Oral appliances may be highly effective in treating obstructive sleep apnea
NEW YORK, U.S.: Certain traits may define a type of obstructive sleep apnea (OSA) that can be effectively treated with an oral appliance, according to new research. Continuous positive airway pressure (CPAP) is considered 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 obstructed airflow offers an alternative.
In a recent study, scientists used a clinically applicable method to estimate the traits that cause sleep apnea from routine polysomnography, the test used to diagnose sleep apnea. In the process, they identified five traits that appear to determine the effectiveness of an oral appliance in treating OSA. The researchers analyzed polysomnographic data previously gathered from 93 adults who were diagnosed with moderate to severe OSA.
The authors looked at two traits related to the upper airway: pharyngeal collapsibility and muscle compensation. It was found that patients without severe collapsibility benefited more from the oral appliance than those with this trait. Those with a weaker reflex response of the throat muscles that act to maintain an open airway (lower muscle compensation) also benefited more than those with a stronger reflex response. Patients with very mild collapsibility, indicating deficits in other traits, responded less well.
“Sleep apnea is not all the same, but we only recently developed ways to look at a sleep study and determine what traits cause the condition in different patients,” said senior author Dr. Scott Sands, who is an instructor in medicine at Harvard Medical School and an associate physiologist in the Division of Sleep and Circadian Disorders in the Department of Medicine at Brigham and Women’s Hospital. “Since oral appliances work by improving the collapsibility of the upper airway, patients without really severe collapsibility are more likely to benefit from an oral appliance, while those with sleep apnea caused by other traits, such as exaggerated reflex responses to drops in oxygen levels, are less likely to benefit.”
The researchers also found that three traits unrelated to the upper airway helped 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, indicating a higher arousal threshold, promotes better breathing.
Based on these five traits, oral appliances were predicted to be effective in treating sleep apnea in more than half (61%) of the participants. Patients in this group experienced a 73% reduction in the apnea–hypopnea index (AHI), which is the number of breathing pauses per hour lasting 10 seconds or longer. With an oral appliance, they had just eight apneas/hypopneas per hour. The other patient group experienced a smaller reduction in the AHI and had twice the number of breathing pauses with the oral appliance.
The authors said that responses to oral appliances in their study could not be predicted by the severity of sleep apnea or by how overweight the patients were. “Surprisingly, it didn’t seem to matter whether sleep apnea was moderate or very severe,” Sands said. “Oral appliance therapy was remarkably effective in some quite overweight patients with very severe OSA.”
Based on these findings, the authors suggested that, if their results are corroborated in future studies, an oral appliance could be considered, along with CPAP, as a first-line therapy for treating a certain type of OSA.
The study, titled “Polysomnographic endotyping to select obstructive sleep apnea patients for oral appliances,” was published online on Aug. 9, 2019, in the Annals of the American Thoracic Society, ahead of inclusion in an issue.