Mild electronic stimulation therapy to upper airway during sleep effective in reducing OSA

Jan 9 2014

Results published in a new study in the Jan. 9 issue of the New England Journal of Medicine report that mild electronic stimulation therapy to the upper airway during sleep is effective in reducing obstructive sleep apnea (OSA).

In the Stimulation Therapy for Apnea Reduction (The STAR Trial) study, researchers tested an implantable electronic stimulation device called Inspire™ Upper Airway Stimulation (UAS) therapy, designed to significantly reduce the burden of obstructive sleep apnea by delivering stimulation to the hypoglossal nerve timed to each breathing cycle. The mild stimulation is intended to restore tone during sleep to the muscles that control the base of tongue, preventing the tongue from collapsing and obstructing the airway during sleep.

"This device is a first-of-its-kind therapy and has the potential to help the many people suffering from moderate to severe sleep apnea who are unable to use or cannot tolerate CPAP (continuous positive airway pressure)," said Kingman Strohl, MD, senior author of the study and pulmonologist at University Hospitals Case Medical Center and Professor of Medicine at Case Western Reserve University School of Medicine. "At a year following surgical implantation, patients experienced substantial decreases in the number of interruptions of sleep by apnea, and improvements in symptoms of waketime sleepiness, snoring and quality of life." Lead author is Patrick J. Strollo, MD, of the Division of Pulmonary Allergy and Critical Care Medicine at the University of Pittsburgh.

The Phase III safety and efficacy study was conducted at multiple American and European clinical sites. There were 126 participants, 83 percent of whom were men. To enroll, the research participants had to have moderate to severe sleep apnea and be unable to accept or adhere to CPAP therapy. In addition, the patients could not be too heavy (a BMI less than 32), a range of apneas severity in the moderate to moderately severe level, and evidence that the sleep-related obstruction might be at the level of the tongue.

"These selection criteria require careful team assessments of each patient by the surgeon and the sleep specialist," Dr. Strohl said. "And to optimize the stimulation there was a new skill needed in the sleep laboratory to adjust the electrical stimulation over a couple of nights."

Objective outcomes were measured on two scales: The apnea-hypopnea index (AHI; the number of apnea or hypopnea events per hour) and the oxygen desaturation index (ODI; the number of times per hour of sleep that the blood oxygen level drops by more than four percent). At 12 months, the median AHI score decreased 68 percent and the ODI score decreased 70 percent. Most participants reported a reduction of sleep apnea effects and improved quality of life.

After the 12-month assessment, a substudy compared 23 participants who continued with the therapy compared with 23 participants who had the therapy withdrawn for a week. The withdrawal group experienced a sharp rise in their median AHI score, along with snoring and fatigue, indicating that the stimulation by the device was the agent for effectiveness.

According to Dr. Strohl, the results are very encouraging. "While many patients have found help with CPAP, some patients struggle with CPAP or cannot tolerate the mask, and thus remain untreated," he said. "The severity of OSA in this group might not be easily managed by oral appliance or surgery. Upper-airway stimulation could provide an effective alternative," he said.

At home, patients control when the Inspire therapy is turned on and off using a handheld programmer. In contrast to other surgical procedures to treat sleep apnea, Inspire therapy does not require removing or permanently altering an OSA patient's facial or airway anatomy.

More than 18 million Americans suffer from OSA, which is characterized by repeated episodes of upper airway collapse during sleep. Patients with OSA stop breathing frequently during sleep, often for a minute or longer. Daytime sleepiness, depression, weight gain, increase in industrial accidents and diminished quality of life are all commonly observed in people who suffer from OSA as a result of fragmented sleep patterns.

"Studies have shown that sleep apnea is as prevalent as adult diabetes and asthma and the consequences of OSA range from disruptive to life-threatening cardiac problems," said Dr. Strohl, principal investigator for the UH Case Medical Center site. Phase II safety and planning studies were performed at the Louis Stokes Cleveland VA Medical Center. For the Phase III efficacy STAR trial, seven patients participated from UH Case Medical Center. Jonathan Baskin, MD, Clinical Assistant Professor of Otolaryngology and Head & Neck Surgery at Case Western Reserve University School of Medicine and at both the Louis Stokes Cleveland VA Medical Center and UH Case Medical Center, performed pre-surgical assessments and the implantation for both studies.

All data on Inspire UAS therapy are under regulatory review by the FDA. There is a provisional approval for the therapy in Europe. "We expect a careful assessment by the FDA for this first in-class therapy," said Dr. Strohl. The study was funded by Inspire Medical Systems.