Low frequency oscillations assessed by diffuse speckle contrast analysis for foot angiosome concept

Figures

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  Figure 1. DSCA representative results of cross-correlation analysis in one subject according to baseline, occlusion, and release periods at supine posture. (a) Measurement positions of blood flow index (BFI) based on foot angiosome with four-channel DSCA probes on subject’s sole. (b) Raw BFI data. (1) Baseline period in tilt posture. (2) Posture change period. (3) Baseline period in supine posture. (4) Cuff-occlusion period in supine posture. (5) Release period in supine posture. (c) Detrended, normalized (processed), and filtered BFI with band pass filter (BPF) based on sectioned BFIs (Left: Baseline period in supine posture; Center: Cuff-occlusion period in supine posture; Right: Release period in supine posture). (d) Cross correlation analyses among four channels based on (c). (e) Maximum value and its lag time analysis in Ch.1 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\otimes$$\end{document}⊗ Ch.2 relationship.

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  Figure 2. Representative results for PSD by DSCA (a–d) and ECG (e–h) in one subject, according to baseline, occlusion, and release periods during 90° head up tilt posture. (a) Raw BFIs in channel 4. (1) Baseline period in supine posture. (2) Posture change period. (3) Baseline period in 90° head-up tilt posture. (4) Cuff-occlusion period in 90° head-up tilt posture. (5) Release period in 90° head-up tilt posture. (b) Detrended and normalized processed BFI from sectioned BFI in channel 4. (c) PSD analysis in channel 4. (d) Relative PSD pie analysis among three frequency bands in channel 4. (e) Detrended and normalized ECG from sectioned ECG data. (f) HRV (R–R interval) from ECG signal. (g) PSD analysis from HRV. (h) Relative PSD pie analysis from HRV.

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  Figure 3. The pie charts of relative PSD distributions among frequency bands according to baseline, occlusion, and release periods in all subjects during 90° head up tilt posture. (a) DSCA measurement in channel 4. (b) ECG measurement.

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  Figure 4. Representative results for PSD by DSCA (a–c) and ECG (d–f) in one subject, according to supine and head up tilt postures. (a) Detrended and normalized BFI from sectioned BFI in channel 4. (b) PSD analysis in channel 4. (c) PSD pie analysis among three frequency bands in channel 4. (d) HRV (R–R interval) from ECG signal. (e) Relative PSD analysis from HRV. (f) PSD pie analysis from HRV.

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  Figure 5. The pie charts of relative PSD distributions among frequency bands according to baseline, occlusion, and release periods in all subjects during 90° head up tilt protocol. (a) DSCA measurement in channel 4. (b) ECG measurement.

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  Figure 6. Experimental situation using DSCA and ECG. (a) Schematic diagram of the tissue perfusion measurement with DSCA and heart rate variability measurement with ECG. (b) The criteria of DSCA measurement positions in subject’s sole of foot. Red and yellow circles stand for illumination and detector fibers, respectively. (c) ECG measurement positions. (d) Flow chart of the measurement protocol.

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  Figure 7. Flow chart of data analysis for cross-correlation analysis and power spectral analysis in DSCA.