Obstructive sleep apnea (OSA) affects roughly 10 percent of the population (about 30 million people in the U.S.) and of those, 80 percent remain undiagnosed and untreated. Many patients who are diagnosed are not compliant with treatment, but a new device may offer some patients a new and effective alternative.
Currently, the gold standard for treatment of obstructive sleep apnea is the CPAP (continuous positive airway pressure) machine. Unfortunately, studies have shown that even among those who were diagnosed and recommended for treatment with CPAP, more than 30 percent of people with the severe form of the disease chose not to start CPAP treatment, and an additional 15 percent chose to discontinue (effective) treatment with CPAP after 10 months of use despite being advised of the possible negative consequences.
Stated reasons for poor compliance or stopping use of the machine include:
Discomfort of the mask
A sense of claustrophobia when wearing the mask
The noise when the machine is in use (problematic for the bed partner, too)
Given the problem with CPAP and the fact that other treatment options are often not effective, a company called Inspire Medical Systems, Inc. has developed a novel device used to treat OSA.. Recently approved by the FDA, it’s called the Inspire ® Upper Airway Stimulation
How does the Inspire ® device work?
The device consists of a small pulse generator the size of a quarter. It is implanted under the skin in the chest area through a minor procedure similar to implanting a cardiac pacemaker. Two wires come out of the Inspire device, and one has a sensor that is connected directly to the diaphragm. It senses the breathing pattern of the patient, and upon inspiration (breathing in) it sends a signal to the unit which then signals the second wire that is directed to the nerve that innervates the muscles of the tongue (the hypoglossal nerve). With a mild stimulus, this nerve causes the tongue muscles to contract and advance the tongue forward. This movement by the tongue widens the airway, allowing relief of the obstruction that would otherwise occur. The person inhales and exhales normally.
The physician can adjust the stimulation settings with an external programmer and the user can turn it on before going to sleep and turn it off upon awakening.
Who is the right patient for the device?
Individuals who fall into the PAP Failure group may be a good match for the device. These are patients who cannot tolerate the CPAP masks or are unwilling to use it consistently.
Who should not have the device implanted?
Implanting the device is contraindicated in certain patients, including
Any patient diagnosed with CSA or Central Sleep Apnea which means the source of the apnea is due to the brain not sending the signal to breathe;
Patients with OSA who are or intend to become pregnant;
Patients with diseases like Parkinson’s disease or individuals who have collapse of the soft palate. These patients have functional or anatomical abnormality that would compromise the function of the upper airway;
Any patient who may have an MRI in the future.
What is the current data on the Inspire device?
Current data suggest that this is a very promising therapeutic treatment for OSA. Unlike dental and other oral devices that are indicated for mild to moderate obstructive sleep apnea, this device was tested on patients with the more severe form of the disease. The “Stimulation Therapy for Apnea Reduction” (STAR) study[NOTE: When was study conducted? By whom?] that was the key to FDA approval showed that the implanted device decreased the Apnea Hypopnea Index (AHI) by 78 percent.
A new study on implantable devices for OSA presented this year at the meeting of the Associated Professional Sleep Societies followed patients over a three-year period and showed AHI decreased 84 percent.
Any interaction with the diaphragm risks the annoying but not serious consequence of hiccups. Secondly, similar to a cardiac pacemaker, once you implant the Inspire device, the two leads will likely become surrounded by scar tissue, which means it could be quite difficult to remove if the need arises later on. For example, if the patient loses a great deal of weight and his or her doctor believes that OSA would no longer be an issue, it might be problematic to remove the device.
Other new therapies in the pipeline
Another new device used for neuro stimulation, currently without a name, is made by ImThera ® and is undergoing clinical trials pending approval by the FDA. This device does not require a connection to the diaphragm and stimulates the tongue on a constant basis. It may limit the problem of hiccups or other stimulatory issues with the diaphragm, but at the cost of constant contraction of the muscles in the mouth.
In light of the severe consequences of untreated obstructive sleep apnea, any legitimate new therapeutic options are always welcome.
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Eli Hendel, M.D., is a board-certified internist/pulmonary specialist with board certification in Sleep Medicine. An Assistant Clinical Professor of Medicine at Keck-University of Southern California School of Medicine, and Qualified Medical Examiner for the State of California Department of Industrial Relations, his areas include asthma, COPD, sleep disorders, obstructive sleep apnea, and occupational lung diseases. Favorite hobby? Playing jazz music. Find him on Twitter @Lung_doctor.