Low-cost noninvasive continuous blood pressure monitor

A novel design is proposed to measure the Arterial Blood Pressure (BP) using the vascular unloading technique controlling the pressure cuff acting on the air pump speed instead of a servo valve. The BP monitoring in a continuous way allows identifying the hypertension or hypotension states in order to avoid damage of vital organs such as the heart and brain in critically ill patients. Depending on the clinical evaluation, this procedure can be done invasively using an arterial catheter, or noninvasively using, for example, the volume clamp method or vascular unloading technology. In the last case, the finger BP is monitored by a photoplethysmography device coupled to an inflatable cuff controlled by a servo valve to keep constant the diameter of the artery. The cost of commercial devices using this operation principle is relatively high in comparison with noninvasive intermittent BP monitors. A prototype was built based on the Arduino platform, and tested based on the International Protocol of Validation of BP Measurement Instruments in adults. As a result, a low-cost device (components cost around EUR 150) was built. From the Bland–Altman analysis, the mean and standard deviation (SD) were determined as 5.09 ± 12.27 for the Systolic BP, − 1.72 ± 12.56 for the Diastolic BP, and 0.68 ± 11.08 for the Mean BP. Similar results were reported for commercial devices that employ the vascular unload technique controlling the cuff pressure through a servo valve. Then, the proposed device is a low-cost alternative to measure BP with results similar to commercial devices.