EP-4739202-A1 - SPATIOTEMPORAL-BASED DETECTION AND CORRECTION OF MOTION ARTIFACT FOR MEASUREMENT OF ARTERIAL PRESSURE WAVEFORM

EP4739202A1EP 4739202 A1EP4739202 A1EP 4739202A1EP-4739202-A1

Abstract

A method and system for spatiotemporal management of motion artifacts/blood pressure drifts in an arterial pressure waveform. The system includes an elastomeric sensor array in touch with a surface patch of skin over a superficial artery of a subject, an actuator mounted over the elastomeric sensor array, and a camera mounted on the actuator to capture image data that a controller processes. The elastomeric sensor array is digitally or mechanically into a pulsatile area and a non-pulsatile area. The controller measures the arterial pressure waveform having motion artifacts caused by elastomeric sensor array deformation on the skin over the artery in the pulsatile area and over the skin adjacent to the artery in the non-pulsatile area. Further, the controller determines spatiotemporal information of the motion artifact in the pulsatile and non- pulsatile areas, correcting the arterial pressure waveform by removing the motion artifact based on the spatiotemporal information to determine the physiological parameters.

Inventors

THANIKACHALAM, Mohan
UPTON, Emily
ALEIFERIS, Stamatios
RAJAMANICKAM, Gokul, Prasath

Assignees

Dynocardia, Inc.

Dates

Publication Date: 20260513
Application Date: 20240702

Claims (20)

1. A method for spatiotemporal management of motion artifacts in a physiological waveform comprising: receiving image data from a sensor array that is in touch with a skin of a subject;measuring a physiological waveform based on the image data, wherein the physiological waveform comprises motion artifact caused by sensor array deformation or movement on the skin over an artery in a pulsatile area in response to an external positive pressure being applied thereto and by sensor array deformation or movement over the skin adjacent to the artery in a non-pulsatile area: determining information relating to the motion artifact in the pulsatile area and in the non-pulsatile area; correcting the physiological waveform by removing or suppressing the motion artifact based on at least the information relating to the motion artifact in the non-pulsatile area; and determining physiological parameters of the subject based on the corrected physiological waveform.
2. The method, as claimed in claim 1, wherein the physiological waveform is representative of an arterial pressure, and wherein the determining the information comprises: detecting a characteristic of the motion artifact in the pulsatile area; detecting the characteristic or another characteristic of the motion artifact in the non- pulsatile area; determining the information of the motion artifact in the pulsatile area and the motion artifact in the non-pulsatile area.
3. The method as claimed in claim 2, responsive to the pulsatile area and the non-pulsatile area not being separated, the controller digitally separating the pulsatile area and the non- pulsatile area in the image data by: estimating a displacement of the image data at each time point; determining a variance of a signal over time-based on the displacement; performing a temporal Fourier transform of the displacement of the image data at all locations based on the variance of the signal over time; determining areas with the transformed displacement that meet a predefined threshold; and segmenting the areas with the transformed displacement that meet the predefined threshold into the pulsatile area and the areas with the transformed displacement that does not meet the predefined threshold into the non-pulsatile area.
4. The method, as claimed in claim 2, wherein the detecting the characteristic of the motion artifact in the non-pulsatile area comprises: determining a plurality of parameters associated with the non-pulsatile area; determining at least one reference region in the image data based on the plurality of parameters; filtering residual pulsatile signal from at least one reference region; and detecting the characteristric of the motion artifact in the non-pulsatile area based on the filtered residual signal from at least one reference region.
5. The method, as claimed in claim 4, wherein the residual pulsatile signal is filtered from the at least one reference region by applying one of a median average filter, a moving median average filter, and a Fourier transform low pass filter.
6. The method as claimed in claim 4, wherein the plurality of parameters determines the reference region that surrounds the pulsatile area with adequate distance from the pulsatile area to remove low-amplitude effects that the arterial pressure waveform and a large possible area to maximize spatial pattern recognition used to impute the changes within the pulsatile area due to the artifactual motion.
7. The method, as claimed in claim 4, detecting the characteristic or another characteristic of the motion artifact in the non-pulsatile area based on the filtered residual signal from at least one reference region comprises: determining a temporal derivative using a frequency filter; and detecting the characteristic or another characteristic of the motion artifact in the non- pulsatile area based on the temporal derivative.
8. The method, as claimed in claim 2, wherein the detecting the characteristic of the motion artifact in the pulsatile area comprises: matching a template to detect changes in a pulse waveform morphology that trigger the high-frequency artifact flag; and detecting the characteristic of the motion artifact in the pulsatile area based on the template.
9. The method, as claimed in claim 1, wherein the correcting the physiological comprises: detecting a type of motion artifact in the pulsatile area and in the non-pulsatile area; detecting whether an artifact flag is raised responsive to the detecting the type of motion; and applying a correction technique to remove the motion artifact from the physiological waveform based on at least the information, the raised artifact flag, and the type of the motion artifact in the pulsatile area and in the non-pulsatile area.
10. The method, as claimed in claim 1, wherein generating the physiological waveform based on the image data comprises: transforming the image data into a linear temporal signal; and generating the physiological waveform based on the linear temporal signal.
11. A system for management of a motion artifact, comprising: a sensor array in touch with a surface patch of a skin of a subject, wherein the elastomeric sensor array comprises camera that captures image data of the elastomeric sensor array; and a controller, communicatively coupled to the camera, configured to: measure an arterial pressure waveform based on the image data, wherein the arterial pressure waveform comprises a motion artifact caused by a respective deformation or movement of the sensor array on the skin over the artery in a pulsatile area in response to positive pressure being applied thereto and over the skin adjacent to the artery in a non-pulsatile area. determine information of the motion artifact in the pulsatile area and in the non- pulsatile area, correct the arterial pressure waveform by removing the motion artifact based on the determined information, and determine the physiological parameters of the subject based on the corrected arterial pressure waveform.
12. The system, as claimed in claim 11, wherein the sensor array is segmented into a first sensor array mounted on the skin over the artery and a second sensor array mounted on the skin adjacent to the artery, wherein the first sensor array and the second sensor array are separated from each other at a predefined distance, and wherein the actuator is mounted over the first sensor array representing the pulsatile area, and a second actuator is mounted over the first sensor array representing the non- pulsatile area.
13. The system, as claimed in claim 11, wherein the sensor array is segmented into a first sensor array mounted on the skin over the artery and a second sensor array mounted on the skin adjacent to the artery, wherein the first sensor array and the second elastomeric sensor array are separated from each other at a predefined distance, the system further comprising an actuator having an actuated state in which a controlled amount of pressure isolates a spatiotemporal signal from an artery’ of the subject, and wherein the actuator is segmented into a first actuator mounted over the first sensor array representing the pulsatile area and a second actuator mounted over the first sensor array representing the non-pulsatile area.
14. The system, as claimed in claim 11, wherein the determining the information of the motion artifact in the pulsatile area and the non-pulsatile area comprises: detecting the motion artifact in the pulsatile area; detecting the motion artifact in the non-pulsatile area; determining spatiotemporal information of the motion artifact in the pulsatile area and in the non-pulsatile area.
15. The system, as claimed in claim 14, wherein the sensor array has only one camera that sees the pulsatile area and the non-pulsatile area such that the pulsatile area and the non-pulsatile area are not separately sensed, the controller digitally separating the pulsatile area and the non-pulsatile area in the image data by: estimating a displacement of the image data at each time point; determining a variance of a signal over time-based on the displacement; performing a temporal Fourier transform of the displacement of the image data at all locations based on the variance of the signal over time; determining areas with the transformed displacement that meet a predefined threshold; and segmenting the determined areas with the transformed displacement that meet the predefined threshold into the pulsatile area and the areas with the transformed displacement that does not meet the predefined threshold into the non-pulsatile area.
16. The system, as claimed in claim 14. wherein the detecting the motion artifact in the non- pulsatile area comprises: determining a plurality 7 of parameters associated with the pulsatile area; determining a reference region in the image data based on the plurality of parameters; filtering residual pulsatile signal from the reference region; and detecting the motion artifact in the non-pulsatile area based on the fdtered residual signal from the reference region.
17. The system, as claimed in claim 16, wherein the residual pulsatile signal is filtered from the reference region by applying one of a median average filter, a moving median average filter, and a Fourier transform low pass filter.
18. The system, as claimed in claim 16, wherein the plurality of parameters comprises one or more of an adjacency to the pulsatile area to capture the sensor array deformations, a distance from the pulsatile area to remove low-amplitude, and a length of the pulsatile area.
19. The system, as claimed in claim 16, wherein the detecting the motion artifact in the non- pulsatile area based on the filtered residual signal from the reference region, comprises: determining a temporal derivative using a frequency filter; and detecting the motion artifact in the non-pulsatile area based on the temporal derivative.
20. The system, as claimed in claim 14, wherein the detecting the motion artifact in the pulsatile area comprises: matching a template to detect changes in a pulse waveform morphology that trigger the high-frequency artifact flag; and detecting the motion artifact in the pulsatile area based on the template.

Description

SPATIOTEMPORAL-BASED DETECTION AND CORRECTION OF MOTION ARTIFACT FOR MEASUREMENT OF ARTERIAL PRESSURE WAVEFORM CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of priority to U.S. Provisional Patent Application No. 63/525.519 filed July 7, 2023, which is hereby incorporated by reference in its entirety. TECHNICAL FIELD OF THE INVENTION [0002] The present invention relates to non-invasive periodic or continuous measurement of physiological parameters. More specifically, to use skin surface displacements and forces for spatiotemporal-based detection and correction of motion artifacts to accurately capture and assess arterial pressure (or other physiological phenomena) waveform despite movement. BACKGROUND [0003] The real-time capture of the arterial pressure waveform and its assessment to measure physiological parameters are essential for monitoring and assessing health inside and outside a medical facility. The physiological parameters are, but are not limited to, heart rate, blood pressure, respiratory rate, cardiac output, and other advanced hemodynamic parameters. The physiological parameters generally provide moment-to-moment information for making medical decisions during illness and operative procedures, as well as long-term information in helping to prevent and manage chronic diseases. [0004] W02019/195120A1 titled Tactile Blood Pressure Imager, which is incorporated by reference in its entirety herein, a Tactile Blood Pressure Imager (TBPI) includes an optomechanical force sensor array to measure skin deformation or displacement over a surficial artery such as the radial artery at a wrist of a patient. The TBPI provides a periodic and continuous measure of the arterial pressure waveform used to measure blood pressure, heart rate, respiratory rate, and advanced hemodynamic parameters. WO/2022/035841 entitled Optomechanical Method to Measure Arterial Pulse and Assess Cardiopulmonary Hemodynamics, which is incorporated by reference in its entirety7 here, discloses and discusses optomechanical sensor systems having structures and processes capable of measuring surface displacement due to arterial pressures. [0005] During the measurement of the arterial pressure waveform, unintentional motion can induce mechanical forces that can lead to artifactual or inaccurate measurements of the arterial pressure waveforms. For example, regular operation of the device, wrist, hand, arm, body motions, or vibrational motions from vehicles or transport can generate artifactual forces that can corrupt an arterial pressure waveform, thus making it challenging to measure psychological parameters. Further, vibratory motions during patient transport may be of a similar frequency as the pulse. The movement of the hand, fingers, or other body parts can lead to a displacement of soft tissue and skin over the artery, which can corrupt the arterial pressure measurement. These motion artifacts cause a superposed deformation and displacement of the soft tissue and the skin leading to artifactual measurements of the arterial pressure waveform. A specific challenge presented by trying to isolate motion artifacts from a physiological signal such as one representing an arterial pressure is that the frequency of the motion artifact and the signal of interest can overlap, making it difficult to simply subtract out the artifact signal to reveal the signal of interest. Due to overlapping information in the spectral content of the signal of interest and the artifactual signal, isolating the artifactual signal from the signal of interest is not straightforward. Further complicating the isolation of the signal of interest is that over time tissue can relax, for example, which can cause a slow drift in the signal of interest, making it difficult to track over time while removing artifactual noise from the signal of interest. Thus, the aspects disclosed herein can account for not just motion artifacts but also blood pressure drift due to tissue relaxation. [0006] The previously referenced patent applications offer no methods for mitigating these motion artifacts and blood pressure drift. Hence there is a need to detect and correct the motion artifacts/blood pressure drift to measure the arterial pressure waveform accurately. SUMMARY [0007] Without limiting the scope and details of the present disclosure as described herein, an important aspect of motion artifact/blood pressure drift correction techniques herein is that it takes into account effects on an area just outside or adjacent the pulsatile area (called £'non- pulsatile” area herein) to eliminate or suppress these effects to provide a true and accurate representation of a physiological parameter, such as arterial pressure. In other words, the present disclosure does not look at the pulsatile area only; it inspects the area nearby to help isolate artifactual movements that corrupt or degrade a signal of interest such as blood pressure. A single sensor (e.g.,