Wearable neuromuscular stimulation system for treatment of dyspnoea

Abstract

The present invention provides a wearable neuromuscular stimulation system for treatment of dyspnoea comprising a garment configured to be worn about a body of a user; and at least one vibratory stimulation module secured to the garment and comprising a housing enclosing a vibration source mounted such as to focus vibrations generated by the vibration motor in a direction towards the body of the user, reduce variations in vibration strength and / or frequency delivered to the user, and reduce variations in power requirements to drive the system.

Description

Field of the invention

[0001] The present invention relates to a wearable neuromuscular stimulation system for treatment of dyspnoea including a garment optionally incorporating one or more respiration sensors for detecting inspiration, expiration and breathing patterns. The system is adapted to trigger the delivery of neuromuscular stimulation based on information obtained from the one or more sensors or an alternative means of monitoring breathing to apply a therapy in-phase with breathing via an array of vibration modules disposed about the garment in order to, for example, reduce dyspnoea.Background of the invention

[0002] There is a significant unmet need for improved treatments to relieve the most challenging symptom of Chronic Obstructive Pulmonary Disease (COPD), namely breathlessness. Breathlessness, clinically referred to as dyspnoea, can be particularly debilitating and is central to how COPD progresses. The perception of breathlessness can cause significant anxiety, distress, and leads to the avoidance of physical activity. Over time this leads to a loss of physical fitness, leading to further breathlessness and eventually the need for hospitalisation. COPD is the third leading cause of death in the US, where there are 16 million diagnosed COPD sufferers. Breathlessness in COPD affects an estimated 36 million European and 391.9 million people worldwide. By giving COPD sufferers a tool to help them relieve and control their breathlessness, there is huge potential to significantly improve their quality of life and, longer term, to help reduce healthcare costs and avoid hospitalisations.

[0003] In-phase chest wall vibration (CWV) is a known mechanism for reducing the symptom of breathlessness in COPD patients. "In-phase" refers to the way in which vibratory neuromuscular stimulation is applied to discreet locations on the chest during inspiration and during expiration (upper intercostal muscles during inspiration, lower intercostal muscles during expiration). This type of neuromuscular stimulation (which may also be referred to as neurostimulation) has been verified as effective in controlled lab environments and studies have been published to this effect. In CWV, it is important that vibrations be delivered in a distinct frequency range (60 to 150 Hz), with most of the evidence supporting 100Hz as an optimal vibration frequency. One such system and method is disclosed in International patent application WO2010071919A1.

[0004] To deliver the stimulation in-phase, there is a requirement to accurately and reliably detect the onset and end of inspiration and expiration in real time. Various sensors such as respiratory inductive plethysmography (RIP) bands may be repurposed to facilitate the detection of breathing phase and have been used to measure respiration rate and air volumes for several decades, with the primary application being in sleep studies.

[0005] There is however a need for a more streamlined, portable, and low cost means of enabling in-phase neuromuscular stimulation which provides a more consistent and reliable delivery of vibratory stimulation to the body of the patient in order to allow patients to receive this therapy effectively in "real world" settings, for example at home, in a clinic or in an ambulatory setting for prolonged periods while a patient completes activities of daily living or exercise programmes, for example.

[0006] The present invention has therefore been developed with a view to addressing the above mentioned needs in order to provide an improved means of delivering vibratory stimulation therapy to patients suffering from COPD, in addition to any other suitable application in which vibratory neuromuscular or neurostimulation is required.Summary of the invention

[0007] According to an aspect of the present invention there is provided a wearable neuromuscular stimulation system for treatment of dyspnoea comprising a garment configured to be worn about a body of a user; and at least one vibratory stimulation module secured to the garment and comprising a housing enclosing a vibration source mounted such as to optimise the delivery of vibration energy generated by the vibration source in a direction towards the body of the user.

[0008] Preferably, the stimulation system comprises one or more respiration sensors distributed about the garment.

[0009] Preferably, the housing comprises a base on which the vibration source is mounted, and an upper enclosure surrounding the vibration source and secured to the base.

[0010] Preferably, the vibratory stimulation module comprises an isolating element configured to reduce or eliminate the transfer of vibration from the base to the upper enclosure.

[0011] Preferably, the isolating element is configured to facilitate vibrations from the vibration source to propagate in a direction normal to the base.

[0012] Preferably, the isolating element comprises a flexible skirt connecting the base to the upper enclosure.

[0013] Preferably, the flexible skirt circumscribes the base and the housing comprises a keyway into which an outer perimeter of the skirt is secured.

[0014] Preferably, the isolating element comprises a spring.

[0015] Preferably, the spring is defined by one or more coil springs connecting the base to the upper enclosure.

[0016] Preferably, the vibratory stimulation module comprises a shock absorber disposed between the base and the upper enclosure.

[0017] Preferably, the upper enclosure comprises a resiliently deformable material.

[0018] Preferably, the upper enclosure comprises a shape memory material.

[0019] Preferably, the garment comprises a dock for receiving and retaining the at least one vibratory stimulation module.

[0020] Preferably, the dock comprises a pocket for receiving the at least one vibratory stimulation module.

[0021] Preferably, the dock is configured to mechanically isolate the vibratory stimulation module from compressive forces generated by tension in the garment.

[0022] Preferably, the garment comprises a pressure sensor configured to monitor the fit of the garment.

[0023] Preferably, the wearable neuromuscular stimulation system comprises a controller operable to drive the vibration motor in response to feedback from the one or more respiration sensors.

[0024] Preferably, the controller is operable to modulate the frequency and / or amplitude of vibrations generated by the vibration source.

[0025] Preferably, the controller comprises an algorithm operable to monitor a signal generated by each of the respiration sensors and to compare the signals in order to facilitate a determination of a breathing phase and / or pattern of the user based on the relative values of the generated signals.

[0026] Preferably, the vibration source comprises an eccentric rotating mass motor.

[0027] Preferably, the vibration source is operable to produce vibrations in a frequency range of between 50Hz and 150Hz, more preferably between 75Hz and 125Hz, most preferably 100Hz.

[0028] Preferably, the vibration source is operable to produce vibrations in an amplitude range of between 1G and 50G, more preferably between 20G and 30G, most preferably 25G.

[0029] Preferably, the respiration sensors comprise at least a first sensor arranged on the garment in a first orientation extending, in use, transversely of a chest of the user, and at least a second sensor extending in a second orientation offset to the first orientation.

[0030] As used herein, the term "garment" is intended to mean an item or items which can be securely worn about one or more parts of the body, and for example may take the form of a vest for location about the torso of a user but equally may be a sleeve or cuff type form factor to be worn about one or more arm or leg of the user.

[0031] As used herein, the term "vibration source" is intended to mean a mechanical, electromechanical, electromagnetic or electronic device that is operable to generate a vibration output in response to an electrical input, for example a vibration motor such as an eccentric mass motor or piezoelectric device.

[0032] As used herein, the term "spring" is intended to mean an element adapted to undergo resilient deformation such as compression and extension in order to isolate one component from another and may include a coil spring, a leaf spring, a torsion spring, an elastomer based spring or other resiliently deformable material, a gas spring or a spring / damper assembly.Brief description of the drawings

[0033] The present invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates an embodiment of a wearable neuromuscular stimulation system for treatment of dyspnoea according to the present invention; Figure 2 illustrates a perspective view from above of a vibratory stimulation module forming part of the wearable neuromuscular stimulation system shown in Figure 1; Figure 3 illustrates a perspective view from below of the vibratory stimulation module of Figure 2; Figure 4 illustrates a sectioned view of the vibratory stimulation module of Figures 2 and 3 showing a vibration motor contained within a housing; Figure 5 illustrates an enlarged view of the portion labelled as "B" in Figure 4; Figure 6 illustrates a perspective view of a base forming part of the housing for the vibration motor; Figure 7 illustrates the baseplate of Figure 6 with the vibration motor located thereon; Figure 8 illustrates an alternative embodiment of a vibratory stimulation module forming part of the wearable neuromuscular stimulation system shown in Figure 1; Figure 9 illustrates a sectioned perspective view of the vibratory stimulation module shown in Figure 8; Figure 10 illustrates an alternative perspective view of the vibratory stimulation module of Figure 9; Figure 11 illustrates a sectioned elevation of the vibratory stimulation module of Figure 9 and 10; Figure 12 illustrates an enlarged view of the portion labelled as "A" in Figure 11; and Figure 13 illustrates a sectioned side elevation of an exemplary vibratory stimulation module secured within a pocket of the wearable neuromuscular stimulation system of the invention. Detailed description of the invention

[0034] Referring now to Figure 1 of the accompanying drawings there is illustrated a wearable neuromuscular stimulation system for treatment of dyspnoea, generally indicated as 10, according to an embodiment of the present invention. The system 10 comprises a garment 12 which in the embodiment illustrated is in the form of a vest designed to be worn snugly yet comfortable on the body of the user, and preferably about the torso / chest region in order to monitor the breathing phase of the user. The term "breathing phase" is intended to mean a given portion of the breathing cycle of a user, being related to the lung volume of the user at that instance, the breathing phase typically reciprocating between the inspiration phase in which the lung volume is increasing, and the expiration phase in which the lung volume is decreasing, and which is however also intended to cover points or phases intermediate these two extremes. In the embodiment illustrated the garment 12 is of a minimalist design in order to be relatively lightweight and to avoid restricting movement of the user, and to be therefore unobtrusive. The system 10 can therefore be worn for prolonged periods and during ambulatory activity or the like. The garment 12 is preferably formed at least in part from elastic material and is further preferably provided with means such as straps or other tensioning elements or the like in order to allow the fit of the garment 12 on the user to be tailored to provide the necessary body conformity. It will be appreciated that although the system 10 of the embodiment illustrated is configured for treating dyspnoea and thus designed to be worn about the torso / chest of the user, the system 10 may be configured to be worn about any other region of the body to which neuromuscular stimulation is to be applied.

[0035] The system 10 is preferably provided with one or more respiration sensors (not shown) disposed about the garment 12 for use in the real time detection of the inspiration and expiration of a user's breathing, in particular but not exclusively to facilitate the provision of in-phase neuromuscular stimulation to provide relief from the symptoms of Chronic Obstructive Pulmonary Disease (COPD). The respiration sensors may be of any suitable type, for example a sensor which undergoes measurable changes in electrical properties as the garment 12 expands and contracts in response to the user breathing. While less preferred it will be appreciated that the respiration sensors may be omitted or supplemented by the use of alternative means of achieving the real time detection of the user's breathing phases, for example a respiration mask which may be operable directly or indirectly to actuate the in-phase neuromuscular stimulation effected by the garment 12.

[0036] In the embodiment illustrated it is preferred that the array of the respiration sensors (not shown) are located on or distributed about the garment 12 so as to be positioned at various locations about the chest when the garment 12 is worn as intended. The garment 12 may be formed from any suitable material or combination of materials, and for example may be partially or wholly formed from an elastic fabric material such as bamboo charcoal blend. In addition one or more regions of the garment 12 may comprise relatively inelastic material such as polyester in order to provide mechanical isolation for the vibration modules from tensile forces seen by the garment 12 during fitting, as described in detail hereinafter.

[0037] It is beneficial for the respiration sensors (not shown) to be positioned at different locations or levels of the chest, for example for monitoring different disease states and accurately monitoring or sensing breathing phases, movements or patterns. For example the array of sensors may comprise sensors oriented to extend, when the garment 12 is worn about the chest of the user, transversely or laterally across the chest of the user, and preferably across the upper and lower chest region. Additional vertically and diagonally extending sensors are preferably also employed to measure different regions of chest expansion / contraction.

[0038] By combining and analysing the resulting signals from the respiration sensors and / or respiration mask (not shown) if utilised, it is possible to detect many different breathing patterns. In particular the use of respiration sensors integrated into the garment 12 allows for a three dimensional mapping of breathing mechanics specific to the wearer of the garment 12. The combination of signals obtained from the array of respiration sensors and / or respiration mask allows reliable and accurate detection of respiratory phase during periods of atypical breathing patterns such as dynamic hyperinflation, when respiratory rates may be elevated and relative changes in chest circumference from breath to breath reduced. A simultaneous change in electrical properties of sensors placed at different locations on the garment 12 provides a reliable signal to indicate chest expansion and therefore inspiration.

[0039] The system 10 preferably comprises a local controller (not shown), preferably integrated into the garment 12, and which receives signals from the respiration sensors and / or the respiration mask or associated equipment. The controller runs an algorithm that monitors the signal generated by each of the respiration sensors and / or mask, for example comparing the signals from two or more of the sensors, from which comparison various determinations regarding the breathing phase or pattern of the user can be determined.

[0040] The output signal from the respiration sensors and / or mask can then be used to actuate an array of vibratory stimulation modules 14 illustrated in Figures 2 to 7 and which are also disposed about the garment 12, each at a location which corresponds to an anatomical site to which neuromuscular stimulation is to be effectively applied in order to treat a particular condition. For example in the embodiment illustrated where the system 10 is configured for treating dyspnoea the vibratory stimulation modules 14 are positioned on the garment 12 to apply vibratory stimulation to the upper and lower intercostal muscles that form part of and move the chest wall. As noted above the garment 12 has an adjustable and / or stretch fit in order to accommodate different sized users and to allow for a closely conforming fit in order to both effectively monitor breathing phase and to efficiently deliver vibratory stimulation as required. In use the garment 12 is applied to the user and is then adjusted in tightness / fit to ensure good contact with the region of the body to be treated, with the user ultimately deciding on the fit that is comfortable. This will likely vary from person to person and may vary for the same user depending on the circumstances, such as a particular activity being undertaken, type of clothing being worn over or under the garment 12, environment conditions, etc. As a result there may be significant variation in the fit of the garment 12, which will then have an impact of the intensity of the vibratory stimulation that will be applied by the vibratory stimulation modules 14, impacting the efficacy of the treatment.

[0041] The vibratory stimulation modules 14 comprises a housing 16 enclosing a vibration source in the form of a vibration motor 18, the housing 16 being suitable secured to the garment 12 and through which housing 16 vibratory stimulation is transmitted to the anatomical site from the vibration motor 18. The vibration source or motor 18 may be of any suitable form, for example a mechanical, electromechanical, electromagnetic or electronic device that is operable to generate a vibration output in response to an electrical input. The vibration motor 18 may for example comprise a piezoelectric element or, as illustrated in Figures 2 to 7, an eccentric rotating mass based motor. For treating dyspnoea it is the amplitude and frequency of vibration that is important, not the type of vibration motor 18 employed, as the amplitude dictates the strength of vibration experienced by the user and correct frequency range is required for effective therapy.

[0042] Vibration produced by an eccentric rotating mass is an example of "Driven Harmonic Vibration", meaning there is an external driving force causing the vibration. The excitation input is the rotation of the eccentric mass around the central motor shaft. A DC voltage controls the speed of the motor (the two are directly proportional) and therefore the frequency of the generated vibration. Eccentric rotating mass motors work over a range of voltages. As the applied voltage is increased, the vibration frequency increases proportionally, and vibration amplitude will also increase.

[0043] When modelling such a vibration motor: F 0 = mrω 2 where: F 0 is the amplitude of the centrifugal force, m is the mass of the eccentric mass, r is the distance from the motor shaft to the centre of the eccentric mass ω is the angular velocity of the motor.

[0044] The driving current of the eccentric rotating mass motor is proportional to the torque 'load' seen by the motor. As vibration energy is taken out of the system 10, the torque required to continue spinning the eccentric mass will increase, as will the current.

[0045] Strength of vibration is referred to as vibration amplitude (a), which is measured in acceleration, G (acceleration caused by earth gravitational pull), and is dependent on the centripetal force (F c ) and the mass of the body the motor is attached to, the target mass (M). F c = Ma

[0046] For the wearable neuromuscular stimulation system 10 of the invention the amplitude of vibration is important as it dictates the strength of vibration experienced by the user. When utilising a vibration motor 18, in particular one containing moving parts such as an eccentric rotating mass motor, it is necessary to encase the vibration motor 18 inside the housing 16 to protect the vibration motor 18 and the user, primarily to ensure consistent operation. This does however have an impact on the operation of the system 10. As the vibration motor 18 is encased in the housing 16, vibrations can be transferred in any direction and into anything touching the housing 16, both on the inner and outer sides of the garment 12. The flexible garment 12 provides a degree of constraint to the vibration motor 18 on one side and the body of the user provides constraint on the other side. This configuration can give rise to variations in the current required to drive the vibration motor 18 and / or variations in the strength of the vibrations experienced by the user, given the variations in the fit of the garment and other external influences.

[0047] For example, an object (such as a hand) contacting the outer garment 12 over one of the vibratory stimulation modules 14 may reduce displacement of the vibratory stimulation module 14, meaning less vibration energy is extracted. This may alter the current required to drive the vibration motor 18. In addition the object, if placed with sufficient pressure against the vibratory stimulation module 14, may affect the strength of vibrations experienced by the user, as it may begin to contribute to M, the target mass.

[0048] When the garment 12 is applied more tightly to the user the vibration stimulation modules 14 are more tightly constrained to the body of the user and may cause the body to contribute to M, the target mass, altering the strength of vibrations experienced by the user. This would also have the effect of reducing displacement, altering current requirements for a given speed of rotation of the vibration motor 18.

[0049] In empirical testing it has been observed that the above effects can have an impact on vibration frequency (due to changes voltage and therefore changes in velocity of motor spin), which is a critical requirement to provide accurate and effective levels of vibration.

[0050] The wearable neuromuscular stimulation system 10 addresses the above shortcomings by designing the housing 16 to focus the vibrations generated by the vibration motor 18 in a direction towards the respective anatomical site on the body of the user. The housing 16 comprises a base 20 on which the vibration motor 18 is securely mounted, and an upper enclosure 22 extending from the base 20 to surrounding and enclose the vibration motor 18. The base 20 is preferably planar in form and comprising a relative rigid material such as a polymer or the like. The base 20 is connected to the upper enclosure 22 by means of an isolating element in the form of a flexible gasket or skirt 24 which circumscribes and is substantially coplanar with the base 20. The skirt 24 may for example be over-moulded on the base 20. The outer perimeter of the skirt 24 is secured at or adjacent a lower rim of the upper enclosure 22, and in the embodiment illustrated is suitable captured within a keyway or channel 24 provided on an inner wall of the upper enclosure 22. The flexible skirt 24 is configured to allow the base 20 to undergo movement relative to the upper enclosure 22 in a direction substantially normal to the plane of the base 20. The flexible skirt 24 may be formed from any suitable material providing the necessary resilience to allow the base to oscillate relative to the upper enclosure 22 in response to operation of the vibration motor 18, and may for example be a silicone or rubber or the like.

[0051] By isolating the base 20 from the upper enclosure 22, the flexible skirt 24 significantly reduces dissipation or transfer of the vibration energy from the vibration motor 18 to the upper enclosure 22 from where it would be lost, improving efficiency of the vibration delivery to the chest of the user. In other words by reducing losses of the vibrational energy generated in directions that do not face towards the body the vibratory stimulation module 14 effectively focuses or optimises the vibrational energy directed towards and thus delivered to the body of the user. As the base 20 can vibrate substantially independently of the upper enclosure 22, the provision of the isolating skirt 24 also reduces the effects on vibration strength experienced by the user, and on power to maintain a constant vibration frequency, when the garment 12 is applied at different tightness levels and when objects such as hands make contact with the upper enclosure 22 through the outer shell of the garment 12. The flexible skirt may also be configured to provide a sealing function between the base 20 and the upper enclosure 22.

[0052] Referring now to Figures 8 to 12 there is illustrated a vibratory stimulation module, generally indicated as 114, according to an alternative embodiment of the invention. In this alternative embodiment like components have been accorded like reference numerals and unless otherwise stated perform a like function.

[0053] The vibratory stimulation module 114 again comprises a housing 116 having a base 120 on which is securely mounted a vibration motor 118, the housing 116 further comprising an upper enclosure 122 extending from the base 120 and surrounding the vibration motor 118. In this embodiment the housing 116 is cylindrical in shape but it will be appreciated that any other suitable shape may be employed. The base 120 and upper enclosure 122 are connected by an isolating element in the form of a pair of coil springs 124 which allow the base 120 to vibrate relatively independently of the upper enclosure 122. This again allows the vibratory stimulation module 114 to focus the vibrations from the vibration motor 116 towards the anatomical site directly below the base 120, reducing losses to the surroundings, in particular the upper enclosure 122. The pair of springs 124 are configured and / or arranged to allow the base 120 to undergo movement relative to the upper enclosure 122 in a direction substantially normal to the plane of the base 120. Referring in particular to Figures 11 and 12 the base 122 preferably comprises a stepped outer rim 140 which is seated about a corresponding radially inwardly extending shoulder 142 at the lower rim of the upper enclosure 122 in order to prevent separation of the base 120 and upper enclosure 122. A shock absorber in the form of a rubber or foam o-ring 144 is preferably provided between the rim 140 and shoulder 142, and may also provide a sealing function between the base 120 and the upper enclosure 122.

[0054] Referring to Figure 12 the garment 12 may comprise pockets 28 for receiving and retaining the vibratory stimulation modules 14, 114. The pockets 28 are preferably formed integrally with the garment 12, but may for example be comprised of a relatively rigid or inelastic dock 32 for receiving the vibratory stimulation module 14, 114, which dock 32 is secured to the adjacent, relatively elastic material of the garment 12. In this way the stiffer material will serve to isolate the vibratory stimulation module 14, 114 from tensile forces experienced by the garment 12 as it is tightened to fit the user. This isolation further acts to reduce the variability in forces applied to the exterior of the housing 16, 116 as hereinbefore described, thus reducing variability in the strength / amplitude of the vibrations applied to the user and reducing variations in power requirements as the system 10 attempts to maintain a consistent vibration frequency.

[0055] The vibratory stimulation modules 14, 114 may be provided with additional features to augment the functionality hereinbefore described. For example a pressure sensor (not shown) may be associated with one or more of the vibratory stimulation modules 14, 114 in order to allow the controller (not shown) to receiving feedback regarding the level of tightness of the garment 12. Such data may be useful for informing the user on the correct / optimum fit of the garment 12, allowing power adjustments to be made to the vibration motors 18, 118, or to provide an alarm signal when the garment 12 is overtightened, which may adversely affect operation.

[0056] The vibratory stimulation modules 14, 114 may also be provided with sound insulation (not shown) on the housing 16, 116, preferably on an interior surface thereof, in order to absorb any sound or vibration energy that may be directed away from the body.

[0057] The housing 16, 116 may also be at least partially formed from a resilient deformable material, or a shape memory material such as nitinol, which would allow the housing 16, 116 to deform in response to tension in the garment 12 without impacting on the operation of the vibration motor, and which would then return to the unstressed shape once the tension has been sufficiently removed. For example the housing 16, 116 may be generally rigid or semi-rigid but have an upper or surrounding layer of a resiliently deformable material.

[0058] In a wearable device, efficient consumption of power is paramount. By reducing the variations in the motor torque required to maintain the correct vibration frequency, it is possible to utilise a vibration motor 16, 116 that is optimally selected or designed to meet power requirements and maximise efficiency. This allows the use of a motor that is as small as possible and runs at correct speeds on the least power. In an exemplary embodiment the vibration motor 18, 118 operates on a 5V input and generates vibrations at 100 Hz [+ / - 10Hz] and at amplitudes of 25 G [+ / - 15G]. It will of course be understood that these are exemplary values which may be varied as required.

[0059] The wearable system 10 of the present invention provides a simple and low cost, yet reliable means of delivering neuromuscular stimulation therapy. The system 10 is compact, lightweight and discreet, allowing a user to wear the garment 12 in most conventional settings and thus enjoy the benefits of in-phase CWV at any time or place. The use of the vibratory stimulation modules 14, 114 to focus vibrations ensures that power consumption is optimised, extending the operating window of the system 10 and providing the user with the requisite therapy for prolonged periods of time.

Examples

Embodiment Construction

[0034]Referring now to Figure 1 of the accompanying drawings there is illustrated a wearable neuromuscular stimulation system for treatment of dyspnoea, generally indicated as 10, according to an embodiment of the present invention. The system 10 comprises a garment 12 which in the embodiment illustrated is in the form of a vest designed to be worn snugly yet comfortable on the body of the user, and preferably about the torso / chest region in order to monitor the breathing phase of the user. The term "breathing phase" is intended to mean a given portion of the breathing cycle of a user, being related to the lung volume of the user at that instance, the breathing phase typically reciprocating between the inspiration phase in which the lung volume is increasing, and the expiration phase in which the lung volume is decreasing, and which is however also intended to cover points or phases intermediate these two extremes. In the embodiment illustrated the garment 12 is of a minimalist desi...

Field of the invention

[0001] The present invention relates to a wearable neuromuscular stimulation system for treatment of dyspnoea including a garment optionally incorporating one or more respiration sensors for detecting inspiration, expiration and breathing patterns. The system is adapted to trigger the delivery of neuromuscular stimulation based on information obtained from the one or more sensors or an alternative means of monitoring breathing to apply a therapy in-phase with breathing via an array of vibration modules disposed about the garment in order to, for example, reduce dyspnoea.Background of the invention

[0002] There is a significant unmet need for improved treatments to relieve the most challenging symptom of Chronic Obstructive Pulmonary Disease (COPD), namely breathlessness. Breathlessness, clinically referred to as dyspnoea, can be particularly debilitating and is central to how COPD progresses. The perception of breathlessness can cause significant anxiety, distress, and leads to the avoidance of physical activity. Over time this leads to a loss of physical fitness, leading to further breathlessness and eventually the need for hospitalisation. COPD is the third leading cause of death in the US, where there are 16 million diagnosed COPD sufferers. Breathlessness in COPD affects an estimated 36 million European and 391.9 million people worldwide. By giving COPD sufferers a tool to help them relieve and control their breathlessness, there is huge potential to significantly improve their quality of life and, longer term, to help reduce healthcare costs and avoid hospitalisations.

[0003] In-phase chest wall vibration (CWV) is a known mechanism for reducing the symptom of breathlessness in COPD patients. "In-phase" refers to the way in which vibratory neuromuscular stimulation is applied to discreet locations on the chest during inspiration and during expiration (upper intercostal muscles during inspiration, lower intercostal muscles during expiration). This type of neuromuscular stimulation (which may also be referred to as neurostimulation) has been verified as effective in controlled lab environments and studies have been published to this effect. In CWV, it is important that vibrations be delivered in a distinct frequency range (60 to 150 Hz), with most of the evidence supporting 100Hz as an optimal vibration frequency. One such system and method is disclosed in International patent application WO2010071919A1.

[0004] To deliver the stimulation in-phase, there is a requirement to accurately and reliably detect the onset and end of inspiration and expiration in real time. Various sensors such as respiratory inductive plethysmography (RIP) bands may be repurposed to facilitate the detection of breathing phase and have been used to measure respiration rate and air volumes for several decades, with the primary application being in sleep studies.

[0005] There is however a need for a more streamlined, portable, and low cost means of enabling in-phase neuromuscular stimulation which provides a more consistent and reliable delivery of vibratory stimulation to the body of the patient in order to allow patients to receive this therapy effectively in "real world" settings, for example at home, in a clinic or in an ambulatory setting for prolonged periods while a patient completes activities of daily living or exercise programmes, for example.

[0006] The present invention has therefore been developed with a view to addressing the above mentioned needs in order to provide an improved means of delivering vibratory stimulation therapy to patients suffering from COPD, in addition to any other suitable application in which vibratory neuromuscular or neurostimulation is required.Summary of the invention

[0007] According to an aspect of the present invention there is provided a wearable neuromuscular stimulation system for treatment of dyspnoea comprising a garment configured to be worn about a body of a user; and at least one vibratory stimulation module secured to the garment and comprising a housing enclosing a vibration source mounted such as to optimise the delivery of vibration energy generated by the vibration source in a direction towards the body of the user.

[0008] Preferably, the stimulation system comprises one or more respiration sensors distributed about the garment.

[0009] Preferably, the housing comprises a base on which the vibration source is mounted, and an upper enclosure surrounding the vibration source and secured to the base.

[0010] Preferably, the vibratory stimulation module comprises an isolating element configured to reduce or eliminate the transfer of vibration from the base to the upper enclosure.

[0011] Preferably, the isolating element is configured to facilitate vibrations from the vibration source to propagate in a direction normal to the base.

[0012] Preferably, the isolating element comprises a flexible skirt connecting the base to the upper enclosure.

[0013] Preferably, the flexible skirt circumscribes the base and the housing comprises a keyway into which an outer perimeter of the skirt is secured.

[0014] Preferably, the isolating element comprises a spring.

[0015] Preferably, the spring is defined by one or more coil springs connecting the base to the upper enclosure.

[0016] Preferably, the vibratory stimulation module comprises a shock absorber disposed between the base and the upper enclosure.

[0017] Preferably, the upper enclosure comprises a resiliently deformable material.

[0018] Preferably, the upper enclosure comprises a shape memory material.

[0019] Preferably, the garment comprises a dock for receiving and retaining the at least one vibratory stimulation module.

[0020] Preferably, the dock comprises a pocket for receiving the at least one vibratory stimulation module.

[0021] Preferably, the dock is configured to mechanically isolate the vibratory stimulation module from compressive forces generated by tension in the garment.

[0022] Preferably, the garment comprises a pressure sensor configured to monitor the fit of the garment.

[0023] Preferably, the wearable neuromuscular stimulation system comprises a controller operable to drive the vibration motor in response to feedback from the one or more respiration sensors.

[0024] Preferably, the controller is operable to modulate the frequency and / or amplitude of vibrations generated by the vibration source.

[0025] Preferably, the controller comprises an algorithm operable to monitor a signal generated by each of the respiration sensors and to compare the signals in order to facilitate a determination of a breathing phase and / or pattern of the user based on the relative values of the generated signals.

[0026] Preferably, the vibration source comprises an eccentric rotating mass motor.

[0027] Preferably, the vibration source is operable to produce vibrations in a frequency range of between 50Hz and 150Hz, more preferably between 75Hz and 125Hz, most preferably 100Hz.

[0028] Preferably, the vibration source is operable to produce vibrations in an amplitude range of between 1G and 50G, more preferably between 20G and 30G, most preferably 25G.

[0029] Preferably, the respiration sensors comprise at least a first sensor arranged on the garment in a first orientation extending, in use, transversely of a chest of the user, and at least a second sensor extending in a second orientation offset to the first orientation.

[0030] As used herein, the term "garment" is intended to mean an item or items which can be securely worn about one or more parts of the body, and for example may take the form of a vest for location about the torso of a user but equally may be a sleeve or cuff type form factor to be worn about one or more arm or leg of the user.

[0031] As used herein, the term "vibration source" is intended to mean a mechanical, electromechanical, electromagnetic or electronic device that is operable to generate a vibration output in response to an electrical input, for example a vibration motor such as an eccentric mass motor or piezoelectric device.

[0032] As used herein, the term "spring" is intended to mean an element adapted to undergo resilient deformation such as compression and extension in order to isolate one component from another and may include a coil spring, a leaf spring, a torsion spring, an elastomer based spring or other resiliently deformable material, a gas spring or a spring / damper assembly.Brief description of the drawings

[0033] The present invention will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates an embodiment of a wearable neuromuscular stimulation system for treatment of dyspnoea according to the present invention; Figure 2 illustrates a perspective view from above of a vibratory stimulation module forming part of the wearable neuromuscular stimulation system shown in Figure 1; Figure 3 illustrates a perspective view from below of the vibratory stimulation module of Figure 2; Figure 4 illustrates a sectioned view of the vibratory stimulation module of Figures 2 and 3 showing a vibration motor contained within a housing; Figure 5 illustrates an enlarged view of the portion labelled as "B" in Figure 4; Figure 6 illustrates a perspective view of a base forming part of the housing for the vibration motor; Figure 7 illustrates the baseplate of Figure 6 with the vibration motor located thereon; Figure 8 illustrates an alternative embodiment of a vibratory stimulation module forming part of the wearable neuromuscular stimulation system shown in Figure 1; Figure 9 illustrates a sectioned perspective view of the vibratory stimulation module shown in Figure 8; Figure 10 illustrates an alternative perspective view of the vibratory stimulation module of Figure 9; Figure 11 illustrates a sectioned elevation of the vibratory stimulation module of Figure 9 and 10; Figure 12 illustrates an enlarged view of the portion labelled as "A" in Figure 11; and Figure 13 illustrates a sectioned side elevation of an exemplary vibratory stimulation module secured within a pocket of the wearable neuromuscular stimulation system of the invention. Detailed description of the invention

[0034] Referring now to Figure 1 of the accompanying drawings there is illustrated a wearable neuromuscular stimulation system for treatment of dyspnoea, generally indicated as 10, according to an embodiment of the present invention. The system 10 comprises a garment 12 which in the embodiment illustrated is in the form of a vest designed to be worn snugly yet comfortable on the body of the user, and preferably about the torso / chest region in order to monitor the breathing phase of the user. The term "breathing phase" is intended to mean a given portion of the breathing cycle of a user, being related to the lung volume of the user at that instance, the breathing phase typically reciprocating between the inspiration phase in which the lung volume is increasing, and the expiration phase in which the lung volume is decreasing, and which is however also intended to cover points or phases intermediate these two extremes. In the embodiment illustrated the garment 12 is of a minimalist design in order to be relatively lightweight and to avoid restricting movement of the user, and to be therefore unobtrusive. The system 10 can therefore be worn for prolonged periods and during ambulatory activity or the like. The garment 12 is preferably formed at least in part from elastic material and is further preferably provided with means such as straps or other tensioning elements or the like in order to allow the fit of the garment 12 on the user to be tailored to provide the necessary body conformity. It will be appreciated that although the system 10 of the embodiment illustrated is configured for treating dyspnoea and thus designed to be worn about the torso / chest of the user, the system 10 may be configured to be worn about any other region of the body to which neuromuscular stimulation is to be applied.

[0035] The system 10 is preferably provided with one or more respiration sensors (not shown) disposed about the garment 12 for use in the real time detection of the inspiration and expiration of a user's breathing, in particular but not exclusively to facilitate the provision of in-phase neuromuscular stimulation to provide relief from the symptoms of Chronic Obstructive Pulmonary Disease (COPD). The respiration sensors may be of any suitable type, for example a sensor which undergoes measurable changes in electrical properties as the garment 12 expands and contracts in response to the user breathing. While less preferred it will be appreciated that the respiration sensors may be omitted or supplemented by the use of alternative means of achieving the real time detection of the user's breathing phases, for example a respiration mask which may be operable directly or indirectly to actuate the in-phase neuromuscular stimulation effected by the garment 12.

[0036] In the embodiment illustrated it is preferred that the array of the respiration sensors (not shown) are located on or distributed about the garment 12 so as to be positioned at various locations about the chest when the garment 12 is worn as intended. The garment 12 may be formed from any suitable material or combination of materials, and for example may be partially or wholly formed from an elastic fabric material such as bamboo charcoal blend. In addition one or more regions of the garment 12 may comprise relatively inelastic material such as polyester in order to provide mechanical isolation for the vibration modules from tensile forces seen by the garment 12 during fitting, as described in detail hereinafter.

[0037] It is beneficial for the respiration sensors (not shown) to be positioned at different locations or levels of the chest, for example for monitoring different disease states and accurately monitoring or sensing breathing phases, movements or patterns. For example the array of sensors may comprise sensors oriented to extend, when the garment 12 is worn about the chest of the user, transversely or laterally across the chest of the user, and preferably across the upper and lower chest region. Additional vertically and diagonally extending sensors are preferably also employed to measure different regions of chest expansion / contraction.

[0038] By combining and analysing the resulting signals from the respiration sensors and / or respiration mask (not shown) if utilised, it is possible to detect many different breathing patterns. In particular the use of respiration sensors integrated into the garment 12 allows for a three dimensional mapping of breathing mechanics specific to the wearer of the garment 12. The combination of signals obtained from the array of respiration sensors and / or respiration mask allows reliable and accurate detection of respiratory phase during periods of atypical breathing patterns such as dynamic hyperinflation, when respiratory rates may be elevated and relative changes in chest circumference from breath to breath reduced. A simultaneous change in electrical properties of sensors placed at different locations on the garment 12 provides a reliable signal to indicate chest expansion and therefore inspiration.

[0039] The system 10 preferably comprises a local controller (not shown), preferably integrated into the garment 12, and which receives signals from the respiration sensors and / or the respiration mask or associated equipment. The controller runs an algorithm that monitors the signal generated by each of the respiration sensors and / or mask, for example comparing the signals from two or more of the sensors, from which comparison various determinations regarding the breathing phase or pattern of the user can be determined.

[0040] The output signal from the respiration sensors and / or mask can then be used to actuate an array of vibratory stimulation modules 14 illustrated in Figures 2 to 7 and which are also disposed about the garment 12, each at a location which corresponds to an anatomical site to which neuromuscular stimulation is to be effectively applied in order to treat a particular condition. For example in the embodiment illustrated where the system 10 is configured for treating dyspnoea the vibratory stimulation modules 14 are positioned on the garment 12 to apply vibratory stimulation to the upper and lower intercostal muscles that form part of and move the chest wall. As noted above the garment 12 has an adjustable and / or stretch fit in order to accommodate different sized users and to allow for a closely conforming fit in order to both effectively monitor breathing phase and to efficiently deliver vibratory stimulation as required. In use the garment 12 is applied to the user and is then adjusted in tightness / fit to ensure good contact with the region of the body to be treated, with the user ultimately deciding on the fit that is comfortable. This will likely vary from person to person and may vary for the same user depending on the circumstances, such as a particular activity being undertaken, type of clothing being worn over or under the garment 12, environment conditions, etc. As a result there may be significant variation in the fit of the garment 12, which will then have an impact of the intensity of the vibratory stimulation that will be applied by the vibratory stimulation modules 14, impacting the efficacy of the treatment.

[0041] The vibratory stimulation modules 14 comprises a housing 16 enclosing a vibration source in the form of a vibration motor 18, the housing 16 being suitable secured to the garment 12 and through which housing 16 vibratory stimulation is transmitted to the anatomical site from the vibration motor 18. The vibration source or motor 18 may be of any suitable form, for example a mechanical, electromechanical, electromagnetic or electronic device that is operable to generate a vibration output in response to an electrical input. The vibration motor 18 may for example comprise a piezoelectric element or, as illustrated in Figures 2 to 7, an eccentric rotating mass based motor. For treating dyspnoea it is the amplitude and frequency of vibration that is important, not the type of vibration motor 18 employed, as the amplitude dictates the strength of vibration experienced by the user and correct frequency range is required for effective therapy.

[0042] Vibration produced by an eccentric rotating mass is an example of "Driven Harmonic Vibration", meaning there is an external driving force causing the vibration. The excitation input is the rotation of the eccentric mass around the central motor shaft. A DC voltage controls the speed of the motor (the two are directly proportional) and therefore the frequency of the generated vibration. Eccentric rotating mass motors work over a range of voltages. As the applied voltage is increased, the vibration frequency increases proportionally, and vibration amplitude will also increase.

[0043] When modelling such a vibration motor: F 0 = mrω 2 where: F 0 is the amplitude of the centrifugal force, m is the mass of the eccentric mass, r is the distance from the motor shaft to the centre of the eccentric mass ω is the angular velocity of the motor.

[0044] The driving current of the eccentric rotating mass motor is proportional to the torque 'load' seen by the motor. As vibration energy is taken out of the system 10, the torque required to continue spinning the eccentric mass will increase, as will the current.

[0045] Strength of vibration is referred to as vibration amplitude (a), which is measured in acceleration, G (acceleration caused by earth gravitational pull), and is dependent on the centripetal force (F c ) and the mass of the body the motor is attached to, the target mass (M). F c = Ma

[0046] For the wearable neuromuscular stimulation system 10 of the invention the amplitude of vibration is important as it dictates the strength of vibration experienced by the user. When utilising a vibration motor 18, in particular one containing moving parts such as an eccentric rotating mass motor, it is necessary to encase the vibration motor 18 inside the housing 16 to protect the vibration motor 18 and the user, primarily to ensure consistent operation. This does however have an impact on the operation of the system 10. As the vibration motor 18 is encased in the housing 16, vibrations can be transferred in any direction and into anything touching the housing 16, both on the inner and outer sides of the garment 12. The flexible garment 12 provides a degree of constraint to the vibration motor 18 on one side and the body of the user provides constraint on the other side. This configuration can give rise to variations in the current required to drive the vibration motor 18 and / or variations in the strength of the vibrations experienced by the user, given the variations in the fit of the garment and other external influences.

[0047] For example, an object (such as a hand) contacting the outer garment 12 over one of the vibratory stimulation modules 14 may reduce displacement of the vibratory stimulation module 14, meaning less vibration energy is extracted. This may alter the current required to drive the vibration motor 18. In addition the object, if placed with sufficient pressure against the vibratory stimulation module 14, may affect the strength of vibrations experienced by the user, as it may begin to contribute to M, the target mass.

[0048] When the garment 12 is applied more tightly to the user the vibration stimulation modules 14 are more tightly constrained to the body of the user and may cause the body to contribute to M, the target mass, altering the strength of vibrations experienced by the user. This would also have the effect of reducing displacement, altering current requirements for a given speed of rotation of the vibration motor 18.

[0049] In empirical testing it has been observed that the above effects can have an impact on vibration frequency (due to changes voltage and therefore changes in velocity of motor spin), which is a critical requirement to provide accurate and effective levels of vibration.

[0050] The wearable neuromuscular stimulation system 10 addresses the above shortcomings by designing the housing 16 to focus the vibrations generated by the vibration motor 18 in a direction towards the respective anatomical site on the body of the user. The housing 16 comprises a base 20 on which the vibration motor 18 is securely mounted, and an upper enclosure 22 extending from the base 20 to surrounding and enclose the vibration motor 18. The base 20 is preferably planar in form and comprising a relative rigid material such as a polymer or the like. The base 20 is connected to the upper enclosure 22 by means of an isolating element in the form of a flexible gasket or skirt 24 which circumscribes and is substantially coplanar with the base 20. The skirt 24 may for example be over-moulded on the base 20. The outer perimeter of the skirt 24 is secured at or adjacent a lower rim of the upper enclosure 22, and in the embodiment illustrated is suitable captured within a keyway or channel 24 provided on an inner wall of the upper enclosure 22. The flexible skirt 24 is configured to allow the base 20 to undergo movement relative to the upper enclosure 22 in a direction substantially normal to the plane of the base 20. The flexible skirt 24 may be formed from any suitable material providing the necessary resilience to allow the base to oscillate relative to the upper enclosure 22 in response to operation of the vibration motor 18, and may for example be a silicone or rubber or the like.

[0051] By isolating the base 20 from the upper enclosure 22, the flexible skirt 24 significantly reduces dissipation or transfer of the vibration energy from the vibration motor 18 to the upper enclosure 22 from where it would be lost, improving efficiency of the vibration delivery to the chest of the user. In other words by reducing losses of the vibrational energy generated in directions that do not face towards the body the vibratory stimulation module 14 effectively focuses or optimises the vibrational energy directed towards and thus delivered to the body of the user. As the base 20 can vibrate substantially independently of the upper enclosure 22, the provision of the isolating skirt 24 also reduces the effects on vibration strength experienced by the user, and on power to maintain a constant vibration frequency, when the garment 12 is applied at different tightness levels and when objects such as hands make contact with the upper enclosure 22 through the outer shell of the garment 12. The flexible skirt may also be configured to provide a sealing function between the base 20 and the upper enclosure 22.

[0052] Referring now to Figures 8 to 12 there is illustrated a vibratory stimulation module, generally indicated as 114, according to an alternative embodiment of the invention. In this alternative embodiment like components have been accorded like reference numerals and unless otherwise stated perform a like function.

[0053] The vibratory stimulation module 114 again comprises a housing 116 having a base 120 on which is securely mounted a vibration motor 118, the housing 116 further comprising an upper enclosure 122 extending from the base 120 and surrounding the vibration motor 118. In this embodiment the housing 116 is cylindrical in shape but it will be appreciated that any other suitable shape may be employed. The base 120 and upper enclosure 122 are connected by an isolating element in the form of a pair of coil springs 124 which allow the base 120 to vibrate relatively independently of the upper enclosure 122. This again allows the vibratory stimulation module 114 to focus the vibrations from the vibration motor 116 towards the anatomical site directly below the base 120, reducing losses to the surroundings, in particular the upper enclosure 122. The pair of springs 124 are configured and / or arranged to allow the base 120 to undergo movement relative to the upper enclosure 122 in a direction substantially normal to the plane of the base 120. Referring in particular to Figures 11 and 12 the base 122 preferably comprises a stepped outer rim 140 which is seated about a corresponding radially inwardly extending shoulder 142 at the lower rim of the upper enclosure 122 in order to prevent separation of the base 120 and upper enclosure 122. A shock absorber in the form of a rubber or foam o-ring 144 is preferably provided between the rim 140 and shoulder 142, and may also provide a sealing function between the base 120 and the upper enclosure 122.

[0054] Referring to Figure 12 the garment 12 may comprise pockets 28 for receiving and retaining the vibratory stimulation modules 14, 114. The pockets 28 are preferably formed integrally with the garment 12, but may for example be comprised of a relatively rigid or inelastic dock 32 for receiving the vibratory stimulation module 14, 114, which dock 32 is secured to the adjacent, relatively elastic material of the garment 12. In this way the stiffer material will serve to isolate the vibratory stimulation module 14, 114 from tensile forces experienced by the garment 12 as it is tightened to fit the user. This isolation further acts to reduce the variability in forces applied to the exterior of the housing 16, 116 as hereinbefore described, thus reducing variability in the strength / amplitude of the vibrations applied to the user and reducing variations in power requirements as the system 10 attempts to maintain a consistent vibration frequency.

[0055] The vibratory stimulation modules 14, 114 may be provided with additional features to augment the functionality hereinbefore described. For example a pressure sensor (not shown) may be associated with one or more of the vibratory stimulation modules 14, 114 in order to allow the controller (not shown) to receiving feedback regarding the level of tightness of the garment 12. Such data may be useful for informing the user on the correct / optimum fit of the garment 12, allowing power adjustments to be made to the vibration motors 18, 118, or to provide an alarm signal when the garment 12 is overtightened, which may adversely affect operation.

[0056] The vibratory stimulation modules 14, 114 may also be provided with sound insulation (not shown) on the housing 16, 116, preferably on an interior surface thereof, in order to absorb any sound or vibration energy that may be directed away from the body.

[0057] The housing 16, 116 may also be at least partially formed from a resilient deformable material, or a shape memory material such as nitinol, which would allow the housing 16, 116 to deform in response to tension in the garment 12 without impacting on the operation of the vibration motor, and which would then return to the unstressed shape once the tension has been sufficiently removed. For example the housing 16, 116 may be generally rigid or semi-rigid but have an upper or surrounding layer of a resiliently deformable material.

[0058] In a wearable device, efficient consumption of power is paramount. By reducing the variations in the motor torque required to maintain the correct vibration frequency, it is possible to utilise a vibration motor 16, 116 that is optimally selected or designed to meet power requirements and maximise efficiency. This allows the use of a motor that is as small as possible and runs at correct speeds on the least power. In an exemplary embodiment the vibration motor 18, 118 operates on a 5V input and generates vibrations at 100 Hz [+ / - 10Hz] and at amplitudes of 25 G [+ / - 15G]. It will of course be understood that these are exemplary values which may be varied as required.

[0059] The wearable system 10 of the present invention provides a simple and low cost, yet reliable means of delivering neuromuscular stimulation therapy. The system 10 is compact, lightweight and discreet, allowing a user to wear the garment 12 in most conventional settings and thus enjoy the benefits of in-phase CWV at any time or place. The use of the vibratory stimulation modules 14, 114 to focus vibrations ensures that power consumption is optimised, extending the operating window of the system 10 and providing the user with the requisite therapy for prolonged periods of time.

Examples

Embodiment Construction

[0034]Referring now to Figure 1 of the accompanying drawings there is illustrated a wearable neuromuscular stimulation system for treatment of dyspnoea, generally indicated as 10, according to an embodiment of the present invention. The system 10 comprises a garment 12 which in the embodiment illustrated is in the form of a vest designed to be worn snugly yet comfortable on the body of the user, and preferably about the torso / chest region in order to monitor the breathing phase of the user. The term "breathing phase" is intended to mean a given portion of the breathing cycle of a user, being related to the lung volume of the user at that instance, the breathing phase typically reciprocating between the inspiration phase in which the lung volume is increasing, and the expiration phase in which the lung volume is decreasing, and which is however also intended to cover points or phases intermediate these two extremes. In the embodiment illustrated the garment 12 is of a minimalist desi...

Claims

1. A wearable neuromuscular stimulation system for treatment of dyspnoea comprising a garment configured to be worn about a body of a user; and at least one vibratory stimulation module secured to the garment and comprising a housing enclosing a vibration source mounted such as to optimise the delivery of vibration energy generated by the vibration motor in a direction towards the body of the user.

2. A wearable neuromuscular stimulation system according to claim 1 comprising one or more respiration sensors distributed about the garment.

3. A wearable neuromuscular stimulation system according to claim 1 or 2 in which the housing comprises a base on which the vibration source is mounted, and an upper enclosure surrounding the vibration source and secured to the base.

4. A wearable neuromuscular stimulation system according to claim 3 in which the vibratory stimulation module comprises an isolating element configured to reduce or eliminate the transfer of vibration from the base to the upper enclosure.

5. A wearable neuromuscular stimulation system according to claim 4 in which the isolating element is configured to facilitate vibrations from the vibration source to propagate in a direction normal to the base.

6. A wearable neuromuscular stimulation system according to claim 5 in which the isolating element comprises a flexible skirt connecting the base to the upper enclosure.

7. A wearable neuromuscular stimulation system according to claim 6 in which the flexible skirt circumscribes the base and the housing comprises a keyway into which an outer perimeter of the skirt is secured.

8. A wearable neuromuscular stimulation system according to any of claims 5 to 7 in which the isolating element comprises a spring.

9. A wearable neuromuscular stimulation system according to any of claims 3 to 8 in which the upper enclosure at least partially comprises a resiliently deformable material.

10. A wearable neuromuscular stimulation system according to any preceding claim in which the garment comprises a dock for receiving and retaining the at least one vibratory stimulation module and which is configured to mechanically isolate the vibratory stimulation module from compressive forces generated by tension in the garment.

11. A wearable neuromuscular stimulation system according to any preceding claim in which the garment comprises at least one pressure sensor configured to monitor the fit of the garment.

12. A wearable neuromuscular stimulation system according to claim 2 comprising a controller operable to drive the vibration source in response to feedback from the one or more respiration sensors.

13. A wearable neuromuscular stimulation system according to claim 12 in which the controller is operable to modulate the frequency and / or amplitude of vibrations generated by the vibration source.

14. A wearable neuromuscular stimulation system according to any preceding claim in which the vibration source comprises an eccentric rotating mass motor.

15. A wearable neuromuscular stimulation system according to any preceding claim in which the vibration source is operable to produce vibrations in a frequency range of between 50Hz and 150Hz, more preferably between 75Hz and 125Hz, most preferably 100Hz.

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