Tilt angle correction for ultrasound-based membrane thickness measurement

Abstract

A septum imaging device includes at least one electronic processor programmed to perform a septum imaging method, including: receiving ultrasound imaging data of a septum of a patient, the ultrasound imaging data being acquired by an associated ultrasound imaging probe with the probe at a plurality of different observable probe angles ([beta] obs); determining, for each observable probe angle, a corresponding apparent thickness (dI) of the septum of the patient from the received ultrasound data acquired at that observable probe angle; and estimating the thickness (dD) of the septum of the patient based at least on the apparent thickness (dI).

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 63 / 407,769, filed on September 19, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] The following generally involves respiratory therapy technology, mechanical ventilation technology, ventilator-induced lung injury (VILI) technology, ultrasound probe technology and related technologies. Background Art

[0004] Diaphragm ultrasound (US) allows quantification of diaphragm thickness, strain (rate) and excursion and thus also of respiratory rate and duration of each contraction. Diaphragm thickness (expressed as thickening fraction) and strain reflect contractile activity and are closely related to diaphragm electrical activity and diaphragm pressure. Therefore, thickness and strain can be used as surrogate measures of respiratory effort. Applications of diaphragm US include diaphragm function assessment, atrophy detection, weaning prediction and management of mechanical ventilation (MV) settings. Other applications could be asynchrony detection and proportional ventilation (non-invasive neurally adjusted ventilatory assist (NAVA)). The use of diaphragm US in mechanical ventilation is gaining interest and therefore technical issues and use cases are currently being investigated.

[0005] The diaphragm thickening fraction (TFdi or TFDI) measured by ultrasound (US) is performed by an operator who observes the patient and takes ultrasound images at end-inspiration and end-expiration. The diaphragm thickness fraction is determined by subtracting the end-inspiratory thickness from the end-expiratory thickness and then dividing the difference by the expiratory thickness according to Equation 1:

[0006]

[0007] Where T eiAs the end-inspiratory thickness. The thickness of the diaphragm that varies during the respiratory cycle (i.e., thickening during inspiration) is a surrogate for the patient's respiratory effort (see, e.g., Tuinman PR, Jonkman AH, Dres M, Shi ZH, Goligher EC, Goffi A, de Korte C, Demoule A, Heunks L, Respiratory muscle ultrasonography: methodology, basic and advanced principles and clinical applications in ICU and ED patients - a narrative review, Intensive Care Med., 46, No. 4, 594-605, April 2020, doi: 10.1007 / s00134-019-05892-8, Epub 2020 Jan 14, PMID: 31938825; PMCID: PMC7103016).

[0008] Diaphragm thickness measurements can be obtained using ultrasound (US) imaging. However, such measurements may be affected by artificial thickening if the US beam does not pass perpendicularly through the diaphragm. If the US beam is tilted relative to the surface normal α, then the diaphragm thickness appears to be d / cosα, i.e., it appears thicker than it actually is by a factor of 1 / cosα. This may result in inaccurate diaphragm thickness measurements.

[0009] Certain improvements are disclosed below to overcome these and other problems. Summary of the invention

[0010] In one aspect, a diaphragm imaging apparatus comprises: at least one electronic processor programmed to perform a diaphragm imaging method, comprising: receiving ultrasound imaging data of a patient's diaphragm, the ultrasound imaging data being acquired by an associated ultrasound imaging probe using the probe at a plurality of different observable probe angles (β obs ) obtain; for each observable probe angle, determine the corresponding apparent thickness (d) of the patient's diaphragm according to the received ultrasound data obtained at the observable probe angle I ); and at least based on the apparent thickness (d I ) to estimate the thickness of the patient's diaphragm (d D ).

[0011] In another aspect, a diaphragm imaging method includes: using at least one electronic controller, receiving ultrasound imaging data of the diaphragm of a patient, the ultrasound imaging data being acquired by an associated ultrasound imaging probe using the probe at a plurality of different observable probe angles (β obs ) obtain; for each observable probe angle, determine the corresponding apparent thickness (d) of the patient's diaphragm according to the received ultrasound data obtained at the observable probe angle I ); and at least based on the apparent thickness (d I ) to estimate the thickness of the patient's diaphragm (d D ).

[0012] One advantage resides in obtaining accurate membrane thickness measurements.

[0013] Another advantage resides in correcting the angle of an ultrasound probe used to image the diaphragm to obtain accurate diaphragm thickness measurements.

[0014] Another advantage resides in providing feedback to the user to correct the tilt angle of the ultrasound probe when imaging the diaphragm.

[0015] Another advantage resides in correcting for artifacts in diaphragm thickness measurements.

[0016] A given embodiment may provide none, one, two, more, or all of the aforementioned advantages, and / or may provide other advantages as will become apparent to one of ordinary skill in the art upon reading and understanding this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure may take the form of various components and arrangements of components, and various steps and arrangements of steps.The drawings are only for the purpose of illustrating the preferred embodiments and are not to be construed as limiting the disclosure.

[0018] Figure 1 An illustrative diaphragm imaging apparatus according to the present disclosure is diagrammatically shown.

[0019] Figure 2 Shows Figure 1 Different embodiments of the device probe.

[0020] Figures 3 to 5 Shows Figure 1 Example operation of the probe.

[0021] Figure 6 Shown by Figure 1 An example flow chart of operations appropriately performed by a device. DETAILED DESCRIPTION

[0022] As used herein, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. As used herein, a statement that two or more parts or components are "coupled", "connected", or "engaged" shall mean that the parts are joined, operate together, or act in conjunction, either directly or indirectly (i.e., through one or more intermediate parts or components), so long as there is a link. Directional phrases used herein (such as, but not limited to, top, bottom, left, right, upper, lower, front, rear, and their derivatives) relate to the orientation of elements shown in the accompanying drawings and do not limit the scope of the claimed invention unless explicitly enumerated therein. The words "comprising" or "including" do not exclude the presence of elements or steps other than those described herein and / or listed in the claims. In a device comprising several components, several of these components may be implemented by the same item of hardware.

[0023] Reference Figure 1 , a diaphragm imaging device 1 is shown. A mechanical ventilator 2 is shown, which is configured to provide ventilation therapy to an associated patient P. Figure 1 As shown, the mechanical ventilator 2 includes an outlet 4 that can be connected to a patient breathing circuit 5 to deliver mechanical ventilation to a patient P. The patient breathing circuit 5 includes typical components of a mechanical ventilator, such as an inlet line 6, an optional outlet line 7 (which can be omitted if the ventilator uses a single-limb patient circuit), a connector or port 8 for connecting to an endotracheal tube (ETT) 16, and one or more respiratory sensors (not shown), such as a gas flow meter, a pressure sensor, an end-tidal carbon dioxide (etCO 2 ) sensors, etc. The mechanical ventilator 2 is designed to deliver air, air-oxygen mixture or other breathable gas (supply not shown) to the outlet 4 at a programmed pressure and / or flow rate to ventilate the patient via the ETT. The mechanical ventilator 2 also includes at least one electronic processor or controller 13 (e.g., an electronic processor or microprocessor), a display device 14, and a non-transitory computer-readable medium 15 storing instructions executable by the electronic controller 13.

[0024] Figure 1 Diagrammatically illustrated is a patient P intubated with an ETT 16 (whose lower portion is within the patient P and therefore shown in phantom). A connector or port 8 is connected to the ETT 16 to operably connect to a mechanical ventilator 2 to deliver breathable air to the patient P via the ETT 16. Mechanical ventilation provided by the mechanical ventilator 2 via the ETT 16 can treat a variety of conditions, such as various types of lung conditions (such as emphysema or pneumonia), viral or bacterial infections that affect breathing (such as COVID-19 infection or severe influenza), cardiovascular conditions where the patient P receives oxygen-enriched breathable gas, etc.

[0025] Figure 1 Also shown is a medical imaging device 18 (also referred to as an image acquisition device, imaging device, etc.). As primarily described herein, the medical imaging device 18 comprises an ultrasound (US) medical imaging device 18. The illustrative embodiment employs brightness mode (B-mode) ultrasound imaging to assess the diaphragm thickness metric. However, other types of ultrasound imaging or data are contemplated, such as motion mode (M-mode) data collected as a single ultrasound line over a time interval, etc.

[0026] In a more specific example, the medical imaging device 18 includes an ultrasound probe 20 configured to image the diaphragm of the patient P. The US probe 20 is positioned to acquire US imaging data (i.e., US images) 24 of the diaphragm of the patient P. For example, the US probe 20 is configured to acquire imaging data of the diaphragm of the patient P and more particularly US imaging information related to the size (e.g., position, thickness, etc.) of the diaphragm of the patient P during inspiration and expiration when the patient P undergoes mechanical ventilation therapy with the mechanical ventilator 2. In one example, the medical imaging device 18 includes an electronic processor 21 configured to control the ultrasound imaging device 18 to acquire the US image 24, and also includes a non-transitory computer-readable medium 23 storing instructions executable by the electronic processor 21. The medical imaging device 18 may also include a display device 25. In another example, the electronic processor 13 of the mechanical ventilator 2 controls the ultrasound imaging device 18 to receive ultrasound imaging data 24 of the diaphragm of the patient P from the US probe 20. The ultrasound probe 20 allows for continuous and automatic acquisition of diaphragm thickness data (Tdi) from the acquired ultrasound imaging data 24.

[0027] Figure 2 An example of an ultrasound probe 20 is shown. The orientation of the probe 20 can be adjusted or moved relative to the skin of the patient P so as to compensate for the tilt angle α of the probe 20 during the imaging of the diaphragm of the patient P. To this end, the probe 20 includes an actuator 22 configured to move the ultrasound probe 20 relative to the skin of the patient P. The actuator 22 may include any suitable components, such as a thrust generating device (i.e., a fan), a gyroscope, etc. The actuator 22 is configured to provide thrust (at Figure 2 ) in order to move (and properly orient) the probe 20 relative to the skin of the patient P during imaging of the septum.

[0028] Figures 3 to 5 An example operation of the US probe 20 is shown. Figures 3 to 5 As shown, the ultrasound beam 26 is in the shape of a flat fan and is emitted from the ultrasound probe 20 toward the surface of the diaphragm D. The diaphragm D is approximately flat and has a physical thickness d D like Figures 3 to 5 The physical thickness d Dvaries during the respiratory cycle due to the contraction of the diaphragm muscle sheets. The physical diaphragm thickness d D At the end of inspiration, the maximum, and due to the relaxation of the diaphragm, the physical diaphragm thickness d D The intersection of the US beam fan 26 and the diaphragm D is at Figures 3 to 5 denoted as a diaphragm image or representation 28. The first normal vector is the unit length normal vector to the plane of the US fan beam 26. Therefore, the normal vector It is also the unit length normal vector to the plane of the image or representation 28 of the diaphragm D in the ultrasound image. The second normal vector is the unit length normal vector to the surface of the physical membrane D. There is an angle β between the first normal vector and the second normal vector, and according to The angle β is defined as the scalar product of vectors, where “·” represents the dot product (i.e., scalar product). The physical thickness of the diaphragm D is Figures 3 to 5 Indicated as thickness d D However, in the US imaging data 24, the observed thickness d of the image 28 of the diaphragm D is I is broadened by a factor of 1 / sin|β|, where |·| represents an absolute value. In other words, the observed thickness d of the image 28 of the diaphragm D in the US imaging data 24 is I for: Note that in the limiting case where the US fan beam 26 is oriented at 90° to the plane of the diaphragm D, then β = 90°, and sin(β) = 1, and the imaged diaphragm thickness d I Equal to the physical diaphragm thickness d D , that is, d I =d D However, it is often difficult or impossible to achieve this ideal vertical orientation using an external ultrasound probe 20 in an intercostal or subcostal position. Instead, the angle β is often less than (or greater than) 90°, so d I >d D , which is due to the US beam fan 26 being tilted away from the perpendicular to the diaphragm D.

[0029] The US probe 20 can be moved by the operator relative to the skin surface of the patient P to acquire US imaging data 24. If the fan shape of the US beam 26 remains in a single plane, then the angle β does not change because the image plane does not change. Therefore, the thickness d of the image 28 of the septum D I On the other hand, if the US probe 20 is tilted so that the image plane changes, the angle β changes. Figure 4 As shown, the US probe 20 is tilted, with Figure 3 The position of the US probe 20 is shown in the reverse manner. Figure 4As shown, when the US probe 20 is tilted relative to the surface of the diaphragm D, the first unit normal vector of the fan-shaped US beam 26 The orientation of the diaphragm D changes, resulting in a change in angle β. The thinnest appearance of intersection 28 occurs when angle β is 90°, but as previously mentioned, such a perpendicular orientation may be difficult or impossible to achieve with a physical US probe. Moreover, since the diaphragm D is an internal organ, angle β cannot be directly observed or measured.

[0030] In some examples, one or more external sensors (eg, cameras—not shown) may be used to determine the angle between the image plane of the fan-shaped US beam 26 and the skin surface S, such as Figure 5 As shown. Since the surface S of the skin is generally not parallel to the diaphragm D, the angle β cannot be directly inferred from the observed value of the angle of the ultrasound probe 20 relative to the skin. However, changes in the orientation of the US probe relative to the skin may be associated with changes in the angle β between the plane of the US sector 26 and the plane of the diaphragm D. Since the ultrasound acquisition frame rate is relatively fast (e.g., typically at least about 10 Hz or higher), the angle β may also change by changing the angle of the ultrasound probe 20 to the skin. In one method, the apparent (i.e., imaged) diaphragm thickness is measured for several angles of the ultrasound probe 20 relative to the skin (and therefore equivalently for several different values ​​of the angle β). and the apparent (i.e., imaged) membrane thickness d I The minimum value is considered to be equal to the physical diaphragm thickness d D If the fan beam 26 cannot be positioned completely perpendicular to the plane of the diaphragm D, then d D This estimate of may not be exact; however, since the derivative As β approaches 90°, it becomes smaller, so d D The estimate of d may be sufficiently accurate. Note that D This estimate is made for different points in the respiratory cycle, usually including at least the end of inspiration (d D thickest) and end-tidal (d D thinnest).

[0031] If greater accuracy is required, then the I The US probe angle curve should follow the expected For example, the observable angle between the ultrasound probe 20 and the skin is expressed as angle β skin , can be in different β obs Acquire several ultrasound images at the same time to generate (d I , β obs ) data set. The angle β is given as β = β obs -β ref , where βref is the unobservable angle β between the fan beam 26 and the plane of the diaphragm D and the observable angle β between the fan beam 26 and the skin obs (or other observable US probe angle reference). Then, (d I , β obs ) The set of data points is fitted to the equation Substitute β = β obs -β ref ,get The two unknown fitting parameters are d D and angle β ref In order to adapt to (d I , β obs ) data points, we can fit them to a sinusoidal curve and then match them to Likewise, d D This estimate is made for different points in the respiratory cycle, usually including at least the end of inspiration (d D thickest) and end-tidal (d D If images are acquired at 10 Hz or faster (i.e., at least 10 images per second), and the respiratory rate of the respiratory cycle is usually no faster than about 60 breaths per minute (1 Hz), even for neonatal patients, then the image can be viewed at the observable angle β. obs Sweep the ultrasound probe 20 two or three times within the range to collect sufficient data, for example by manually tilting the US probe 20 and monitoring the observable angle β by an external sensor. obs , as described herein.

[0032] The non-transitory computer readable medium 15 of the mechanical ventilator 2 and / or the non-transitory computer readable medium 23 of the US imaging device 18 store instructions executable by the electronic controller 13 (and / or the electronic processor 21) to perform the diaphragm imaging method or process 100. Although primarily described in terms of the electronic controller 13 / non-transitory computer readable medium 15 of the mechanical ventilator 2, the method 100 may be similarly performed by the electronic processor 21 / non-transitory computer readable medium 23 of the US imaging device 18.

[0033] Reference Figure 6 , and continue to refer to Figures 1 to 5, an illustrative embodiment of a diaphragm imaging method 100 is illustrated as a flow chart. In operation 102, US imaging data 24 of the diaphragm of a patient P is acquired using an ultrasound probe 20 and sent to an electronic controller 13. In some embodiments, the US imaging data 24 is acquired while the patient P is undergoing mechanical ventilation therapy with a mechanical ventilator 2. The US imaging data 24 includes data related to the geometry (e.g., position, thickness, etc.) of the diaphragm of the patient P. To this end, the electronic controller 13 can control the ultrasound probe 20 to acquire the ultrasound imaging data 24, and receive the ultrasound imaging data 24 of the diaphragm of the patient P from the ultrasound probe 20. These images are not necessarily acquired while the patient P is receiving mechanical ventilation, but can be acquired (for example) before the patient is intubated.

[0034] In operation 103, the tilt angle β of the ultrasound probe 20 is calculated based on the US imaging data 24. To this end, the position of the diaphragm surface of the patient P is determined based on the US imaging data 24. For example, the clinician can acquire the US imaging data 24 at a plurality of different orientations (i.e., different angles) relative to the skin of the patient P. The position of the diaphragm surface can be determined based on the US imaging data 24 acquired at a plurality of different orientations. Based on the determined position of the diaphragm surface, the tilt angle β of the probe 20 can be calculated.

[0035] Once the tilt angle β of the probe 20 is calculated, corrective action can be performed. In some embodiments, in operation 104, a representation 30 of the calculated tilt angle α can be displayed on the display device 14 of the mechanical ventilator 2 (or on the display device 25 of the medical imaging device 18). The operator of the probe 20 can then adjust the orientation of the probe 20 relative to the skin of the patient P until the desired tilt angle β of the probe 20 is reached. In some examples, a representation 30 of the standard tilt angle β can be displayed on the display device 14, and a representation of the current tilt angle β of the probe 20 can also be displayed. The operator can then move the probe 20 until the current tilt angle β matches the standard tilt angle β.

[0036] In other embodiments, tactile feedback may be provided to the operator of the probe 20 in operation 105. The tactile feedback may be provided by the actuator 22 of the probe 20 (e.g., a thrust generating device or a gyroscope may vibrate to indicate to the operator that the probe 20 orientation should be changed, the probe 20 automatically moved, etc.). In a specific example, the calculated tilt angle β is different from the standard tilt angle β' (i.e., the normal to the image plane). The difference between the calculated tilt angle β and the normal to the skin surface S) is determined and tactile feedback can be provided until the calculated tilt angle β matches the angle β'.

[0037] In operation 106, a diaphragm thickness metric (i.e., a thickness of the diaphragm or a diaphragm thickening fraction) may be calculated based on the US imaging data 24 and / or the calculated tilt angle β. The displayed representation 30 may include a representation of the calculated diaphragm thickness metric. In one example, the diaphragm thickness metric includes a diaphragm thickening ratio that indicates the diaphragm thickness during inspiration relative to the diaphragm thickness during exhalation. In another example, the diaphragm thickness metric includes an average diaphragm thickness over a plurality of breathing cycles.

[0038] In operation 107 , one or more parameters of the mechanical ventilation therapy delivered to the patient P by the mechanical ventilator 2 may be adjusted, for example based on the calculated diaphragm thickness metric, the tilt angle β of the probe 20 , etc.

[0039] In some embodiments, the actual tilt angle β can be estimated, and the operator can wait for the correct tilt angle β of the US beam (i.e., during manual scanning / pose change), or correct the artificial thickening caused by the tilt angle β of the probe 20 (i.e., for a given pose). Since the US imaging data 24 is formed by a collection of diverging US beams, the same geometric distortion of the septum thickness also occurs for each beam. However, the US imaging data 24 is typically resampled to a Cartesian grid. Therefore, the divergence of the beam is compensated, and the septum appears in the image as two straight lines with a distance d / sin|β|.

[0040] The operator continuously changes the tilt angle β of the probe 20 in a back-and-forth motion, which can be done at about 2 Hz (ie, as Figure 4 The diaphragm thickness is continuously measured within the acquired US image 24 (ie, as shown in FIG. Figure 5 as shown), and yields the thinnest estimate (because d / sin|β has a lower limit on d, i.e., the apparent thickness can never be shorter than the true thickness).

[0041] The operator continuously changes the tilt angle β of the probe 20 back and forth, and the diaphragm thickness is continuously measured. Additionally, the tilt angle γ of the US probe 20 relative to the laboratory coordinate system is measured. For example, this can be achieved using an accelerometer or magnetometer integrated in the US probe 20 (which can measure the angle γ between the US probe 20 and the earth's magnetic field) or by tracking the probe with an external sensor (e.g., optically (i.e., using a camera) or via a radio frequency (RF) tag). The measurement provides pairs of data points (e.g., angle, thickness, etc.). A model of the apparent diaphragm thickness as a function of the actual thickness and angle is fitted (where the model only contains an artificial thickening of 1 / sin|β and an unknown angle between the diaphragm normal and the 0° angle in the laboratory coordinate system). The model parameters of the actual thickness are provided to the user. The benefit of this method is that it acquires all images from an ultrasound scan using the probe 20, thereby making a robust estimate of the tilt angle β of the probe 20.

[0042] During the initialization phase of the method 100, a scan of the US probe 20 across a wide range of tilt angles β may be performed, including tracking the 3D position and orientation of the probe 20 (e.g., optically, via an RF tag, etc.) to generate US images. From these images, the location of the local diaphragm surface may be determined. During inspiration and expiration of the patient P, US images 24 of the diaphragm may be acquired with the probe 20. The tilt angle β of the probe 20 may be estimated using the surface model and the determined local diaphragm surface, and the orientation of the probe 20 may be corrected based on the estimated tilt angle β.

[0043] The tactile feedback operation 105 can be performed in various ways. For example, the US probe 20 is guided to the correct orientation. Then, the gyroscope constituting the actuator 22 is activated, which is naturally used to maintain the probe 20 in its orientation. The gyroscope 22 can be integrated in the US probe 20, or it can be installed as an additional component to the US probe. For example, in order to offset a posture change of 5 rad / s with a torque of 0.1 Nm, a gyroscope 22 with a 5 cm diameter flywheel of 150 g rotating at 25 k RPM is required. Another method is to stabilize the US probe 20 based on the torque generated by the thrust generated by the axial or centrifugal fan provided as an additional component of the actuator 22. Similarly, this thrust generating device 22 can be integrated in the US probe 20, or it can be installed as an additional component to the US probe 20. For example, a 7.5x7.5 cm 2 A centrifugal fan (eg, ebm-papst RL 48-19 / 14) can generate a thrust of about 1 N (ie, a torque of about 0.1 Nm when applied 10 cm from the point of rotation). Active feedback can also be used to ensure an optimal contact area between the US probe 20 and the patient P.

[0044] In another embodiment, a 3D US probe 20 or a US probe 20 with two orthogonal fans is used. The US imaging data 24 is converted into a 3D point cloud, and two 3D planes are fitted into the 3D point cloud in a robust manner (using, for example, the RANSAC method). Finally, the orthogonal plane distances are provided to the operator.

[0045] It is beneficial to synchronize the US imaging data 24 with the mechanical ventilator 2 (i.e., automatically perform thickness measurements within a time window around maximum inspiration and maximum expiration). This synchronization can be accomplished using a common clock. Synchronization between the US probe 20 and the mechanical ventilator 2 allows comparison of measurements from different breaths. If consecutive breaths have similar respiratory muscle activity, points in the respiratory cycle can be selected from multiple breaths so that the selected measurements give a thickening fraction with a minimum diaphragm thickness at each point, which can ensure that the correct tilt angle β of the US probe 20 is used. This process can be applied to subcostal and intercostal data acquisition scenarios.

[0046] The present disclosure has been described with reference to preferred embodiments. Modifications and changes may occur to others after reading and understanding the foregoing detailed description. It is intended that the exemplary embodiments be interpreted as including all such modifications and changes as long as they fall within the scope of the appended claims or their equivalents.

Claims

1. A diaphragm imaging device, comprising: At least one electronic processor programmed to perform a diaphragm imaging method comprising: receiving ultrasound imaging data of the diaphragm of the patient, the ultrasound imaging data being acquired by an associated ultrasound imaging probe using the probe to observe the diaphragm at a plurality of different observable probe angles (β obs ) obtain; For each observable probe angle, a corresponding apparent thickness (d I );as well as At least based on the apparent thickness (d I ) to estimate the thickness of the patient's diaphragm (d D ).

2. The apparatus of claim 1, wherein the estimating comprises: The thickness (d D ) is estimated as the apparent thickness (d I ) is the minimum apparent thickness in the 3. The apparatus of claim 1 , wherein the estimating comprises: Each of the apparent thicknesses (d I ) and its corresponding observable probe angle (β obs ) are fitted to the expected relationship between apparent thickness and observable probe angle.

4. The device according to claim 3, wherein the corresponding apparent thickness (d I ) and each observable probe angle (β obs ) is expected to have a relationship and the unknown fitting parameter is the thickness of the patient's diaphragm (d D ) and reference angle β ref .

5. The device according to claim 1, wherein the observable angle (β obs ) is measured during said reception by: determining the location of a surface of the patient's diaphragm based on ultrasound imaging data of a size of the patient's diaphragm; and The associated tilt angle of the ultrasound imaging probe (20) is calculated based on the determined position of the surface of the diaphragm.

6. The apparatus of claim 5, wherein determining the position of the surface of the patient's diaphragm based on the ultrasound imaging data of the size of the patient's diaphragm comprises: acquiring ultrasound imaging data of the dimension of the patient's diaphragm based on a plurality of different orientations of the associated ultrasound imaging device relative to the patient's skin; The position of the surface of the diaphragm is determined by the acquired ultrasound imaging data of the size of the diaphragm of the patient.

7. The apparatus of claim 1, wherein the method further comprises: Based on the estimated thickness (d D ) to perform a corrective action, the corrective action comprising: A representation of the calculated tilt angle is displayed on a display device.

8. The apparatus of claim 1, wherein the method further comprises: Based on the estimated thickness (d D ) to perform a corrective action, the corrective action comprising: Tactile feedback is provided to an operator of the associated ultrasound imaging device via the associated ultrasound imaging device.

9. The apparatus of claim 8, wherein the corrective action comprises: determining a location of a surface of a diaphragm of the patient based on ultrasound imaging data of a size of the diaphragm of the patient; as well as A standard tilt angle of the associated ultrasound imaging device is determined by the determined position of the surface of the diaphragm, at which the associated ultrasound imaging device is able to image the surface of the diaphragm of the patient.

10. The apparatus of claim 9, wherein the corrective action comprises: determining a difference between the calculated tilt angle and the standard tilt angle; and The tactile feedback is provided until the calculated tilt angle matches the standard tilt angle.

11. The device according to claim 1, further comprising: an ultrasound imaging device, comprising an ultrasound probe configured to acquire the ultrasound imaging data of the size of the diaphragm of the patient; The ultrasound probe includes an actuator disposed on a portion of the ultrasound probe and configured to move the ultrasound probe relative to the patient's skin.

12. The device of claim 1, wherein calculating the associated tilt angle of the ultrasound imaging device comprises: One or more sensors are used to calculate the tilt angle.

13. The apparatus of claim 1, wherein the method further comprises: calculating a diaphragm thickness metric based on the received ultrasound imaging data of the diaphragm of the patient; as well as A representation of the calculated membrane thickness metric is displayed on a display device.

14. The apparatus according to claim 1, further comprising: a mechanical ventilator configured to deliver mechanical ventilation therapy to the patient, wherein receiving the ultrasound imaging data of the size of the diaphragm occurs during inspiration and expiration while the patient is undergoing mechanical ventilation therapy using the mechanical ventilator; and the method further comprises: An associated mechanical ventilator is controlled to adjust one or more parameters of the mechanical ventilation therapy delivered to the patient based on the calculated diaphragm thickness metric.

15. A method of diaphragm imaging, comprising utilizing at least one electronic controller: receiving ultrasound imaging data of the diaphragm of the patient, the ultrasound imaging data being acquired by an associated ultrasound imaging probe using the probe to observe the diaphragm at a plurality of different observable probe angles (β obs ) obtain; For each observable probe angle, a corresponding apparent thickness (d I );as well as At least based on the apparent thickness (d I ) to estimate the thickness of the patient's diaphragm (d D ).

Images