If you're unable to tolerate CPAP, there's a new sleep apnea treatment available but there are a lot of factors to consider before trying it. In this article, find out if Inspire is for you.
What is Inspire therapy for sleep apnea?
Inspire Upper Airway Stimulation (UAS) received FDA approval for moderate to severe obstructive sleep apnea (OSA) in 2014. In some ways, Inspire is similar to a cardiac pacemaker. Cardiac pacemakers stimulate the heart muscle to beat, but Inspire stimulates the hypoglossal nerve to maintain tone in the tongue muscles. The muscles of the tongue, particularly the genioglossus, are implicated in obstructive sleep apnea. During sleep, muscle tone decreases throughout the body, including the genioglossus, which causes the tongue base to fall back and promote obstruction in the upper airway. This is a major physical contributor to OSA. Interestingly, overweight and obese patients tend to have larger tongues due to fat deposition, and this may be one of the factors that link excess weight and obstructive sleep apnea.
With the Inspire sytem, an implantable pulse generator (IPG) is surgically placed in the subcutaneous (just below the surface of the skin) tissue by an otolaryngologist - also known as an ear, nose and throat surgeon or ENT. A stimulation lead runs from the IPG to the hypoglossal nerve, adjacent to the base of the tongue. A "sensing" lead runs in the opposite direction from the stimulation lead to lie over the chest wall. This lead allows the Inspire to monitor the respiratory cycle. The ENT who performs these procedures is required to have undergone special training in implanting the Inspire.
Once implanted, the patient is given a remote control to turn the device on when he or she goes to sleep. The Inspire works by gently stimulating the hypoglossal nerve and maintaining tongue muscle tone during the inhalation phase of respiration.
Is Inspire UAS the right treatment for you?
Who is a candidate for Inspire? Here are the criteria:
- Moderate to severe obstructive sleep apnea. Specifically, the patient must have had a sleep apnea test showing an AHI >20 but <65.
- Age 22 years or older.
- Drug-induced sleep endoscopy does not demonstrate complete concentric collapse at the level of the soft palate. What this means is that the Inspire surgical team will need to give you sedative medication until you are unconscious and then visualize your upper airway. If there is complete collapse at the soft palate level, then the Inspire would not be expected to work well for you because the system prevents collapse at the tongue level and doesn't affect the soft palate.
- Failure or intolerance of positive airway pressure PAP, i.e. CPAP or BPAP, to adequately treat OSA.
- Failure is defined as a residual AHI >20 despite PAP usage.
- Intolerance is defined as inability to use PAP > 4 hours per night for at least 5 nights a week OR unwillingness to use PAP after trying it.
How well does it work?
The study that led to the FDA approving Inspire for OSA involved 126 patients at 22 different sites. The results showed that, on follow-up one year later, more than half the patients that were treated with Inspire had a >50% reduction in their AHI (Apnea-Hypopnea Index, or average number of repiratory events per hour) and an AHI <20 on repeat sleep apnea testing. The results also showed that Inspire UAS patients had a 25% reduction in the oxygen desaturation index (ODI). ODI is the number of oxygen drops to a certain degree (usually the criteria is a 3 or 4% drop) per hour during the study. In other words, Inspire patients suffered fewer oxygen drops during the night. Intermittent hypoxia (low oxygen) is implicated in a number of the medical disorders that are associated with sleep apnea, including atrial fibrillation and heart failure.
Who should not get Inspire?
The FDA stipulated a number of contraindications that would rule out candidacy for Inspire. These are:
- Patients that already have an implantable medical device that may have a negative interaction with Inspire. These might include permanent pacemakers (PPMs), automatic internal defibrillators (AICDs), deep brain stimulators (DBS), and other devices. If you have one of these devices, or any other implanted medical device that utilizes electrical current, check with the doctor who manages this device before pursuing Inspire.
- Non-obstructive forms of sleep apnea. Patients with significant degrees of central or mixed (also called complex) sleep apnea would not be expected to benefit from Inspire. The FDA's criterion is central or mixed apneas representing <25% of abnormal breathing events on your sleep study .
- If you are pregnant or intend to become pregnant.
- Medical disorders that affect the neurological function that controls the upper airway. Potential diseases in this category include certain strokes (especially those involving the brainstem), spasmodic dysphonia, several forms of muscular dystrophy, and a number of neurodegenerative conditions such as ALS (Lou Gehrig's disease) and advanced Parkinson's disease.
- Patients who will need MRI. Inspire, like most implantable medical devices, is incompatible with MRI. Some patients require MRI scans for surveillance of their disease, such as certain cancers, and would not be eligible for Inspire.
- Anatomy that would impair upper airway stimulation (see discussion of soft palate collapse above).
- Inability to operate the Inspire remote control.
Like all procedures, Inspire has the potential adverse effects. Complications may include:
- Nerve damage or trauma, including paralysis of the tongue
- Damage to blood vessels adjacent to the device
- Discomfort from the electrical stimulation
- Autoimmune responses to the implant including allergy and rejection of the device
- Weakness or soreness of the tongue
- Scarring of tissues (fibrosis) that leads to damage of adjacent body structures when removing device
- Local irritation or swelling
- Impairment of throat muscle function including hoarseness, difficulty swallowing (dysphagia), and difficulty speaking (dysphasia)
- Dry mouth
- Restriction of tongue movement
- Tongue sores (abrasions) due to rubbing against sharp or broken teeth
- Failure of system due to part movement
What Other Alternative OSA Treatment Options Exist?
Certainly, pursuing Inspire for your obstructive sleep apnea is a big decision. For some patients who have had difficulty with traditional CPAP or BPAP, it may be a good treatment option. However, as a sleep medicine physician, I would recommend consideration for trials of other non-invasive OSA treatments prior to having a device surgically implanted in your body, such as:
- APAP (auto-CPAP) and auto-BPAP. These machines result in net lower pressures and may be tolerable when fixed-pressure CPAP and BPAP were not.
- Oral appliances for sleep apnea (mandibular advancement devices) such as the ApneaRx; these devices are considered first line for mild-moderate sleep apnea (AHI 5-30) and second line for severe sleep apnea (AHI >30). Make sure you get a device that is FDA-approved for obstructive sleep apnea and not just approved for snoring.
- Provent Sleep Apnea Therapy; this has the same recommendation for sleep apnea treatment as the ApneaRx (1st line for mild-moderate OSA and second line for severe OSA).
- A positional sleep apnea device may be helpful if the AHI is significantly greater in supine sleep compared with non-supine body positions.
- Winx Therapy System for Sleep Apnea; this device uses oral pressure therapy to stabilize the soft palate and tongue and prevent airway obstruction during sleep.
If you do pursue an oral appliance, Provent, a positional device, or Winx and are able to tolerate the treatment, you should then have a repeat sleep apnea study to verify the efficacy of the treatment.
Joseph Krainin, M.D., FAASM is the founder of Singular Sleep, the world's first online sleep center. He is a Fellow of the American Academy of Sleep Medicine and board-certified in both sleep medicine and neurology. He has been practicing medicine for over 10 years.
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