Night Ambulatory Monitoring Of Blood Pressure Clinical Study Protocol

Elevated Blood Pressure (BP) is a chronic medical condition with a prevalence of about 45% in the middle-aged population.

The particular interest of this project is given to the diagnosis and treatment of so-called nocturnal hypertension. Unfortunately, current monitoring practice relies on the use of occlusive pneumatic cuffs inflated around the arm to assess BP. Based on oscillometric technique, occlusive cuffs perform intermittent BP measurements every 20 minutes, thus providing only a limited view of the BP regulation landscape. In addition, oscillometric measurement performs a full occlusion of the measured arm inducing awakening reactions, and leading to non-representative overestimated BP values. The non-occlusive measurement of BP is thus an unsolved problem of modern medicine.

The aim of the NAMBP (Night Ambulatory Monitoring of Blood Pressure) project is to develop, implement and test in clinical trials a first-ever non-occlusive BP sensor to be used during sleep.

A novel technology for the non-occlusive measurement of BP from photoplethysmographic (optical) signals, known as Pulse Wave Analysis (PWA), has been investigated for the past decade by the Centre Suisse d'Electronique et de Microtechnique (CSEM, Neuchâtel, Switzerland). The herein proposed system - the CSEM Pulse Watch - consists in a single sensor (watch-like device) attached at the wrist that measures photoplethysmographic waveforms induced by the pulsatility of the skin arteries of the wrist. These waveforms are then post-processed via PWA: The system will detect features in the measured waveforms that correlate, through the phenomenon of wave reflections, to the underlying BP of the patient.