Reproducibility of cutaneous thermal hyperaemia assessed by laser Doppler flowmetry in young and older adults

Objectives The primary objective of this study was to assess the inter-day reproducibility of cutaneous thermal hyperaemia, as assessed using integrating-probe laser Doppler flowmetry (LDF), in young and older men. A secondary objective was to identify the most reproducible form of data expression. Methods Cutaneous thermal hyperaemia was assessed on the forearm in 14 young (25 ± 1 year) and 14 older (65 ± 1 year) men, using integrating-probe LDF. The test was repeated 7–14 days later. The baseline, initial peak, and plateau phases of the data traces were identified and expressed as raw cutaneous vascular conductance (CVC), CVC normalised to baseline (%CVCBL), and CVC normalised to 44 °C vasodilatation (%CVCMAX). Reproducibility was assessed using the coefficient of variation (CV) and intraclass correlation coefficient (ICC) statistics. Results The inter-day reproducibility was dependent on how the data were expressed. The reproducibility of the initial peak and plateau was equally acceptable in both young and older adults when data were expressed as %CVCMAX (e.g., CVs ranging from 4 to 11%). However, the baseline phase was poorly reproducible in both groups irrespective of the data presentation method used (e.g., CVs ranging from 25 to 35%). Furthermore, expressing data as raw CVC or as %CVCBL generally showed poor reproducibility for both groups and all phases of the test (e.g., CVs ranging from 15 to 39%). Conclusion Integrating-probe LDF is a reproducible technique to assess cutaneous thermal hyperaemia on the forearm when data are expressed as %CVCMAX in healthy young and older adults without history of hypertension or taking system drugs.