Development of a Device Based on Oscillometry and Photoplethysmography for Measuring Blood Pressure

Blood pressure is a very important physiological parameter given it provides information about the state of the cardiovascular system. The present work describes the development of an electromechanical device to measure the systolic and diastolic blood pressure in the digital artery. The measurements are based on the onset of the photoplethysmographic pulse signal when the artery is decompressed during the deflation of a neonatal cuff placed on the middle finger. The device consists of an optical sensor, a pressure transducer, an electronic system based on an Arduino development board and a graphical computer interface written in Matlab. To validate our device we used a Portapres® system. Simultaneous pressure measurements made with our device and the Portapres® were continuously recorded from 9 subjects in sitting and standing positions. The systolic (SBPDA) and diastolic (DBPDA) blood pressures measured from the digital artery were analytically compared. Results obtained for the SBPDA yielded R2 values of 0.59 and 0.76, as well as 0.59 and 0.85 for the DBPDA for the sitting and standing positions evaluated. A comparison of SBPDA values using the Bland-Altman plot yielded mean values of µ = 3.88 ± 11.97 mmHg and µ = −0.6 ± 9.59 mmHg for the sitting and standing position, respectively.