System and method for determining a patient's respiratory effort

Abstract

A method for determining a patient's respiratory effort and associated patient-ventilator asynchrony includes acquiring first impedance data corresponding to a first region of the patient's lungs, the first region including at least one subordinate region of the lungs, during application of positive expiratory pressure, and optionally acquiring second impedance data corresponding to a second region of the lungs, and comparing the first impedance data to one or more of the second impedance data, flow rate in the patient's breathing circuit, pressure in the breathing circuit, historical impedance data for the first region, and stored patterns for impedance data for the first region. Related systems for determining patient respiratory effort are also disclosed.

Description

Technical Field

[0001] (Claim of Priority) This application is a national stage entry under 35 U.S.C. § 371 of International Patent Application PCT / IB2020 / 059439, filed Oct. 7, 2020, designating the United States and published as International Patent Publication WO 2021 / 074747 A1 on Apr. 22, 2021, and claims the benefit under Article 8 of the Patent Cooperation Treaty to U.S. Provisional Patent Application No. 62 / 916,929, filed Oct. 18, 2019, regarding "SYSTEMS AND METHODS FOR DETERMINING A RESPIRATORY EFFORT OF A PATIENT".

[0002] (Field of the Invention) Embodiments of the present disclosure generally relate to systems and methods for determining a patient's respiratory effort. More specifically, embodiments of the present disclosure relate to a method, related apparatus, and system for determining a respiratory effort of a patient, and / or asynchrony between the patient and a ventilator, such as ineffective inspiratory effort, based on impedance data of at least a dependent region of the lungs and / or information derived from the impedance data.

Background Art

[0003] The treatment of patients with respiratory insufficiency requires mechanical ventilation support. Patients with respiratory insufficiency, such as those with acute respiratory distress syndrome (ARDS), may receive mechanical ventilation support and positive end-expiratory pressure (PEEP). Unfortunately, the patient and the mechanical ventilator may become asynchronous. Patient-ventilator asynchrony is defined by an inadequate interaction between the patient and the mechanical ventilator. Patient-ventilator asynchrony affects 35-43% of patients wearing a ventilator and is associated with poor patient outcomes, such as prolonged mechanical ventilation use and increased in-hospital mortality. One consequence of patient-ventilator asynchrony is ineffective inspiratory effort (also referred to as "wasted effort"), which occurs when the patient's effort to initiate a breath is not recognized by the mechanical ventilator and the mechanical ventilator does not respond to the patient's breathing attempt. Ineffective inspiratory effort (IEE) during exhalation is defined as an inspiratory effort (by the patient) that cannot trigger ventilation by the ventilator and is the most common type of patient-ventilator asynchrony. The exact incidence of IEE varies and depends on several factors, such as the specific patient, mechanical ventilation (MV) settings, sedation level, and patient arousal state.

[0004] Unfortunately, despite the importance of detecting the patient's effort and the harmful effects of asynchrony on patient outcomes, even experts find it difficult to detect the patient's effort and asynchrony based solely on the ventilator waveform. Typically, to reduce the incidence of wasted effort asynchrony, the patient's effort is detected using invasive techniques such as esophageal catheters and measurement of diaphragmatic electrical activity (Eadi measurement). For example, the patient's effort can be detected using esophageal pressure tracing, esophageal balloons, or neurally adjusted ventilatory assist (NAVA). However, both esophageal pressure and NAVA monitoring require invasive and complex procedures, such as catheter positioning. SUMMARY OF THE INVENTION MEANS FOR SOLVING THE PROBLEM

[0005] In some embodiments, a method for determining a patient's respiratory effort includes obtaining first impedance data corresponding to a first region of the patient's lungs, the first region including at least one dependent region of the lungs; comparing the first impedance data with one or more of second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region of the lungs, flow within the patient's breathing circuit, pressure within the breathing circuit, and past impedance data of the first region, and stored patterns for the impedance data of the first region; and identifying the occurrence of the patient's respiratory effort based on the comparison.

[0006] In a further embodiment, a system for determining a patient's respiratory effort includes an electrical impedance tomography system, at least one processor coupled to the electrical impedance tomography system, and at least one non-transitory computer-readable storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to obtain first impedance data corresponding to at least one dependent region of the patient's lungs by the electrical impedance tomography system, and compare the first impedance data with one or more of second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region of the lungs, flow within the patient's breathing circuit, pressure within the breathing circuit, past impedance data of the first region, and stored patterns for the impedance data corresponding to the first region of the lungs, and based on the comparison, execute a process of identifying the respiratory effort.

[0007] In yet another embodiment, a system for determining a patient's respiratory effort includes an electrical impedance tomography system and a controller, the electrical impedance tomography system being operably coupled to the controller. The controller includes at least one processor and at least one non-transitory computer-readable storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to cause the electrical impedance tomography system to obtain first impedance data of a first region of the patient's lungs, the first region including a dependent region of the lungs; compare the first impedance data with one or more of second impedance data corresponding to a non-dependent region of the patient's lungs, a flow rate within the patient's respiratory circuit, a pressure within the respiratory circuit, past impedance data of the first region, and a stored pattern regarding the impedance data of the first region; and based on the comparison, identify the patient's respiratory effort.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 7

DETAILED DESCRIPTION OF THE INVENTION

[0009] This provisional patent application is related to Appendices A and B, each of which is attached hereto and which also form part of the present disclosure. The published documents referred to in the "References" section at the end of Appendix A are hereby incorporated herein by reference.

[0010] The drawings presented herein are not meant to be actual diagrams of specific materials, components, or systems, but are merely idealized representations used to illustrate embodiments of the present disclosure.

[0011] The following description provides specific details, such as material types, dimensions, and processing conditions, in order to fully describe embodiments of the present disclosure. However, those skilled in the art should understand that the embodiments of the present disclosure can be implemented without these specific details. In fact, the embodiments of the present disclosure can be implemented together with conventional manufacturing techniques used in the industry. Furthermore, the following description does not form a complete process flow, device, or system for determining a patient's respiratory effort, the asynchrony between the patient and the ventilator, or related methods. Only the process actions and structures necessary to understand the embodiments of the present disclosure will be described in detail below. Other operations for determining a patient's respiratory effort or the asynchrony between the patient and the ventilator can be performed using prior art. In addition, the accompanying drawings of this application are not drawn to scale and are for illustrative purposes only. Additionally, elements common between the drawings may sometimes have the same numerical notation.

[0012] In the following detailed description, reference is made to the accompanying drawings which form a part hereof and which illustrate specific embodiments by which the present disclosure can be practiced. Such embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. However, it should be understood that this detailed description and specific examples are given by way of illustration only and not by way of limitation, while showing examples of embodiments of the present disclosure. Various substitutions, changes, additions, rearrangements, or combinations thereof within the scope of the present disclosure will be apparent to those skilled in the art from the present disclosure.

[0013] In accordance with common practice, various features illustrated in the drawings may not be drawn to scale. The drawings presented herein are not meant to be actual diagrams of a particular device (e.g., a device, a system, etc.) or method, but are merely notations used to explain various embodiments of the present disclosure. Therefore, for clarity of explanation, the dimensions of various shaped parts may be appropriately enlarged or reduced. In addition, for clarity of explanation, some parts of the drawings may be simplified. Therefore, the drawings may not depict all of the components of a given device or all of the operations of a particular method.

[0014] The information and signals described herein can be represented by any of a variety of techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout this description may be represented by voltage, current, electromagnetic waves, magnetic fields and particles, optical fields and particles, or any combination thereof. Depending on the drawing, in order to clarify the display and explanation, some signals are shown as a single signal. As should be understood by those skilled in the art, a signal may correspond to a signal bus, in which case the bus may have various bit widths, and the present disclosure can be implemented in any number of data signals including a single data signal.

[0015] The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein can be implemented or performed with a general purpose processor, a dedicated processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The general purpose processor may be considered a special purpose processor while executing instructions (e.g., software code) stored on a computer readable medium. Also, the processor may be implemented as a combination of computing devices, such as, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0016] Further, note that embodiments may be described with respect to processes depicted as flowcharts, flow diagrams, structural diagrams, or block diagrams. In a flowchart, operational acts may be described as a sequential process, but many of these acts may be performed in another order, in parallel, or substantially simultaneously. Further, the order of the acts may be rearranged. A process may correspond to a method, function, procedure, subroutine, subprogram, etc. And the methods disclosed herein may be implemented in hardware, software, or both. When implemented in software, the functions may be stored or transmitted as one or more instructions or code on a computer readable medium. A computer readable medium includes both a computer storage medium and a communication medium including any medium that facilitates transfer of a computer program from one place to another.

[0017] As used herein, the singular forms following "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0018] As used herein, the term "can, may" with respect to a material, structure, feature, or method indicates that their use in the implementation of embodiments of the present disclosure is contemplated, and to avoid suggesting that such terms should exclude or must exclude other suitable materials, structures, features, and methods that can be used in combination therewith, they are used in preference to the more restrictive term "is".

[0019] As used herein, the "dependent" region of the lung means a lower region, such as a region of the lung near the patient's back (not a region of the lung near the patient's chest), and includes the same. The dependent region of the lung may include its dorsal region and may sometimes be referred to as the posterior region of the lung.

[0020] As used herein, the "non-dependent" region of the lung means an upper region of the lung, such as a region of the lung near the patient's chest, and includes the same. The non-dependent region of the lung may include its anterior region and may sometimes be referred to as the anterior region of the lung.

[0021] As used herein, the phrase "impedance data" refers to signals from an electrical impedance tomography system and also includes information obtained from the signals of the electrical impedance tomography system. Non-limiting examples of information obtained from the signals of the electrical impedance tomography system include images (EIT images), plethysmographs obtained from EIT data, airway compliance, and perfusion.

[0022] In this specification, it should be understood that when referring to elements by terms such as "first", "second", etc., unless such limitations are explicitly stated, they do not limit the quantity or order of those elements. Rather, such terms may be used in this specification as a convenient way to distinguish two or more elements or entities of an element. Thus, a reference to a first element and a second element does not mean that only two elements can be used, or that the first element must precede the second element in some way. Also, unless otherwise specified, a set of elements may include one or more elements.

[0023] As used herein, the term "substantially" with respect to a given parameter, characteristic, or state means that the given parameter, characteristic, or state is met with a small difference, such as within acceptable manufacturing tolerances, to the extent that would be understood by one of ordinary skill in the art, and includes that. For example, a parameter that is substantially met may be met at least about 90%, at least about 95%, or even at least about 99%.

[0024] As used herein, the phrase "about" when used in reference to a given parameter includes the recited value and has a meaning determined by the context (e.g., including the degree of error associated with the measurement of a given parameter, variations due to manufacturing tolerances, etc.).

[0025] According to the embodiments described in this specification, a patient's respiratory effort can be determined using non-invasive techniques. In some embodiments, impedance data (e.g., EIT plethysmograph) of at least one dependent region of the lung is compared with one or more of the past impedance data of at least one dependent region of the lung, the impedance data of the non-dependent regions of the lung, airway pressure, airway flow, and stored patterns regarding the impedance data of at least one dependent region, to detect asynchrony between the patient and the ventilator, such as ineffective effort (IEE; also referred to as "ineffective inspiratory effort"). In some embodiments, a relative increase in the impedance of the dependent regions of the lung, an increase in the flow within the airway, the pressure within the airway, the past impedance data of at least one dependent region, or a stored pattern regarding the impedance of at least one dependent region, when there is no corresponding increase in the impedance of the non-dependent regions of the lung, can be used to detect the patient's respiratory effort (such as asynchrony between the patient and the ventilator). The impedance of the dependent regions, the impedance data of the non-dependent regions, the flow within the airway, the pressure within the airway, the past impedance data of at least one dependent region, and the stored patterns regarding the impedance data of at least one dependent region can each be determined non-invasively. In response to detecting asynchrony between the patient and the ventilator, corrective measures can be taken, such as adjusting the parameters of the ventilator, to reduce the incidence of asynchrony. Related systems and devices for detecting asynchrony between the patient and the ventilator are also disclosed. Thus, a patient's respiratory effort and / or asynchrony between the patient and the ventilator can be detected by non-invasive methods, such as an EIT system of a mechanical ventilator.

[0026] FIG. 1 is a schematic diagram of a portion of an EIT system 100 showing a plurality of electrodes 110 disposed around a region of interest (e.g., the chest) of a patient 105. The electrodes 110 of a conventional EIT system 100 are often physically fixed with an electrode belt 103. Typically, the arrangement of the electrodes 110 is substantially parallel to the axis 102, crossing the patient's cranio-caudal axis 104. Although FIG. 1 shows the electrodes 110 disposed only partially around the patient 105, the electrodes 110 can be disposed around the entire patient 105 for measurement or according to a particular region of interest desired. The electrodes 110 can be coupled to a computing system (not shown) configured to control the operation of the electrodes 110 and perform reconstruction of the EIT image.

[0027] FIG. 2 is a schematic diagram showing a cross-section of the chest of the patient 105 along the plane of the electrodes. A voltage for injecting an excitation current into the patient between electrode pairs can be applied to a pair of electrodes 110 (the electrodes are denoted by + and - signs). As a result, voltages (e.g., V1, V2, V3~V n ) are detected at other electrodes and can be measured by the EIT system 100. The current injection can generate an excitation current at different electrode pairs and be performed for a measurement cycle according to a circular pattern.

[0028] FIG. 3 is a schematic block diagram of an EIT system 300 according to an embodiment of the present disclosure. The EIT system 300 may include an electrode belt 310 operably coupled to a data processing system 320. The electrode belt 310 and the data processing system 320 may be coupled together via a wired connection (e.g., a cable) and / or may have communication modules that communicate wirelessly with each other. The data processing system 320 may include a processor 322 operably coupled to an electronic display 324, an input device 326, and a memory device 328. The electronic display 324, together with the data processing system 320, can be configured into a single form factor for an EIT device coupled to the electrode belt 310. In some embodiments, the electronic display 324 and the data processing system 320 may be separate units of an EIT device coupled to the electrode belt 310. In yet another embodiment, the EIT system 300 may be integrated within another host system configured to perform additional medical measurements and / or procedures, in which case the electrode belt 310 can be coupled to a port of the host system that already implements its own input device, memory device, and electronic display. Thus, the host system may have EIT processing software installed therein. Such software may be incorporated into the host system prior to on-site use or can be updated after installation.

[0029] Processor 322 can coordinate communication between various devices and execute instructions stored in the computer-readable medium of memory device 328 to direct current excitation, data acquisition, data analysis, and / or image reconstruction. By way of example, memory device 328 may include a library of finite element meshes to be used by processor 322 to model a patient's body within a region of interest for performing image reconstruction. In some embodiments, memory device 328 includes historical data of a patient's lung impedance (such as impedance data of a region of interest (e.g., a dependent region) and impedance data of other regions of the lung), and / or patterns of the patient's lung impedance data. Input device 326 can include devices such as a keyboard, touch screen interface, computer mouse, remote control, mobile device, or other device configured to receive information so that processor 322 can receive input from an operator of EIT system 300. Thus, in the case of a touch screen interface, electronic display 324 and input device 326 for receiving user input may be integrated within the same device. Electronic display 324 can be configured to receive data and output an EIT image reconstructed by the processor for viewing by an operator. Additional data (such as numerical data, graphs, trend information, and other information deemed useful to the operator) can also be generated by processor 322 from only the measured EIT data or in combination with other non-EIT data from other devices coupled thereto. Such additional data can be displayed on electronic display 324.

[0030] EIT system 300 may include components not shown and, as would be understood by one of ordinary skill in the art, may include one or more analog / digital converters, signal processing circuits, demodulation circuits, power supplies, etc. to assist with communication with electrode belt 310 and / or current excitation.

[0031] FIG. 4 is a schematic diagram of a system for identifying a patient's respiratory effort and asynchrony between the patient and a ventilator. For example, FIG. 4 shows a system 400 for determining whether a given patient 410 connected to a mechanical ventilator 408 exhibits asynchrony with this mechanical ventilator 408. The system 400 can include a ventilator system 402, an EIT system 404, and a controller 406 for operating the system 400, specifically the ventilator system 402 and the EIT system 404. The ventilator system 402 and the EIT system 404 are operably coupled to the controller 406.

[0032] In some embodiments, the ventilator system 402 includes a mechanical ventilator 408 that provides respiratory support or assistance to the patient 410. For example, the mechanical ventilator 408 can provide a medical gas flow that can include one or more of air, oxygen, nitrogen, and helium. In some embodiments, the medical gas flow can further include additives such as aerosol drugs or anesthetics. The ventilator system 402 can further include a breathing circuit 412, an inspiratory limb 414, a patient rim 416, and a patient connection 418. In some embodiments, the mechanical ventilator 408 can provide a medical gas flow to the breathing circuit 412 through the inspiratory limb 414 that connects to the intake port 420 of the mechanical ventilator 408. The medical gas can flow (e.g., move) through the inspiratory limb 414 to the patient rim 416 of the breathing circuit 412. Thus, the mechanical ventilator 408 can supply medical gas to the patient 410 through the patient connection 418.

[0033] Exhalation from the patient 410 can be returned to the mechanical ventilator 408 through the patient connection 418 and the patient rim 416. In some embodiments, exhalation can be directed to the expiratory limb 422 of the breathing circuit 412 via one or more valves (e.g., check valves). For example, the ventilator system 402 can further include a plurality of check valves that can be disposed at various points along the breathing circuit 412 to allow only medical gas flow in a desired direction along an appropriate path toward or away from the patient 410.

[0034] Furthermore, the exhaled air may be returned to the mechanical ventilator 408 through the exhalation port 424 of the mechanical ventilator 408.

[0035] In some embodiments, the exhalation port 424 may include an adjustable flow control valve for adjusting the pressure within the breathing circuit 412. By adjusting the flow valve, backpressure can be generated, which is applied to the patient 410 during exhalation to generate positive end-expiratory pressure. Thus, the system 400 can include any conventional system that provides PEEP therapy to the patient 410. Further, other systems and configurations recognized by those skilled in the art are also included within the scope of the present disclosure.

[0036] The ventilator system 402 may further include one or more gas monitoring sensors 426. In some embodiments, the one or more gas monitoring sensors 426 can be disposed within the patient connection portion 418 of the breathing circuit 412. In other embodiments, the one or more gas monitoring sensors 426 can be fluidly connected to the breathing circuit 412 or any other component of the ventilator system 402. In some embodiments, the gas monitoring sensor 426 may include one or more of a pressure, flow rate, and gas concentration sensor. As will be described in more detail below, the controller 406 and the mechanical ventilator 408 can use the one or more gas monitoring sensors 426 to monitor the operation of the ventilator 408 and ultimately control and provide information (e.g., feedback to a user (e.g., a clinician)). In some embodiments, the one or more gas monitoring sensors 426 may include any conventional gas sensor.

[0037] The EIT system 404 may include any of the EIT systems described above with respect to FIGS. 1-3 and is operable in accordance with any of the above-described embodiments. In some embodiments, the EIT system 404 may include any conventional EIT system. Additionally, as described above, the EIT system 404 may be operably coupled to the controller 406 and can provide information regarding the measurements performed by the EIT system 404 to the controller 406. In some embodiments, the EIT system 404 may be completely independent of the ventilator system 402 and can determine that the PEEP has been changed during operation through each pressure sensor operably coupled to the EIT system 404. In one or more embodiments, the EIT system 404 may also include a respective electronic display and input device separate from the display and / or input device of the ventilator system 402. Further, it is possible to input (e.g., manually input) information regarding the PEEP and / or other ventilation parameters using the electronic display and input device of the EIT system 404.

[0038] The controller 406 may include a processor 428 coupled to a memory 430 and input / output components 432. The processor 428 may include a microprocessor, a field programmable gate array, and / or other suitable logic devices. The processor 428 is capable of executing instructions stored in the computer-readable medium of the memory device 430 to command current excitation, data acquisition, data analysis, image reconstruction, and / or determination of asynchrony between the patient and the ventilator. The memory 430 may be a volatile and / or non-volatile medium (e.g., ROM, RAM, magnetic disk storage media, optical storage media, flash memory devices, and / or other suitable storage media) configured to store data, and / or other types of computer-readable storage media (e.g., non-transitory computer-readable storage media). The memory 430 can store algorithms and / or instructions for operating the ventilator system 402 and the EIT system 404 for execution by the processor 428. For example, the controller 406 may include the data processing system 320 described above with respect to FIG. 3. In some embodiments, the processor 428 is operably coupled to a computing device (e.g., via the Internet) that is operably coupled to the controller 406, such as a server or a personal computer, to transmit data thereto. The input / output components 432 may include a display, a touch screen, a keyboard, a mouse, and / or other suitable types of input / output devices configured to receive input from an operator and supply output to the operator. In some embodiments, the memory 430 may include past data of the impedance of the patient's lungs (impedance data of the region of interest (e.g., the dependent region)), and impedance data of other regions of the lungs, etc.

[0039] Continuing to refer to FIG. 4, the system 400 can be configured to apply ventilatory support using a ventilator system 402 and further to determine the patient's respiratory effort and the presence of asynchrony between the patient and the ventilator, such as ineffective effort. In some embodiments, the system 400 is configured to provide a level of PEEP to the patient based on the determined respiratory effort and / or asynchrony between the patient and the ventilator. PEEP increases the baseline pressure within the patient's respiratory system such that natural exhalation by the patient maintains a higher airway pressure than respiration without PEEP therapy. Previous PEEP pressures have been between 0 and 40 cmH2O, although higher PEEP pressures may be used.

[0040] In some embodiments, an EIT system 300, 404, and / or the system 400 can be used to determine ineffective effort. FIG. 5 is a simplified flowchart illustrating a method 500 for determining a patient's respiratory-related effort. The method 500 can include placing a plurality of electrodes of an EIT system (e.g., EIT system 100) around the patient's chest. Operation 504 can include applying a current between the electrodes of the plurality of electrodes. Operation 506 can include using the electrodes of the plurality of electrodes to determine impedance data regarding at least a first region of the patient's lungs. Operation 508 can include obtaining either or both of a gas flow within the patient's breathing circuit and a pressure within the patient's breathing circuit. Operation 510 can include comparing the impedance data of the first region with one or more of past impedance data of the first region, a stored pattern regarding the impedance data of the first region, impedance data of at least a second region of the patient's lungs, gas flow within the breathing circuit, and pressure within the patient's breathing circuit to determine whether the patient's respiratory effort and / or asynchrony between the patient and the ventilator has occurred. Operation 512 can include, in response to a determination that the patient's respiratory effort has occurred, optionally determining whether the respiratory cycle continued after the patient's respiratory effort to identify ineffective effort asynchrony. Operation 514 can include providing one or more corrective measures to a mechanical ventilator in communication with the patient.

[0041] Operation 502 includes arranging a plurality of electrodes of the EIT system around the patient's chest. In some embodiments, operation 502 includes operably connecting the patient to a mechanical ventilator. In some embodiments, the EIT system includes any of the EIT systems described above (EIT system 100, EIT system 300, EIT system 404), and the patient is connected (communicates) to a mechanical ventilator such as the mechanical ventilator 408 of FIG. 4. However, the present disclosure is not limited thereto, and the patient may be connected to a mechanical ventilator.

[0042] Operation 504 includes applying a current between the electrodes of the plurality of electrodes. In some embodiments, a voltage for injecting an excitation current into the patient between electrode pairs is sequentially applied between a pair of electrodes, and the voltage is measurable at other electrodes of the EIT system. As described above with reference to FIG. 2, current injection can be performed for a measurement cycle by generating an excitation current with different electrode pairs and following a circular pattern. In some embodiments, operation 504 occurs simultaneously with the provision of mechanical ventilation to the patient, such as via PEEP therapy. However, the present disclosure is not limited thereto, and operation 504 may be performed without providing mechanical ventilation to the patient.

[0043] Operation 506 includes using the electrodes of the plurality of electrodes to determine impedance data regarding a first region of the patient's lung. In some embodiments, operation 506 further includes determining impedance data for at least one second region of the patient's lung. In some embodiments, determining impedance data regarding at least the second region of the patient is performed substantially simultaneously with determining impedance data regarding the first region of the patient's lung using the electrodes of the plurality of electrodes. In some embodiments, the voltage data (corresponding to the impedance data) of the first region and at least the second region are measured simultaneously.

[0044] In some embodiments, the first region of the patient's lung includes a dependent (e.g., dorsal, posterior) region of the patient's lung. The dependent region may include a portion of the lung near the patient's back. That is, the dependent region includes a portion of the lung that is close to the bed when the patient is lying face down and looking up. In some embodiments, the first region includes at least one dependent region. In some embodiments, the first region includes only the dependent regions of the patient's lung. However, the present disclosure is not limited thereto, and in other embodiments, the first region includes the dependent regions and non-dependent regions of the patient's lung. In this specification, the first region may be referred to as the "ineffective effort region of interest" (IEROI).

[0045] At least one second region may include at least one region of the patient's lung that is different from the first region. In some embodiments, at least one second region includes a non-dependent (e.g., ventral, anterior) region of the patient's lung. The non-dependent region may include a portion of the patient's lung near the patient's chest (and distal from the back). That is, the non-dependent region includes a portion of the lung that is away from the bed when the patient is lying face down and looking up. In some embodiments, at least one second region has no (does not include) dependent regions of the lung and does not include the IEROI.

[0046] FIG. 6A is a diagram showing a graph of the flow rate measured in a patient's airway, the airway pressure, and the impedance data (delta Z) of the patient's lungs measured in the posterior and anterior regions. In FIG. 6A, graph 602 represents an EIT plethysmograph of a first region of the lung, which may include a dependent region of the lung and includes the IEROI. Graph 604 represents an EIT plethysmograph of a second region of the lung over the same period as the EIT plethysmograph of the first region of the lung. Graph 606 represents the gas flow in the patient's breathing circuit, and graph 608 represents the pressure in the patient's breathing circuit over the same period. The gas flow and pressure in the patient's breathing circuit can be measured by a gas monitoring sensor (e.g., gas monitoring sensor 426 (FIG. 4)), a ventilator (e.g., mechanical ventilator 408 (FIG. 4)), or both. As shown in FIG. 6A, the EIT plethysmograph (first impedance data) of the first region, at least one EIT plethysmograph (second impedance data) of the second region, the flow rate in the patient's breathing circuit, and the pressure can each be measured substantially simultaneously, where the X-axis represents the respective measurement times.

[0047] The EIT plethysmograph of the first region and at least the EIT plethysmograph of the second region can be obtained simultaneously and during mechanical ventilation support and PEEP therapy, such as during an ascending and descending PEEP procedure for alveolar and / or lung recruitment, as described in U.S. Patent Application Publication No. 2019 / 0246949, the entire disclosure of which is incorporated herein by reference. The EIT plethysmograph of the first region and at least one EIT plethysmograph of the second region can represent the sum of the baseline impedances of the pixels of the respective first and at least second regions of the EIT image of the lung. For example, referring to FIG. 6B, an EIT image showing the dependent and non-dependent regions of the patient's lung is illustrated. The lower half of FIG. 6B can represent the dependent region of the lung, and the upper half can represent the non-dependent region of the lung. The plethysmograph represents the sum of the impedances in a region of interest and can also be obtained from the pixel values determined after applying an image reconstruction algorithm to the impedance data.

[0048] Referring back to FIGS. 5 and 6A, operation 506 includes measuring impedance data within the first region. In some embodiments, operation 506 further includes measuring impedance data within a second region of the lung over time. In some embodiments, the measured impedance data is represented as the relative change in impedance of each of the first and second regions of the lung (e.g., with respect to a reference baseline impedance in each of the first and second regions). In some embodiments, the reference baseline is the average of a set of voltages acquired during an initial period of the EIT system.

[0049] Returning to FIG. 5, operation 508 includes obtaining one or both of the gas flow and the pressure within the patient's breathing circuit. In some embodiments, obtaining the gas flow and the pressure within the patient's breathing circuit includes measuring the gas flow and the pressure. In other embodiments, the gas flow and pressure are obtained from a ventilator, which can control the gas flow and pressure. In some embodiments, the gas flow within the patient's breathing circuit can be measured by a gas monitoring sensor such as gas monitoring sensor 426 (FIG. 4). The gas monitoring sensor can be located anywhere within the patient's breathing circuit. The pressure within the patient's breathing circuit can be measured by a gas monitoring sensor, which can include the same gas monitoring sensor or a different gas monitoring sensor that measures the gas flow. In some embodiments, one or both of the gas flow or the pressure within the patient's breathing circuit can be measured by a ventilator such as mechanical ventilator 408 (FIG. 4).

[0050] Operation 510 may include comparing the impedance data of the first region with one or more of the past impedance data of the first region, the stored pattern for the impedance data of the first region, the impedance data of the second region, the gas flow within the patient's breathing circuit, and the pressure within the patient's breathing circuit to determine whether patient respiratory effort and / or asynchrony between the patient and the ventilator has occurred. For example, referring to FIG. 6A, the first impedance data (graph 602) of the first region of the lung can be compared with one or more of the impedance data (graph 604) of the second region of the lung, the flow rate within the breathing circuit (graph 606), and the pressure within the breathing circuit (graph 608). The shaded region 610 in FIG. 6A represents the time frame during which asynchrony of ineffective effort occurred. During the period within the shaded region 610, the impedance within the first region (dependent region) increases as indicated by arrow 601 without a corresponding increase in impedance of the second region (non-dependent region) as shown in graph 604, without an increase in flow rate as shown by arrow 605, and without an increase in airway pressure as shown by arrow 607. That is, the impedance within the second region does not show a corresponding increase with respect to the impedance within the first region. Additionally, during the same period, the flow and pressure within the airway also do not show changes such as those occurring during a normal breathing cycle. Thus, by comparing the impedance data of the first region with one or more of the impedance data of at least one second region, the flow rate within the airway, and the pressure within the airway, patient respiratory effort and asynchrony between the patient and the ventilator (e.g., ineffective effort) can be determined. In a further embodiment, asynchrony between the patient and the ventilator can be determined based on a comparison of the impedance of the first region with the historical value of the impedance of the first region, the stored pattern for the impedance data of the first region, or both. In some embodiments, asynchrony between the patient and the ventilator can be determined based on a comparison of the impedance of the first region with the impedance of the first region during a past normal breathing cycle or an ineffective effort cycle.

[0051] Operation 512 may include determining whether the respiratory cycle continued after the patient's respiratory effort, as appropriate, in response to a determination that the patient's respiratory effort occurred, to identify ineffective effort asynchrony.

[0052] Operation 514 includes providing one or more corrective measures to a mechanical ventilator in communication with the patient in response to the identification of ineffective effort asynchrony. In some embodiments, the one or more corrective measures include changing ventilator parameters such as PEEP, I:E (inspiration to expiration, also referred to as ventilation rate) relationship, respiratory rate, and trigger settings, and providing an indication of asynchrony between the patient and the ventilator (such as on input / output component 432 (FIG. 4)).

[0053] FIG. 6C is a diagram showing a graph of flow rate measured in the patient's airway, airway pressure, and impedance data of the patient's lungs measured in the posterior region and the anterior region, according to an embodiment of the present disclosure. This graph shows, respectively, the flow rate of gas to the patient in the patient's respiratory circuit, the pressure in the patient's respiratory circuit, an EIT plethysmograph measured over time in a first region of the lungs, and an EIT plethysmograph measured over time in at least one second region of the lungs over the same time range during ineffective effort asynchrony. Graph 612 may include a dependent region of the lungs and represents an EIT plethysmograph of a first region of the lungs including IEROI, graph 614 represents an EIT plethysmograph of a second region of the lungs over the same period as the EIT plethysmograph of the first region of the lungs, graph 616 represents the flow of gas in the patient's respiratory circuit, and graph 618 represents the pressure in the patient's respiratory circuit.

[0054] The patient's ineffective breathing effort occurs during the period corresponding to the shaded region 620. Arrow 611 indicates a slight increase in impedance within the first region without causing a corresponding increase in impedance within at least one second region. The second region shows a decrease in impedance immediately after the shaded region 620, and a decrease in air content within at least one second region is shown. Since arrows 615 and 617 each indicate that the flow rate or pressure does not increase at the time corresponding to the slight increase in impedance (arrow 611) within the first region, it is confirmed that the change (increase) in impedance within the first region corresponds to a patient effort that does not trigger the mechanical ventilation cycle, indicating asynchrony (ineffective effort) between the patient and the ventilator. That is, the change (increase) in impedance within the first region corresponds to the patient's breathing effort, and such breathing effort, as shown by the flow rate and pressure curves, does not trigger the mechanical ventilation cycle, resulting in asynchrony between the patient and the ventilator.

[0055] FIG. 6D is a diagram showing graphs of the flow rate measured in a patient's airway, the airway pressure, and the impedance data of the patient's lungs measured in the posterior region and the anterior region, according to an embodiment of the present disclosure. In FIG. 6D, graph 622 represents the pressure in the patient's breathing circuit, graph 624 represents the gas flow in the patient's breathing circuit, graph 626 represents the volume of gas introduced into the patient's breathing circuit through a ventilator, and graph 628 is an EIT plethysmograph of the dependent region of the patient's lungs. A reverse trigger (also called "reverse triggering"; a type of asynchrony that occurs when patient effort occurs after the start of ventilation by a ventilator) occurs at the time indicated by line 621. In response to the reverse triggering, the impedance in the dependent region of the patient's lungs shows a positive wave only during the second ventilation cycle corresponding to line 621, and the volume graph 626 shows respiratory stacking. The positive wave of impedance at time 623 shows the relationship between the contraction of the diaphragm and the impedance in the dependent region. At time 625, the impedance in the dependent region decreases in response to an assist cycle via a ventilator starting at time 623, indicating that reverse triggering has occurred and there is asynchrony between the patient and the ventilator. At time 625, the patient does not respond to the ventilation provided by the mechanical ventilator.

[0056] Therefore, by comparing impedance data from at least one dependent region of a patient's lung with one or more historical values of impedance data from at least one dependent region of the lung, a stored pattern regarding impedance data of the dependent region of the lung, simultaneous impedance data of a second region of the patient's lung (at least a part of which includes a non-dependent region of the lung), simultaneous gas flow within the patient's airway, and simultaneous pressure within the airway, the respiratory effort of the patient, the asynchrony between the patient and the ventilator, or both can be detected (identified). Without being bound by a particular theory, it is believed that by analyzing the impedance of the dependent region of the lung, as the dependent region of the lung is more responsive to diaphragmatic activity than the non-dependent region of the lung, the asynchrony between the patient and the ventilator can be detected. Therefore, the respiratory effort (with the diaphragm) by the patient can be monitored through the impedance activity of the dependent region of the lung.

[0057] In some embodiments, a relative increase in impedance within a dependent region not accompanied by one or more of a corresponding increase in impedance within the second region, an increase in gas flow within the airway, or an increase in pressure within the airway may be indicative of asynchrony between the patient and the ventilator such as ineffective effort. It would be advantageous to be able to detect the asynchrony between the patient and the ventilator through non-invasive means by applying a voltage to the patient's chest with EIT. Further, the asynchrony between the patient and the ventilator can be detected during the use of a mechanical ventilator and an EIT system without the need for additional devices or invasive catheters. On the other hand, conventional methods for determining asynchrony between a patient and a ventilator include, for example, esophageal pressure tracing (requiring an esophageal balloon) and neurally adjusted ventilatory assistance (NAVA), both of which require the placement of a catheter and are invasive techniques.

[0058] Examples Using electrical activity monitoring of the diaphragm (Edi) of piglets, verification was performed for the detection of ineffective effort based on impedance data (EIT) of the dependent regions of the lungs, or image data obtained from this data. Figure 7 is a diagram showing the flow rate and airway pressure measured in the airway of a piglet, the impedance data of the lungs measured in the posterior and anterior regions, and a graph of the electrical activity of the diaphragm. Ineffective effort is shown in the shaded area 702 of the graph.

[0059] The respiratory effort of an animal can be observed by an increase in the electrical activity of the diaphragm (indicated by arrow 704), accompanied by an increase in airway pressure and a slight increase in the impedance of the dependent regions of the lungs (indicated by arrow 706) at a time corresponding to no airway flow. Therefore, a slight increase in the impedance of the dependent regions during a time period when there is no flow in the airway or no increase in flow or pressure may indicate ineffective effort asynchrony.

[0060] Further non-limiting embodiments of the present disclosure are described below.

[0061] Embodiment 1: In a method for determining a patient's respiratory effort, the method includes obtaining first impedance data corresponding to a first region of the patient's lungs, the first region including at least one dependent region of the lungs, comparing the first impedance data with one or more of second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region of the lungs in the patient's respiratory circuit, flow rate in the respiratory circuit, pressure in the respiratory circuit, past impedance data of the first region, and a stored pattern regarding the impedance data of the first region, and identifying the occurrence of the patient's respiratory effort based on the comparison.

[0062] Embodiment 2: The method according to Embodiment 1, wherein the step of obtaining first impedance data corresponding to a first region of the patient's lungs includes obtaining first impedance data of only the dependent regions of the lungs.

[0063] Embodiment 3: The step of obtaining the first impedance data corresponding to the first region of the patient's lung includes the step of obtaining the first impedance data while the patient is operably communicating with a ventilator, according to the method described in Embodiment 1 or Embodiment 2.

[0064] Embodiment 4: The step of comparing the first impedance data includes the step of comparing the first impedance data with the past impedance data of the first region, according to the method described in any one of Embodiments 1 to 3.

[0065] Embodiment 5: The step of comparing the first impedance data with one or more of the second impedance data corresponding to the second region of the patient's lung including at least one non-dependent region of the lung of the patient, the past impedance data of the first region, and the stored pattern regarding the impedance data of the first region includes the step of comparing the first impedance data with each of the second impedance data, the flow rate, and the pressure over the same period, according to the method described in any one of Embodiments 1 to 4.

[0066] Embodiment 6: The step of comparing the impedance data with one or more of the second impedance data corresponding to the second region of the patient's lung including at least one non-dependent region of the lung of the patient, the past impedance data of the first region, and the stored pattern regarding the impedance data of the first region includes the step of determining the ineffective effort of the patient, according to the method described in any one of Embodiments 1 to 5.

[0067] Embodiment 7: The step of obtaining the first impedance data corresponding to the first region of the patient's lung includes the step of obtaining the first impedance data corresponding to the dependent region and the non-dependent region of the lung, according to the method described in any one of Embodiments 1 to 6.

[0068] Embodiment 8: The method according to any one of Embodiments 1 to 7, wherein the step of obtaining the first impedance data corresponding to the first region of the lung of the patient includes the step of obtaining an EIT pre - plethysmograph of the first region of the lung.

[0069] Embodiment 9: The method according to any one of Embodiments 1 to 8, further including the step of determining the asynchrony between the patient and the ventilator in response to measuring an increase in the first impedance without increasing the pressure or the flow rate in the breathing circuit.

[0070] Embodiment 10: The method according to any one of Embodiments 1 to 9, further including the step of determining the asynchrony between the patient and the ventilator in response to measuring an increase in the first impedance without a corresponding increase in the second impedance.

[0071] Embodiment 11: The method according to any one of Embodiments 1 to 10, wherein the step of comparing the first impedance data with one or more of the second impedance data corresponding to a second region of the lung of the patient including at least one non - dependent region of the lung of the patient, the flow rate in the breathing circuit of the patient, the pressure in the breathing circuit, the past impedance data of the first region, and the stored pattern regarding the impedance data of the first region includes the step of determining a reverse trigger event.

[0072] Embodiment 12: In a system for determining a patient's respiratory effort, the system includes an electrical impedance tomography system, at least one processor coupled to the electrical impedance tomography system, and at least one non-transitory computer-readable storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to obtain first impedance data corresponding to at least one dependent region of a patient's lungs by the electrical impedance tomography system, and compare the first impedance data with one or more of the flow rate in the patient's breathing circuit, the pressure in the breathing circuit, second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region, past impedance data of the first region, and a stored pattern of impedance data corresponding to the first region of the lungs, and based on this comparison, identify the respiratory effort. The system includes at least one non-transitory computer-readable storage medium for performing the steps.

[0073] Embodiment 13: The system according to Embodiment 12 further includes at least one gas monitoring sensor operably coupled to the system, and the at least one gas monitoring sensor is configured to measure one or both of the pressure and the flow rate in the breathing circuit.

[0074] Embodiment 14: In the step of identifying the patient's respiratory effort by comparing the first impedance data with one or more of the flow rate in the patient's breathing circuit, the pressure in the breathing circuit, second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region, past impedance data of the first region, and a stored pattern of impedance data corresponding to the first region of the lungs, the system according to Embodiment 12 or Embodiment 13 includes a step of determining the asynchrony between the patient and the ventilator in response to measuring an increase in the first impedance without an increase in one or more of the second impedance, the flow rate, and the pressure in the breathing circuit.

[0075] Embodiment 15: The system according to any one of Embodiments 12 to 14, wherein the command is further configured to cause the at least one processor to initiate a respiratory cycle in response to identifying asynchrony between the patient and the ventilator.

[0076] Embodiment 16: The step of comparing the first impedance data with one or more of a stored pattern of flow rate in the patient's breathing circuit, pressure in the breathing circuit, second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region, past impedance data of the first region, and impedance data corresponding to the first region of the lungs includes comparing the first impedance data with the second impedance data in response to determining an increase in the first impedance without a corresponding increase in one or both of the pressure and the flow rate in the breathing circuit. The system according to any one of Embodiments 12 to 15.

[0077] Embodiment 17: The step of obtaining, by the electrical impedance tomography system, first impedance data corresponding to at least one dependent region of a patient's lungs includes obtaining the first impedance data only for the dependent regions of the lungs. The system according to any one of Embodiments 12 to 16.

[0078] Embodiment 18: The step of comparing the first impedance data with one or more of a stored pattern of flow rate in the patient's breathing circuit, pressure in the breathing circuit, second impedance data corresponding to a second region of the patient's lungs including at least one non-dependent region, past impedance data of the first region, and impedance data corresponding to the first region of the lungs includes comparing the first impedance data with each of the flow rate in the breathing circuit, the pressure in the breathing circuit, the second impedance data, and the past impedance data of the first region. The system according to any one of Embodiments 12 to 17.

[0079] Embodiment 19: In a system for determining a patient's respiratory effort, the system includes an electrical impedance tomography system and a controller, the electrical impedance tomography system being operably coupled to the controller, the controller including at least one processor and at least one non-transitory computer-readable storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to cause the electrical impedance tomography system to obtain first impedance data for a first region of the patient's lungs, the first region including a dependent region of the lungs; compare the first impedance data with one or more of second impedance data corresponding to a non-dependent region of the patient's lungs, a flow rate within the patient's breathing circuit, a pressure within the breathing circuit, past impedance data for the first region, and a stored pattern for the impedance data of the first region; and based on the comparison, identify the patient's respiratory effort.

[0080] Embodiment 20: The system according to Embodiment 19, further comprising a ventilator in communication with the patient and operably coupled to the controller, the ventilator being configured to provide a breathing cycle to the patient in response to identifying the patient's respiratory effort.

[0081] Embodiments of the present disclosure may be subject to various modifications and alternative forms, and specific embodiments have been shown by way of example in the drawings and detailed herein. However, it should be understood that the present disclosure is not limited to the particular forms disclosed. Rather, the present disclosure encompasses all modifications, variations, combinations, and alternatives falling within the scope of the present disclosure as defined by the following appended claims and their legal equivalents.

Claims

1. In a method for a system to determine a patient's respiratory effort, the method comprises: a step of an electrical impedance tomography system non-invasively acquiring first impedance data of a first region of a patient's lung, wherein the first region includes at least one posterior region of the lung; comparing, via a processor, an increase or decrease in the first impedance data with an increase or decrease in one or more of: a flow rate within the patient's breathing circuit, a pressure within the breathing circuit, second impedance data of a second region of the patient's lung including at least one anterior region of the patient's lung, wherein the first region is not completely included in the second region, second impedance data of the second region of the patient's lung, impedance data of the first region during a past normal breathing cycle, and impedance data of the first region during a futile effort cycle; identifying, via the processor, an occurrence of the patient's respiratory effort based on the comparison; and determining, via the processor, whether the patient's respiratory effort is futile.

2. The method according to claim 1, wherein the step of acquiring the first impedance data of the first region of the patient's lung comprises acquiring the first impedance data of only the posterior region of the lung.

3. The method according to claim 1, wherein the step of acquiring the first impedance data of the first region of the patient's lung comprises acquiring the first impedance data while the patient is operably communicating with a ventilator.

4. Via the processor, comparing an increase or decrease in the first impedance data with second impedance data of a second region of the patient's lungs including at least one anterior region of the patient's lungs, the flow rate in the patient's breathing circuit, the pressure in the breathing circuit, the increase or decrease in the first impedance data, the first impedance data of the first region during the past normal breathing cycle, and the first impedance data of the first region during the ineffective effort cycle, the first region not being completely included in the second region, the method comprising, via the processor, comparing the first impedance data with each of the second impedance data, the flow rate, and the pressure over the same period, according to claim 1.

5. Comparing an increase or decrease in the impedance data with second impedance data of a second region of the patient's lungs including at least one anterior region of the patient's lungs, the flow rate in the patient's breathing circuit, the pressure in the breathing circuit, the increase or decrease in the first impedance data, the first impedance data of the first region during the past normal breathing cycle, and the first impedance data of the first region during the ineffective effort cycle, the first region not being completely included in the second region, the method comprising determining an ineffective effort of the patient, according to claim 1.

6. The step of obtaining first impedance data of a first region of the patient's lungs includes obtaining first impedance data of the posterior region and the anterior region of the lungs, according to claim 1.

7. The step of obtaining first impedance data of a first region of the patient's lungs includes obtaining an EIT plethysmograph of the first region of the lungs, according to claim 1.

8. The method according to claim 1 further includes determining asynchrony between the patient and the ventilator in response to measuring an increase in the first impedance data without increasing the pressure or the flow rate in the breathing circuit.

9. The method of claim 1, further comprising determining asynchrony between the patient and the ventilator in response to measuring an increase in the first impedance data without a corresponding increase in the second impedance data.

10. The step of comparing an increase or decrease in the first impedance data with one or more of an increase or decrease in the second impedance data of a second region of the patient's lungs including at least one anterior region of the patient's lungs within the breathing circuit, the pressure within the breathing circuit, the flow rate within the breathing circuit, the impedance data of the first region of the patient's lungs during the past normal breathing cycle, and the impedance data of the first region during the ineffective effort cycle, which step includes determining a reverse trigger event.

11. In a system for determining a patient's respiratory effort, the system comprises: an electrical impedance tomography system; at least one processor coupled to the electrical impedance tomography system; at least one non-transitory computer-readable storage medium storing instructions which, when executed by the at least one processor, cause the at least one processor to: non-invasively acquire first impedance data of a first region of the patient's lungs including at least one posterior region of the patient's lungs by the electrical impedance tomography system; receive a flow rate from within the patient's breathing circuit and a pressure from within the breathing circuit; Increasing or decreasing the first impedance data is compared with the second impedance data of a second region of the patient's lungs including at least one anterior region of the patient's lungs, the first region not being completely included in the second region, the second impedance data of the second region of the patient's lungs, the impedance data of the first region during past normal breathing cycles, and one or more increases or decreases in the impedance data of the first region during ineffective effort cycles, and based on the comparison, identifying the patient's breathing effort and determining whether the patient's breathing effort is ineffective, and at least one non-transitory computer-readable storage medium for causing the steps to be performed, and a system including the same.

12. The system further includes at least one gas monitoring sensor operably coupled to the system, the at least one gas monitoring sensor being configured to measure one or both of the pressure and the flow rate in the breathing circuit. The system according to claim 11.

13. The step of identifying the patient's breathing effort by comparing an increase or decrease in the first impedance data with the second impedance data of a second region of the patient's lungs including at least one anterior region of the patient's lungs, the first region not being completely included in the second region, the second impedance data of the second region of the patient's lungs, the impedance data of the first region during past normal breathing cycles, and one or more increases or decreases in the impedance data of the first region during ineffective effort cycles includes determining the asynchrony between the patient and the ventilator in response to measuring the increase in the first impedance data without an increase corresponding to one or more of the second impedance data, the flow rate, and the pressure in the breathing circuit. The system according to claim 11.

14. The system according to claim 11, wherein the instructions are further configured to cause the at least one processor to initiate a breathing cycle in response to identifying the asynchrony between the patient and the ventilator.

15. The step of comparing the first impedance data with one or more of the second impedance data of a second region of the patient's lungs including at least one anterior region, the second impedance data of a second region of the patient's lungs where the first region is not completely included in the second region, the impedance data of the first region during the past normal breathing cycle, and the impedance data of the first region during the ineffective effort cycle, the flow rate in the breathing circuit of the patient, the pressure in the breathing circuit, comprises comparing the first impedance data with the second impedance data in response to determining the increase in the first impedance data without a corresponding increase in one or both of the pressure and the flow rate in the breathing circuit. The system according to claim 11.

16. The step of obtaining, by the electrical impedance tomography system, first impedance data of at least one posterior region of a patient's lungs comprises obtaining the first impedance data of only the posterior region of the lungs. The system according to claim 11.

17. The step of comparing an increase or decrease in the first impedance data with an increase or decrease in one or more of the second impedance data of a second region of the patient's lungs including at least one anterior region, the second impedance data of a second region of the patient's lungs where the first region is not completely included in the second region, the impedance data of the first region during the past normal breathing cycle, and the impedance data of the first region during the ineffective effort cycle, the flow rate in the breathing circuit of the patient, the pressure in the breathing circuit, comprises comparing the first impedance data with each of the flow rate in the breathing circuit, the pressure in the breathing circuit, the second impedance data, and the impedance data of the first region during the past normal breathing cycle. The system according to claim 11.

18. In a system for determining a patient's breathing effort, the system comprises an electrical impedance tomography system, and a controller, wherein the electrical impedance tomography system is operably coupled to the controller, and the controller at least one processor, and at least one non-transitory computer-readable storage medium storing instructions that, when executed by the at least one processor, cause the at least one processor to non-invasively obtain first impedance data of a first region of the patient's lungs for the electrical impedance tomography system, the first region including a posterior region of the lungs; receive a flow rate from within the patient's breathing circuit and a pressure from within the breathing circuit; compare an increase or decrease in the first impedance data with second impedance data of a second region of the patient's lungs including at least one anterior region of the patient's lungs, where the first region is not completely included in the second region, the flow rate within the patient's breathing circuit, the pressure within the breathing circuit, the impedance data of the first region during past normal breathing cycles, and one or more increases or decreases in the impedance data of the first region during ineffective effort cycles; determine the patient's breathing effort based on the comparison and determine whether the patient's breathing effort is ineffective; a system comprising at least one non-transitory computer-readable storage medium for causing the steps to be executed. **Claim 19** The system according to claim 18, further comprising a ventilator in communication with the patient and operably coupled to the controller, the ventilator configured to provide a breathing cycle to the patient in response to identifying the patient's breathing effort.

Images