Evaluating the performance of automated sphygmomanometers using a patient simulator

Automated sphygmomanometers use the oscillometric method to measure blood pressure, which is based on an algorithm that relates the amplitude of the oscillometric waveform pulses and the pressure inside the cuff. Validation uses empirical information from clinical trials conducted by each manufacturer. Consequently, measurement algorithms are not harmonized, being based on distinct arterial waveforms, according to each group of volunteers of the clinical test. In the present study, a patient simulator was used to generate standardized, consistent oscillometric waveform pulses to test the algorithms used in six sphygmomanometers.

Six different upper arm and wrist-based automated sphygmomanometers were tested using a patient simulator comprising four different blood pressure levels, Psys/dia (mmHg): 80/50; 120/80; 150/100; 200/150. The devices were also submitted to conformity assessment. The variance of repeatable measurements was also analyzed.

All tested automated sphygmomanometers complied with metrological requirements, presenting results within the range of ±2 mmHg for static calibration. Systematic discrepancies, greater than 20 mmHg, were observed between sphygmomanometers' results from upper arm and wrist-based models. Differences reaching 12.8 mmHg in diastolic pressure results were observed among upper arm devices.

These results may have a clinical impact and indicate the need for a standardized algorithm, with a harmonized approach for validation. Moreover, the algorithm of the wrist-based devices is being affected by the use of the brachial artery waveform as reference for its validation, which also reveals that the current approach needs standardization, especially regarding the use of patient simulators.24299305.