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Myths and methodologies: Reliability of forearm cutaneous vasodilatation measured using laser‐Doppler flowmetry during whole‐body passive heating
Author(s) -
Gemae Mohamed R.,
Akerman Ashley P.,
McGarr Gregory W.,
Meade Robert D.,
Notley Sean R.,
Schmidt Madison D.,
Rutherford Maura M.,
Kenny Glen P.
Publication year - 2020
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/ep089073
Subject(s) - laser doppler velocimetry , reliability (semiconductor) , forearm , medicine , doppler effect , vasodilation , cardiology , blood flow , biomedical engineering , anatomy , physics , thermodynamics , power (physics) , astronomy
Laser‐Doppler flowmetry (LDF) is commonly used to assess cutaneous vasodilatation responses, but its reliability (i.e. consistency) during whole‐body passive heating is unknown. We therefore assessed the reliability of LDF‐derived indices of cutaneous vasodilatation during incremental whole‐body heating. Fourteen young men (age: 24 (SD 5) years) completed three identical trials, each separated by 1 week. During each trial, a water‐perfused suit was used to raise and clamp oesophageal temperature at 0.6°C (low‐heat strain; LHS) and 1.2°C (moderate‐heat strain; MHS) above baseline. LDF‐derived skin blood flow (SkBF) was measured at three dorsal mid‐forearm sites, with local skin temperature clamped at 34°C. Data were expressed as absolute cutaneous vascular conductance (CVC abs ; SkBF/mean arterial pressure) and normalised to maximal conductance (%CVC max ) achieved via simultaneous local skin heating to 44°C and increasing oesophageal temperature to 1.8°C above baseline. Between‐day reliability was characterised as measurement consistency across trials, while within‐day reliability was characterised as measurement consistency across adjacent skin sites during each trial. Between‐ and within‐day absolute reliability (coefficient of variation) generally improved with increasing heat strain, changing from poor (>25%) at baseline, poor‐to‐moderate (15–34%) at LHS, and moderate (10–25%) at MHS. Generally, these estimates were more consistent when expressed as %CVC max . Conversely, relative reliability was mostly acceptable (intraclass correlation coefficient ≥0.70) during LHS and when data were expressed as CVC abs . These findings indicate that the consistency of LDF‐derived CVC estimates during heat stress depends on the level of heat strain and method of data expression, which should be considered when designing and interpreting experiments.