-time of hyperemia.