TTP Ventus, UK-based developer of Disc Pump, a tiny, quiet, and very efficient pump, and Sommetrics, US-based creator of aerSleep negative-pressure treatment system for obstructive sleep apnea, teamed up to develop the slimmed-down tetherless aerSleep system. aerSleep has just recently been approved for marketing to patients in Canada.
Obstructive sleep apnea is caused by airway collapse during sleep, resulting in breathing impairment and long-term health complications. It has been estimated that there are 22 million sufferers in the US alone. Conventional treatment involves continuous positive airway pressure, where sufferers wear a face mask tethered to a bedside air pump, which pumps air into their lungs all night. While this treatment is effective for most sufferers, for many the mask can be uncomfortable, and the pump is bulky and loud, while the tether can make sleep difficult.
In lieu of using positive air pressure, Sommetrics was in the process of developing a negative pressure system that can draw a vacuum on the outside of the throat, helping to shift the throat tissue and tongue forward, thereby keeping the airway open. They had planned to use a bedside vacuum pump and tether – a major disadvantage of the conventional positive-pressure system. However, upon meeting with TTP Ventus, Sommetrics realized that their Disc Pump, a miniaturized pump that operates silently, could be the key to creating a tetherless, battery-operated, and completely integrated unit. The result is aerSleep.
You can see a video about the product and the collaboration here:
Medgadget asked Tom Harrison, Business Development Manager of TTP Ventus, and Jerry Aarestad, Co-Founder of Sommetrics some questions about the concept and their collaboration.
Conn Hastings, Medgadget: Can you give us some background on obstructive sleep apnea and the long-term health issues it can create?
Jerry Aarestad, Sommetrics: Obstructive sleep apnea, also known as OSA, occurs when a person’s upper airway is blocked by the tongue and other soft tissue while sleeping, reducing or even stopping airflow. The condition afflicts more than 20 percent of adults worldwide. In the U.S., only 20 percent of sufferers are properly diagnosed by a sleep physician, and of those only 10 percent are compliant with the prescribed CPAP (continuous positive airway pressure) system for treatment. There are a variety of reasons why patients might choose to not use CPAP, most of them having to do with an inability to tolerate the system. In short, the result is that only a small percentage of sufferers are being treated and yet, left unchecked, OSA leads to fatigue, reduced cognitive function, and is linked to diabetes, heart disease, and other serious health conditions.
Medgadget: Please tell us about the current treatments for obstructive sleep apnea, and their limitations.
Jerry Aarestad: Current treatments range from CPAP and dental appliances to upper airway surgery and nerve stimulation. This is not a comprehensive list, of course, and each treatment has its own limitations.
Tom Harrison, TTP Ventus: The most prevalent treatment, CPAP, is effective in opening the airway, but it requires users to wear a mask over their mouth and/or nose and has them tethered to a beside pump via a hose. So, whilst the fundamental airway collapse is addressed, users pay a price in terms of comfort and “freedom” – i.e. the ability to turn and roll during sleep – which ultimately impacts long term compliance rates. For those patients who can’t tolerate CPAP – as many as 50% – there are other options, but all with their downsides. For example, mandibular advancement devices open the airway by moving the lower jaw forward relative to the rest of the head. Whilst this approach can work for some individuals, it can also lead to joint pain in the jaw.
Medgadget: How does aerSleep differ from other products for obstructive sleep apnea?
Tom Harrison: The neat thing about aerSleep is how Sommetrics has flipped the solution around versus CPAP: instead of applying positive pressure internally, they apply negative pressure externally. It’s a great example of a simple-yet-brilliant way of approaching an old problem in a new way. For traditional CPAP systems to apply positive pressure within the airway, a blower with a high air flow capacity is required; this is necessary to keep pace with the peak air flow as patients breathe in. In being worn on (and applying therapy to) the soft tissues of the neck, aerSleep operates independently of the breathing path. This means that a smaller, less powerful pump can be used. Lower power in turn means that the device can be run all night from a battery, opening the possibility to create a cordless device in support of the ambition to make the product wearable.
Jerry Aarestad: We believe that providing a mask-free solution that is silent, compact, highly transportable, does not require extensive cleaning, and that provides untethered mobility enabling people to sleep on their back, sides, and in some cases their stomach, is a solution that is unique and game-changing. aerSleep is the first solution of its kind to treat obstructive sleep apnea.
Medgadget: Is Disc Pump a key component in the device? How did it affect the design?
Tom Harrison: From our perspective, the Sommetrics device is an excellent example of how the unique feature set of our pump can enable entirely new product categories. Disc Pump is unusual for a pump in being silent and vibration-free. Clearly these features are important for a sleep application, particularly where the product is a wearable device. Aside from that, for its size the pump packs a punch in terms of the pressure and flow it delivers, which helps manage battery size. Being compact also makes the job of integrating it into a wearable that much easier.
Jerry Aarestad: Disc Pump is most certainly a key component of the aerSleep system. CPAP therapy is delivered to the mask with an air hose, which tethers the patient to the bedside device. The moment we saw Disc Pump, we quickly recognized its liberating feature of being able to silently deliver therapy without any tether. We have integrated our therapy collar and Disc Pump into one unit and now have a smaller, very portable aerSleep product.
Medgadget: So how does Disc Pump work to maintain a vacuum? Does it run continuously or intermittently?
Tom Harrison: The pump operates on a principle of ‘resonant acoustics’. To generate pressure, we wobble a piezo-electric actuator up and down within the pump. The motion is tiny; the total displacement is only a fraction of the width of a human hair. However, by using a specially-designed acoustic cavity we can set up a standing wave in the air within the cavity, allowing us to create very high pressures. We then rectify this pressure wave with an ultra-fast passive valve.
In terms of how the pump can be operated, Disc Pump is designed to work in both continuous and intermittent regimes; either may be appropriate depending on the requirements of the application. When run continuously, the amplitude of the drive signal can be adjusted to determine the pressure and flow the pump generates. A differentiating characteristic of the pump is how precisely it can be controlled in this way; pressure can be held within a few Pascals of a set point, for example.
The response time of the pump is fast; it will turn on and off in just a couple of milliseconds, where a traditional motor-driven pump might take hundreds of milliseconds. This fast response time means that intermittent operation is also possible, which can help to conserve power and extend runtime in applications where the pump is battery powered.
Medgadget: Disc Pump can run silently, which is a clear advantage in a device people use during sleep. How does the pump design enable this silent operation?
Tom Harrison: Traditional pumps tend to operate between a few hundred and a few thousand cycles per minute. Disc Pump cycles 21,000 per second, or around 1.26 million cycles per minute. This frequency is above the range of human hearing and so whilst the pump does emit sound, it is inaudible to us. The trick to enabling the pump to cycle this quickly is in the combination of its piezo-electric actuator and ultra-fast passive valve.
Product page: aerSleep…
More about Disc Pump…