Accurate diaphragm thickness and function assessment using ultrasound and mechanical ventilator signals

Abstract

A diaphragm measurement device includes at least one electronic processor programmed to perform a diaphragm measurement method including: receiving ultrasound imaging data of dimensions of a diaphragm of a patient during inspiration and expiration when the patient is subjected to mechanical ventilation treatment with a mechanical ventilator; receiving breathing data of the patient during inspiration and expiration when the patient is subjected to the mechanical ventilation treatment; calculating a diaphragm thickness metric based on the received ultrasound imaging data of the diaphragm of the patient and the received respiration data; and displaying a representation of the calculated diaphragm thickness metric on a display device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 63 / 354,824, filed on June 23, 2022, the contents of which are incorporated herein by reference. Technical Field

[0003] The following content generally relates to the fields of respiratory therapy, mechanical ventilation, ventilator-induced lung injury (VILI), mechanical ventilation weaning, and related fields. Background Art

[0004] Diaphragm ultrasound (US) allows quantification of diaphragm thickness, strain (rate) and excursion, and with this also allows quantification of respiratory rate and duration of each contraction. Diaphragm thickness (expressed as thickening fraction) and strain reflect contractile activity and are well correlated with diaphragm electrical activity and diaphragm pressure. Therefore, thickness and strain can be used as surrogate markers for respiratory effort. Applications of diaphragm ultrasound include estimation of diaphragm function, atrophy detection, off-line prediction and management of mechanical ventilation (MV) settings. Other applications can be asynchronous detection and proportional ventilation (non-invasive neurally regulated ventilatory assist (NAVA)). The application of diaphragm ultrasound in mechanical ventilation is gaining more and more attention, and therefore, technical issues and use cases are currently being studied.

[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 the end of inspiration and end of 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 Formula 1:

[0006]

[0007] Where T ei is the end-inspiratory thickness.

[0008] Several studies have evaluated the correlation between TFdi and respiratory effort. In one study (see, for example, E. Oppersma et al., "Functional assessment of the diaphragm by speckle trackingultrasound during inspiratory loading," Journal of Applied Physics, 2017), diaphragm strain can be similarly measured in real time at the apposition area. For example, in this study, functional estimates of the diaphragm by speckle trackingultrasound during inspiratory loading were analyzed. Speckle tracking ultrasound technology allows the detection and tracking of diaphragm strain over time by analyzing acoustic markers called specks. These specks are formed by the interference of ultrasound waves scattered from physical structures with a size comparable to the wavelength of ultrasound. Both diaphragm strain and diaphragm strain rate are related to transdiaphragmatic pressure Pdi (strain r 2 =0.72; strain rate r 2 =0.80) and diaphragm electrical activity EAdi (strain r 2 =0.60; strain rate r 2 =0.66) is highly correlated.

[0009] The problem is the reliability of diaphragm thickness measurements. Accuracy, repeatability, and reproducibility are limited due to the thin form factor of the diaphragm, motion and macro-deformation of the diaphragm and surrounding structures and tissues, device manipulation (angle, position, motion), poor image quality, and operator skill. The variability and uncertainty of TFDI can be very high (see, for example, Goligher EC et al. 2015 “Measuring diaphragm thickness with ultrasound in mechanically ventilated patients: feasibility, reproducibility and validity”. Intensive Care Med. 2015 Apr;41(4):642-9. doi:10.1007 / s00134-015-3687-3. Epub 2015 Feb 19. Errata: Intensive Care Med. 2015 Apr;41(4):734. Sebastien-Bolz, Steffen [Corrected to Bolz, Steffen-Sebastien], PMID: 25693448; Tuinman PR et al. 2020 “Respiratory muscle ultrasonography: methodology, basic and advanced principles and clinical applications in ICU and ED patients—a narrative review”. Critical Care Med. 2020 Apr;46(4):594-605. doi:10.1007 / s00134-019-05892-8. Epub 2020 Jan 14. PMID: 31938825; PMCID: PMC7103016). For example, Goligher reported a thickness variation of 0.3 mm ± 0.3 mm. In this example, the margin of error (0.6 mm) is twice the nominal thickness variation (0.3 mm). This uncertainty undermines confidence in clinical decisions based on TFDI, such as those regarding pressure support, weaning, and extubation (see, e.g., Tuinman).

[0010] In addition to the measurement errors mentioned above, another source of variability in TFDI is the variation in breathing effort / work of breathing (WOB) between multiple breaths. This is reflected in the ventilator waveform that varies over time. If TFDI is measured and averaged over different breaths without accounting for the variability in WOB, this will obviously increase the margin of error in TFDI.

[0011] Another source of expected variation in practice is disease-induced diaphragmatic atrophy, which may make the signal-to-noise ratio higher.

[0012] Another study (e.g., see O'Hara DN et al., 2020, "Ultrasonographic modeling of diaphragm function: A novel approach to respiratory assessment," PLoS ONE 15(3): e0229972. https: / / doi.org / 10.1371 / journal.pone.0229972) measured diaphragm thickness Tdi at different levels of negative inspiratory force (NIF) using a handheld NIF meter. The NIF meter determines the strength of the respiratory muscles by recording the negative airway pressure generated when the patient attempts to breathe through a mouthpiece with a closed valve. Tdi was measured with an ultrasound probe at expiratory NIF = -30 cmH2O, NIF = -60 cmH2O, and maximum NIF. A quadratic function was used to fit the relationship between NIF and Tdi. O'Hara believes that it is possible to use a statistical function to predict maximum NIF based on ultrasound measurements. This has the advantage of eliminating patient factors that may limit NIF measurements, such as the ability to form a tight seal at the lips or to follow the instructions of a respiratory technician, or patients with a depressed mental or neurological status.

[0013] Certain improvements that overcome these and other problems are disclosed below. Summary of the invention

[0014] In one aspect, a diaphragm measurement device includes at least one electronic processor programmed to perform a diaphragm measurement method, the diaphragm measurement method comprising: receiving ultrasound imaging data of the size of a patient's diaphragm during inspiration and exhalation while the patient is undergoing mechanical ventilation therapy using a mechanical ventilator; receiving breathing data of the patient during inspiration and exhalation while the patient is undergoing mechanical ventilation therapy; calculating a diaphragm thickness metric based on the received ultrasound imaging data of the patient's diaphragm and the received breathing data; and displaying a representation of the calculated diaphragm thickness metric on a display device.

[0015] In another aspect, a diaphragm measurement method includes utilizing at least one electronic controller to: receive ultrasound imaging data of a size of a patient's diaphragm during inspiration and exhalation while the patient is undergoing mechanical ventilation therapy utilizing a mechanical ventilator; receive breathing data of the patient during inspiration and exhalation while the patient is undergoing mechanical ventilation therapy; calculate a diaphragm thickness metric based on the received ultrasound imaging data of the patient's diaphragm and the received breathing data; and display a representation of the calculated diaphragm thickness metric on a display device.

[0016] One advantage resides in facilitating weaning of a patient from mechanical ventilation therapy.

[0017] Another advantage is the use of the ventilator waveform to reduce the margin of error in the estimation of diaphragm thickness.

[0018] Another advantage resides in determining respiratory function based on correlation between ventilator waveforms and changes in diaphragm thickness.

[0019] Another advantage resides in determining sedation level based on correlation between ventilator waveform and changes in diaphragm thickness.

[0020] A given embodiment may provide none, one, two, more, or all of the advantages described above, and / or may provide other advantages that will be apparent to one of ordinary skill in the art upon reading and understanding the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The disclosure may take form in various components and arrangements of components, and in various steps and arrangements of steps.The drawings are only for illustrating preferred embodiments and are not to be construed as limiting the disclosure.

[0022] Figure 1 An illustrative diaphragm measurement device according to the present disclosure is diagrammatically shown.

[0023] Figure 2 Shown by Figure 1 An example flow chart of operations suitably performed by the system.

[0024] Figure 3 - Figure 5 shows a method for using Figure 1 The device generates a dataset of diaphragm thickness measurements. DETAILED DESCRIPTION

[0025] As used herein, the singular forms of "a", "an", and "the" include plural references unless the context clearly indicates otherwise. As used herein, the expression that two or more parts or components are "coupled", "connected", or "engaged" shall mean that these parts are directly or indirectly (i.e., through one or more intermediate parts or components), connected, operated, or act together, as long as there is a link. Directional phrases as used herein, such as, for example, but not limited to, top, bottom, left, right, upper, lower, front, rear, and their derivatives, are related to the direction of the elements shown in the figures and do not limit the scope of the claimed invention unless explicitly stated therein. The words "comprise" or "include" do not exclude the presence of elements or steps other than those described herein and / or listed in the claims. In a device consisting of several components, several of these components may be implemented by the same hardware.

[0026] refer to Figure 1, a diaphragm measurement 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 in , 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 for a mechanical ventilator, such as an inlet line 6, an optional outlet line 7 (this can be omitted if the ventilator adopts 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 (etCO2) sensor, etc. The mechanical ventilator 2 is designed to deliver air, an 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 that can be executed by the electronic controller 13.

[0027] Figure 1 A patient P is diagrammatically shown with an ETT 16 inserted (its lower portion is located inside the patient P and is therefore shown in phantom). A connector or port 8 is connected to the ETT 16 to operably connect the 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 diseases, such as various types of lung diseases (such as emphysema or pneumonia), viral or bacterial infections that affect breathing (such as COVID-19 infection or severe influenza), cardiovascular diseases where the patient P receives oxygen-enriched breathable gas, etc.

[0028] Figure 1 A medical imaging device 18 (also referred to as an image acquisition device, imaging device, etc.) is also shown. 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 estimate the diaphragm thickness metric. However, other types of ultrasound imaging or data are also contemplated, such as motion mode (M-mode) data collected as a single ultrasound line over a certain time interval, etc.

[0029] In a more specific example, the medical imaging device 18 includes an ultrasound patch 20 that can be worn by the patient P (e.g., worn on the abdomen or chest of the patient P to image the patient's diaphragm, such as Figure 1). The US patch 20 is positioned to acquire US imaging data (i.e., US image) 24 of the diaphragm of the patient P. For example, the US patch 20 is configured to acquire imaging data of the diaphragm of the patient P, and more specifically, to acquire US imaging data related to the thickness of the diaphragm of the patient P during inspiration and expiration when the patient P undergoes mechanical ventilation therapy using the mechanical ventilator 2. The electronic processor 13 controls the ultrasound imaging device 18 to receive the ultrasound imaging data 24 of the diaphragm of the patient P from the US patch 20. Although Figure 1 Only one US patch 20 is shown in FIG. 1 , but it will be appreciated that any suitable number of patches may be attached to the patient P. The ultrasound patch(es) 20 allow for continuous and automatic acquisition of diaphragm thickness data (Tdi) from acquired ultrasound imaging data 24 .

[0030] The non-transitory computer readable medium 15 stores instructions executable by the electronic controller 13 to perform the diaphragm measurement method or process 100 .

[0031] refer to Figure 2 And continue to refer to Figure 1 , illustrates an illustrative embodiment of a diaphragm measurement method 100 in the form of a flow chart. At operation 101, US imaging data 24 of the diaphragm of a patient P during inspiration and expiration is received when the patient is undergoing mechanical ventilation therapy using a mechanical ventilator 2. To this end, the electronic controller 13 can control the ultrasound patch 20 to acquire ultrasound imaging data 24 and receive ultrasound imaging data 24 of the diaphragm of the patient P from the ultrasound patch 20. These images are not necessarily acquired when the patient P is mechanically ventilated, but (for example) can be acquired before the patient is intubated.

[0032] At operation 102, respiratory data of patient P during inspiration and exhalation is received when the patient is subjected to mechanical ventilation therapy using a mechanical ventilator 2. The respiratory data of patient P may include one or more of the airway pressure in the airway of patient P or the airway flow in the airway of patient P measured by the mechanical ventilator 2 during ventilation therapy. In some examples, the respiratory data of patient P may include an average airway pressure value or an average airway flow value at the end of inspiration and at the end of exhalation. In other examples, the respiratory data of patient P may be the maximum airway pressure or the maximum airway flow value and the minimum airway pressure or the minimum airway flow value at the end of inspiration and at the end of exhalation. It should be understood that the image acquisition operation 101 and the respiratory data operation 102 may be performed in any suitable order, or simultaneously.

[0033] At operation 103, a diaphragm thickness metric may be calculated based on the received US imaging data 24 of the diaphragm and the received respiration data of the patient P. In one example, the diaphragm thickness metric includes a diaphragm thickening ratio, which indicates the diaphragm thickness during inspiration relative to the diaphragm thickness during expiration. In another example, the diaphragm thickness metric includes an average diaphragm thickness over a plurality of respiratory cycles.

[0034] To calculate the diaphragm thickness metric, the electronic controller 13 is configured to receive the Tdi signal from the ultrasound imaging data 24 and the pressure p (or flow v) signal from the mechanical ventilator 2. The electronic controller 13 applies regression analysis to estimate the relationship (e.g., function, model, etc.) between the Tdi signal and the pressure or flow data (i.e., Tdi=f(pv or Tdi=f(v)). Based on the relationship, the electronic controller 13 is configured to determine Tdi expiration =f(p expiration ) (i.e., the relationship during exhalation) and Tdi inspiration =f(p inspiration ) (i.e., the relationship during inspiration), and then determine the diaphragm thickness change ΔTdi and the diaphragm thickening fraction TFDI as a measure of diaphragm thickness. Input value p inspiration and p expiration This may be the minimum and maximum airway pressure recorded, or the average airway pressure during inspiration and expiration (eg, the average of 10 or 100 subsequent cycles).

[0035] Figure 3 and Figure 4 An example of generating a diaphragm thickness metric is shown. Figure 3 An example of determining the change in diaphragm thickness (ΔTdi) is shown. Figure 3 The example shown in FIG. 1 shows diaphragm thickness data Tdi as a function of the ventilator waveform (i.e., pressure p or flow v, depending on the respiratory data received at operation 102) relative to the diaphragm thickness change ΔTdi. This is because (1) more data points are acquired using the ultrasound patch 20; (2) intermediate data points ( Figure 3 ); (3) more precisely determine the inspiration and expiration points, i.e., based on the ventilator waveform rather than by looking at the patient P or ultrasound imaging data24; and (4) take into account the cycle-to-cycle variation, i.e., the variation of inspiration and / or expiration pressure and volume between multiple breaths, so that the confidence interval can be reduced ( Figure 3 , and has a value of 95%). Figure 4 An alternative example is shown where two functions may be fit (one during inhalation, and one during exhalation).

[0036] In some embodiments, the regression analysis may be a linear regression analysis, because according to formula (2), the relationship between Tdi and pressure p (or flow v) is a straight line with a slope S:

[0037] S=ΔTdi / Δp or S=ΔTdi / Δv (2)

[0038] In some embodiments, the change in diaphragm thickness ΔTdi may be divided by the average thickness during inspiration or expiration (ie, the diaphragm thickening fraction TFDI). An advantage of using TFDI is that the slope becomes less sensitive to changes in average thickness over time (eg, due to atrophy).

[0039] In other embodiments, the logarithm of the thickness may be used to calculate the diaphragm thickness metric since the slope is constant with respect to changes in mean thickness (ie, any factor becomes a fixed offset in the logarithmic scale).

[0040] Return to see Figure 2 At operation 104, a representation 30 of the calculated diaphragm thickness metric is displayed on the display device 14 of the mechanical ventilator 2. In some examples, when multiple ultrasound patches 20 are attached to different locations on the chest of the patient P, the representation 30 may include a color map showing the activity distribution of the diaphragm.

[0041] In some embodiments, the diaphragm thickness metric may be calculated as a ratio of the diaphragm thickness of the diaphragm to one of the airway pressure or the airway flow in the airway of the patient P. In such embodiments, the ratio of the diaphragm thickness of the diaphragm to one of the airway pressure or the airway flow in the airway of the patient P comprises the compliance of the airway of the patient P.

[0042] The slope S of the linear regression relationship provides insight into the behavior and effectiveness of diaphragm muscle activity as a function of MV support of patient P and sedation therapy of patient P. The slope S can be displayed as an indication 30 on the display device 14 of the mechanical ventilator 2. This relationship S is more informative than a single TFDI point without the need for any further reference or information. The diaphragm thickness change ΔTdi reflects the patient's effort ("input"), while the airway pressure and / or flow reflect the result ("output"). Depending on the level of support, the ratio between output and input (i.e. 1 / S) indicates the overall "compliance" of the respiratory system of patient P.

[0043] Figure 5A and Figure 5B An example of using the slope S of the linear regression relationship between diaphragm thickness Tdi and airway pressure (or flow) to inform the patient of breathing effort and effectiveness is shown in FIG. Figure 5APatient effort in different situations is shown. Goligher (2015) mentioned that if there is no activity from the diaphragm, the thickness of the diaphragm will not change (i.e., a flat line with a slope of zero). If the pressure support decreases, the slope should increase. The more the slope increases, the more the patient P responds to mechanical ventilation therapy. Assuming that the end-tidal CO2 does not rise due to respiratory (i.e., diaphragmatic) failure, in this case, CO2 begins to pull the muscles via chemoreceptors, provided that the sedation level remains unchanged. In order to monitor the impact of changes in respiratory rate, additional indicators such as power of breathing (POB), POB per liter of air (POB / L), work of breathing (WOB), and WOB per liter of air (WOB / L) can be used as additional inputs. Figure 5B A surrogate indicator of breathing efficiency in, for example, a spontaneous breathing test (SBT) is shown, where the first curve 1 is more efficient (i.e., greater pressure fluctuations but less effort) than the second curve 2. In this case, the slope S of the second curve 2 is 1 / S, because Figure 5A In comparison, the axes are swapped.

[0044] In some embodiments, instead of using slope S (or the inverse 1 / S) as support or sedation levels change, changes in slope ΔS can be used to provide insight into the behavior and effectiveness of diaphragm activity as a function of MV support for patient P and sedation therapy for patient P.

[0045] The parameters S, 1 / S and ΔS can be displayed as indications 30 on the display device 14 of the mechanical ventilator 2 to provide clinical decision support, such as distinguishing between active and passive (i.e., using the mechanical ventilator 2) breathing to guide sedation therapy, indicating and monitoring sedation levels, determining the optimal pressure support level in PSV or the K setting in PAV / PAV+ (where K is the unloading percentage), determining preparation before a weaning spontaneous breathing trial (SBT), such as monitoring lung mechanics in the case of lung disease (i.e., a larger slope S means less flow, provided that the MV setting remains unchanged), monitoring the neuromuscular drive strength of the patient P, detecting phrenic nerve dysfunction or damage (e.g., placing a sensor on each side of the chest and intentionally paralyzing the left and right nerves in turn. In both cases, the diaphragm should work in the same way. If not, one of the nerves is damaged), determining whether the slope change between breaths can be used as an indicator of asynchrony, etc. The parameter S or (1 / S) may be relevant to monitoring CPAP home therapy, where the patient breathes spontaneously and the ventilator keeps the pressure nearly constant (ie, S = ΔTdi / Δv).

[0046] If the patient P breathes spontaneously, the "compliance" of the respiratory system (what fraction of the muscle work is converted into airflow) can be measured. This ratio can be monitored and displayed in time to see how the patient's "breathing exercise" behaves and develops over time.

[0047] In some embodiments, the MV setting is constant. In other embodiments, the pressure and flow settings may be varied, or a controlled breathing maneuver may be performed while the trend of Tdi or TFDI is measured. This will provide more information about the status of the patient P and the effectiveness of the treatment. For example, a strong response of the diaphragm muscle to changes in pressure support or sedation indicates that the muscle is in good condition and that the treatment is within the sensitive range (i.e., not overtreated).

[0048] Return to see Figure 2 , in some embodiments, at operation 105, the mechanical ventilator 2 can be controlled to adjust one or more parameters of the mechanical ventilation therapy delivered to the patient based on the calculated diaphragm thickness metric. For example, the effort slope S and / or maximum effort can be used to guide a respiratory muscle training program for patient P. The program can be performed multiple times a day to restore and improve respiratory muscle strength. For example, the clinical team can select the maximum slope that the patient can tolerate and for how long. The mechanical ventilator 2 can automatically change support to increase / decrease respiratory activity as required by the clinical team. As a safety feature, the mechanical ventilator 2 can monitor respiratory rate, end-tidal CO2, SpO2, and other parameters to decide to switch to a standby mode and interrupt the training program.

[0049] At optional operation 106, a responsiveness index (RI) for the patient P may be calculated as a ratio of a change in the compliance of the patient's airway to a change in one or more mechanical ventilation settings of the mechanical ventilator 2. In some examples, the mechanical ventilator 2 may be controlled to adjust one or more parameters of the mechanical ventilation therapy delivered to the patient P based on the calculated responsiveness index. In other examples, the representation 30 may also include a representation of the RI calculated and displayed on the display device 14.

[0050] Using knowledge of respiratory muscle activity from diaphragmatic ultrasound or similar devices, and by adjusting the support of the mechanical ventilator 2, the patient's responsiveness to such changes (i.e. changes in the slope S of respiratory muscle activity) can be monitored. According to RI = ΔS / Δsupport, this can be the change in the slope of respiratory muscle activity divided by the change in support (pressure support ventilation PSV, proportional assist ventilation PAV, here the same PAV+, pressure regulated volume control PRVC, neurally regulated ventilatory assistance NAVA, etc.), where Δsupport represents the change in support level in the change in pressure p or the change in volume / flow v. The RI can be used to guide the sedation strategy in an open-loop or closed-loop solution, i.e. by controlling a sedation device that is configured to provide sedation to the patient P. Other inputs, such as end-tidal CO2, blood gas analysis, minute ventilation and ventilator settings, can be used by the electronic controller 13 to ensure its safe operation.

[0051] For anesthesiologists, the RI can potentially be used to quantify sedation levels. Typically, sedation levels are measured using the Ramsay Sedation Scale, a qualitative measurement. It categorizes a patient's sedation level into six categories ranging from severe agitation to deep coma. Typically, clinicians observe a patient's response to commands or tactile and auditory stimuli. Quantitative measurements are less easy to interpret, and automated measurement of the RI could facilitate the use and application of sedation scores in mechanical ventilation therapy.

[0052] In some embodiments, the medical professional may want to check the status of the patient P. This can be achieved by checking the slope S or slope change ΔS displayed on the display device 14 periodically (e.g., every 12 hours) by pressing and / or holding a button on the mechanical ventilator 2. Pressing the button will remove support for a few minutes. This can reveal the RI.

[0053] The present disclosure has been described with reference to preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiments be interpreted as including all such modifications and alterations as long as they fall within the scope of the appended claims or their equivalents.

Claims

1. A diaphragm measurement device, comprising: At least one electronic processor programmed to perform a diaphragm measurement method comprising: receiving ultrasound imaging data of a dimension of a diaphragm of a patient during inspiration and expiration while the patient is undergoing mechanical ventilation therapy utilizing a mechanical ventilator; receiving respiratory data of the patient during inspiration and expiration while the patient is undergoing the mechanical ventilation therapy; calculating a diaphragm thickness measure based on the received ultrasound imaging data of the diaphragm and the received respiration data of the patient; and A representation of the calculated diaphragm thickness metric is displayed on a display device.

2. The apparatus of claim 1, wherein the diaphragm thickness metric comprises a diaphragm thickening ratio indicating diaphragm thickness during inspiration relative to diaphragm thickness during expiration.

3. The apparatus of claim 1, wherein the diaphragm thickness metric comprises an average diaphragm thickness over a plurality of breathing cycles.

4. The apparatus according to claim 1, further comprising: An ultrasound imaging device comprising an ultrasound patch attached to a portion of the patient, wherein the at least one electronic processor controls the ultrasound imaging device to receive the ultrasound imaging data of the diaphragm of the patient from the ultrasound patch.

5. An apparatus according to claim 1, wherein the respiratory data of the patient includes one of airway pressure or airway flow in the patient's airway, and the at least one electronic processor is further programmed to calculate the diaphragm thickness metric based on the airway pressure or the airway flow.

6. The apparatus according to claim 5, wherein the respiratory data comprises mean airway pressure or airway flow values ​​at the end of inspiration and at the end of expiration. 7 . The apparatus according to claim 5 , wherein the respiratory data comprises a maximum airway pressure or a maximum airway flow value and a minimum airway pressure or a minimum airway flow value at the end of inspiration and at the end of expiration.

8. The apparatus of claim 1, wherein the at least one electronic processor is further programmed to calculate the diaphragm thickness metric as a ratio of the diaphragm thickness of the diaphragm to the airway pressure in the airway of the patient.

9. The apparatus of claim 1, wherein the at least one electronic processor is further programmed to calculate the diaphragm thickness metric as a ratio of the diaphragm thickness of the diaphragm to the airway flow in the airway of the patient.

10. The apparatus of claim 9, wherein the at least one electronic processor is further programmed to: A patient's responsiveness index is calculated as a ratio of a change in compliance of the airway of the patient to a change in one or more mechanical ventilation settings of an associated mechanical ventilator.

11. The apparatus of claim 10, wherein the at least one electronic processor is further programmed to: 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 responsiveness index.

12. The apparatus of claim 11, wherein the at least one electronic processor is further programmed to: A representation of the calculated reactivity index is displayed on the display device.

13. The apparatus of claim 1 , wherein the at least one electronic controller is configured to: 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.

14. The apparatus according to claim 1, further comprising: A mechanical ventilator is configured to deliver mechanical ventilation therapy to the patient.

15. A method for measuring diaphragm muscle, comprising: receiving ultrasound imaging data of a dimension of a diaphragm of a patient during inspiration and expiration while the patient is undergoing mechanical ventilation therapy utilizing a mechanical ventilator; receiving respiratory data of the patient during inspiration and expiration while the patient is undergoing the mechanical ventilation therapy; calculating a diaphragm thickness measure based on the received ultrasound imaging data of the diaphragm and the received respiration data of the patient; as well as A representation of the calculated diaphragm thickness metric is displayed on a display device.

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