COMMENTARY

Oral Appliance Therapy in OSA: A Better Way to Ensure Success

Aaron B. Holley, MD

Disclosures

August 16, 2016

Oral Appliance Therapy Works, But...

Oral appliance therapy is an effective treatment for obstructive sleep apnea syndrome (OSAS).[1] We know that thinner patients with mild to moderate, positional OSA are most likely to benefit.[2] We also know that using an individually fabricated adjustable oral appliance optimizes performance.[3] Unfortunately, these devices are expensive, and once they are made, they can't be reissued to different patients. As a result, titration in the sleep laboratory before construction usually isn't possible, so there is no way to know for sure whether the appliance will work for a given patient before paying for it to be made.

Traits That Predict Oral Appliance Success

Investigators at Brigham and Women's Hospital in Boston, Massachusetts, have been studying the physiologic mechanisms that lead to respiratory instability and breathing events (eg, apneas and hypopneas) during sleep.[4] In a recent paper that was published online in the American Journal of Respiratory and Critical Care Medicine,[5] the sleep group from Brigham and Women's Hospital described physiologic traits that predict oral appliance success. They used an elegant model to quantify the four major physiologic traits that contribute to OSAS: arousal threshold, loop gain, critical closing pressure, and genioglossus activity.[6,7] All four traits were measured in liters/min (LPM) of ventilation on polysomnography, first without treatment and then with an oral appliance in place.

Not surprisingly, they found that higher ventilatory levels during sleep could be achieved with the oral appliance. However, no change was found in arousal threshold, upper-airway gain, or loop gain. Integrating values for baseline loop gain and upper airway collapsibility, they were able to predict successful oral appliance therapy, defined as a 50% reduction in the apnea-hypopnea index (AHI) with an AHI on therapy < 10 episodes/hour, with 100% sensitivity and 87.5% specificity using their model. To date, models using such factors as baseline AHI, body mass index, age, cephalometrics, or the presence of positional OSAS have not come close to performing as well.[2,8,9]

Can This Be Replicated?

In my opinion, the investigators at Brigham and Women's Hospital are pushing the entire field closer to being able to provide individualized treatment for OSA. I do have doubts about whether other sleep laboratories can replicate their results. I don't question their validity, but I'm not sure how many sleep centers have the expertise to assess physiologic OSAS traits using continuous positive airway pressure (CPAP) dial-downs. In addition, an extra in-lab CPAP titration to define physiology could cost as much or more than an oral appliance. The same group found a way to estimate the arousal threshold using standard polysomnography parameters.[10] Hopefully, they can do the same for some of the other traits.

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