System and method for detecting positive end expiratory pressure (PEEP) using diaphragm ultrasound

Abstract

A respiratory monitoring device includes at least one electronic processor programmed to perform a respiratory monitoring method including: receiving ultrasound imaging data of a septum of a patient during inspiration and expiration as a function of time while the patient is subjected to mechanical ventilation treatment using a mechanical ventilator; receiving respiration data of the patient during inspiration and expiration as a function of time while the patient is subjected to mechanical ventilation treatment with the mechanical ventilator; calculating an endogenous positive end expiratory pressure (iPEEP) value for the patient based on the ultrasound imaging data and the respiration data; and displaying a representation of the calculated iPEEP value 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 / 444,353, filed on February 9, 2023, 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, prevention of ventilator-induced lung injury (VILI), and related fields. Background Art

[0004] Intrinsic positive end-expiratory pressure (PEEP), also known as autoPEEP or iPEEP, occurs when expiratory time is shorter than the time required to fully deflate the lungs to their functional residual capacity (FRC), thereby preventing the lungs and chest wall from reaching a point of elastic equilibrium. This is sometimes referred to as "gas trapping." When this problem occurs, a portion of each subsequent tidal volume may be trapped in the patient's lungs, a phenomenon sometimes referred to as breath packing or dynamic overinflation, leading to elevated end-expiratory pressures in the alveoli. If this is not recognized, depending on the ventilation mode, this can lead to barotrauma, volutrauma, reduced tidal volumes, hypotension, patient-ventilator asynchrony, or death. The main pathophysiological factors involved are insufficient time to empty the lungs and / or expiratory flow limitation (EFL), such as dynamic small airway collapse due to the pressure of overinflated lung units, primarily in chronic obstructive pulmonary disease (COPD).

[0005] Diaphragmatic ultrasound (US) allows quantification of diaphragm thickness, strain (rate), and excursion, thereby also quantifying respiratory rate and the duration of each contraction. Diaphragm thickness (expressed as fractional thickening) and strain reflect contractile activity and are closely related to diaphragmatic electrical activity and transdiaphragmatic pressure. Therefore, thickness and strain can be used as surrogates for respiratory effort. Applications of diaphragmatic US include assessment of diaphragmatic function, detection of atrophy, prediction of weaning, and management of mechanical ventilation (MV) settings.

[0006] Ultrasound (US) measurements of diaphragm thickness are usually quantified as the diaphragm thickening fraction (TFdi or TFDI). The diaphragm thickening fraction measurement is performed by an operator who observes the patient and takes ultrasound images at the end of inspiration and expiration. With appropriate positioning of the ultrasound probe (usually in an intercostal position), the upper and lower borders or surfaces of the diaphragm appear as contrast lines in the ultrasound image, and the diaphragm thickness is the distance between these two contrast lines in the image (appropriate correction may be required for the angular position of the ultrasound beam relative to the surface normal of the diaphragm plane). Then, according to Equation 1, the diaphragm thickness T is calculated from the diaphragm thickness measured at the end of expiration. ee Subtract the diaphragm thickness T measured at the end of inspiration fromei , and divide the difference by the diaphragm thickness T at end-expiration ee , to determine the membrane thickness fraction:

[0007]

[0008] where TFdi is the fractional thickness of the diaphragm.

[0009] The presence of intrinsic PEEP is detected by automatic or manual inspection of the flow curve (ie, by checking whether there is still expiratory flow before starting a new inspiration). The value of intrinsic PEEP can be obtained by an expiratory breath-hold maneuver (ie, by forcibly reducing the expiratory flow to zero, thereby causing alveolar and airway pressures to reach equilibrium and measuring the airway pressure (equal to intrinsic PEEP). This is very effective for passive patients during controlled mechanical ventilation.

[0010] However, for patients who actively breathe during spontaneous breathing or assisted ventilation, the presence of intrinsic PEEP can cause the patient to start an inspiratory effort during the expiratory phase to overcome the intrinsic PEEP and then trigger a new breath. Therefore, it is difficult to detect PEEP manually or automatically by checking the pressure and flow curves. In addition, it is much more difficult to reliably measure the intrinsic PEEP value in the presence of respiratory muscle activity because during the expiratory breath hold maneuver, it is impossible to determine how much of the measured positive airway obstruction pressure is caused by expiratory muscle activity. In this case, a feasible method is to measure the drop in esophageal pressure (as a substitute for pleural pressure) before inspiration begins, and then subtract the part caused by the respiratory muscle activity determined according to the esophageal pressure. However, because this method is invasive, a dedicated ventilator system is required to support esophageal pressure measurement, and a time-consuming calibration step is required, so it is not routinely used.

[0011] Several improvements are disclosed below to overcome these and other problems. Summary of the Invention

[0012] In one aspect, a respiratory monitoring device includes at least one electronic processor programmed to perform a respiratory monitoring method comprising: receiving ultrasound imaging data of a patient's diaphragm as a function of time during inspiration and expiration while the patient is undergoing mechanical ventilation therapy using a mechanical ventilator; receiving respiratory data of the patient as a function of time during inspiration and expiration while the patient is undergoing mechanical ventilation therapy; calculating an intrinsic positive end-expiratory pressure (iPEEP) value for the patient based on the ultrasound imaging data and the respiratory data; and displaying a representation of the calculated iPEEP value on a display device.

[0013] In another aspect, a respiratory monitoring method includes receiving, with an electronic controller, ultrasound imaging data of a patient's diaphragm during inspiration and expiration as a function of time while the patient is undergoing mechanical ventilation therapy; receiving respiratory data of the patient during inspiration and expiration as a function of time while the patient is undergoing mechanical ventilation therapy using a mechanical ventilator; calculating a positive end-expiratory pressure (PEEP) value for the patient based on the ultrasound imaging data and the respiratory data; and displaying a representation of the calculated PEEP value on a display device.

[0014] One advantage of the present invention is that it non-invasively determines the intrinsic PEEP value of a patient who is receiving mechanical ventilation but actively breathing.

[0015] Another advantage of the present invention is that mechanical ventilation operation is adjusted to compensate for non-zero intrinsic PEEP.

[0016] Another advantage of the present invention is that ultrasound imaging data is used in conjunction with at least one ventilator waveform to determine an intrinsic PEEP value for a patient receiving mechanical ventilation.

[0017] A given embodiment may provide none, one, two, more, or all of the advantages recited above, and / or may provide other advantages that will be apparent to one skilled in the art upon reading and understanding this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present disclosure may take the form of various components and arrangements of components, and various steps and arrangements of steps. The drawings are only for illustrating preferred embodiments and are not to be construed as limiting the present disclosure.

[0019] Figure 1 An illustrative respiratory monitoring device according to the present disclosure is schematically shown.

[0020] Figure 2 Shown by Figure 1 An example flow chart of operations suitably performed by the system.

[0021] Figure 3 An example is shown where the patient begins inspiratory maneuver before the mechanical ventilator begins applying inspiratory pressure.

[0022] Figure 4 An example flow chart for detecting an intrinsic PEEP value is shown. DETAILED DESCRIPTION

[0023] As used herein, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" also include plural meanings. As used herein, statements about two or more parts or components being "coupled", "connected" or "engaged" shall mean that these parts are directly or indirectly (i.e., through one or more intermediate parts or components) connected, operate or cooperate as long as there is a link. Unless expressly stated therein, directional phrases used herein, such as, for example, but not limited to, top, bottom, left, right, upper, lower, front, rear and their derivatives, relate to the orientation of the elements shown in the accompanying drawings and do not limit the scope of the claimed invention. The words "comprise" or "comprising" do not exclude the presence of other elements or steps than those described herein and / or listed in the claims. In an apparatus consisting of multiple devices, several of these devices may be implemented by the same hardware.

[0024] The following describes the use of diaphragm ultrasound to detect and measure intrinsic positive end-expiratory pressure (iPEEP) in actively breathing patients undergoing mechanical ventilation. Diaphragm ultrasound is a non-invasive imaging modality readily available in the ICU and is used to visualize the diaphragm. Diaphragm ultrasound allows clinicians to determine the thickness and thickness fraction of the diaphragm, from which respiratory activity and, therefore, the onset of inspiration can be inferred to determine iPEEP.

[0025] refer to Figure 1 , shows a diaphragm measuring device 1. A mechanical ventilator 2 is shown configured to provide ventilation therapy to an associated patient P. Figure 1 As shown in FIG, a mechanical ventilator 2 is 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 conduit 6 (also referred to as an inspiratory limb 6), an optional outlet conduit 7 (also referred to as an expiratory limb 7; this may be omitted if the ventilator employs a single-limb patient circuit), a connector or port 8 for connection to an endotracheal tube (ETT) 16, or a mask or other patient interface, and one or more respiratory sensors (not shown), such as a gas flow meter, a pressure sensor, an end-tidal carbon dioxide (etCO2) sensor, and / or the like. The mechanical ventilator 2 is designed to deliver air, an air-oxygen mixture, or other breathable gas (supply source not shown) to the inspiratory limb 6 of the patient breathing circuit 5 at a programmed pressure and / or flow rate to ventilate the patient via the ETT, and optionally also to process exhaled air received at the mechanical ventilator 2 via the expiratory limb 7 of the patient breathing circuit 5. Mechanical ventilator 2 also includes at least one electronic processor or controller 13 (eg, an electronic processor or microprocessor), a display device 14 , and a non-transitory computer-readable medium 15 storing instructions executable by electronic controller 13 .

[0026] Figure 1 A patient P is schematically illustrated (most of which is located internally within the patient P and is therefore shown in phantom). A connector or port 8 is connected to the ETT 16, thereby operatively connecting the mechanical ventilator 2 to deliver breathable air to the patient P via the ETT 16. Mechanical ventilation provided by the mechanical ventilator via the ETT 16 can be used to treat a variety of conditions, such as various types of lung diseases (e.g., emphysema or pneumonia), viral or bacterial infections that affect breathing (e.g., COVID-19 infection or severe influenza), cardiovascular conditions in which the patient P receives oxygen-enriched breathable gas, and the like.

[0027] 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 also contemplated, such as motion mode (M-mode) data collected as a single ultrasound line over a certain time interval, A-mode, etc.

[0028] In some examples, the medical imaging device 18 includes an ultrasound probe 20 configured to acquire ultrasound imaging data (i.e., ultrasound images) 24 of the diaphragm of the patient P. In a more specific example, the medical imaging device 18 includes an ultrasound patch 20 wearable by the patient P (e.g., worn in position on the abdomen or chest of the patient P) to image the patient's diaphragm, such as Figure 1 ). The ultrasound patch 20 is positioned to acquire an ultrasound image 24 of the diaphragm of the patient P. For example, the ultrasound patch 20 is configured to acquire imaging data of the diaphragm of the patient P, and more specifically, to acquire ultrasound image 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 image data 24 of the diaphragm of the patient P from the ultrasound patch 20. Although Figure 1 Only one ultrasound patch 20 is shown in FIG. 1 , but it will be appreciated that any suitable number of patches may be affixed to the patient P. The ultrasound patch(es) 20 allow for continuous and automatic determination of diaphragm thickness data (T di ) from acquired ultrasound image data 24 .

[0029] The non-transitory computer readable medium 15 stores instructions executable by the electronic controller 13 to perform the respiration monitoring method or process 100 .

[0030] refer to Figure 2 , and continue to refer to Figure 1An illustrative embodiment of a respiratory monitoring method 100 is schematically shown as a flow chart. At operation 101, while the patient P is undergoing mechanical ventilation therapy using a mechanical ventilator 2, ultrasound imaging data 24 of the diaphragm of the patient P during inspiration and expiration as a function of time is received. To this end, the electronic controller 13 may control the ultrasound patch 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 patch 20 and / or the medical imaging device 18.

[0031] At operation 102, respiratory data is received as a function of time for patient P during inspiration and expiration while the patient is undergoing mechanical ventilation therapy using a mechanical ventilator 2. Typically, operations 101 and 102 are performed simultaneously, i.e., within the same time interval. The respiratory data for patient P may include one or more of an airway pressure in the airway of patient P or an airway flow in the airway of patient P measured by the mechanical ventilator 2 during ventilation therapy. Notably, airway pressure and airway flow are commonly monitored during mechanical ventilation, and therefore, such data are generally applicable to any patient receiving mechanical ventilation.

[0032] At operation 103, a measure of diaphragm thickness as a function of time is calculated based on the received ultrasound imaging data 24 of the diaphragm of the patient P. As previously noted, in operation 101, if the ultrasound probe is properly positioned, typically in an intercostal position, the upper and lower boundaries or surfaces of the diaphragm appear as contrast lines in the ultrasound image, and the spacing between these two contrast lines in the image is measured (possibly also with appropriate corrections for the angular position of the ultrasound beam relative to the surface normal of the diaphragm plane). However, unlike the case where a diaphragm thickening fraction or ratio is determined (see Equation 1), for the iPEEP measurement disclosed herein, operation 103 determines diaphragm thickness as a function of time with sufficient temporal resolution to detect the onset of an inspiratory effort by the patient P as the onset of an increase in diaphragm thickness. This is in contrast to the case where a diaphragm thickening fraction or ratio is determined (see Equation 1). Figure 3 This can be seen in the lower curve of , which shows the onset of the inspiratory effort (at Figure 3 The onset of inspiratory effort corresponds to the time when the diaphragm thickness begins to increase, as the patient's inspiratory effort is achieved through contraction of the diaphragm and its resulting thickening.

[0033] At operation 104, an iPEEP value is calculated for the patient P based on the ultrasound imaging data 24 and the respiration data. For example, the iPEEP value is calculated based on the diaphragm thickness metric (from diaphragm thickness metric calculation operation 103) and the respiration data as a function of time. To do so, a time corresponding to the onset of inspiration is identified based on (i) the determined diaphragm thickness metric, (ii) the received respiration data, or (iii) a combination of both. In one example, the iPEEP value is calculated as where R is the respiratory resistance of the patient's lungs, and is the identified airflow at the time corresponding to the start of inspiration, which is part of the received respiratory data of the patient. In another example, an updated iPEEP value applied by the mechanical ventilator 2 can be determined based on the received respiratory data 24, and a total PEEP value can be calculated as the sum of the calculated iPEEP value and the determined updated iPEEP value.

[0034] In some embodiments, the received respiratory data of the patient P as a function of time includes a ventilator flow waveform generated during mechanical ventilation therapy. In this embodiment, the iPEEP calculation operation 104 includes: (i) detecting the onset of an inspiratory effort of the patient P based on the ultrasound imaging data 24; (ii) determining an airflow value in the lungs of the patient P at the time of the detected onset of the inspiratory effort of the patient P based on the ventilator flow waveform; and (iii) calculating an iPEEP value based on the determined airflow value in the lungs of the patient P at the time of the detected onset of the inspiratory effort of the patient P. In some embodiments, the mechanical ventilator 2 is triggered to initiate a breath based on the determined onset of the inspiratory effort of the patient P.

[0035] In a specific example, see now Figure 3 , the onset of inspiratory effort is detected by ultrasound-based diaphragm thickness measurement (i.e., when the diaphragm begins to thicken). Figure 3 The corresponding airflow value is determined by looking at the ventilator flow waveform shown in . If the airflow is not zero at this time, this indicates the presence of iPEEP. Another indication of the presence of iPEEP is the time delay between the flow inflection point and the start of the patient's inspiratory effort. This is because the diaphragm (and other respiratory muscles) need time to first balance the iPEEP in order to generate a smaller pressure drop (i.e., in a closed-circuit state) or to start an inspiratory flow (i.e., in an open-circuit state). The mechanical ventilator 2 and the ultrasonic imaging device 18 need to be synchronized to obtain accurate results. For example, when the ventilator and the ultrasonic device are synchronized, the start of the respiratory muscle action detected by ultrasound from the diaphragm can be used to trigger the next breath (e.g., see U.S. Provisional Application No. 63 / 426,069, filed on November 17, 2022).

[0036] Figure 3 An example of a ventilator flow waveform is shown, which may be displayed on the display device 14. A flow waveform (shown in FIG. Figure 3 at the top of the diaphragm) and the membrane thickness waveform (shown at Figure 3 The dotted line indicates the onset of inspiration. Since intrinsic PEEP must be overcome first, the onset of diaphragm thickening begins during the expiratory phase. In alternative embodiments, a pressure waveform may also be displayed.

[0037] refer to Figure 4 , as shown in the flow chart Figure 2 The data inputs are the diaphragm thickness metric 200 as a function of time determined as described above, and the flow rate as a function of time. and airway pressure P, both of which are routinely measured during mechanical ventilation. In operation 204, a time t=0 corresponding to the start of an inspiratory effort is detected, for example by identifying Figure 3 The inflection point of the diaphragm thickness metric 200 as a function of time is indicated by the vertical dashed line in FIG. In operation 206 , the airway pressure P at time t=0 corresponding to the start of the inspiratory effort is obtained from the respiratory data 202 . ao (0).

[0038] Next, in operation 208, the iPEEP value is determined. iPEEP is the pressure in the airway (P ao ) and alveoli (P al ). Figure 4 In the single-compartment model indicated in block 208, it can be deduced that, according to formula 1, the value is equal to the respiratory resistance R and the flow rate The product of:

[0039]

[0040] Respiratory resistance values ​​can be determined as disclosed, for example, in U.S. Provisional Application No. 63 / 407,772, filed on September 19, 2022.

[0041] Once the iPEEP value is known, it can be recommended to increase the PEEP setting by an amount equal to the iPEEP. This "total" PEEP can be recommended as a set point for the new PEEP value to eliminate the iPEEP (and thereby allow the lungs to empty completely due to the greater driving pressure). In addition, the expiratory time required to completely empty the lungs can be estimated and recommended based on this iPEEP value. Other recommended actions can include reducing the tidal volume and respiratory rate. It is important to note that in addition to recommending the above actions to the caregiver, these actions can also be automatically implemented and controlled in a closed-loop system. The onset of the respiratory muscles can also be obtained by surface EMG synchronized with the ventilator to determine the iPEEP.

[0042] review Figure 2 At operation 105, a representation 30 of the calculated PEEP value is displayed on the display device 14. 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 distribution of diaphragm activity.

[0043] In some embodiments, at operation 106, the mechanical ventilator 2 may 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, an adjustment to at least one mechanical ventilation setting of the mechanical ventilator 2 may be determined based on the calculated PEEP value. The determined adjustment may be applied to the mechanical ventilator 2 to adjust the mechanical ventilation therapy for the patient P. The determined adjustment may be displayed on the display device 14 as a suggested adjustment for adjusting the mechanical ventilation therapy for the patient P. The determined adjustment may be, for example, a change in expiratory time, a change in pressure applied by the mechanical ventilator 2 during exhalation, and the like.

[0044] In some embodiments, instead of calculating the diaphragm thickness metric at operation 103 , a negative pressure value may be determined based on the respiratory effort of the patient P. In response to the calculated iPEEP value being above a threshold, a modified configuration of the mechanical ventilator 2 may be determined that effectively applies negative pressure to the patient P during exhalation (or below the PEEP setting) during mechanical ventilation therapy to assist exhalation of the patient P. The determined modified configuration may be displayed on the display device 14 , or the mechanical ventilator 2 may be controlled to implement the determined modified configuration.

[0045] In this embodiment, during the exhalation phase, negative pressure is applied to the expiratory limb 7 of the patient breathing circuit 5 (see Figure 1 ) to help exhalation (i.e., achieve faster exhalation) by generating a greater pressure difference between the alveoli and the airways. From another perspective, the negative pressure operation applied to the expiratory limb 7 actively draws air out of the lungs of the patient P, thereby removing residual air from the lungs, which would otherwise cause iPEEP to have an undesirable positive value. The negative pressure value can be calculated based on the intrinsic PEEP value determined using the model. The negative pressure value can be suggested to the caregiver, or it can be automatically implemented and controlled in a closed-loop system. In the case of limited expiratory flow, a reduction in airway pressure during the expiratory phase may not result in a reduction in flow before a new inspiration is started. However, monitoring the change in flow just before a new inspiration is started after applying a change in airway pressure during the expiratory phase allows the presence of expiratory flow limitation to be detected. This can be indicated to the caregiver. If expiratory flow limitation is detected, a higher PEEP value can be suggested, or a higher PEEP value can be automatically implemented using a closed-loop solution.

[0046] In some embodiments, instead of calculating the diaphragm thickness metric at operation 103, a diaphragm excursion value for the diaphragm for consecutive breaths may be determined based on the ultrasound imaging data 24 as a function of time. In response to an increase or decrease in the diaphragm excursion value for consecutive breaths over time meeting an alarm criterion, an alarm 30 may be displayed on the display device 14.

[0047] In this embodiment, the excursion of the diaphragm can be measured using ultrasound. If the excursion can be measured in an absolute manner, a gradual excursion will indicate an increase in lung expansion due to dynamic overinflation. This provides an additional (i.e., indirect) way to detect intrinsic PEEP using ultrasound. The advantage is that it allows a direct measurement of the cumulative effect of intrinsic PEEP without the need to integrate the flow curve. This information is very important because chest expansion activates receptors, causing arousal and discomfort. In addition, lung expansion increases the risk of overstretching and VILI.

[0048] In some embodiments, the PEEP calculation operation 104 may include determining an amount of lung sliding of the patient's lungs for consecutive breaths based on speckle tracking performed on the ultrasound imaging data 24 as a function of time. In response to an increase or decrease in the amount of lung sliding for consecutive breaths over time meeting an alarm criterion, an alarm 30 may be displayed on the display device 14.

[0049] In this embodiment, while the excursion of the diaphragm provides direct information about lung volume and, therefore, about the gradual increase in end-expiratory volume due to intrinsic PEEP, indirect information can also be obtained from the pleura. Lung ultrasound with speckle tracking allows quantification of the amount of lung sliding. It is expected that as lung volume gradually increases, the location of the spots during the end-expiratory phase will shift caudally, while the distance between the spots will also increase. This effect may be small from breath to breath, but it can be detected over several respiratory cycles and can therefore trigger an alarm. This embodiment will measure the cumulative effect of intrinsic PEEP.

[0050] In some embodiments, the electronic controller 13 is programmed to control a mechanical ventilator 2 having an inspiratory limb and an expiratory limb to perform mechanical ventilation on a patient; and during mechanical ventilation, in response to determining that the iPEEP is above a threshold, adjust the patient's mechanical ventilation to apply negative pressure on the expiratory limb during an expiratory phase of the patient's mechanical ventilation.

[0051] In some embodiments, the electronic controller 13 is programmed to: determine the diaphragm excursion of a patient undergoing mechanical ventilation for consecutive breaths based on ultrasound imaging data of the diaphragm as a function of time; and display an alarm on the display device 14 in response to an increase or decrease in the excursion of the diaphragm for consecutive breaths over time meeting an alarm criteria.

[0052] In some embodiments, the electronic controller 13 is programmed to: determine the amount of lung sliding of the lungs of a patient undergoing mechanical ventilation for consecutive breaths based on ultrasound imaging data of the lungs as a function of time; and display an alarm on the display device 14 in response to an increase or decrease in the amount of lung sliding for consecutive breaths over time meeting an alarm criterion.

[0053] The present disclosure has been described with reference to preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the foregoing detailed description. The exemplary embodiments are intended to be construed as including all such modifications and alterations as come within the scope of the appended claims or their equivalents.

Claims

1. A respiratory monitoring device comprising at least one electronic processor programmed to perform a respiratory monitoring method comprising: receiving ultrasound imaging data as a function of time of a diaphragm of a patient during inspiration and expiration while the patient is undergoing mechanical ventilation therapy using a mechanical ventilator; receiving respiratory data as a function of time for the patient during the inspiration and expiration while the patient is undergoing the mechanical ventilation therapy; calculating an intrinsic positive end-expiratory pressure (iPEEP) value for the patient based on the ultrasound imaging data and the respiratory data; as well as A representation of the calculated iPEEP value is displayed on a display device.

2. The apparatus of claim 1 , wherein the method further comprises: determining a diaphragm thickness metric as a function of time based on received ultrasound imaging data of the diaphragm of the patient; Wherein the iPEEP value is calculated based on the diaphragm thickness measurement as a function of time and the respiratory data.

3. The apparatus of claim 2, wherein the calculation of the iPEEP value comprises: identifying a time corresponding to the onset of inspiration based on the determined diaphragm thickness metric; as well as The iPEEP value is calculated at the identified time corresponding to the onset of inspiration.

4. The apparatus of claim 2, wherein the calculation of the iPEEP value comprises: identifying a time corresponding to the onset of inspiration based on the received respiratory data; as well as The iPEEP value is calculated at the identified time corresponding to the onset of inspiration.

5. The apparatus of claim 3, wherein the iPEEP value is calculated as: where R is the respiratory resistance of the patient's lungs, and is the airflow at said identified time corresponding to the onset of inspiration, is a portion of the respiratory data received from the patient.

6. The apparatus of claim 1 , wherein the received respiratory data as a function of time of the patient comprises a ventilator flow waveform generated during the mechanical ventilation therapy, and calculating the iPEEP value comprises: detecting the onset of an inspiratory effort by the patient based on the ultrasound imaging data; determining, based on the ventilator flow waveform, an airflow value from the lungs of the patient at the onset of a detected inspiratory effort of the patient; as well as The iPEEP value is calculated based on the determined airflow value from the lungs of the patient at the onset of a detected inspiratory effort of the patient.

7. The apparatus of claim 6, wherein the method further comprises: Based on the determined onset of inspiratory effort by the patient, the mechanical ventilator is triggered to initiate a breath.

8. The apparatus of claim 1 , wherein the method further comprises: determining a diaphragm excursion value of the diaphragm for successive breaths based on the ultrasound imaging data as a function of time; as well as In response to an increase or decrease in the diaphragm excursion value over time for the consecutive breaths meeting an alarm criterion, an alarm is displayed on the display device.

9. The apparatus of claim 2, wherein calculating the iPEEP value based on the calculated diaphragm thickness metric comprises: determining an amount of lung sliding of a lung of the patient for consecutive breaths based on speckle tracking performed on the ultrasound imaging data as a function of time; as well as In response to an increase or decrease in the amount of lung sliding over time for the consecutive breaths meeting an alarm criterion, an alarm is displayed on the display device.

10. The apparatus of claim 1, wherein the method further comprises: determining a negative pressure value based on the patient's respiratory effort; as well as responsive to the calculated iPEEP value being above a threshold, determining a modified configuration of the mechanical ventilator to be effective to apply negative pressure to the patient during exhalation of the patient during the mechanical ventilation therapy to assist exhalation of the patient; as well as (i) displaying the determined modified configuration on the display device, or (ii) controlling the mechanical ventilator to implement the determined modified configuration.

11. The apparatus of claim 1 , wherein the method further comprises: determining an updated iPEEP value applied by the mechanical ventilator based on the received respiratory data; A total PEEP value is calculated as the sum of the calculated iPEEP value and the determined updated iPEEP value.

12. The apparatus of claim 1 , wherein the method further comprises: determining an adjustment of at least one mechanical ventilation setting of the mechanical ventilator based on the calculated iPEEP value; as well as (i) applying the determined adjustment to the mechanical ventilator, or (ii) displaying the determined adjustment as a suggested adjustment on the display device.

13. The apparatus of claim 11 , wherein the determined adjustment comprises one of: changes in expiratory time; and The change in pressure applied by the mechanical ventilator during exhalation.

14. The apparatus of 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; and A mechanical ventilator is configured to deliver mechanical ventilation therapy to the patient.

15. A respiratory monitoring method comprising: Using electronic controllers: receiving ultrasound imaging data as a function of time of a diaphragm of a patient during inspiration and expiration while the patient is undergoing mechanical ventilation therapy using a mechanical ventilator; receiving respiratory data as a function of time for the patient during the inspiration and expiration while the patient is undergoing the mechanical ventilation therapy; calculating a positive end-expiratory pressure (PEEP) value for the patient based on the ultrasound imaging data and the respiratory data; as well as A representation of the calculated PEEP value is displayed on a display device.

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