Myths and methodologies: Reliability of forearm cutaneous vasodilatation measured using laser‐Doppler flowmetry during whole‐body passive heating

Gemae, Mohamed R.; Akerman, Ashley P.; McGarr, Gregory W.; Meade, Robert D.; Notley, Sean R.; Schmidt, Madison D.; Rutherford, Maura M.; Kenny, Glen P.

doi:10.1113/ep089073

Cited by 6 publications

(5 citation statements)

References 77 publications

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“…Second, without the use of a normalization procedure, it remains difficult to compare between various sites and individuals using the absolute SkBF and CVC values in human studies. Indeed, a prior study has shown that the absolute resting CVC values within participants were poor between days but improved with the application of heat strain ( Gemae et al, 2021 ). Thus, caution is advised when interpreting SkBF data where comparisons between individuals or locations are made.…”

Section: Discussionmentioning

confidence: 99%

Multiple Laser Doppler Flowmetry Probes Increase the Reproducibility of Skin Blood Flow Measurements

et al. 2022

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Cutaneous microcirculatory perfusion is commonly measured using laser Doppler flowmetry (LDF) probes, which provide a continuous, non-invasive quantification of skin blood flow (SkBF). However, inhomogeneities in the skin’s microvasculature density contribute to a decrease in reproducibility whenever an LDF probe is removed and replaced, as is the case during pre- and post-intervention or between-day measurements. Therefore, this study aimed to determine whether increasing the total number of individual LDF probes in a localized area improves the reproducibility of the measurement. Seven laser Doppler probes were secured in a custom-made acrylic holder designed to attach to the skin’s surface easily. SkBF, local skin temperature (Tsk), and blood pressure (BP) were assessed in 11 participants (6 M, 5 F, 42 ± 15 years). SkBF and Tsk were measured from the dorsal forearm (arm trial) for 5 min. Next, the multi-laser device was moved to the lateral side of the calf (leg trial), and measurements were obtained for 5 min. Each arm and leg trial was cyclically repeated three times, and all trials were separated by intermissions lasting 10–15 min. The average SkBF and the cutaneous vascular conductance (CVC) from all possible LDF probe combinations were not statistically different across the three arm and leg trials. Two-way mixed-effects models with absolute agreement were used to compute the intraclass correlation coefficient (ICC) for CVC, and the minimum ICC increased with the addition of LDF probes. The ICC of the average CVC from seven LDF probes was 0.96 between the arm trials and 0.91 between the leg trials, which suggests that there is excellent reliability and little difference between trials following the removal and replacement of the device. Moreover, all individual ICC values from ≥3 LDF probe combinations were greater than 0.70 (i.e., good reliability). These data suggest that SkBF measurements with multiple laser Doppler probes in a custom-made holder have excellent reproducibility after replacing the probes within the same participant. Therefore, this application could provide more reproducible assessments between repeated measurements (e.g., before and after exercise or clinical procedures) where the LDF probes must be removed and replaced within the same location.

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Section: Discussionmentioning

confidence: 99%

Multiple Laser Doppler Flowmetry Probes Increase the Reproducibility of Skin Blood Flow Measurements

et al. 2022

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“…Further, all participants were habitually active (i.e., performed ≥30 min of structured physical activity at least twice per week) as determined by a standardized questionnaire (Baecke et al, 1982). Data from the young men have been reported as part of a larger project assessing the reliability of microvascular, sudomotor, and cardiovascular autonomic function (Akerman et al, 2021; Gemae et al, 2021; Rutherford et al, 2021). Given the exploratory nature of the study, no a priori power analysis was performed.…”

Section: Methodsmentioning

confidence: 99%

“…Participants completed one screening session and one experimental session in a temperature‐controlled laboratory (~25°C). The experimental sesssion for the young group was the first of three sessions reported in our previous work (Akerman et al, 2021; Gemae et al, 2021; Rutherford et al, 2021). The firstexperimental session for the young group was chosen as it provided the most naïve assessment between both age groups.…”

Section: Methodsmentioning

confidence: 99%

Revisiting regional variation in the age‐related reduction in sweat rate during passive heat stress

Schmidt

Notley

Meade

et al. 2022

Physiological Reports

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Aging is associated with attenuated sweat gland function, which has been suggested to occur in a peripheral‐to‐central manner. However, evidence supporting this hypothesis remains equivocal. We revisited this hypothesis by evaluating the sweat rate across the limbs and trunk in young and older men during whole‐body, passive heating. A water‐perfused suit was used to raise and clamp esophageal temperature at 0.6°C (low‐heat strain) and 1.2°C (moderate‐heat strain) above baseline in 14 young (24 (SD 5) years) and 15 older (69 (4) years) men. Sweat rate was measured at multiple sites on the trunk (chest, abdomen) and limbs (biceps, forearm, quadriceps, calf) using ventilated capsules (3.8 cm2). Sweat rates, expressed as the average of 5 min of stable sweating at low‐ and moderate‐heat strain, were compared between groups (young, older) and regions (trunk, limbs) within each level of heat strain using a linear mixed‐effects model with nested intercepts (sites nested within region nested within participant). At low‐heat strain, the age‐related reduction in sweat rate (older‐young values) was greater at the trunk (0.65 mg/cm2/min [95% CI 0.44, 0.86]) compared to the limbs (0.42 mg/cm2/min [0.22, 0.62]; interaction: p = 0.010). At moderate‐heat strain, sweat rate was lower in older compared to young (main effect: p = 0.025), albeit that reduction did not differ between regions (interaction: p = 0.888). We conclude that, contrary to previous suggestions, the age‐related decline in sweat rate was greater at the trunk compared to the limbs at low‐heat strain, with no evidence of regional variation in that age‐related decline at moderate‐heat strain.

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“…half-width) of a 95% confidence interval for the paired difference between means (Maxwell et al, 2008). The upper 10% threshold (in units of cutaneous vascular conductance normalized to maximum vasodilatation; % CVC max ) was defined a priori as the smallest effect size of interest (SESOI; Anvari & Lakens, 2021;Gemae et al, 2021; see below for further explanation). A sample size based on a maximum precision of 5% CVC max (i.e.…”

Section: Sample Size Estimationmentioning

confidence: 99%

“…To evaluate the potential importance of between-region differences in the NO contribution to local skin heating, we identified the SESOI (i.e. the smallest between-region difference that we would not want to miss) a priori (Anvari & Lakens, 2021;Gemae et al, 2021). By examining previous research, we determined that acute ischaemic stress, ageing and chronic disease were consistently associated with alterations in the plateau response to local heating by as little as 10% CVC max (Black et al, 2008;Minson et al, 2002;Stewart et al, 2008).…”

Section: Smallest Effect Size Of Interestmentioning

confidence: 99%

Regional variation in nitric oxide‐dependent cutaneous vasodilatation during local heating in young adults

McGarr

King

Saci

et al. 2021

Experimental Physiology

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Regional variations in cutaneous vasodilatation during local skin heating exist across the body. While nitric oxide (NO) is a well-known modulator of this response, the extent of regional differences in NO-dependent cutaneous vasodilatation during local skin heating remains uncertain. In 16 habitually active young adults (8 females; 25 ± 5 years), cutaneous vascular conductance, normalized to maximum vasodilatation (% CVC max ), was assessed at the upper chest, abdomen, dorsal forearm, thigh and lateral calf during local skin heating. Across all regions, local skin temperatures were simultaneously increased from 33 to 42 • C (1 • C per 10 s), and held until a stable heating plateau was achieved (∼40 min). Next, with local skin temperature maintained at 42 • C, 20 mM of N G -nitro-L-arginine methyl ester (L-NAME) was continuously infused at each site until a stable L-NAME plateau was achieved (∼40 min). The difference between heating and L-NAME plateaus was identified as the NO contribution for each region. There was no evidence for region-specific responses at baseline (P = 0.561), the heating plateau (P = 0.351) or L-NAME plateau (P = 0.082), but there was for the NO contribution (P = 0.048). Overall, point estimates for between-region differences in the NO contribution varied across the body from 0 to 19% CVC max . The greatest effects were observed for the abdomen, wherein the NO contribution was consistently greater than for the other regions (range: 9-19% CVC max ). The chest was consistently lower than the other regions (range: 7-19% CVC max ). The smallest effects were observed between limb regions (range: 0-2% CVC max ). These findings advance our understanding of the mechanisms influencing regional variations in the cutaneous vasodilator response to local skin heating in young adults.

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Myths and methodologies: Reliability of forearm cutaneous vasodilatation measured using laser‐Doppler flowmetry during whole‐body passive heating

Cited by 6 publications

References 77 publications

Multiple Laser Doppler Flowmetry Probes Increase the Reproducibility of Skin Blood Flow Measurements

Multiple Laser Doppler Flowmetry Probes Increase the Reproducibility of Skin Blood Flow Measurements

Revisiting regional variation in the age‐related reduction in sweat rate during passive heat stress

Regional variation in nitric oxide‐dependent cutaneous vasodilatation during local heating in young adults

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