New test methods reveal how foot blood vessels respond to stress
Researchers compared three ways to test whether small blood vessels in the foot work properly—finding that heating and drug stimulation produce more reliable, consistent results than the traditional occlusion test. The findings could improve how doctors screen for circulatory problems linked to diabetes and aging, potentially catching vascular disease earlier.
Originaltitel: Cutaneous microvascular reactivity in the foot evaluated by optical multimodal pointwise and imaging techniques and different stimuli.
Diagnostiska mätningar av blodflöde i fotens hudkärl visar sig ge mer tillförlitliga resultat när värmestimulering eller kemisk vasodilation används istället för cirkulationsstopps-tester. Svenska forskare från Linköpings universitet jämförde tre stimuleringsmetoder på 30 friska försökspersoner med optiska mättekniker. Vid värmestimulering och kemisk vasodilation (metyldnikotinat) ökade syremättnaden i väven betydligt mer än vid cirkulationsstopp — mellan 79–88 procent jämfört med cirka 77 procent. Variationen mellan individer för syremättnadsmätningar var låg (3–7 procent), medan blodflödesmätningar varierade kraftigt (över 30 procent). Resultaten är relevanta för leverantörer av diagnostisk utrustning och för utveckling av standardiserade test för kärlhälsa. Då metoderna ger skilda utslag kan val av stimuleringsteknik bli avgörande för diagnostisk noggrannhet i kliniska tillämpningar.
UNLABELLED: Skin microvascular reactivity tests for the lower extremity apply stimuli such as ankle occlusion (post-occlusive reactive hyperemia, PORH), local heating (LH), or the vasoactive drug methyl nicotinate (MN). AIM: Evaluate microvascular reactivity in dorsal foot skin comparing PORH, LH and MN stimuli. METHOD: Thirty healthy participants 20-65 years of age were enrolled in a protocol using pointwise and imaging optical techniques for perfusion and oxygen saturation. Mean values and between-subjects coefficient of variation (CV) for perfusion and oxygen saturation were compared. RESULTS: The PORH, LH and MN stimuli caused significant increases in oxygen saturation and perfusion from baseline values (p < 0.001). The oxygen saturation was higher during LH than during PORH (pointwise technique; mean 88.8% vs 79.7%; p < 0.001) and higher during MN than during PORH (imaging; 86.7% vs 77.2%; p < 0.001). Perfusion was higher during LH than during PORH (pointwise; 1.60%RBC × mm/s vs 0.53%RBC × mm/s; p < 0.001) and higher during MN than during PORH (imaging; 1.04%RBC × mm/s vs 0.54%RBC × mm/s; p < 0.001). The CV for oxygen saturation was 2.8% vs 6.3% (pointwise; LH and PORH) and 7.4% vs 6.0% (imaging; MN and PORH). Corresponding values for perfusion were >30%. CONCLUSION: The responses in oxygen saturation and perfusion were higher during MN and LH stimuli than for PORH. A few outliers were observed after MN with a slower and lower response. Microcirculatory oxygen saturation has a lower between-subjects variation than perfusion (CV 3-7% vs >30%) during PORH, LH and MN stimuli.