HILTON HEAD—Continuous positive airway pressure (CPAP) remains the most effective treatment for obstructive sleep apnea (OSA). However, many patients with OSA have difficulty tolerating CPAP, and overall compliance continues to be a barrier.
Although CPAP compliance may be improved by clinical troubleshooting or technologic improvements, the number of alternative therapies is increasing. The evidence base for most of these treatments is scant. Further research is needed, including data identifying patient characteristics such as phenotypes that can help predict specific responses to therapy.
The Search for Better Treatments
Alternative treatments can be categorized into those that use a mechanistic approach—including nasal expiratory PAP, oral airway pressure, and oral appliances—and those from the emerging arena of neurologic approaches such as upper airway stimulation. This latter therapy, which involves a pacemaker-like device that is implanted in the anterior chest wall and stimulates a branch of the hypoglossal nerve, has the potential to become a mainstay treatment, said Raghu Upender, MD, Assistant Professor in Neurology and Medical Director of the Vanderbilt Sleep Disorders Center in Nashville. “The idea behind this is if you increase the tonic activation of the tongue, you can keep it away from the back of the throat because it acts as a pharyngeal dilator and opens the airway,” Dr. Upender said at Vanderbilt University’s 37th Annual Contemporary Clinical Neurology Symposium.
Early studies have reported some positive results. In a pivotal safety and efficacy study of CPAP-intolerant patients with moderate-to-severe OSA (Strollo et al), investigators found that the median apnea–hypopnea index (AHI) score decreased 68%, from the baseline value of 29.3 events per hour to 9.0 events per hour. “So you brought someone with severe sleep apnea down to moderate,” Dr. Upender said. “For most sleep doctors this is still too high. But again, it’s much better than [a 29.3 value]. “We believe that the cardiovascular complications that occur with sleep apnea are dose-dependent, so the more severe your apnea, the greater the risk. By reducing it … you are helping to reduce the risk of these complications.”
Among all patients, the mean BMI was 28.4, which may have been a factor in the outcomes, according to Dr. Upender. “Most of our patients have a BMI greater than 30, so they selected … patients who were not obese, [although there were] comorbid conditions like hypertension and diabetes in a significant number of subjects,” he said. “This could change the field if it proves to be effective and has minimal side effects. Most people seem to tolerate this stimulation. They may have had some discomfort; but again, this is an initial study. We really have to gain more experience with this.” Dr. Upender said that his center plans to participate in the initial clinical rollout of the device. “We’ll probably have to be very selective on whom we choose,” he emphasized. “I’m not sure if this therapy is going to be effective in people who are morbidly obese, where there may be much more tissue pressure that narrows the airway. This may be a good treatment for people with mild obesity or who are moderately overweight.”
Nasal Expiratory PAP
Nasal expiratory PAP involves two devices, each containing a disk that wraps around one nostril and a unidirectional valve that gives minimal resistance when the patient breathes in, but closes when he or she breathes out. Clinical study results have been largely positive, but Dr. Upender generally will not use it for severe sleep apnea and has found tolerance to be an issue for some of his patients.
“[One patient] found it to be ineffective because she often opened her mouth, and when you open your mouth, the device becomes ineffective,” he reported. “[Her] snoring continued, and so she decided that [the treatment was] not for her.”
Oral appliances include mandibular-advancing devices, which are custom made to fit in the patient’s teeth and cause the jaw and tongue to move forward, creating more space in the back of the throat. The new remote-controlled mandibular positioner involves a sleep technician using a temporary device, along with overnight polysomonography, to determine the optimal mandibular position for eliminating snoring or apnea before fitting the patient for a permanent version of the device. Patient comfort and compliance has been a problem with several of these appliances, particularly those available over the counter, and their relatively high cost can also be a barrier to use.
Clinical studies have shown the mandibular positioner to have high predictive value. “Thirty of 32 patients who had a successful titration in the laboratory also had successful results with the permanent device,” Dr. Upender said, citing a study by Remmers et al. “It also has high negative predictive value: only five of 29 patients had good results … when they failed the titration. So this might help distinguish which patients might benefit from this therapy.”