Correlation analysis of human upper arm parameters to oscillometric signal in automatic blood pressure measurement

Figures

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  Figure 1. An oscillometry-based automatic sphygmomanometer. Blood pressure pulses are propagated from the heart to the brachial artery, and the pressure is transmitted to the cuff of the device through upper arm parameters. The cuff pressure and corresponding oscillometric signal are recorded by the automatic sphygmomanometer. (a) Blood pressure pulse wave inside brachial artery, (b) Cuff pressure measured by automatic sphygmomanometer, (c) Oscillometric signal, which records cuff pressure oscillation.

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  Figure 2. Models and phantom configuration for parametric study and experiment. (a) Analytical model based on pressure propagation through concentric components, (b) Simple FEM model based on the simplified human arm anatomy, (c) Actual MRI image of cross-section of human upper arm, (d) MRI-based FEM model from the MRI image in (c), (e) Cross-sectional view of fabricated phantom based on the MRI image in (c).

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  Figure 3. Upper arm parameters varied in the parametric study and experiment. Four physiological components were considered in the parametric study. Nine parameters in the four physiological components were investigated in the parametric study with the MRI-based FEM model, and among them, the inner radius of the artery (in bold) letters is varied within phantoms for the experiment. The baseline and the range of the parameters’ values used for the parametric study are presented.

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  Figure 4. Experimental setup and flow chart with the cardiovascular simulator and the signals obtained from the experiment. (a) Human brachial pulse waveform and that created by the cardiovascular simulator, recorded just before the phantom, (b) Experimental setup with the cardiovascular simulator: pump mimicking heart is actuated to create the pressure waveform that reproduces the pulse wave in the human circulatory system, (c) Oscillometric signals obtained from the analytical model, MRI-based FEM model, experiment, and human, respectively. (d) Flow chart of the experimental procedure.

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  Figure 5. Oscillometric signal evaluation indices with meaningful range indicated. (a) Setting of the meaningful range of the oscillometric signal based on the maximum amplitude algorithm, and definition of an amplitude index and a shape index. Example calculation of two indices with the oscillometric signal obtained through (b) the modeling, and (c) the experiment.

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  Figure 6. Parametric study results. The percentage change in amplitude index of oscillometric signal when upper arm parameters are varied for each model. (a) Parametric study results with analytical model and simple FEM model, (b) Parametric study results with MRI-based FEM model and experiment.

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  Figure 7. Correlation analysis between inner artery radius and oscillometric signal—Experiment with phantoms. (a) Oscillometric signals (envelope only, time-axis normalized to the meaningful range) obtained from the experiment with different artery radius, (b) Amplitude index (ordinate) with various artery radius, (c) Shape index (abscissa) with various artery radius.