Title: Real-time embedded control for continuous measurement of blood pressure: methodologic innovations

Authors: Leonardo Casal; Alejandro Mazzadi

Addresses: Lab. de Biomateriales, Biomecánica y Bioinstrumentación, Universidad Nacional de San Martín (UNSAM), San Martín, Buenos Aires, Argentina ' Centro de Estudios en Salud y Medio Ambiente (CESyMA), Universidad Nacional de San Martín (UNSAM), San Martín, Buenos Aires, Argentina

Abstract: Continuous blood-pressure (BP) waveform can be measured by the volume-clamp method, where a closed-loop control over a fast pneumatic actuator reproduces BP in a finger cuff. Frequent interruptions, however, are necessary to update arterial-wall compliance to a maximum. We implemented an embedded control in hard real time that measures BP without those interruptions. A microcontroller executes the control system at 2 ms while a computer asynchronously handles the most demanding tasks. The system's design included the following methodological innovations: 1) the arterial-compliance changes were estimated with high-frequency vibrations superimposed on the cuff pressure; 2) this information was used to update the control setpoint to maximum compliance, thus avoiding measurement interruptions; 3) the closed-loop stability was guaranteed with a recurrent redesign of the control; 4) the arterial-wall dynamics were identified for each subject in the control's design, thus improving the method's performance.

Keywords: volume clamp method; closed-loop control; blood pressure; arterial compliance.

DOI: 10.1504/IJES.2021.121084

International Journal of Embedded Systems, 2021 Vol.14 No.6, pp.592 - 601

Received: 23 Nov 2020
Accepted: 12 Mar 2021
Published online: 24 Feb 2022 *

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