Originally Published MPMN May 2009

ENGINEERING SOLUTIONS: MDEA

Sleep Apnea System Helps Body Treat Self

Stephanie Steward

Watching several family members suffer from sleep apnea made Rajiv Doshi acutely aware of the drawbacks of available treatment options. As a doctor, he had a solid understanding of the pathophysiology of sleep apnea. As a caretaker, he went in search of a better solution.

“I felt that a simple yet efficacious device could be created that utilized the body’s own breathing to help heal itself,” says Doshi of the philosophy behind the Provent sleep apnea therapy system. Doshi began making initial prototypes by hand before founding Ventus Medical (Belmont, CA; www.ventusmedical.com). To make the device mass producible, he then turned to contract design and manufacturing firm Lunar (San Francisco; www.lunar.com) to help develop the valve technology that is the key to the device’s function.
This collaboration resulted in the creation of the single-use device for obstructive sleep apnea. Attached over the nose with a hypoallergenic adhesive, the device’s valve mechanism creates expiratory positive airway pressure to keep the user’s airway open while sleeping. The valve design enabled the engineers to keep the device small. “The pressure created by this unique valving system eliminates the need for the cumbersome and uncomfortable blower, tubing, and mask system used in continuous positive airway pressure (CPAP) therapy,” says John Edson, president of Lunar.
Traditional CPAP systems rely on an external air blower to create pressurized airflow, which can cause discomfort for the patient and can be expensive. Building on Doshi’s philosophy to use the body’s natural breathing to create an alternative to traditional CPAP therapy, Ventus and Lunar created the MicroValve so that upon inhalation, the valve opens and allows nearly unobstructed airflow. On exhalation, the valve closes and air passing through the nose is directed through two small air channels, creating the expiratory positive airway pressure required to maintain an open airway during sleep.
“Optimizing the design of the valve and the materials used was very important to achieve the desired inspiratory and expiratory resistances,” says Edson. The device has been clinically shown to provide statistically significant reduction in the apnea/hypopnea index, which measures the severity of sleep disruptions and frequency of decreased oxygen levels in the blood known as desaturations, he adds.
With the key component of the device designed, Lunar turned its attention to how to best attach the device to the user’s nose and make it comfortable to wear while sleeping—an objective that was already an improvement over most of the larger masks often associated with CPAP systems. After completing focus group research and testing, Lunar recommended using a hypoallergenic adhesive to adhere the device to the outside of the nose rather than developing the device so that it would be inserted deep into the nostrils. The design team also extensively researched nostril and nose anthropometric data and analyzed nose shape data studies to determine how to make the device one-size-fits-all. In order to accommodate the widest possible range of nostril and nose geometries, the team opted to use individual nostril components instead of a one-piece nose-covering device, Edson says.
Because the device is designed to significantly improve the user’s experience, it has been shown to improve patient compliance. “Provent therapy is easily sampled through prescribing physicians and represents a new option for those looking for an alternative to CPAP therapy,” Doshi says.

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