# US 2022/0045451 A1 · Systems and methods for motion compensation in ultrasonic respiration monitoring

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- Number: US 2022/0045451 A1
- Document ID: US20220045451A1
- Status: Published application
- Kind: A1
- Application number: 17/311,590
- Filed: 2019-12-10
- Published: 2022-02-10
- Earliest claimed: 2018-12-11
- Assignees: Respinor AS
- Applicants: Respinor AS
- Inventors: Morten ERIKSEN; George REFSETH; Knut LØKLINGHOLM; Nioclay BERARD-ANDERSEN; Nicolas SOUZY; Torgeir HAMSUND
- Web page: https://patentgrep.com/patent/US20220045451A1

## CPC

- A61B 5/0816: {Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00)}
- A61B 5/1126: {using a particular sensing technique}
- A61B 5/1135: {by monitoring thoracic expansion}
- A61B 2562/0219: Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Described herein are example methods, devices and systems for motion compensation in ultrasonic respiration monitoring. A respiration detection system includes a first probe placed on a front side of a patient's body and a second probe placed on a dorsal side of the body. The first probe includes an ultrasound transducer, a first accelerometer unit and a magnetic field sensor unit, and the second probe includes a second accelerometer unit and magnetic field sensor unit. Due to respiration of the patient, the abdominal region of the body moves, creating measurement errors when an ultrasound beam is directed towards an internal structure (internal tissue region) inside the patient's body. Correction for such measurement errors uses input data from the first and second accelerometer units and the magnetic field sensor unit.

## Claims

### Claim 1

A respiration detection system comprising:
a first probe (102) comprising:
an ultrasonic transducer (112) stationary located within the first probe and having a transceiving face (113) oriented at an acute angle (Ω) relative to a front plane (114) of the first probe (102), wherein the ultrasonic transducer (112) is configured to produce an ultrasound beam (143) at the transceiving face (113) for transmission into an internal structure inside the body of a patient,
a first accelerometer unit (121), and
a first magnetic field unit (122), wherein the ultrasonic transducer (112), the first accelerometer unit (121), and the first magnetic field unit (122) are stationary located in the first probe (102); and
a second probe (104) comprising:
a second accelerometer unit (128), and
a second magnetic field unit (129), wherein the second accelerometer unit (128) and the second magnetic field unit (129) are stationary located in the second probe (104);
wherein the ultrasonic transducer (112), the first and second accelerometer units (121; 128), and the first and second magnetic field units (122; 129) are coupled to a signal processor (134),
wherein the first probe (102) is configured to be placed on a front side (103) of the body (101) of the patient, and
wherein the second probe (104) is configured to be placed on a dorsal side (105) of the body (101),
wherein signals from the first accelerometer unit (121) indicate first spatial orientations of the first probe (102) with the ultrasound transducer (112) and the first magnetic field unit (122) therein,
wherein signals from the second accelerometer unit (128) indicate second spatial orientations of the second probe (104) with the second magnetic field unit (129) therein,
wherein the first and second spatial orientations are relative to a fixed coordinate frame, and
wherein signals from the first magnetic field unit (122) in interaction with the second magnetic field unit (129) and orientations of the magnetic field units (122; 129) as provided by signals from the first and second accelerometer units (121; 128) are inputs to the signal processor (134) to calculate variable spatial distance between the first and second probes (102; 104) and thereby calculate spatial movement and orientation of the ultrasonic transducer (112) as induced by respiration of the patient.

### Claim at position 2

2-3. (canceled)

### Claim 4 (depends on 1)

The respiration detection system of claim 1, wherein the spatial movement and the orientation are related to at least one of heave, roll, pitch and yaw type movements.

### Claim 5 (depends on 1)

The respiration detection system of claim 1,
wherein the ultrasonic transducer (112) is located in the first probe (102) by means of a body (115) of a first material comprising ultrasound non-sonolucent material which extends towards the front plane (114) of the first probe (102),
wherein the body (115) of the first material surrounds a recess (116) extending from the transceiving face (113) towards the front plane (114),
wherein a first body part (117) of a second material comprising ultrasound sonolucent material is located in the recess at and in front of the transceiving face (113) of the ultrasonic transducer (112) towards the front plane (114), and
wherein a second body part (117) of the second material is applied onto a front surface of the body of the first material and made integrally engaged therewith, the first and second body parts being integral.

### Claim 6 (depends on 1)

The respiration detection system of claim 1, wherein the ultrasonic transducer (112) is engaged within a socket-like member (120) forming a transducer recess (116), and being of ultrasound non-sonolucent material.

### Claim 7 (depends on 5)

The respiration detection system of claim 5, wherein a front surface of the body (117) of the second material comprises an inherent tacky property, an attachment face (117′) for an adhesive member (124) or a double-sided adhesive tape, or an engagement face for a tacky layer of a body of a third material.

### Claim at position 7

8-13. (canceled)

### Claim 14 (depends on 1)

The respiration detection system of claim 1, wherein a first one of the first magnetic field unit (122) and the second magnetic field unit (129) comprises a magnetic field sensor device, and wherein the other one of the first magnetic field unit (122) and the second magnetic field unit (129) comprises an electromagnet device configured to generate a magnetic field to be detected by the magnetic field sensor device, and wherein the magnetic field is related to distance between the first and second probes (102; 104).

### Claim at position 9

15-16. (canceled)

### Claim 17 (depends on 1)

The respiration detection system of claim 1, wherein the first probe (102) is configured to be placed on the front side (103) of the patient's body at a position aligned with the second probe (104) on the dorsal side (105) of the patient's body.

### Claim 18 (depends on 1)

The respiration detection system of claim 1, wherein the second accelerometer unit (128) provides for measurement of tilt angles of a surface supporting the dorsal side (105) of the patient's body.

### Claim at position 12

19-20. (canceled)

### Claim 21 (depends on 1)

The respiration detection system of claim 1, wherein the signal processor (134) is configured to calculate, based on inputs from the first and second accelerometer units (121; 128) and from the first magnetic field unit (122) interacting with the second magnetic field unit (129), movement and orientation of the ultrasonic transducer (112) in the first probe (102) in relation to an expected direction of motion of the internal structure (144) inside the body of the patient relative to a longitudinal axis of the patient, the movement and orientation of the ultrasonic transducer (112) being related to respiration parameters associated with the respiratory muscles of the patient.

### Claim 22 (depends on 21)

The respiration detection system of claim 21, wherein the internal structure is one of a liver (144), spleen, or kidney of the patient.

### Claim 23 (depends on 21)

The respiration detection system of claim 21, wherein the expected direction of motion of the internal structure (144) is a function of thoracic diaphragm movement (145) in the patient's body.

### Claim 24 (depends on 1)

The respiration detection system of claim 1, wherein:
the ultrasonic transducer (112) in the first probe (102) is configured to receive ultrasound echo signals from the internal structure;
the second magnetic field unit (129) is configured to generate a magnetic field transmitted to and detected by the first magnetic field unit (121);
the signal processor (134) is configured to calculate:
an orientation of the first accelerometer unit (121) relative to the fixed coordinate frame using derived parameters from the first accelerometer unit (121),
the derived parameters as unit vectors representing an orientation of the ultrasound beam and an orientation of the first magnetic field unit (122),
an orientation of the second accelerometer unit (128) relative to the fixed coordinate frame using further derived parameters from the second accelerometer unit (128),
the further derived parameters including body back (105) support tilt angle (a) and unit vectors representative of a spatial direction from the second magnetic field unit to the first magnetic field unit (122),
an orientation of the second magnetic field unit (129),
an expected direction of motion of the internal structure (144) relative to a longitudinal axis of a torso of the patient during exhalation of the patient, and
any varying distance between the first and second magnetic field units (122; 129) based on the detection of the magnetic field,
the orientation of the ultrasound beam, the orientation of the first magnetic field unit (122), and the orientation of the second magnetic field unit (129) being relative to the fixed coordinate frame; and
the signal processor (134) is further configured to process results from the calculated orientations of the first and second accelerometer units (121; 128), derived parameters from the first and second accelerometer units, and the varying distance to generate correction parameters to compensate for measurement errors in received ultrasound echo signals caused by the spatial movement and orientation of the ultrasonic transducer (112) as induced by respiration of the patient.

### Claim 25 (depends on 24)

The respiration detection system of claim 24 wherein to generate the correction parameters, the signal processor is further configured to:
decompose a vector representing the distance between the first magnetic field unit (122) and the second magnetic field unit (129) along the direction of the ultrasound beam;
differentiate in time the decomposed vector representing the distance to yield incremental motion values;
add the incremental motion values to incremental Doppler effect motion values as detected by use of ultrasound echo signals from the internal structure in at least a same time interval;
correct the added motion values for an instantaneous cosine value of an angle between the ultrasound beam and direction of motion of the internal structure; and
sum the corrected and added motion values to obtain internal structure position variations describing corrected respiratory parameters.

### Claim 26 (depends on 1)

The respiration detection system of claim 1, wherein the first probe (102) is configured to be placed on the patient's body to direct an ultrasonic beam towards an internal structure inside the patient's body and receive ultrasonic echo signals from the internal structure,
the first probe (102) further comprising a housing (110) with a cavity (111),
the ultrasonic transducer (112) being located in the cavity (111), a transceiving face (113) of the ultrasonic transducer (112) being at an acute angle (Ω) relative to the front plane (114) of the housing at or adjacent a cavity mouth of the cavity (111) of the housing (110),
wherein the ultrasonic transducer (112) is fixedly located in the cavity (111) of the housing (110) by way of an open-ended socket-like member (120) of ultrasound non-sonolucent material which provides a recess that extends from the transceiving face (113) towards the front plane (114),
wherein a first body part (117) of an ultrasound sonolucent material is located in the socket-like member (120) at and in front of the transceiving face (113) of the ultrasonic transducer (112) towards the front plane (114),
wherein the first accelerometer unit (121) and the first magnetic field detection unit (122) are connected to a printed circuit board (119) within the cavity (111) of the housing (110),
wherein a front surface of the first probe (102) exhibits at least one of an inherent tacky property, an attachment face for an adhesive member or a double-sided tacky tape, or an engagement face for a tacky body layer, and
wherein the ultrasonic transducer (112) is configured to connect to a transceiver section of the signal processor (134).

### Claim 27

(canceled)

### Claim 28 (depends on 26)

The respiration detection system of claim 26, wherein the ultrasonic transducer (112) and the open-ended socket-like member (120) extend from the printed circuit board (119).

### Claim at position 21

29-52. (canceled)

### Claim 53

A respiration detection system comprising:
a first probe (102) comprising:
an ultrasonic transducer (112) stationary located within the first probe and having a transceiving face (113) oriented at an acute angle (Ω) relative to a front plane (114) of the first probe (102), wherein the ultrasonic transducer (112) is configured to produce an ultrasound beam (143) at the transceiving face (113) for transmission into an internal structure inside the body of a patient, wherein the internal structure is one of a liver (144), spleen, or kidney of the patient,
a first accelerometer unit (121), and
a first magnetic field unit (122), wherein the ultrasonic transducer (112), the first accelerometer unit (121), and the first magnetic field unit (122) are stationary located in the first probe (102); and
a second probe (104) comprising:
a second accelerometer unit (128), and
a second magnetic field unit (129), wherein the second accelerometer unit (128) and the second magnetic field unit (129) are stationary located in the second probe (104);
wherein the ultrasonic transducer (112), the first and second accelerometer units (121; 128), and the first and second magnetic field units (122; 129) are coupled to a signal processor (134),
wherein the first probe (102) is configured to be placed on a front side (103) of the body (101) of the patient,
wherein the second probe (104) is configured to be placed on a dorsal side (105) of the body (101),
wherein signals from the first accelerometer unit (121) indicate first spatial orientations of the first probe (102) with the ultrasound transducer (112) and the first magnetic field unit (122) therein,
wherein signals from the second accelerometer unit (128) indicate second spatial orientations of the second probe (104) with the second magnetic field unit (129) therein,
wherein the first and second spatial orientations are relative to a fixed coordinate frame,
wherein signals from the first magnetic field unit (122) in interaction with the second magnetic field unit (129) and orientations of the magnetic field units (122; 129) as provided by signals from the first and second accelerometer units (121; 128) are inputs to the signal processor (134) to calculate variable spatial distance between the first and second probes (102; 104) and thereby calculate spatial movement and orientation of the ultrasonic transducer (112) as induced by respiration of the patient,
wherein a first one of the first magnetic field unit (122) and the second magnetic field unit (129) comprises a magnetic field sensor device, and wherein the other one of the first magnetic field unit (122) and the second magnetic field unit (129) comprises an electromagnet device configured to generate a magnetic field to be detected by the magnetic field sensor device, and wherein the magnetic field is related to distance between the first and second probes (102; 104), and
wherein the signal processor (134) is configured to calculate, based on inputs from the first and second accelerometer units (121; 128) and from the first magnetic field unit (122) interacting with the second magnetic field unit (129), movement and orientation of the ultrasonic transducer (112) in the first probe (102) in relation to an expected direction of motion of the internal structure (144) inside the body of the patient relative to a longitudinal axis of the patient, the movement and orientation of the ultrasonic transducer (112) being related to respiration parameters associated with the respiratory muscles of the patient.

### Claim 54

A respiration detection system comprising:
a first probe (102) comprising:
an ultrasonic transducer (112) stationary located within the first probe and having a transceiving face (113) oriented at an acute angle (Ω) relative to a front plane (114) of the first probe (102), wherein the ultrasonic transducer (112) is configured to produce an ultrasound beam (143) at the transceiving face (113) for transmission into an internal structure inside the body of a patient, wherein the internal structure is one of a liver (144), spleen, or kidney of the patient,
a first accelerometer unit (121), and
a first magnetic field unit (122), wherein the ultrasonic transducer (112), the first accelerometer unit (121), and the first magnetic field unit (122) are stationary located in the first probe (102); and
a second probe (104) comprising:
a second accelerometer unit (128), and
a second magnetic field unit (129), wherein the second accelerometer unit (128) and the second magnetic field unit (129) are stationary located in the second probe (104);
wherein the ultrasonic transducer (112), the first and second accelerometer units (121; 128), and the first and second magnetic field units (122; 129) are coupled to a signal processor (134),
wherein the first probe (102) is configured to be placed on a front side (103) of the body (101) of the patient,
wherein the second probe (104) is configured to be placed on a dorsal side (105) of the body (101),
wherein signals from the first accelerometer unit (121) indicate first spatial orientations of the first probe (102) with the ultrasound transducer (112) and the first magnetic field unit (122) therein,
wherein signals from the second accelerometer unit (128) indicate second spatial orientations of the second probe (104) with the second magnetic field unit (129) therein,
wherein the first and second spatial orientations are relative to a fixed coordinate frame,
wherein signals from the first magnetic field unit (122) in interaction with the second magnetic field unit (129) and orientations of the magnetic field units (122; 129) as provided by signals from the first and second accelerometer units (121; 128) are inputs to the signal processor (134) to calculate variable spatial distance between the first and second probes (102; 104) and thereby calculate spatial movement and orientation of the ultrasonic transducer (112) as induced by respiration of the patient,
wherein the first probe (102) is configured to be placed on the patient's body to direct the ultrasound beam towards the internal structure inside the patient's body and receive ultrasonic echo signals from the internal structure,
the first probe (102) further comprising a housing (110) with a cavity (111),
the ultrasonic transducer (112) being located in the cavity (111), a transceiving face (113) of the ultrasonic transducer (112) being at an acute angle (Ω) relative to the front plane (114) of the housing at or adjacent a cavity mouth of the cavity (111) of the housing (110),
wherein the ultrasonic transducer (112) is fixedly located in the cavity (111) of the housing (110) by way of an open-ended socket-like member (120) of ultrasound non-sonolucent material which provides a recess that extends from the transceiving face (113) towards the front plane (114),
wherein a first body part (117) of an ultrasound sonolucent material is located in the socket-like member (120) at and in front of the transceiving face (113) of the ultrasonic transducer (112) towards the front plane (114),
wherein the first accelerometer unit (121) and the first magnetic field detection unit (122) are connected to a printed circuit board (119) within the cavity (111) of the housing (110),
wherein a front surface of the first probe (102) exhibits at least one of an inherent tacky property, an attachment face for an adhesive member or a double-sided tacky tape, or an engagement face for a tacky body layer,
wherein the ultrasonic transducer (112) is configured to connect to a transceiver section of the signal processor (134),
wherein the ultrasonic transducer (112) is mounted at a bottom region of the open-ended socket-like member (120), and
wherein the ultrasonic transducer (112) and the open-ended socket-like member (120) extend from the printed circuit board (119).

### Claim 55 (depends on 53)

The respiration detection system of claim 53, wherein the first probe (102) is configured to be placed on the front side (103) of the patient's body at a position aligned with the second probe (104) on the dorsal side (105) of the patient's body.

### Claim 56 (depends on 53)

The respiration detection system of claim 53, wherein the acute angle (Ω) is in a range of 0 to 60 degrees.

### Claim 57 (depends on 54)

The respiration detection system of claim 54, wherein the acute angle (Ω) is in a range of 0 to 60 degrees.

### Claim 58

A system for motion compensation in ultrasound-based detection of respiration parameters of a human, the system comprising:
a first probe (102) configured to be attached to a front body surface (103) of the human, the first probe (102) having an ultrasound transducer (112), a first accelerometer unit (121), and a first magnetic field unit (122);
a second probe (104) configured to be attached to a dorsal body surface (105) of the human, the second probe (104) having a second accelerometer unit (122), and a second magnetic field unit (129); and
a signal processor (134) coupled to the ultrasonic transducer (112), the first and second accelerometer units (121; 128), and the first and second magnetic field units (122; 129);
wherein the ultrasound transducer (112) in the first probe (102)7 is configured to transmit an ultrasound beam into an internal structure (144) inside the body of the human and receive ultrasound echo signals from the internal structure;
wherein the second magnetic field unit (129) is configured to generate a magnetic field transmitted to and detected by the first magnetic field unit (122); and
wherein the signal processor is configured to:
calculate an orientation of the first accelerometer unit (121) relative to a fixed coordinate frame using derived parameters from the first accelerometer unit (121), and further calculating the derived parameters as unit vectors representing an orientation of the ultrasound beam and an orientation of the first magnetic field unit (122);
calculate an orientation of the second accelerometer unit (128) relative to the fixed coordinate frame using further derived parameters, and calculating the further derived parameters including body back support tilt angle (a) and unit vectors representative of a spatial direction from the second magnetic field unit (129) to the first magnetic field unit (122), an orientation of the second magnetic field unit (129), and an expected direction of motion of the internal structure relative to a longitudinal axis of a torso of the human during exhalation;
calculate any varying distance between the first and second magnetic field units (122; 129) based on the detection of the magnetic field; and
process results from the calculated orientations of the first and second accelerometer units (121; 128), and further derived parameters from the first and second accelerometer units (121; 128), and the varying distance measured by the first and second magnetic field units (122; 129) to generate correction parameters to compensate for measurement errors in the received ultrasound echo signals caused by motion of the ultrasound transducer (112).

### Claim 59 (depends on 58)

The system of claim 58, wherein the signal processor is configured to generate correction parameters by:
decomposing a vector representing the distance between the first magnetic field unit (122) and the second magnetic field unit (129) along the direction of the ultrasound beam;
differentiating in time the decomposed vector representing the distance to yield incremental motion values;
adding the incremental motion values to incremental Doppler effect motion values as detected by use of the ultrasound echo signals from the internal structure in at least a same time interval;
correcting the added motion values for an instantaneous cosine value of an angle between the ultrasound beam and direction of motion of the internal structure; and
summing the corrected and added motion values to obtain internal structure position variations describing corrected respiratory parameters.

### Claim 60 (depends on 58)

The system of claim 58, wherein the signal processor (134) is configured to calculate, based on inputs from the first and second accelerometer units (121; 128) and from the first magnetic field unit (122) interacting with the second magnetic field unit (129), movement and orientation of the ultrasonic transducer (112) in the first probe (102) in relation to an expected direction of motion of the internal structure (144) relative to the longitudinal axis of the human, the movement and orientation of the ultrasonic transducer (112) being related to respiration activity.

### Claim 61 (depends on 58)

The system of claim 58, wherein the motion of the internal structure is a function of thoracic diaphragm movement in the body of the human.

### Claim 62 (depends on 58)

The system of claim 58, wherein continuous variations in any one of beam orientation, bed angle, and abdominal surface motion are utilized in the compensation.

### Claim 63 (depends on 62)

The system of claim 62, wherein the compensation assumes that an abdominal surface of the human moves in a direction (vmm) perpendicular to a surface on which the human rests.

### Claim 64 (depends on 58)

The system of claim 58, wherein:
the first and second accelerometer units are configured to measure tilt based on a direction of gravity, wherein the first and second accelerometer units comprise 3-axis accelerometer units; and
the first magnetic field unit is configured to measure up and down motion of the first probe (102) with the assistance of the magnetic field emitted by the second magnetic field unit (129), wherein the measured tilt and measured up and down motion are used to compensate for the measurement errors.

### Claim 65 (depends on 58)

The system of claim 58, wherein the second accelerometer unit (128) of the second probe (104) is configured to measure the tilt angle (a) of a bed surface on which the human rests, assuming that the internal structure moves along a same direction as the bed surface.

### Claim 66 (depends on 58)

The system of claim 58, wherein the signal processor is configured to compute an angle between the ultrasound beam and direction of motion of the internal structure for each motion increment instead of assuming that the angle has a stationary value.

### Claim 67 (depends on 66)

The system of claim 66, wherein the internal structure is one of a liver, spleen or kidney of the human.

### Claim 68 (depends on 59)

The system of claim 59, wherein continuous variations in any one of beam orientation, bed angle, and abdominal surface motion are utilized in the compensation.

### Claim 69 (depends on 64)

The system of claim 64, wherein the second accelerometer unit (128) of the second probe (104) is configured to measure the tilt angle (a) of a bed surface on which the human rests, assuming that the internal structure moves along a same direction as the bed surface.

### Claim 70 (depends on 64)

The system of claim 64, wherein the signal processor is configured to compute an angle between the ultrasound beam and direction of motion of the internal structure for each motion increment instead of assuming that the angle has a stationary value.