Patient-Specific Oscillometric Blood Pressure Measurement.

Abstract

Most automatic cuff blood pressure (BP) measurement devices are based on oscillometry. These devices estimate BP from the envelopes of the cuff pressure oscillations using fixed ratios. The values of the fixed ratios represent population averages, so the devices may only be accurate in subjects with normal BP levels. The objective was to develop and demonstrate the validity of a patient-specific oscillometric BP measurement method. The idea of the developed method was to represent the cuff pressure oscillation envelopes with a physiologic model, and then estimate the patient-specific parameters of the model, which includes BP levels, by optimally fitting it to the envelopes. The method was investigated against gold standard reference BP measurements from 57 patients with widely varying pulse pressures. A portion of the data was used to optimize the patient-specific method and a fixed-ratio method, while the remaining data were used to test these methods and a current office device. The patient-specific method yielded BP root-mean-square-errors ranging from 6.0 to 9.3 mmHg. On an average, these errors were nearly 40% lower than the errors of each existing method. The patient-specific method may improve automatic cuff BP measurement accuracy. A patient-specific oscillometric BP measurement method was proposed and shown to be more accurate than the conventional method and a current device.