Wrist cuff method determines mean arterial pressure in dual-cuff blood pressure system

Mean arterial pressure (MAP) is the pressure in the arteries averaged over time. Oscillometric blood pressure (BP) monitors determine the value of MAP by processing arterial pulses in the cuff. Cuff pressure at the point of largest pulse amplitude is equal to MAP. The oscillometric determination of MAP is subject to errors resulting from wave reflections and stroke volume variability. We developed an experimental system that uses two cuffs in order to improve accuracy of noninvasive BP measurement. The system consists of a compact module with pneumatic and electronic circuits, two detachable cuffs (arm and wrist), and a notebook computer connected to the module via a USB cable. This study concentrated on improvements in the determination of MAP using the wrist cuff pulses. The smallest wrist cuff amplitude in the middle segment of BP test was determined as the point of MAP. The corresponding arm cuff pressure was the value of MAP. Waveforms and cuff pressures from 40 BP tests were used to determine oscillometric, wrist cuff, and calculated MAP values and the values were compared. The results indicated that it is possible to determine MAP from wrist cuff pulse amplitudes and that the wrist cuff method may be more accurate than the oscillometric method.