GB2572421A

GB2572421A - Titration of mandibular advancement device

Info

Publication number: GB2572421A
Application number: GB1805218.3A
Authority: GB
Inventors: Wiffen Richard; Higginbottom Simon; Thomas Joshua
Original assignee: ARIA HEALTHCARE Ltd
Current assignee: ARIA HEALTHCARE Ltd
Priority date: 2018-03-29
Filing date: 2018-03-29
Publication date: 2019-10-02
Also published as: GB201805218D0; WO2019186122A1

Abstract

The invention is concerned with the titration of a mandibular advancement device 10 used for the treatment of obstructive sleep apnoea and related snoring. The invention relates to the processing of audio data captured by a microphone 34, which is placed by the bed during sleeping, to derive snoring data using signal processing logic 36. Titration logic 38 then receives the snoring data and uses it to determine a required setting or adjustment to the mandibular advancement device 10 for it to be effective in the alleviation of the snoring. Information concerning the necessary adjustment/settings of the mandibular advancement device 10 is then output through an interface 40 for implementation. The output is preferably either delivered to a user in the form of adjustment/setting directions displayed on a screen, or to control a device capable of automatic adjustment of the mandibular advancement device 10. The recording of the snoring is preferably carried out using the microphone of a smartphone, with the smartphone running an application which performs both the processing of the snoring data and the communication of information concerning the necessary adjustment of the mandibular advancement device, preferably through displaying adjustment instructions on the screen of the phone.

Description

TITRATION OF MANDIBULAR ADVANCEMENT DEVICE

The present invention is concerned with titration of a mandibular advancement device.

Mandibular advancement devices are used to treat obstructive sleep apnoea (in US English, apnea) and snoring. Obstructive sleep apnoea will be referred to hereinafter as OSA.

Snoring and OSA are associated conditions. In the great majority of cases OSA is accompanied by snoring and snore like sounds associated with restrictive breath. Snoring is caused by air turbulence resulting from the vibration or disruption of the tissue and structure of the upper airway. Such disruption of the tissue and structure of the airway may result in obstruction or even closure of the upper airway characteristic of OSA. In the majority of cases reductions or increases in frequency and intensity of snoring will correlate with increases or reductions in OSA.

Snoring is often a source of sleep disruption to the bed partner of the snorer which can be deleterious to health and to personal relationships. In the long term snoring, even when not immediately associated with OSA, may cause inflammation, swelling and damage to the tissue of the upper airway that may in turn encourage the development of OSA.

OSA has a range of deleterious effects on the health of the sufferer. It can for example reduce the flow of air to the lungs, causing an increase in the partial pressure of CO2 and a consequent decrease in O2 levels and increase of CO2 levels in the blood and in bodily tissues. Blood pH level is reduced (a condition referred to as acidosis) and the quality of sleep, as well as other bodily functions, are impaired.

OSA sufferers often suffer from fatigue and other effects of sleep deprivation, such as napping in the daytime. Concentration can be seriously impaired and it is thought that OSA may be a causative factor in a significant proportion of road accidents.

Numbers of patients presenting to clinicians with chronic snoring and OSA have become large. A factor in this increase may be the increasing level of obesity in western populations, which is a causative factor in both conditions.

One form of therapy for OSA involves the use of a CPAP (continuous positive airway pressure) device, which applies a moderate air pressure above ambient to the airways of the sufferer, often through a mask worn over the nose and mouth. In modern CPAP machines the pressure applied is automatically controlled (titrated) based on one or more factors which may include the rate of exhalation of air. The air supplied is typically humidified to avoid drying the airways. CPAP is recognised to be effective in reducing OSA and snoring where the patient complies with the treatment regime, but patients are naturally averse to wearing a mask in bed, especially as the humidified air can make the mask and face uncomfortably damp. Hence rates of compliance with CPAP treatment regimes are known to be low. Also the high incidence of these conditions makes the provision of CPAP on a broad basis financially and practically problematic.

An alternative approach to treatment of OSA and snoring involves the use of a mandibular advancement device. An example is provided is W02017/006129 (Aria Healthcare Ltd.). Such devices are worn in the patient's mouth and serve as their name implies to maintain the mandible in a somewhat advanced position -that is, the mandible is somewhat forward of the position that it might otherwise adopt. This tends to expand the upper airway forwardly, helping to restore its cross section despite obstructions resulting for example from a tongue which is somewhat enlarged due to obesity. It is also thought that advancing the mandible may apply tension to the muscles connected to the airway and thereby increase airway patency. There is extensive clinical evidence that mandibular advancement devices can be an effective treatment for OSA. Patient compliance is thought to be less problematic with these devices than with CPAP because they prove less inconvenient and uncomfortable to many patients. Mandibular advancement devices can also be less costly to manufacture than CPAP apparatus.

Where a patient is suitable for treatment using a mandibular advancement device, correct titration of the device will reduce both snoring and OSA and a patient's motivation or objective in using this form of therapy may be either to reduce snoring or to limit or eliminate OSA or a combination of these two.

Despite their advantages, mandibular advancement devices are often not the first form of treatment provided by clinicians. ForOSA,CPAP istypicaIly preferred. It is thought that challenges involved in the early use of mandibular advancement devices by the patient and in their titration (adjustment) currently stand in the way of their more widespread adoption.

Titration involves, in particular, adjustment of the extent to which the mandible is advanced or in some cases, simply arresting the mandible from falling backwards. In the device described in W02017/006129 this adjustment is made using a screw mechanism which moves a lower plate of the device forward/backward with respect to an upper plate. The optimal degree of advancement is a compromise. Too little advancement renders the device ineffective. Excessive advancement increases discomfort and could prove injurious. At present effective titration requires intensive management by a clinician and can require several interactions between patient and clinician over a period of time. Typically it might involve having the patient wear the AD for a few nights initially on a neutral setting, to determine whether the patient is able to tolerate the device, which can initially cause excess salivation and other adverse reactions. If this trial is encouraging then the clinician may next adjust the device to advance the mandible with a view to actually alleviating the symptoms. This adjustment may be repeated based e.g. on patient feedback. But such feedback is not necessarily a good guide to the effectiveness of the device. A patient does not know what goes on while he/she is asleep and cannot directly judge whether snoring or OSA are being prevented. The clinician may suggest that the patient spends a night in a sleep laboratory, where the relevant condition can be closely monitored. But this is an expensive resource in itself. The patient's sleep pattern is likely to be affected by the unfamiliar surroundings. Snoring and OSA vary from night to night so data from a single night's observation is unreliable. An effective titration process may require trial of the device at multiple settings, but this is not possible in a single night in a sleep laboratory, and the expense of multiple nights' observation is not sustainable.

It is also recognised that even where titration is done accurately the determination is time limited. Changes in the individual patient, particularly changes in weight, either weight gain or loss, and the process of ageing may necessitate changes to titration. Muscle tension induced by mandible advance may dissipate over time as the body adjusts and the muscles stretch and relax.

Because of such problems, and the significant additional costs associated with more intensive clinician supervision, the tendency is for clinicians to prescribe a self-titrating CPAP instead of a mandibular advancement device.

Additionally a mandibular advancement device may be used by a person solely for the purpose of reducing his or her snoring, often motivated by a desire to reduce disruption to a bed partner. Such purchases are frequently made without recourse to the support and involvement of a clinician. Titration in such circumstances is generally reliant on the subjective perception of the bed partner. Such perceptions can be wildly inaccurate as they are influenced by the nonsnoring bed partner's own sleep quality and state of mind.

The failure of an individual to titrate a mandibular advancement device optimally may lead the individual to conclude wrongly that the device does not work for them due to insufficient device and consequent jaw advancement or because is to uncomfortable or injurious due to excessive advancement. Uncertainty as to whether the device has been optimally adjusted may induce anxiety which has a psychological effect on sleep and wellbeing. The goal of rapid optimal adjustment of a mandibular device over the first nights and weeks of use is therefore a critical factor in an individual's continued effective use of the device.

There is a need for an improved mode of titration of a mandibular advancement device. The invention provides an apparatus, system, application and method according to the appended claims.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:Figure lisa view from above and one side of a mandibular advancement device suitable for use in the present invention, which belongs to the prior art;

Figures 2a and 2b show the mandibular advancement device from one side, the degree of advancement of a lower tray being different in the two views;

Figure 3 illustrates usage of a system embodying the present invention;

Figure 4 is a set of graphs demonstrating reduction in snoring achieved using a mandibular advancement device; and

Figure 5 is a set of graphs demonstrating improvement in the level of blood oxygen in a sleeper using the mandibular advancement device.

Figures 1 and 2 are reproduced from W02017/006129. The illustrated mandibular advancement device 10 will be briefly described herein in order that its use in relation to the present invention can be clearly understood, but for greater detail as to its construction and function, and for examples of other devices which could be used in the present invention, the attention of the reader is directed to W02017/006129. Also W02017/006129 is hereby incorporated by reference.

The mandibular advancement device 10 has:

an upper tray 12 for receiving the upper dental arch of the wearer; a lower tray 14 for receiving their lower dental arch; and adjustment mechanisms 16a, 16b for adjusting advancement of the lower tray 14 relative to the upper tray 12.

The upper and lower trays 12, 14 are shaped to engage with the teeth and may have contact surfaces formed by thermo-formable material, in order that they can be customised for a specific wearer, a process colloquially referred to as boil-and-bite. Other embodiments may use trays of a different form. In the present example the upper and lower trays 12, 14 are linked through flexible connecting portions 18a, 18b. Adjustment mechanisms 16a, 16b each comprise an adjustment screw 20 received in a lug 22 carried in this example by the lower tray 14 and threadedly engaged in it so that turning the adjustment screw 20 causes its head 24 to be advanced or retracted. The head 24 abuts an inner surface of the corresponding connecting portion 18. Comparing Figure 2a with Figure 2b it will be apparent that the position of the head 24 determines the position of a radiussed bend 26 in the connecting portion 18, and so determines the advancement of the lowertray 14, which is more advanced in Figure 2b than in Figure 2a.

This particular mandibular advancement device 10 is presented by way of illustration and example. The invention can be implemented using other types of adjustable mandibular advancement device.

The present embodiment makes use of the microphone of a computing device to monitor snoring and, on the basis of the resultant snoring data, to provide a user with directions for titration of the mandibular advancement device 10. The process can be thought of as a control loop with feedback, as Figure 3 is intended to illustrate.

Box 30 in Figure 3 represents a computing device which takes the form of a smartphone in the present embodiment although any suitable computing device could be used in another embodiment of the invention, including without limitation a tablet, a microphone-equipped laptop or desktop, or a PDA. The use of a compact portable device such as a smart phone is however especially preferred and computing device 30 will hereinafter be referred to simply as the phone. It has been found that the audio recording fidelity of modern smartphones makes them very well suited to the present invention.

The phone 30 runs an application (computer program) which monitors sound data of a person 32 wearing the mandibular advancement device 10 and in response provides directions for its adjustment. When the person goes to bed, he/she places the phone 30 nearby, e.g. on a nightstand (not shown) next to the bed, with the application running. The application monitors its environment using sensors including at least a microphone 34, which typically will be the on-board microphone of the phone 30. In this way a signal representative of sound in the vicinity of the person 32 is obtained. This signal may include snoring by the person 32, but it may also include any of a wide range of other ambient noises.

Signal processing logic 36 is implemented by the application to discriminate between snoring/resistive breath and other noises. The word snoring as used throughout the present description and claims includes the harsh grunt or snort-like sounds colloquially referred to by that word but also other sounds indicative of resistance or partial obstruction of the airway. Suitable signal processing techniques are known in the art and the details will not be described herein. Artificial intelligence methods may be used. These methods may involve machine learning. Neural nets or Gaussian methods may be used. In the present embodiment the signal processing logic 36 serves to determine in real time whether the person 32 is snoring or not.

The output of the signal processing logic 36 comprises snoring data, which is to say data relating to snoring ofthe person 32. The form of this data may be very simple, such as a record of total time spent snoring in a night, or it may be more complex, including e.g. number and time of snores, times of commencement and cessation of snoring, data relating to amplitude, sounds indicative of apnoeic events or airway resistance.

The sound data is supplemented by a matrix of other data supplied or obtained from the person 32 such as gender, age, weight, medical conditions, teeth and jaw information, levels of discomfort or salivation associated with use of the device, variations in sleep pattern and lifestyle that impact on snoring inter-night and intra-night variability.

The snoring data is supplied to titration logic 38 which determines whether adjustment of the mandibular advancement device 10 is required and if so what its new setting should be. This determination is supplied to user interface logic 40 which provides the person 32 with directions for adjustment ofthe mandibular advancement device 10. These directions may for example be displayed on the screen of the phone 30. In the simplest terms, the titration logic 38 is able to respond to excessive snoring by directing that the mandibular advancement device 10 be adjusted to further advance the mandible of the person 32. In the absence of snoring, it may be appropriate to reduce advancement ofthe mandible until a suitable setting is reached.

The adjustments are to be made by the person 32, and the following night the mandibular advancement device 10 - adjusted as directed - is once more worn by the person, whose snoring is once more monitored by the application. In this way the control loop is closed.

The phone 30 may output snoring data and a matrix of information provided by the user and may also receive snoring data and a matrix of information collected from other users of the application to and from a remote server (not shown in Figure 3). It may do this through a wide area network which may be the internet, using for example a wireless connection to a domestic router. Operation of numerous such individual systems can thus provide a set of data representing the outcome of numerous uses of the mandibular advancement device 10 at a range of settings by a range of users with different physiological and demographic characteristics. This data can thus be used to refine the titration logic 38, which may itself be implemented using suitable statistical and/or machine learning techniques. Thereby titration logic 38 may make its directions to an individual based on the individual's snoring data and matrix of information, using logic refined through analysis of the outcomes of that direction on multiple users with similar snoring data and matrix information.

In the illustrated embodiment the titration logic 38 is implemented within the application running on the phone 30. Changes to the titration logic 38 following its refinement would be made through updates of the application. But in other embodiments the snoring data may be supplied through the wide area network to a remote server (not shown) in which the titration logic is implemented, the output of the titration logic then being returned to the phone 30 through the network.

The titration logic 38 may receive data derived from an additional sensor beyond the microphone 34, or from more than one additional sensor. In particular, the system may use a sensor responsive to air flow due to breathing. A suitable sensor may be worn on the upper lip of the person 32 to detect air flow through the nose. A surface acoustic wave sensor may be used for this purpose. To avoid any need for a physical connection to the phone 30, which would inconvenience the person 32 during sleep, the sensor or sensors may output their data through a wireless link, which may be a digital link and may for example use the Bluetooth® communications standard. The reduction of airflow caused by OSA may thus be detected in a direct manner as a basis for titration of the mandibular advancement device 10.

The present invention provides a highly effective means of titrating the mandibular advancement device which can be implemented without expensive equipment and without the inconvenience for the user in for example sleeping in a lab. It can be used to reduce or possibly in suitable cases to eliminate the involvement of a clinician in the titration process, with huge attendant cost savings. Networked versions of the device can compile objective quantitative data usable to refine the titration process.

Figure 4 represents audio data for a single user obtained using a smart phone, each of the six graphs being obtained on a different night. The top three graphs were obtained on nights when the subject did not wear a mandibular advancement device. The bottom three show the results when the device was worn. A marked reduction in snoring is apparent during use of the mandibular advancement device.

Figure 5 represents blood oxygen levels of a sleeper without a mandibular advancement device (top two graphs, each representing a respective night) and with it (bottom two graphs). It is apparent that during use of the device the level of blood oxygen was largely maintained above the desirable level of 94% saturation, while without the device it frequently fell below that level.

The embodiments described above serve as examples and not as limitations on the scope of the invention of the appended claims. Numerous variations are possible. For example while there must be some form of interface to enable the mandibular advancement device 10 to be adjusted, this need not necessarily function by providing directions to a user. It would be possible instead to configure the device 10 to be capable of automatic adjustment under the direction of the application, the interface in this case possibly being a wireless connection from the computing device to the device 10.

Claims

1. An apparatus or system for titration of a mandibular advancement device comprising a microphone for sensing sound in the vicinity of a person, signal processing logic for processing the signal from the microphone to compile snoring data, titration logic for determining a required setting or adjustment to the mandibular device using the snoring data, and an interface for outputting the required setting or adjustment to be implemented upon the mandibular advancement device.

2. An apparatus or system as claimed in claim 1 which comprises a computing device running an application and having an onboard microphone.

3. An apparatus or system as claimed in claim 2 in which the computing device is a smart phone, tablet, laptop computer or desktop computer.

4. An apparatus or system as claimed in any preceding claim configured to compile snoring data overnight and to output the required setting or adjustment in the morning.

5. An apparatus or system as claimed in claim 4 configured to compile snoring data over a number of nights and to successively refine the setting or adjustment of the mandibular advancement device based on the resultant snoring data.

6. An apparatus or system as claimed in any preceding claim in which the titration logic is configured to respond to snoring data indicative of excessive snoring by outputting a setting or adjustment which increases advancement of the mandible when the mandibular advancement device is in use.

7. An apparatus or system as claimed in any preceding claim in which the signal processing logic serves to discriminate between snoring and other sounds.

8. An apparatus or system as claimed in any preceding claim which further comprises a sensor configured to be worn by the person and to detect airflow associated with breathing, the titration logic being able to take account of data derived from the sensor as well as the snoring data in determining the required setting or adjustment.

9. An apparatus or system as claimed in any preceding claim in which the titration logic determines the required setting or adjustment to the mandibular device using the snoring data and a matrix of other information provided by the person.

10. An apparatus or system as claimed in any preceding claim in which the titration logic is based upon the snoring data and a matrix of other information provided by the person and the snoring data and a matrix of other information provided via a remote data server by other users of the apparatus or system.

11. An application for titration of a mandibular advancement device, the application being suitable for running on a computing device to cause it to:

sense sounds through a microphone;

process the signal from the microphone to compile snoring data;

determine on the basis of the snoring data an adjustment or setting for the mandibular advancement device; and output the adjustment or setting for implementation in the mandibular advancement device.

12. An application as claimed in claim 11 which is for running on a smart phone.

13. An application as claimed in claim 11 or claim 12 configured to compile snoring data overnight and to output the required setting or adjustment in the morning.

14. An application as claimed in claim 13 configured to compile snoring data over a number of nights and to successively refine the setting or adjustment of the mandibular advancement device based on the resultant snoring data.

15. An application as claimed in any of claims 11 to 14 configured to respond to snoring data indicative of excessive snoring by outputting a setting or adjustment which increases advancement of the mandible when the mandibular advancement device is in use.

16. An apparatus or system as claimed in any of claims 11 to 15 in which processing of the signal from the microphone comprises discriminating between snoring and other sounds in that signal.

17. A system for alleviation of snoring and/or sleep apnoea comprising (a) an apparatus or system as claimed in any of claims 1 to 9 or an application as claimed in any of claims 9 to 16 and (b) an adjustable mandibular advancement device.

18. A method of titration of a mandibular advancement device comprising a sensing sound in the vicinity of a person using a microphone associated with a computing device, processing the signal from the microphone to compile snoring data, determining a required setting or adjustment to the mandibular device based upon the snoring data, and an interface for outputting the required setting or adjustment to be implemented upon the mandibular advancement device.