Do modest changes in skin temperature affect the measurement of micro- and macrovascular function?

Figures

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  Figure 1. After an initial 20-minute stabilization in the supine position, baseline haemodynamic including brachial artery velocity and diameter were recorded over 1 minute. Thereafter, an occlusion cuff was inflated to 250 mmHg for 5 minutes and released. Haemodynamic including brachial artery diameter and velocity were monitored over 3 minutes of recovery. After a further 20 minutes recovery, the same procedure was performed in a randomized order when the forearm skin was cooled to 27°C or heated to 35°C. After another 20 minutes recovery period participants were exposed to the other temperature.

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  Figure 2. Comparison of baseline and peak mean values for three FMD measurements conducted at individual (green), cooled (27°C; blue), and heated (35°C; orange) skin temperatures. The illustrated variables include (A) conductance, (B) shear rate, (C) diameter, and (D) skin blood flow. Continuous data (mean per second) is presented for baseline (0 to 30 seconds) and reactive hyperaemia (30 to 90 seconds). P-values (capital P) above the graphs indicate the results of the repeated-measurement ANOVA, while p-values (lowercase p) above the bar represented Holm-Šídák multiple comparisons. For visual representation on individual data, reactive hyperaemia values were either accumulated (for heart rates above 60 bpm) or extended (for heart rates below 60 bpm) to produce 60 values for each post occlusive reactive hyperaemia event.

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  Figure 3. Continuous data (mean per second) is presented in the first 30 seconds for both shear rate and diameter across the three FMD measurements: individual (green), cooled (27°C; blue), and heated (35°C; orange) skin temperatures. The area under the curve (AUC) for shear rate is calculated from cuff release to time when the peak diameter is reached to baseline shear and shear rate value for each second. AUC is shown for (A) the individual FMD, (B) the cooled skin temperature FMD, and (C) the heated skin temperature FMD. Continuous diameter values during reactive hyperaemia are demonstrated for (D) the individual FMD, (E) the cooled skin temperature FMD, and (F) the heated skin temperature FMD with lines indicating peak diameters. The (G) mean FMD (%) is calculated between the absolute peak diameter (mean for three consecutive heart beats) and the absolute baseline diameter (mean for three consecutive heart beats). (H) FMD was normalized with the AUC of shear rate. P-values reflect the results of the repeated-measurement ANOVA.