Upper-Airway Stimulation for Obstructive Sleep Apnea
How safe and effective is upper-airway stimulation at 12 months for the treatment of moderate-to-severe obstructive sleep apnea (OSA)?
Men and women with moderate-to-severe OSA were recruited from 22 academic and private centers if difficulty accepting or adhering to continuous positive airway pressure (CPAP) treatment. A total of 724 subjects underwent screening. Subjects were excluded for body mass index (BMI) >32 kg/m2, neuromuscular disease, severe lung disease, moderate or greater pulmonary hypertension, severe valvular heart disease, New York Heart Association class III heart failure, recent myocardial infarction, severe arrhythmias, uncontrolled hypertension, or active psychiatric disease. Data were collected from November 2010 to March 2013. Patients underwent a surgical procedure to implant the upper-airway stimulation system. The stimulation electrode was placed on the right medial division hypoglossal nerve (Cranial nerve XII) to recruit tongue-protrusion function; the sensing lead was placed between intercostal muscles to detect ventilatory effort; the pulse generator was implanted in the right anterior chest. Participants were instructed on use of a stimulator controller to initiate and terminate therapy on a nightly basis. Follow-up visits at 2, 6, and 12 months included a sleep study. The primary outcome measures were the apnea–hypopnea index (AHI; apnea hypopnea events per hour) and oxygen desaturation index (ODI; the number of times per hour the blood oxygen level drops by ≥4 percentage points from baseline).
Among the screening population, 528 were excluded and 126 underwent implantation, 83% were men, mean age was 54.4 years, and mean BMI was 28.4 kg/m2. The median AHI score at 12 months decreased by 68%, from 29.3 events per hour to 9.0 events per hour (p < 0.001); the ODI score decreased by 70%, from 25.4 events per hour to 7.4 events per hour (p < 0.001). The AHI score was significantly higher among the 23 participants in the therapy-withdrawal group (25.8 vs. 7.6 events per hour, p < 0.001). The ODI results followed a similar pattern. Procedure-related serious adverse event rate was <2%. There was change in BMI during the study, and the median implant time was 140 minutes.
The authors concluded that unilateral stimulation of the hypoglossal nerve, synchronous with ventilation, resulted in significant reductions in the severity of OSA at 1 year.
This uncontrolled cohort study was designed and funded by the sponsor, Inspire Medical Systems, maker of the upper airway stimulation system. By design, this cohort is a unique subset of OSA patients, albeit commonly intolerant of CPAP treatment: BMI <32 kg/m2 and AHI <50. Additionally, 54 of 724 patients were excluded due to concentric palatal collapse detected on sleep endoscopy. There was no control group using CPAP, given the design of the study. The authors concluded the randomized therapy withdrawal part of the study was attributable to upper airway stimulation and not variability in AHI score over time, but this was studied only in stimulation responders. Self-reported daily use of the stimulator was 86%. Future studies may include next-generation stimulators, which can objectively quantify device use similar to CPAP.
Clinical Topics: Sleep Apnea
Keywords: Hypoglossal Nerve, Continuous Positive Airway Pressure, Sleep Apnea, Obstructive
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