Reliability of laser-Doppler flowmetry derived measurements of forearm and calf cutaneous vasodilation during gradual local heating in young adults

Abstract

Objectives: Evaluate reliability of laser-Doppler flowmetry derived cutaneous vasodilation on the upper and lower limbs during gradual local heating.

Methods: In twenty-eight young adults (21 (SD 3) years, 14 females), absolute cutaneous vascular conductance (CVC_abs) and CVC normalized to maximum vasodilation at 44 °C (%CVC_max) were assessed at two adjacent sites on each of the forearm and calf during gradual local skin heating (33-42 °C at 1 °C·5 min^-1) for two identical trials (∼1 week apart). Responses were assessed for baseline, the steady-state heating plateau at 42 °C and the span (i.e. plateau-baseline).

Results: Between-day reliability was characterized as measurement consistency across trials. Within-day reliability was characterized as within-limb measurement consistency across adjacent skin sites. Between- and within-day absolute reliability (coefficient of variation) generally improved with heating, from poor (>25 %) at baseline to good (<10 %) for %CVC_max and moderate (10-25 %) for CVC_abs for plateau and span. However, relative reliability (intraclass correlation coefficient) was generally not acceptable (<0.70) for any condition. Responses were generally consistent for females and males and there were no major forearm and calf differences.

Conclusions: Consistency of CVC estimates improved during gradual local heating with negligible limb and sex differences, which are important considerations for experimental design and interpretation.

Keywords: Endothelium; Measurement error; Microcirculation; Repeatability; Reproducibility; Skin blood flow.