Estimation of the Blood Pressure using Arterial Pressure-Volume Model

An analysis of the conventional blood pressure estimation method of the oscillometric sphygmomanometer was performed through a computer simulation using an arterial pressure-volume(APV) model. A more accurate blood pressure estimation method was proposed from the analysis. Traditionally, the maximum amplitude algorithm was applied on the oscillation waveforms of the APV model to get the mean arterial pressure and the characteristic ratio. In doing so, the shape of pressure waveforms and the cutoff frequency of high-pass filter circuitry strongly affected the estimation of mean arterial pressure and characteristic ratio. This resulted in errors when estimating blood pressure. To find an algorithm independent from the influence of waveform shapes and filter parameters, the volume oscillation of the APV model and the phase shift of the oscillation with FFT were identified by increasing the cuff pressure from 1 mmHg to 200 mmHg (1 mmHg per second). The phase shift between the ranges of volume oscillation was then only observed between the systolic and diastolic blood pressures. The same results were obtained from simulations performed on two different arterial blood pressure waveforms and one hyperthermia waveform.