Method for identifying the location of a stimulator and a field generator - Patents.com

Abstract

The stimulation device (10) comprises a field generator (21) configured to generate a spatial field and a control unit (3) in communication with the field generator. The field generator (21) is configured to be positioned on a human or animal patient (5) such that muscle structures of the patient (5) are activatable by the spatial field. The control unit (3) is configured to control the field generator (21) to generate the spatial field. The control unit (3) is configured to operate the field generator (21) to generate a positioning field having increasing strength.

Description

[Technical field]

[0001] The present invention relates to a stimulation device according to the preamble of independent claim 1 and more particularly to a method for identifying the position of a field generator.

[0002] Such a stimulator having a field generator configured to generate a spatial field and a control unit configured to communicate with and control the field generator to generate the spatial field may be used to be positioned on a human or animal patient to stimulate musculature of the patient with the spatial field, for example, such a stimulator may be used to stimulate suction musculature such as the diaphragm via the phrenic nerve to provide artificial ventilation to the patient. [Background technology]

[0003] In medicine, it is known that for many purposes it is beneficial to activate target tissues in a patient. Such activation may be aimed at therapeutic purposes, where muscle structures are typically activated to achieve an intended therapeutic effect.

[0004] For example, in hospital critical care units, it may be desirable to activate the diaphragm of patients undergoing mechanical ventilation to prevent the drawbacks of disuse of the diaphragm. It has been shown that disuse atrophy of diaphragm muscle fibers occurs already during the first 18-69 hours of mechanical ventilation, and that muscle fiber cross-sectional area decreases by more than 50% during this time. Therefore, it is aimed to activate the diaphragm repeatedly while the patient is undergoing artificial or mechanical ventilation, so that the function of the diaphragm can be maintained, or at least during the weaning period to support the effective recovery of independent respiratory function.

[0005] As another example, in a hospital or other care unit, it may be desirable to provide artificial ventilation to a patient during a therapeutic procedure. Traditionally, such artificial ventilation is provided by mechanically forcing air under positive pressure into the patient's respiratory system. Alternatively, it is known to activate the patient's respiratory musculature to move (pump) air into the lungs by negative pressure.

[0006] To achieve such activation of tissues, particularly muscle structures, within a patient's body, it is known to directly stimulate the tissue or to indirectly activate the tissue through stimulation of certain parts of the nervous system. For example, a target tissue that is muscle tissue can be activated by providing an electrical pulse directly to the tissue or to a nerve associated with the tissue. More specifically, it is known that the diaphragm can be activated by stimulating the phrenic nerve, for example in the patient's neck.

[0007] In this regard, US Patent Application Publication No. 2016 / 0310730 describes an apparatus for reducing ventilation-induced diaphragm disuse in patients receiving artificial respiratory support from a mechanical ventilator (MV). The apparatus includes first and second types of electrode arrays with a plurality of electrodes configured to stimulate the patient's phrenic nerve, and at least one controller for identifying the type of electrode array from at least two different types and generating a stimulation signal for stimulating the patient's phrenic nerve based on the identification of the electrode type. Such electrode-based stimulation is less robust to patient movement and repositioning, and the possible stimulation depth may be significantly limited by bone and fatty tissue. Furthermore, electrode stimulation has been reported to be more painful for patients than electromagnetic stimulation.

[0008] WO 2019 / 154837 also describes an electromagnetic induction device for stimulating a patient's phrenic nerve by a spatial electromagnetic field applied to the patient's neck. The device comprises an electromagnetic field generator having a coil design configured to generate an electromagnetic field in a target shape. The device further comprises a sensor member configured to detect activation of a target tissue and an electromagnetic field adjustment mechanism configured to automatically adjust the position of the electromagnetic field generated by the coil design. To find a suitable position of the electromagnetic field generator such that the phrenic nerve can be effectively stimulated, the device is equipped with a calibration unit in communication with the sensor member and the electromagnetic field adjustment mechanism. The calibration unit of the electromagnetic induction device according to the invention is configured to automatically change the position of the electromagnetic field generated by the coil design and to automatically stop changing the position of the electromagnetic field generated by the coil design when an activation feedback signal is received from the sensor member.

[0009] Although the known devices allow efficient and convenient positioning of the electromagnetic field generator, they have the drawback of requiring a relatively complex structure for automatically varying the electromagnetic field, and the application of the electromagnetic field to position the electromagnetic field generator may have effects on the patient.

[0010] For example, it is known to use different impulse train formats such as "single twitch" or "continuous stimulation" or "ramp followed by plateau" to stimulate the diaphragm in order to identify diaphragm activity.

[0011] However, the single impulses (twitches) appear suddenly and cause discomfort to the patient, especially when combined with other stimulation techniques based on electrical stimulation as well as electromagnetic fields, as single twitches are short, unexpected impulses that cause the patient a "touching an electric fence" sensation, especially when higher stimulation intensities are required.

[0012] Stimulation at a simple plateau, i.e., the "set point" of the electric / electromagnetic field magnitude, produces a tetanic diaphragm contraction, but using such a "set point" produces a "sudden" sensation, just as the sudden and unexpected application of an impulse at high intensity is unpleasant for the patient.

[0013] A gradually increasing train that reaches a plateau and keeps the magnetic field at the set level for a relatively long time may have an undesirable impact on the ventilator frequency, breathing rate, may lead to irregularities in the breathing pattern, or may trigger the ventilator in an undesirable time window, may be incompatible with all ventilator modes, and plateau-shaped rectangular trains at the "set value" must be precisely synchronized to the ventilator and / or patient's inspiration time window, and tetanic diaphragm contractions generate significant tidal volumes, significant flow. If applied too frequently in an undesirable time window of the breathing pattern (e.g., too late in inspiration or too early in expiration), the breathing pattern of the patient or ventilator may be undesirably affected, asynchrony may occur, and patient discomfort may result.

[0014] Furthermore, typical stimulation patterns with plateaus and stimulation above threshold take too much time: at the fastest such stimulation patterns are only possible synchronously with each inspiration, and time is lost finding the correct position of the stimulation applicator (coil or electrode).

[0015] Also, plateau-shaped rectangular trains at the "set point", and even plateau-shaped rectangular trains supplemented with ramps at the beginning and end, do not generate a distinctive signal and it is extremely difficult to separate such stimulation from natural spontaneous breathing. Such separation / reliable identification of stimulated breathing only works in well-sedated patients without spontaneous breathing, or in spontaneously breathing patients, if every second or third breath is stimulated when a change in the breathing pattern occurs.

[0016] Therefore, there is a need for a relatively simple system that allows for gentle and efficient positioning of field generators to appropriately stimulate or activate muscle structures. Summary of the Invention

[0017] According to the present invention this need is solved by a stimulation device as defined by the features of independent claim 1 and by a method for identifying the position of a field generator in a human or animal patient as defined by the features of independent claim 20. Preferred embodiments are the subject matter of the dependent claims.

[0018] In one aspect, the invention provides a stimulation device comprising a field generator and a control unit, the field generator configured to generate a spatial field and to be positioned on a human or animal patient such that muscle structures of the patient are activatable by the spatial field.

[0019] The control unit is in communication with the field generator and is further configured to control the field generator to generate the spatial field and to operate the field generator to generate a positioning field having increasing strength.

[0020] Unless further or otherwise specified in the context of an embodiment or aspect of the invention, the following definitions and explanations apply to all embodiments and aspects of the invention.

[0021] The patient's musculature may be a single muscle or a group of muscles of the patient. Advantageously, the musculature includes inspiratory musculature such as the patient's diaphragm, the patient's external intercostal muscles, the patient's accessory inspiratory muscles, or a combination thereof. By stimulation of any of these musculature or even a combination thereof, aspiration may be effectively induced. In this way, artificial ventilation of the patient may be assisted or induced.

[0022] As used herein, the term "position" refers to location and orientation. Changing the position of an element includes either relocating the element, reorienting the element, or a combination thereof. When an element or component is positioned so that it can do something, it is advantageously positioned and oriented to achieve its respective function. For example, a field generator positioned to stimulate the phrenic nerve may refer to being positioned and oriented such that the phrenic nerve is within the spatial field generated by the field generator.

[0023] The terms "positioned on the body" or, equivalently, "held on the body" refer to being positioned and oriented on the body. With respect to the field generator, these terms may refer to being in physical contact with or in close proximity to the patient's body. The location and orientation of the field generator or its components may therefore be predefined or well-defined as appropriate for activating muscle structures. To be configured to be positioned at an appropriate location, the field generator may be formed to suit the respective location. For example, the field generator may be formed corresponding to the patient's neck so that it may be conveniently positioned there, for example to stimulate the phrenic nerve. The field generator may also be equipped with an appropriate mounting structure for being held or fixed at that location.

[0024] Activation of the muscular system may be induced directly or indirectly by the field generator. For example, direct activation may be induced by providing a spatial field to the muscular system or specific muscles thereof such that the muscular system is stimulated by the spatial field. In such a situation, the muscular system is directly stimulated to be activated. Indirect activation may be induced by providing a spatial field to the muscular system or specific parts of the nervous system associated with the muscular system or specific muscles thereof such that the specific parts of the nervous system are stimulated by the spatial field. In such a situation, the muscular system is activated by stimulating the nervous system. In certain exemplary embodiments in which the diaphragm is intended to be activated, for example for artificial ventilation, indirect activation may be induced by positioning the field generator to stimulate one or both phrenic nerves by being placed in the spatial field generated by the field generator.

[0025] The control unit may be wired or wirelessly coupled to other components, such as field generators or sensor units, for communication therewith. In this manner, signals, such as control signals, may be sent to other components for operation or control. Additionally or alternatively, signals, such as sensor signals, may be received by the control unit. For example, such sensor signals may represent sensed dimensions or physical properties, for example for further evaluation.

[0026] The control unit may be any computing entity suitable for performing relevant tasks to control other components and / or to evaluate signals, such as sensed signals. The control unit may be or comprise a laptop computer, a desktop computer, a server computer, a tablet, a smartphone, etc. The term "control unit" encompasses standalone devices, embedded systems, and combined devices. The control unit may be a distributed system, e.g., a cloud solution, performing different tasks at different locations.

[0027] Typically, a control unit or computer includes a processor or central processing unit (CPU), persistent data storage having a recording medium such as a hard disk, flash memory, etc., random access memory (RAM), read only memory (ROM), communication adapters such as a universal serial bus (USB) adapter, a local area network (LAN) adapter, a wireless LAN (WLAN) adapter, a Bluetooth adapter, etc., and physical user interfaces such as a keyboard, mouse, touch screen, screen, microphone, speakers, etc. A control unit or computer may be embodied with a wide range of components.

[0028] The control unit may be embodied partially or completely as a separate entity or as an integrated part of any other device or entity, for example, the control unit may be integrated into a ventilator, such as embodied in a ventilator machine and / or in an induction device used to perform artificial ventilation of a human or animal patient.

[0029] As used herein, the term "spatial field" refers to any field that allows for stimulation of a target tissue in a patient. Spatial fields may include, inter alia, electric or electromagnetic fields. Such spatial fields allow for direct stimulation of muscle structures for activation or indirect activation of muscle structures via stimulation of the nervous system or via other muscle structures.

[0030] The spatial field may be configured to have a target shape. Such a target shape may be achieved, for example, by providing a locally constrained, targeted electric or electromagnetic field having a peak. The spatial field may be adapted to be active in a target region, which may be a nerve region, muscle region or tissue region to be stimulated with the spatial field (e.g., the phrenic nerve to be stimulated), which may be achieved, for example, by a peak (focal region) of the spatial field. The target shape may generally be any shape of the spatial field or its components that allows for effective stimulation of one or more target nerves, muscles, or other tissues, while minimizing other undesirable stimulation side effects of surrounding, upper or neighboring tissues or nerves. A peak shape is such an example, because it maximizes the effect in the focal region and minimizes the effect outside of this focal region.

[0031] To generate the spatial field, the field generator may comprise a coil design, and thus the term "coil design" may be or comprise at least two coils, or at least one conical or otherwise curved or bulging coil, or at least one cylindrical or otherwise non-flat coil, or at least one miniature coil, i.e., a coil small enough to generate a sharp electromagnetic field, such as a coil with a diameter of 3 cm or less.

[0032] The positioning field can be provided with different portions, at least one of which has an increasing intensity or field strength. For example, the positioning field can have a portion with a linearly increasing intensity (ramp) followed by a portion with a constant intensity (plateau). Thus, advantageously, the time width of the plateau is much smaller than the time width of the ramp. Also sinusoidal intensities with increasing and decreasing portions are possible. Such a ramp without plateaus or with a very short plateau allows only to generate characteristic feedback signal changes without generating significant flows that significantly affect the breathing pattern (i.e. flow thresholds below trigger or tidal volume without impact on lung protection / patient comfort).

[0033] The parameters of the voltage or current waveform applied by the generator to the coil design can affect the temporal characteristics of the electromagnetic field, including pulse shape, amplitude, width, polarity, and repetition frequency, the duration of and the interval between bursts or trains of pulses, the total number of pulses, and the interval between stimulation sessions, the total number of sessions in particular having an effect on the field strength and determining whether and with what intensity or "dose" a target region or tissue can be stimulated.

[0034] In the present invention, the control unit is configured to operate the field generator to generate a positioning field with increasing strength, thereby increasing comfort when setting the stimulator for therapeutic stimulation or activation. In particular, it is possible to reduce or minimize the impact on the breathing pattern, save time, simplify the workflow and avoid further risks. More specifically, applying relatively short pulses of a ramp shape of the spatial field allows conveniently identifying a suitable or even optimized position of the field generator. When used in relation to artificial ventilation, such identification of a suitable position of the field generator allows reducing or preventing large flows that may significantly affect the breathing pattern. In particular, the flow threshold can be kept below the trigger or tidal volume without impact on lung protection or patient comfort.

[0035] Preferably, the control unit is configured to operate the field generator to generate the positioning field for a period of less than about 1 second. Such substantial provision of the positioning field allows for identification of responses caused by the positioning field, while at the same time preventing or minimizing further responses of muscle structures that may upset the patient or produce undesirable effects.

[0036] Preferably, the control unit is configured to operate the field generator to generate a positioning field having characteristic properties. Such characteristic properties may be or include predefined variations in field strength or field shape. By providing a positioning field having a particular property or predefined pattern, it is possible to efficiently identify feedback or reaction of muscle structures that correlate to the positioning field. Thus, an expected time of feedback or reaction may be further included to allow accurate correlation of feedback or reaction to the provision of the positioning field. Also, the correlation between the positioning field pattern and the feedback pattern may be a measure to characterize the properness of the position of the field generator.

[0037] Preferably, the stimulation device comprises a sensor unit in communication with the control unit, the sensor unit configured to be positioned on the patient to sense feedback from the patient's muscle structure and to provide a feedback signal representative of the sensed feedback, and the control unit configured to obtain the feedback signal from the sensor unit.

[0038] As with the field generator, the term "positioned at" when used with respect to the sensor unit may refer to the sensor unit, or a portion thereof, being in physical contact with or away from the patient's body. It may also include, for example, being at least partially disposed within the body, such as within the oral cavity. To be configured to be positioned at a suitable location, the sensor unit may be formed to conform to the location. The sensor unit may also be equipped with a suitable mounting structure for being secured to the location.

[0039] As used herein, the term "sensing feedback from the muscular system" refers to any feedback signal that allows for identifying activation of the muscular system. In particular, such feedback may be feedback identified directly in or from the muscular system, such as, for example, the contraction of one or more muscles of the muscular system. Also, such feedback may be feedback indirectly related to activation of the muscular system. For example, the feedback may be feedback of the patient's respiratory system. More specifically, with respect to activation of aspiration musculature, such as activation of the diaphragm by being stimulated either directly by a field generator or indirectly via stimulation of the phrenic nerve, the feedback may be flow sensed at the patient's mouth or elsewhere in the respiratory system.

[0040] The sensor unit may comprise a single sensor or a group of sensors. For artificial ventilation, the sensor unit may comprise an airway pressure or flow sensor, and the feedback signal may have an airway pressure or flow component. Alternatively or additionally, the sensor unit may comprise an esophageal pressure sensor, and the feedback signal has an esophageal pressure component. Also alternatively or additionally, the sensor unit may comprise a belt, for example an abdominal belt, for sensing the movement of muscle structures, such as the expansion and / or retraction of the diaphragm. Still alternatively or additionally, the sensor unit may comprise electrodes configured to determine the activity of muscle structures, and the feedback signal has an electrode component. Other possible sensors may be an electromyogram (EMG) sensor, an esophageal catheter, or an accelerometer. In addition to the one or more sensors, the sensor unit may further comprise other means, such as a communication adapter, a mounting device, or a similar structure.

[0041] Providing a feedback signal by a sensor unit may include forwarding the feedback signal to a target such as a control unit (push), or allowing the feedback signal to be collected or aggregated by the control unit (pull). Similarly, obtaining a feedback signal by a control unit may be receiving a feedback signal forwarded by the sensor unit, or collecting or aggregating feedback signals from the sensor unit.

[0042] Preferably, the control unit is configured to identify in the acquired feedback signal a characteristic feedback from the patient's musculature induced by a characteristic property of the positioning field, such that by such identification of the characteristic feedback the feedback can be efficiently correlated to the positioning field.

[0043] With respect to the sensor unit, the control unit is preferably configured to store the acquired feedback signals. To be configured to store the acquired feedback signals, the control unit may be equipped with any suitable volatile or permanent data storage structure, such as a hard disk, a memory chip, a RAM, any combination thereof, etc. Alternatively or additionally, the control unit may be connected to an external data storage. Such storage of the feedback signals can conveniently make multiple feedback signals available for evaluation. For example, feedback signals induced by applying a field generator to different locations can be compared and the position giving the most suitable feedback signal can be selected for treatment. In this way, the suitable or best position can be found particularly efficiently in a (semi-)automatic manner. Thus, the control unit is preferably configured to compare the stored feedback signals and select one of the stored feedback signals.

[0044] The control unit is preferably configured to compare the feedback signal strengths of the stored feedback signals when selecting one of the stored feedback signals. In this way, a position that provides a particularly suitable feedback can be selected. In particular, the control unit is preferably configured to select one of the stored feedback signals that has the highest feedback signal strength. The position of the field generator in the patient that is associated with the feedback signal that has the highest feedback signal strength may be identified as the position with the highest stimulation efficiency. This position may therefore be considered as the best position evaluated so that the field generator can be efficiently placed in the best position.

[0045] The control unit is preferably configured to predefine a target feedback signal strength and / or a target feedback signal characteristic, to determine a response time for each of the stored feedback signals, the response time being the time from start of generation of the positioning field to reaching the target feedback signal strength and / or the target feedback signal characteristic, and to compare the determined response times when selecting one of the stored feedback signals. By such configuration, the response times of different positions of the field generator can be included when choosing a suitable position for the field generator.

[0046] Specifically, the control unit is preferably configured to select one of the stored feedback signals that has the shortest response time. This may be performed efficiently, especially in combination with increasing strength of the positioning field. The position of the field generator in the patient associated with the feedback signal that has the shortest response time may be the position with the highest stimulation efficiency. This position may therefore be the best position evaluated so that the field generator can be efficiently placed in the best position.

[0047] Also, the control unit is preferably configured to stop operation of the field generator for generating the positioning field when a predefined target feedback signal strength and / or target feedback signal characteristic is achieved. In this way, activation of muscle structures may be stopped or prevented after feedback is received. Thus, unnecessary or over-activation or associated discomfort may be prevented or reduced.

[0048] Preferably, the positioning field has a linearly increasing intensity, which allows for adapting the patient's sensitivity to the stimulation so that higher intensities can be applied without unduly affecting the patient.

[0049] Preferably, the control unit is configured to operate the field generator to generate the positioning field during an end-expiratory window of the patient's respiratory cycle, which is typically the section of the respiratory cycle where flow is close to zero or pressure is constant. Such generation of the positioning field allows efficient identification of feedback from the patient, particularly when using airway flow or pressure sensors.

[0050] Preferably, the positioning field has a first portion having an increasing intensity and a second portion having a decreasing or constant intensity, the first portion of the positioning field having a first temporal width and the second portion of the positioning field having a second temporal width that is significantly smaller than the first temporal width. Such a ramp stimulation signal allows for comfortable stimulation.

[0051] Therefore, the first duration is preferably at least four times the second duration, advantageously at least eight times the second duration, and more advantageously at least 15 times the second duration.

[0052] Alternatively, the second time span is preferably about 0 seconds. In this manner, an abrupt termination of the application of the positioning field, and thus the activation of the muscle structures, can be achieved.

[0053] Preferably, the positioning field is a field train, which may be generated sequentially or, preferably, as a series of pulses following each other relatively quickly, such that such a train may achieve stimulation of a nerve or muscle such that tetanus or activation is induced.

[0054] Advantageously, the trains are provided by increasing the intensity (field strength) and / or frequency until a target intensity or frequency is achieved (ramp protocol). In this way, sudden cramps or discomfort can be reduced or minimized. All of these parameters are grouped under the term "temporal characteristics" or "temporal parameters" of the spatial field. These temporal parameters can be adjusted manually via an input interface or automatically controlled by an adjustment mechanism or control unit.

[0055] Parameters of the voltage or current waveform applied to generate the spatial field can affect the temporal characteristics of the spatial field, including pulse shape, amplitude, width, polarity, and repetition frequency, the duration of and the interval between bursts or trains of pulses, the total number of pulses, and the interval between stimulation sessions, the total number of sessions in particular having an effect on the strength of the field and determining whether and with what intensity or "dose" a target region or tissue can be stimulated.

[0056] The temporal characteristics and spatial distribution of the spatial field may be adjusted in such a way that a desired activation of muscle structures (activation feedback) is achieved. Thus, activation feedback (signal) may refer to a signal that indicates appropriate characteristics of muscle structure activation, such as a signal that reaches or exceeds a target value (threshold), a signal that exhibits a certain curved pattern or shape, a signal that implements a certain algorithm known to represent appropriate target muscle structure activation at a desired intensity, or any combination thereof. Activation feedback (signal) may include, among other things, feedback regarding the desired muscle structure activation intensity to be reached before the adjustment mechanism stops the change. Appropriate activation feedback signal characteristics may be defined by a user, for example, via an input interface, or detected by an algorithm.

[0057] Thus, the field train preferably includes a sequence of pulses of the spatial field. The term "pulse" with respect to the spatial field refers to multiple pulses of the spatial field generation over a relatively short time period with a relatively short break between two successive pulses. In contrast, a single pulse refers to the spatial field generation over a relatively short time period with a relatively long break between two successive pulses. Typically, the single pulses are provided at a frequency lower than 10 Hertz (Hz), such as 5 Hz or less, or the single pulses are initiated by the user or physician. The pulses of the field train may have a time width of about 10 microseconds (μs) to about 300 μs. Such pulses can activate nerves and muscle structures and are identifiable by the patient or by a sensor. In particular, such single pulses can cause a single twitch of a muscle or muscle structure.

[0058] Therefore, the sequence of pulses preferably includes frequencies in the range of about 15 Hz to about 30 Hz, such frequencies making it possible to achieve a certain degree of continuous perception of the sequence.

[0059] Preferably, the control unit is configured to operate the field generator to generate a regular stimulation field for therapeutically activating the patient's musculature, the maximum intensity of the positioning field being about 40% of the maximum intensity of the regular stimulation field, advantageously about 30% of the maximum intensity of the regular stimulation field, or more advantageously about 20% of the maximum intensity of the regular stimulation field. The therapeutic activation of the musculature may be any targeted or objective activation of musculature via direct or indirect stimulation. For example, it may be activation of suction musculature to induce or assist respiration.

[0060] By making the strength of the positioning field essentially below the strength of the regular stimulation field, the induction of therapeutic or other perceptible effects when positioning the field generator can be prevented or limited. In particular, the positioning field can be made large enough to just allow the feedback signal to be sensed but not to initiate any significant therapeutic effect. For example, with respect to artificial ventilation, the positioning field can be made large enough so that no artificial ventilation of the artificial ventilation cycle is induced but the suction musculature is activated just enough to generate a feedback signal.

[0061] Therefore, the positioning field preferably has characteristics that are different from those of the regular stimulation field. Besides intensity, the characteristics may include the change or progression of the intensity, the temporal occurrence, the time width, etc. By having certain characteristics, the positioning field can be efficiently identified and differentiated from the regular stimulation field.

[0062] Preferably, the stimulation device comprises a user interface having a trigger in communication with a control unit, the control unit being configured to operate the field generator to generate the positioning field upon activation of the trigger. The trigger may be implemented as a physical switch or button, or as a graphical representation on a touch-sensitive screen. Such a trigger allows for manual activation of the positioning field. In this way, the physician may provide the positioning field and check the feedback in real time.

[0063] In another aspect, the invention is a method for identifying a location of a field generator in a human or animal patient for activating musculature of the patient with a spatial field generated by the field generator, the method comprising the steps of (i) placing the field generator in the patient, (ii) operating the field generator by increasing the intensity of the spatial field, (iii) identifying feedback of the patient's musculature, and (iv) defining a location of the field generator in the patient based on the identified feedback of the musculature.

[0064] The method according to the invention and the preferred embodiments thereof described below make it possible to achieve the effects and benefits of the stimulation device and its preferred embodiments described above.

[0065] Muscle feedback may be identified by the practitioner by observing the patient and recognizing the responses associated with operation of the field generator. Preferably, identifying the patient's muscular feedback includes sensing the feedback of the musculature. Such sensing allows the feedback to be accurately recognized and magnitude as required.

[0066] Preferably, the field generator is operated such that feedback of the patient's musculature lasts for less than about 0.5 seconds, preferably less than about 0.2 seconds, such a relatively short stimulus may be sufficient for efficient positioning.

[0067] The method preferably includes a step of comparing a plurality of feedbacks of the muscular system, each obtained from different positions of the field generator on the patient, and defining a position of the field generator on the patient includes identifying one of the plurality of feedbacks of the muscular system as a suitable feedback. Such comparison and identification allows for efficient selection of a particularly suitable position. Thus, defining a position of the field generator on the patient preferably includes selecting a position associated with the suitable feedback.

[0068] Preferably, comparing the multiple feedbacks of the muscular system includes comparing strengths of the feedbacks of the muscular system, and identifying one of the multiple feedbacks of the muscular system as a suitable feedback includes selecting the feedback having the highest strength. The maximum strength of the feedback may indicate stimulation efficiency. Thus, choosing the location that induces the highest feedback strength may achieve efficient identification of the most or most suitable location of the field generator.

[0069] Alternatively or additionally, the method preferably includes the steps of predefining a target feedback strength, determining a response time for each of the multiple feedbacks, which is the time from the start of generating the positioning field to the arrival of the target feedback strength, and comparing the determined response times when identifying one of the multiple feedbacks of the muscular system as a suitable feedback. The time to achieve a certain feedback strength may also indicate stimulation efficiency.

[0070] Specifically, the method preferably includes the step of selecting one of the muscular feedbacks that has the shortest response time, and thus choosing the location that induces the shortest response time may achieve efficient identification of the most or most suitable location of the field generator.

[0071] The method preferably includes the step of ceasing operation of the field generator for generating the positioning field when a predefined target feedback is achieved, in this way unnecessary stimulation to find a suitable position of the field generator can be prevented.

[0072] Preferably, the positioning field has a linearly increasing strength.

[0073] Preferably, the positioning field has a first portion having an increasing intensity and a second portion having a decreasing intensity, the first portion of the positioning field having a first temporal width and the second portion of the positioning field having a second temporal width that is significantly smaller than the first temporal width.

[0074] Therefore, the first duration is preferably at least four times the second duration, advantageously at least eight times the second duration, and more advantageously at least 15 times the second duration.

[0075] Alternatively, the second time span is preferably about 0 seconds.

[0076] Preferably, the positioning field is a field train, whereby the field train preferably comprises a series of pulses of the spatial field, the series of pulses preferably comprising a frequency in the range of about 15 Hz to about 30 Hz.

[0077] Preferably, the maximum intensity of the positioning field is about 40% of the maximum intensity of the regular stimulation field, advantageously about 30% of the maximum intensity of the regular stimulation field, or more advantageously about 20% of the maximum intensity of the regular stimulation field, the regular stimulation field being configured to therapeutically activate the patient's muscle structures.

[0078] Therefore, the positioning field preferably has properties which differ from those of the regular stimulation field.

[0079] Preferably, the method includes the step of manually triggering the field generator to generate the positioning field.

[0080] Preferably, when the field generator is operated, the patient's nervous system, and preferably the patient's phrenic or respiratory nerves, are stimulated. Such stimulation allows for convenient indirect activation of the patient's musculature.

[0081] Preferably, the field generator is operative to generate a positioning field having characteristic properties, such that identifying feedback of the patient's musculature preferably includes identifying activity of the musculature that correlates with the characteristic properties of the positioning field, such that the characteristic properties of the positioning field, such as predefined varying strengths, generally allow efficient and reliable identification of feedback correlated to the field.

[0082] Preferably, feedback of the patient's musculature is identified by sensing flow and / or pressure, in particular the flow or pressure may be the patient's airway flow or airway pressure, such that the field generator is preferably operated during the end-expiratory window of the patient's respiratory cycle.

[0083] Preferably, the method is carried out using a stimulation device as described above. In this way, the method can be efficiently performed, for example in a fully or partially automated manner.

[0084] The stimulation device according to the invention and the method according to the invention are described in detail below by means of exemplary embodiments and with reference to the accompanying drawings, in which: FIG. [Brief description of the drawings]

[0085] [Figure 1] FIG. 2 is a schematic diagram of an embodiment of a stimulation device according to the invention for implementing an embodiment of a method according to the invention. [Diagram 2] 2 is a graph of field and feedback strength for a first mode of finding a suitable position for the field generator of the stimulator of FIG. 1; [Diagram 3] 2 is a graph of field and feedback strength for a second mode of finding a suitable position for the field generator of the stimulator of FIG. 1 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0086] In the following description, some terms may be used for convenience but are not intended to limit the invention. The terms "right", "left", "top", "bottom", "lower" and "upper" refer to directions in the figures. The terminology includes terms explicitly mentioned and their derivatives as well as terms with similar meanings. Spatial terms such as "lower", "lower", "lower", "upper", "proximal", "distal" and the like may also be used to describe the relationship of an element or feature shown in the figures to other elements or features. These spatial terms are intended to encompass different positions and orientations of the device in use or operation in addition to the positions and orientations shown in the figures. For example, if the device in the figures is turned over, an element described as "lower" or "lower" of the other element or feature will be "above" or "on" the other element or feature. Thus, the exemplary term "lower" may encompass both upper and lower positions and orientations. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptions used herein will be interpreted accordingly. Similarly, descriptions of movement along and about various axes include various particular device positions and orientations.

[0087] To avoid repetition in the figures and the description of the various aspects and exemplary embodiments, it should be understood that many features are common to many aspects and embodiments. The omission of an aspect from the description and figures does not imply that the aspect is missing from the embodiment incorporating the aspect. Instead, the aspect may be omitted for clarity and to avoid redundant description. In this context, the following applies to the remainder of the specification: In order to clarify the drawings, if a figure includes a reference sign that is not described in the directly associated part of the specification, reference is made to the previous or subsequent part of the specification. Also, in the case where, for clarity, not all features of a part are given a reference sign in a figure, reference is made to other figures showing the same part. Like numbers in two or more figures represent the same or similar elements.

[0088] 1 shows an artificial ventilation apparatus 1 comprising an artificial ventilation machine 6 and an embodiment of a stimulation device 10 according to the invention. The stimulation device 10 comprises an electromagnetic induction device 2 (hereinafter also called EMI device), a control unit 3 and a sensor unit 4.

[0089] The EMI device 2 comprises an electromagnetic field generator 21 having two coils 211 as a coil design. The coils 211 are located in one common plane and are configured to generate a spatial electromagnetic field. The electromagnetic field has a central target shape with a focal region, in which the electromagnetic field extends to a maximum. The EMI device 2 has a neck arc 221 arranged on the neck 52 of the patient 5 and a mounting device 22 fixed to a bed 51 on which the patient 5 lies. The neck arc 221 is equipped with a joint 222 as a repositioning structure of the EMI device 2. The joint 222 holds the coil 211 on the neck 52 of the patient 5. In operation, the two coils 211 generate an electromagnetic field toward the neck 52 of the patient 5, and due to its target shape, the focal region extends to a maximum in the neck 52.

[0090] The ventilation machine 6 comprises a ventilator 61 as an airflow generator from which a ventilation tube 63 extends, and a mouthpiece 62 as a conduit interface. The mouthpiece 62 is a tube that passes through the patient's mouth and into the respiratory system of the patient 5.

[0091] The sensor unit 4 includes a flow sensor disposed between the mouthpiece 62 and the tube 63, and an abdominal belt as a diaphragm contraction sensor. The control unit 3 is configured to receive a sensor signal provided by the sensor unit 4.

[0092] The control unit 3 has a user interface 31 for exchanging information with a doctor who monitors or sets the mechanically and electromagnetically stimulated artificial ventilation of the patient 5. In particular, the user interface 31 is embodied as a touch screen that allows inputting and outputting information. The control unit 3 is also equipped with a device interface 32 arranged to be coupled by wires 33 to the interface units of the artificial ventilation machine 6, the EMI device 2 and the sensor unit 4. In this way, the control unit 3 communicates with the artificial ventilation machine 6, the EMI device 2 and the sensor unit 4.

[0093] More specifically, the control unit 3 is configured to receive artificial ventilation data regarding the artificial ventilation of the patient 5 from the artificial ventilation machine 6, and control the EMI device 2 to generate an electromagnetic field according to the evaluated artificial ventilation data. Furthermore, the control unit 3 is configured to automatically change the position of the focal region 213 of the electromagnetic field generated by the coil 211 and to manipulate the joint 222 to change the field strength of the electromagnetic field. The purpose of changing the field strength and position of the electromagnetic field 212 is specifically to adjust the electromagnetic field to optimally stimulate the phrenic nerve of the patient 5. After stimulation of the phrenic nerve, the diaphragm as a muscular structure of the patient 5 is activated. Thus, suction is induced.

[0094] The ventilator machine 6 is configured to mechanically ventilate the patient 5 by forcing air through a mouthpiece 62 into the respiratory system of the patient 5. More specifically, the ventilator 61 is configured to deliver air through the mouthpiece 62. The control unit 3 is configured to control the ventilator 61 to deliver air according to a breathing regime defined by the control unit 3. The control unit 3 also governs activation of the diaphragm in coordination with the breathing regime such that activation of the diaphragm via the phrenic nerve is coordinated with mechanical ventilation of the patient 5. In particular, for such therapeutic activation of the diaphragm in coordination with mechanical ventilation, the control unit 3 is configured to operate the field generator 21 such that the coil 211 generates a rhythmic stimulation field. This rhythmic stimulation field stimulates the phrenic nerve which activates the diaphragm.

[0095] In order to be able to provide different treatments during artificial ventilation, the control unit 3 is configured to define combinations of stimulation duration and repetition rate and to operate the EMI device 2 according to the defined stimulation duration and the determined repetition rate. To that end, the control unit 3 offers treatment options to the physician via the user interface 31. The physician chooses the appropriate treatment and sets the associated parameters.

[0096] When setting up the EMI device 2, the field generator 21 and in particular its coil 211 must be appropriately positioned. More specifically, the coil 211 must be placed and oriented so that the electromagnetic field optimally reaches the phrenic nerve. For such positioning of the coil 211, the control unit 3 is configured to operate the EMI device 2 and in particular the field generator 21 to generate positioning fields with increasing strength.

[0097] The positioning field is a field train that includes a series of pulses of an electromagnetic field. Thus, starting from zero intensity, each pulse always has a higher intensity than the previous pulse, such that the field train has a linearly increasing intensity. More specifically, the field train has a first portion with increasing intensity and a second portion with decreasing intensity, the second portion having a time width of 0 seconds. Thus, the positioning field increases in intensity to a maximum intensity and then immediately stops. The maximum intensity of the positioning field is no more than 40%, 30%, or 20% of the maximum intensity of the regular stimulation field.

[0098] The control unit 3 is configured to store as feedback signals the sensor signals received when operating the field generator 21 to generate the positioning field. To find the appropriate position of the coil 211, the control unit 3 is embodied to evaluate the feedback signals in two modes, and the doctor may select on a touch screen the mode to be applied.

[0099] In a first maximum strength mode shown in FIG. 2, the coil 211 is positioned at various different positions on the neck 52 of the patient 5, i.e. in the example of FIG. 2 this is four different positions. The control unit 3 operates the field generator 21 at each of the four positions to provide a positioning field with increasing field strength (I). The control unit 3 also receives and stores feedback signals of all four positions. The control unit 3 then compares the signal strengths of the stored feedback signals and selects one of the stored feedback signals having the highest feedback signal strength. In the example of FIG. 2 this is the feedback signal associated with position 2. The control unit 3 therefore identifies position 2 as the best of the four analyzed positions and provides this information to the doctor.

[0100] In a second shortest response time mode shown in FIG. 3, the coil 211 is also positioned in various different positions on the neck 52 of the patient 5, i.e. in the example of FIG. 3, this is three different positions. The control unit 3 operates the field generator 21 in each of the three positions to provide a positioning field and receives and stores the feedback signals of all three positions. The control unit 3 may also predefine a threshold as a target feedback signal strength, and the doctor may input such threshold via the user interface 31. The control unit 3 then determines a response time, which is the time from the start of the generation of the positioning field to the reaching of the threshold for each of the stored feedback signals. The control unit 3 also compares the determined response times and selects the one of the stored feedback signals with the shortest response time. In the example of FIG. 3, this is the feedback signal associated with position 2. The control unit 3 therefore identifies position 2 as the best of the three analyzed positions and provides this information to the doctor.

[0101] This specification and the accompanying drawings illustrating aspects and embodiments of the present invention should not be construed as limiting the scope of the claims defining the protected invention. In other words, while the present invention has been shown and described in detail in the drawings and above specification, such illustration and description should be considered as explanatory or exemplary and not limiting. Various mechanical, configurational, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present specification and claims. In some cases, well-known circuits, structures, and techniques have not been shown in detail so as not to obscure the invention. Thus, it will be understood that changes and modifications may be made by those skilled in the art within the scope and spirit of the following claims. In particular, the present invention encompasses further embodiments having any combination of features from the different embodiments described above and below. For example, in an advantageous variation of the second shortest response time mode, the control unit stops the operation of the field generator when a threshold value is reached. In this way, the impact on the patient may be reduced.

[0102] The present disclosure also includes all additional features that may not be described above or in the following description, but are individually illustrated in the drawings. Also, individual alternatives of the embodiments and individual alternatives of the features described in the drawings and specification may be waived from the subject matter of the present invention or from the disclosed subject matter. The present disclosure includes subject matter consisting of and including the features defined in the claims or exemplary embodiments.

[0103] Moreover, in the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. A single unit or step may fulfill the functions of several features recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be advantageously used. In particular, terms such as "essentially", "about", "approximately" and the like with respect to an attribute or value also define exactly that attribute or exactly that value, respectively. The term "about" in the context of a given numerical value or range refers to a value or range that is, for example, within 20%, within 10%, within 5%, or within 2% of the given value or range. Components that are described as coupled or connected may be directly coupled electrically or mechanically, or indirectly coupled via one or more intermediate components. Any reference signs in the claims should not be construed as limiting the scope of the technology.

Claims

1. a field generator (21) configured to generate a spatial field; a control unit (3) in communication with said field generator; Equipped with the field generator (21) is configured to be positioned on a human or animal patient (5) such that musculature of the patient (5) is activatable by the spatial field; The control unit (3) is configured to control the field generator (21) to generate the spatial field, A stimulation device (10) characterized in that the control unit (3) is configured to operate the field generator (21) to generate a positioning field having an increasing strength.

2. 2. The stimulation device (10) of claim 1, wherein the control unit (3) is configured to operate the field generator (21) to generate the positioning field for a period of less than about 1 second.

3. 2. The stimulation device (10) of claim 1, wherein the control unit (3) is configured to operate the field generator (21) to generate the positioning field having characteristic properties.

4. a sensor unit (4) in communication with the control unit (3); the sensor unit (4) is configured to be positioned on the patient (5) to sense feedback from the muscle structures of the patient (5) and to provide a feedback signal representative of the sensed feedback; 2. The stimulation device (10) of claim 1, wherein the control unit (3) is configured to obtain the feedback signal from the sensor unit (4).

5. 5. The stimulation device (10) of claim 4, wherein the control unit (3) is configured to identify, in the acquired feedback signal, characteristic feedback from the muscle structures of the patient (5) induced by characteristic properties of the positioning field.

6. 5. The stimulation device (10) of claim 4, wherein the control unit (3) is configured to store the obtained feedback signal.

7. 7. The stimulation device (10) of claim 6, wherein the control unit (3) is configured to compare stored feedback signals and to select one of the stored feedback signals.

8. 8. The stimulation device (10) of claim 7, wherein the control unit (3) is configured to compare feedback signal strengths of the stored feedback signals when selecting one of the stored feedback signals.

9. 9. The stimulation device (10) of claim 8, wherein the control unit (3) is configured to select one of the stored feedback signals having the highest feedback signal strength.

10. 8. The stimulation device of claim 7, wherein the control unit is configured to predefine a target feedback signal strength, determine a response time for each of the stored feedback signals, the response time being the time from the start of generation of the positioning field to the arrival of the target feedback signal strength, and compare the determined response times when selecting one of the stored feedback signals.

11. 8. The stimulation device of claim 7, wherein the control unit is configured to predefine a target feedback signal characteristic, determine a response time for each of the stored feedback signals, the response time being the time from the start of generation of the positioning field to the arrival of the target feedback signal characteristic, and compare the determined response times when selecting one of the stored feedback signals.

12. 11. The stimulation device (10) of claim 10, wherein the control unit (3) is configured to select one of the stored feedback signals that has the shortest response time.

13. 11. The stimulation device (10) of claim 10, wherein the control unit (3) is configured to stop operation of the field generator (21) for generating the positioning field when the predefined target feedback signal strength and / or target feedback signal characteristics are achieved.

14. 5. The stimulation device (10) of claim 4, wherein the sensor unit (4) comprises an airway flow sensor and / or an airway pressure sensor.

15. 15. The stimulation device (10) of claim 14, wherein the control unit (3) is configured to operate the field generator (21) to generate the positioning field during an end-expiratory window of the patient's respiratory cycle.

16. The stimulation device (10) of claim 1, wherein the positioning field has a linearly increasing strength.

17. 2. The stimulation device (10) of claim 1, wherein the positioning field has a first portion having the increasing intensity and a second portion having a decreasing intensity, the first portion of the positioning field having a first duration, and the second portion of the positioning field having a second duration that is significantly smaller than the first duration.

18. 2. The stimulation device (10) of claim 1, wherein the positioning field has a first portion having the increasing intensity and a second portion having a constant intensity, the first portion of the positioning field having a first duration, and the second portion of the positioning field having a second duration that is significantly smaller than the first duration.

19. 18. The stimulation device (10) of claim 17, wherein the first duration is at least four times the second duration, preferably at least eight times the second duration, and more preferably at least 15 times the second duration.

20. 18. The stimulation device (10) of claim 17, wherein the second duration is about 0 seconds.

21. The stimulation device (10) of claim 1, wherein the positioning field is a field array.

22. 22. The stimulation device (10) of claim 21, wherein the field train comprises a series of pulses of the spatial field.

23. 23. The stimulation device (10) of claim 22, wherein the series of pulses includes frequencies in the range of about 15 Hz to about 30 Hz.

24. 2. The stimulation device of claim 1, wherein the control unit is configured to operate the field generator to generate a regular stimulation field to therapeutically activate the muscle structures of the patient, and wherein the maximum intensity of the positioning field is about 40% of the maximum intensity of the regular stimulation field, preferably about 30% of the maximum intensity of the regular stimulation field, or more preferably about 20% of the maximum intensity of the regular stimulation field.

25. 20. The stimulation device (10) of claim 17, wherein the positioning field has characteristics different from those of a regular stimulation field.

26. 2. The stimulation device (10) of claim 1, comprising a user interface having a trigger in communication with the control unit (3), the control unit (3) configured to operate the field generator (21) to generate the positioning field upon activation of the trigger.

27. The stimulation device (10) of claim 1, wherein the field generator comprises a coil and a magnetic stimulator connected to the coil.

28. 1. A method for identifying a position of a field generator (21) in a human or animal patient (5) for activating musculature of the patient (5) by a spatial field generated by the field generator, comprising: placing the field generator (21) on the patient; operating the field generator (21) by increasing the intensity of the spatial field; identifying feedback from the patient's musculature; determining the position of the field generator (21) in the patient (5) based on the identified feedback of the muscle structure; A method comprising:

29. 29. The method of claim 28, wherein the field generator (21) is operated such that the feedback of the patient's musculature lasts for less than about 0.5 seconds, preferably less than about 0.2 seconds.

30. 30. The method of claim 29, wherein identifying feedback of the musculature of the patient (5) comprises sensing the feedback of the musculature.

31. 30. The method of claim 29, comprising comparing a plurality of feedbacks of the muscular system, each obtained from a different position of the field generator on the patient, and wherein defining the position of the field generator on the patient includes identifying one of the plurality of feedbacks of the muscular system as an appropriate feedback.

32. 32. The method of claim 31, wherein defining the position of the field generator (21) on the patient (5) comprises selecting the position associated with the appropriate feedback.

33. 32. The method of claim 31 , wherein comparing the multiple feedbacks of the muscular system comprises comparing strengths of the feedbacks of the muscular system, and wherein identifying one of the multiple feedbacks of the muscular system as the appropriate feedback comprises selecting the feedback having the highest strength.

34. 32. The method of claim 31, comprising predefining a target feedback strength; determining a response time for each of the plurality of feedbacks, the response time being the time from initiation of generation of a positioning field to reaching the target feedback strength; and comparing the determined response times when identifying one of the plurality of feedbacks of the muscular system as the appropriate feedback.

35. 35. The method of claim 34, comprising selecting one of the feedbacks of the muscular system that has the shortest response time.

36. 35. The method of claim 34, comprising ceasing operation of the field generator (21) for generating the positioning field when the predefined target feedback is achieved.

37. The method of claim 28, wherein the positioning field has a linearly increasing strength.

38. The method described in claim 28, wherein the positioning field has a first portion having an increasing intensity and a second portion having a decreasing intensity, the first portion of the positioning field having a first time width, and the second portion of the positioning field having a second time width that is significantly smaller than the first time width.

39. 39. The method of claim 38, wherein the first duration is at least four times the second duration, preferably at least eight times the second duration, and more preferably at least 15 times the second duration.

40. 40. The method of claim 39, wherein the second time span is about 0 seconds.

41. The method described in claim 28, wherein the positioning field is a field array.

42. 42. The method of claim 41 , wherein the field train comprises a series of pulses of the spatial field.

43. 43. The method of claim 42, wherein the series of pulses includes a frequency in the range of about 15 Hz to about 30 Hz.

44. The method described in claim 28, wherein the maximum intensity of the positioning field is approximately 40% of the maximum intensity of the regular stimulation field, advantageously approximately 30% of the maximum intensity of the regular stimulation field, or more advantageously approximately 20% of the maximum intensity of the regular stimulation field, and the regular stimulation field is configured to therapeutically activate the muscle structure of the patient.

45. 45. The method of claim 44, wherein the positioning field has properties that differ from properties of the regular stimulation field.

46. A method as described in claim 28, comprising a step of manually triggering the field generator (21) to generate a positioning field.

47. 29. The method of claim 28, wherein operating the field generator stimulates the patient's nervous system, and preferably the patient's phrenic or respiratory nerves.

48. 29. The method of claim 28, wherein the field generator (21) is operative to generate a positioning field having characteristic properties.

49. 30. The method of claim 28, wherein identifying feedback of the patient's muscular system comprises identifying activity of the muscular system that correlates with a characteristic property of the positioning field.

50. 30. The method of claim 28, wherein the feedback of the patient's musculature is identified by sensing flow and / or pressure.

51. 51. The method of claim 50, wherein the field generator (21) operates during an end-expiratory window of the patient's respiratory cycle.

52. 29. The method of claim 28, performed using a stimulation device according to any one of claims 1 to 27.

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