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Devices for a good night's sleep

  • Article by: THOMAS LEE
  • Star Tribune
  • March 15, 2009 - 10:57 PM

Can't sleep? Try some voltage.

Inspire Medical Systems Inc. has begun a human clinical trial of an implantable device that uses low levels of electricity to treat obstructive sleep apnea (OSA), a serious breathing disorder that prevents a patient from sleeping. The Brooklyn Park-based start-up, a spin off from Medtronic Inc., is developing a system (Inspire II) that continuously monitors a patient's breathing during sleep and then sends regular bursts of electricity to open up restricted airways.

Apnex Medical Inc. of St. Paul is also conducting a clinical trial of a similar therapy. The company claims its technology is easier to implant and more reliable than Inspire II.

Both devices use neurostimulation -- electrical stimulation of the nerves -- to achieve the desired effect. Neurostimulation is a relatively new method to treat OSA, a condition that affects an estimated 30 million to 40 million people in the United States. OSA sufferers can't get enough oxygen during sleep, causing them to frequently wake up. Studies show that severe cases of OSA can even cause obesity, high blood pressure and cardiac arrest.

Investors say OSA is a vastly underserved market. For one thing, many people don't necessarily know they have it because the symptoms are seemingly harmless: snoring, daytime drowsiness. In 2006, only 17.4 percent of patients with moderate to severe cases of OSA received treatment, according to Canaccord Adams Investment Research. The group estimates the global sales of sleep-therapy devices will hit $3 billion in 2010 compared with $1.5 billion in 2006.

However, one medical expert says that the neurostimulation technology still needs additional testing and that some existing therapies are cheaper and probably more effective.

The most common and effective treatment for OSA is Continuous Positive Airway Pressure (CPAP), a mask-like device that keeps airways open by blowing air into a patient's nose and mouth during sleep. But many patients don't like the masks because they're bulky and unappealing, said Dr. John Trusheim, a neurologist and co-director of the sleep lab at Abbott Northwestern Hospital.

A 2005 study published in the New England Journal of Medicine "demonstrated an increased risk of stroke and death from any cause among [OSA] patients despite the administration of various therapies," including CPAP.

Part of the reason, the study says, is patients don't use CPAP properly and other treatments don't work.

Born-again device

Inspire II's clinical trial represents a turning point for the company given its history, said CEO Tim Herbert.

"This is a real significant milestone," Herbert said. "It's really the restart of the project."

Medtronic, best known for its heart pacemakers, first started developing the technology in the early 1990s. But the original Inspire device had design problems: The leads (insulated wires) were not reliable. The system's sensor, which monitors breathing by measuring lung pressure, was located too close to the heart; signals from the heart were interfering with the sensor.

Researchers designed a more robust lead and moved the sensor to the side of the body. Acting on data from the sensor, an impulse generator stimulates the hypoglossal nerve, which instructs the tongue to move forward. The movement opens up the airway.

But Medtronic eventually shelved the project and in 2006 spun off the business as Inspire.

At the time it lost interest in Inspire, "Medtronic didn't have a presence in the sleep market," Herbert said. But Medtronic now "recognizes the value of the technology and the necessity for the continued development of the therapy. It was aggressive in identifying an alternative approach resulting in the spinning off of Inspire."

(Last year Medtronic purchased Restore Medical Inc., another local start-up that is also developing devices to treat snoring and OSA.)

Medtronic kept a minority stake in Inspire and also does some contract manufacturing for the start-up. Dr. Glen Nelson, a former Medtronic vice chairman, joined Inspire as its chairman. Those factors helped Inspire raise around $6.2 million in venture capital from firms such as Kleiner Perkins Caufield & Byers and U.S. Venture Partners, both based in Menlo Park, Calif.

"With Medtronic as an investor, we felt comfortable" with the technology, said Dana Mead, a Kleiner partner. Medtronic's involvement "would give me more confidence." Mead also said he liked the design changes and the Medtronic talent now working at Inspire.

Eventually, 30 patients around the world will be implanted with Inspire II, including at the Minnesota Regional Sleep Disorders Center at Hennepin County Medical Center. Herbert said he hopes to start a large-scale pivotal trial in the United States in 2010, the last step before the company seeks approval from the Food and Drug Administration.

Crosstown competition

But Inspire has competition. Apnex is developing a similar device to stimulate the hypoglossal nerve. The company recently raised $16 million from New Enterprise Associates, Polaris Venture Partners, and Mike Berman, a prominent local medical device entrepreneur.

Apnex CEO Bob Atkinson said they had been watching Medtronic's work for years. The company decided to develop its own system in response to the design flaws that plagued the original Inspire device.

In addition to sturdier leads, Atkinson said Apnex's breathing sensor is more reliable because it uses a technique called "bio-impedance,'' which measures the lung's resistance to an electrical current. When a person inhales, the lungs fill with air, making it harder for an electrical current to pass through. Insight II, by contrast, monitors lung pressure.

Stimulating the hypoglossal nerve makes sense, said Trusheim of Abbott Northwestern, although "it would be hard for neurostimulation to supplant CPAP in terms of cost and effectiveness." Trusheim is not connected to either company.

A CPAP mask costs about $1,000. Inspire's Herbert says he does not yet have enough information but estimates the entire cost of the therapy, including the device and surgery, would approach $30,000.

And like any pacemaker, the device might interfere with MRI scans, Trusheim said.

Still, even 10 percent of OSA patients using neurostimulation would be an impressive number, he said.

"It's a big market," Trusheim said.

Thomas Lee • 612-673-7744

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