Monitoring device for monitoring a physiological parameter and methods thereof

Inventors

Le Guillou, Yann • BODINIER, Quentin

Assignees

Biosency

Abstract

A method to process signals acquired with at least one accelerometer and one gyroscope worn by a subject for evaluating a heart rate and/or a respiratory rate. The method includes: receiving the accelerometer and gyroscope signals at a sampling frequency in a given time window; combining each pair of accelerometer and gyroscope signals in the given window to output an orientation vector for each sampling time using a quaternion representation; applying at least one filter to the orientation signal defined by the orientation vectors to obtain a filtered signal; calculating an average breath cycle and/or time interval separating two consecutive heart beats using an algorithm for modeling an average signal, which iteratively determines the average between the filtered signal and the average signal from a preceding iteration; estimating a heart and/or respiratory rate from the calculated average breath cycle and/or time interval separating two consecutive heart beats.

Core Innovation

The invention evaluates a heart rate and/or a respiratory rate of a subject wearing a monitoring device that comprises at least one accelerometer, at least one gyroscope, and a photoplethysmograph, with a processor including a microprocessor and a controller. The processor estimates a level of activity according to signals acquired by the accelerometer and the gyroscope, compares the level of activity to a predefined threshold, and conditionally activates or deactivates the photoplethysmograph.

The inertial-processing part receives accelerometer and gyroscope signals with a predefined sampling frequency at n sampling times in a given time window to obtain pairs of n successive samples. The processor combines the n successive samples using a quaternion representation to output an orientation vector for each n sampling time, and the orientation vectors collectively define an orientation signal, which is then filtered to obtain a filtered signal for the given time window.

The method calculates an average breath cycle and/or an average time interval separating two consecutive heart beats using an algorithm for modeling an average signal. The algorithm iteratively determines the average breath cycle and/or the average time interval by computing an average signal between the filtered signal of the given time window and an average signal obtained in a preceding iteration for a preceding time window, and the processor estimates the heart rate and respiratory rate from the average breath cycle and the average time interval.

Claims Coverage

The independent claim set includes 1 independent claim. Across this independent claim, the inventive features focus on activity-based photoplethysmograph activation/deactivation and an inertial-signal pipeline that uses quaternion-based orientation signals, filtered orientation signals, and iterative modeling to estimate average breath cycle and inter-beat interval for heart and respiratory rate estimation.

The independent claim combines activity-based activation/deactivation of the photoplethysmograph, quaternion-based orientation vectors, filtered orientation signals, iterative modeling of an average breath cycle and average inter-beat interval, estimation of heart rate and respiratory rate from those modeled quantities, and transmission of selected computed data to a companion device or a server.

Stated Advantages

Documented Applications