As the first FDA-cleared, fully implanted neurostimulation device for obstructive sleep apnea becomes available in additional cities throughout the United States, Sleep Review provides guidance on how to screen patients for this therapy.

Inspire Medical System Inc’s implantable device for the treatment of obstructive sleep apnea (OSA) is the first treatment of its kind cleared by the Food and Drug Administration (FDA). While it is designed for patients who can’t be treated with traditional clinical methods, it isn’t a panacea.

In fact, both the FDA and Inspire Medical have developed guidelines designed to help clinicians make sure the patient fits the medical criteria that are needed for Inspire Upper Airway Stimulation to be an appropriate therapy. While the criteria resemble the screening patients will undergo for the traditional treatments, Inspire screening is more comprehensive—evaluating everything from sleep hygiene to patient anatomy.

Developing the Criteria

Going hand-in-glove with the development of Inspire, which requires an outpatient procedure by an otolaryngologist, the company, with guidance from the FDA, also developed criteria that clinicians need to follow to find the most suitable patients for the therapy. Because the therapy is invasive, it can’t be a first line treatment.

“The patient has to have documentation that they have tried CPAP for at least 3 months,” says Quan Ni, PhD, VP of research at Inspire Medical. Ni led the team that developed the criteria following the clinical trials.

The patients in the original study group had, on average, been diagnosed with OSA at least 5 years prior to undergoing Inspire therapy and had an average age of 55.

In addition to having been unsuccessfully treated with CPAP—which has been documented by a treating physician—potential patients must have an apnea-hypopnea index (AHI) of between 20 and 65. The FDA has set no contraindication for obesity, but Ni says that Inspire recommends that patients have a BMI below 32.

Candidates for Inspire also must undergo a sedated endoscopic procedure during the evaluation process, allowing an ENT physician to observe the patient’s anatomy in a sleep-like state. “We’re looking for a very specific anatomy during the procedure,” Ni says. “We’re looking for a complete concentric collapse at the level of the soft palate. If the patient has a lateral wall collapse in addition to anteroposterior collapse of the soft palate, that’s a contraindication for Inspire.” Ni adds that about 10% to 20% of Inspire candidates cannot get the device due to this contraindication.

Inspire in Action

Inspire_Sleep_Remote

Patients activate Inspire therapy with a remote that gives them about 30 minutes to fall asleep.

Since it was approved for use by the FDA in 2014, hundreds of patients have benefited from the therapy. Ryan Soose, MD, an ENT and director of the University of Pittsburgh Medical Center (UPMC) Division of Sleep Surgery, has implanted about 50 of the devices with good results.

Prior to implanting the device, Soose determines that the patient’s CPAP or dental device is, in fact, not helping to treat OSA. “CPAP, the standard first line therapy, is a robust treatment, but about 50% to 60% of patients don’t use or can’t use it. We troubleshoot the CPAP [device] and see if the patient can actually use it effectively,” he says.

Soose says that patients who have used dental devices to treat their OSA may have changes in their teeth or bite patterns because of these devices that then make the dental devices difficult or ineffective to use.

Once he determines the traditional therapies are, indeed, not working for the patient, he has the patient undergo a traditional sleep study, evaluates the patient’s body weight, then the anatomical phenotype through the use of a sedated endoscopy, and  reviews the quality of the data and scientific literature (Ni says Inspire Medical is in the process of conducting ongoing scientific studies of the implantable therapy in the United States and Germany). Soose then weighs the pros and cons of treatment for the patient. “The patient that’s best has moderate to severe OSA, is not significantly overweight, and has specific, favorable anatomy,” he says.

Another factor that has to be weighed by the clinician when evaluating the patient is that the current Inspire model is not MRI compatible. If a patient needs to undergo an MRI procedure, the device must be removed.

Because the device requires the patient to turn it on at night, they have to have some manual dexterity in order to operate the device’s remote.

The surgery itself is a relatively simple outpatient procedure, and involves no cutting or rearranging of the throat or jaw.

Soose’s patient referrals come through many of the sources that would be expected—primary care physicians, cardiologists, and sleep physicians—but a significant number of patients are self-referred, finding physicians who are trained to implant the Inspire therapy device through the company’s website. (The physician finder tool is simple. Potential patients can simply input their ZIP code, and the names and contact details of physicians nearest them will be delivered in a matter of seconds.)

The Story of Denise H.

Denise Hoover (name used with patient’s permission) discovered the existence of Inspire therapy the old-fashioned way—she read an article in the newspaper. And it came at a fortuitous time.

Diagnosed with OSA about 20 years ago, she underwent surgery to remove her tonsils and uvula. “That worked for awhile, then I used CPAP and I couldn’t tolerate that, then I tried a dental appliance and that didn’t work. I was out of options,” she says.

Hoover first consulted with Patrick Strollo, MD, FCCP, FAASM, medical director of the Sleep Medicine Center at UPMC, about having the Inspire device implanted.

Strollo ordered a sleep study, which Hoover knew would show that she had OSA. She then followed up with Soose, who evaluated her CPAP tolerance and checked to make sure she fit the BMI criteria. Finally, she underwent a sedated endoscopy that showed she was a good candidate for the procedure, which she underwent in May 2014.

Soose notes that many of his Inspire patients know they are difficult cases. “These aren’t patients that are expecting to eliminate their OSA. They’re more accepting of the side effects of OSA treatment,” he says. There are some potential side effects from the treatment, according to the company’s website, ranging from dry mouth or trouble speaking to nerve damage or bleeding.

As with CPAP and other traditional OSA treatments, patients are required to take part in activating the Inspire device nightly. Patients turn on the device with a remote that gives them about 30 minutes to fall asleep. This allows the treatment to be administered very gradually, not interfering with patients’ natural sleep cycle, Ni notes. “As the patient falls asleep, the treatment isn’t very noticeable,” he says.

During follow-up exams, patients are held accountable. A transponder in the device allows clinicians to measure the frequency with which patients use the device. The early version of the device did not allow clinicians to measure the number of hours that patients used it, Ni notes, but self-reporting surveys in the clinical trials had 80% of patients self-reporting that they were using it regularly.

Overcoming Failure

Not every patient who wants Inspire therapy will be able to receive it due to a single or combination of factors—AHI, anatomy, or BMI.

Soose doesn’t see the Inspire therapy as a new magic bullet that will “cure” OSA in those difficult cases. Instead he’s part of a new mindset that sees combination therapy as the route to success. “Patients aren’t well served with a cookie-cutter approach that starts with CPAP and ends with aggressive surgeries,” Soose says. “Today we’re doing more customized therapies, such as weight loss or a combination of therapies. Inspire filled a nice void. It’s shown to be successful with the right clinical and anatomical criteria. You don’t have to hit a home run with therapy.”

Soose, who helped develop the Inspire training program, notes that there are three criteria for a successful outcome: proper patient selection, correct execution of the implant, and proper follow-up (including proper therapy titration). The Inspire training program outlines all of these aspects in detail. “Our goal is to build a comprehensive program,” Ni says.

Currently, there are 30 centers that offer Inspire therapy, which can be found through the website.

C.A. Wolski has seen OSA technology come a long way since he first started reporting on sleep medicine in 2001. He’s particularly inspired by the combination therapy idea being put in practice by Ryan Soose, MD, and others.