New Technology To Measure Traits Causing Sleep Apnea

Certain traits may define a type of obstructive sleep apnea that can be effectively treated with an oral appliance, according to new research published online in the Annals of the American Thoracic Society. With OSA there are times during sleep when air cannot flow normally into the lungs. The collapse of the soft tissues in the back of the throat or tongue usually causes the airflow obstruction.

Continuous positive airway pressure, or CPAP, is consider the gold standard for preventing the obstruction by blowing air through a mask into the nose and throat. However, many patients have trouble sleeping with CPAP. For these patients, an oral appliance that moves the lower jaw forward to prevent the periods of obstruct airflow is often an alternative.

Effectiveness of oral appliance

In “Polysomnographic Endotyping to Select Obstructive Sleep Apnea Patients for Oral Appliances,” Ahmad A. Bamagoos and colleagues identify five traits that appear to determine the effectiveness of an oral appliance in treating OSA. The researchers use their new technology to measure the traits causing sleep apnea through polysomnography; the test use to diagnose sleep apnea. For this study, the researchers analyze polysomnographic data already gather from 93 adults who were diagnose with moderate to severe OSA.

The authors look at two traits relate to the upper airway: collapsibility and muscle compensation. The researchers found that patients without severe collapsibility benefit more from the oral appliance than those without this trait. Those with a weaker reflex response of the throat muscles that act to maintain an open airway (lower muscle compensation) also benefit more than those with a stronger reflex response. Patients with very mild collapsibility, indicating deficits in other traits, respond less well.

The researchers also found that three traits unrelated to the upper airway; which help predict those patients who would respond less well to an oral appliance: higher loop gain, lower arousal threshold and higher ventilatory response to arousal. Loop gain is a measure of how aggressively the brain and lungs respond to falling oxygen and rising carbon dioxide in the blood. Arousal threshold is a measure of how easily a person wakes up from sleep; deeper sleep (higher arousal threshold) promotes better breathing.

Treating sleep apnea

Base on these five traits, oral appliances were predict; so to be effective in treating sleep apnea in more than half (61 percent) of the participants. Patients in this group experience a 73% reduction in the Apnea-Hypopnea Index; which is the number of breathing pauses per hour lasting 10 seconds or longer. (Apnea means no air flow and hypopnea means reduction in airflow). With an oral appliance, they had just eight apneas/hypopneas per hour.

So the other patient group experienced a smaller reduction in the Apnea Hypopnea Index; also had twice the number of breathing pauses remaining with the oral appliance. Hence authors said that responses to oral appliances in their study; which could not be predicted by the severity of sleep apnea or how overweight patients were. “Surprisingly, it didn’t seem to matter whether sleep apnea was moderate or very severe,” Dr. Sands said. “Oral appliance therapy was remarkably effective in some quite overweight patients with very severe OSA.”

“While CPAP is great for some, there remains a large group of patients who really struggle with it,” Dr. Sands said. “For these folks, this study highlights the potential benefit of measuring the underlying causes of their sleep apnea to estimate whether an oral appliance might be an equivalent or better choice over CPAP for the treatment of their sleep apnea.” Dr. Sands add that once the most useful measures for predicting patient outcomes are established; he believes they will be readily incorporated into routine sleep recording systems.