Assessment of the Severity of Ischaemia and the Outcomes of Revascularisation in Peripheral Arterial Disease Patients Based on the Skin Microcirculatory Response to a Thermal Load Test

OBJECTIVE: This study investigated the skin microcirculatory response to a thermal load test using a laser Doppler flowmetry device to evaluate the severity of limb ischaemia and the outcomes of revascularisation in patients with peripheral arterial disease (PAD). METHODS: A total of 34 PAD patients (39 limbs) including 17 critical limb ischaemia (CLI) patients (21 limbs) who underwent revascularisation were enrolled. The skin microcirculation of the dorsal side of the affected foot was investigated for 15 minutes after local heating. The tests were performed both before and after revascularisation, and several parameters gleaned from the microcirculatory fluctuations were analysed and compared with the ankle brachial pressure index and the transcutaneous oxygen tension (tcPO(2)) values. RESULTS: Among the parameters, significant differences were observed between the CLI patients and patients with claudication with regard to the increasing phase time (T(inc)), the difference in the perfusion values at the onset and the peak of the transient increase in blood perfusion (PΔ), the slope of the transient increase in blood perfusion (S(in)), and the slope of the decrease in blood perfusion after the peak (S(de)). In CLI patients, the PΔ, S(in), and S(de) values increased significantly after revascularisation. In the patients with claudication, the changes in the parameters after revascularisation were not statistically significant. The S(de) showed the most statistically significant correlation with the tcPO(2) value (ρ .759, p < .001). CONCLUSIONS: Thermal load testing can be used to evaluate the severity of limb ischaemia in patients with PAD.