Dr. Jason Amatoury
, assistant professor at MSFEA
's Biomedical Engineering Program
, is conducting critical research on a health condition known as obstructive sleep apnea, or OSA. OSA occurs when the upper airway (throat region) repeatedly collapses during sleep and impedes breathing. The disorder is associated with serious health consequences such as cardiovascular disease and neurocognitive impairments. At AUB, Amatoury and his Sleep and Upper Airway Research Group (SUARG)
are combining computational modeling and physiology to better understand the properties of the upper airway and mechanisms that lead to its collapse. They are conducting studies on upper airway muscle stimulation as well as how the position and movement of the hyoid, a mobile bone located under the tongue, impacts airway collapsibility.
Amatoury describes the position of the hyoid bone as the biggest anatomical factor that is a predictor of sleep apnea. In a conversation with Amatoury, he explains what sleep apnea is and how it affects the body. He describes this relatively common condition as a “multifactorial complex disorder" leading to interrupted breathing during sleep. As muscle activity decreases during sleep, the airway soft tissues, including the tongue and soft palate, tend to move back towards the throat to obstruct the passage of air. As the person inhales, the suction further causes the tongue and other soft tissues to move back into the airway so that they block off the airway completely.
Interrupted breathing creates an imbalance in the amount of oxygen and carbon dioxide in the body. The amount of carbon dioxide builds up in the body because it is not being released through the process of exhalation and eventually reaches a toxicity threshold. At the same time, the body is being deprived of oxygen. These factors can induce a cortical arousal, or brief “brain awakening”, where sleep is interrupted to stimulate the necessary muscle activity to facilitate breathing. Sleep remains interrupted until the person's breathing stabilizes. And as the person returns to sleep, the cycle repeats itself. Breathing can be interrupted up to 120 times per hour in severe cases, and breathing could stop for anywhere between 10 to 90 seconds.
The combined effect of frequent interruptions to breathing and sleep are known to be detrimental to well-being. People with sleep apnea commonly experience sleep deprivation, and this, in turn, has been linked with depression and cognitive issues. Disturbances in the levels of oxygen and carbon dioxide in the body are thought to cause cardiovascular disease, heart attack, stroke, high blood pressure, diabetes Type 2, and certain cancers.
Amatoury explains that usually, for diagnosis, people undergo a sleep study, either in a hospital or at home, which involves connecting sensors and other devices to monitor breathing and brain activity. The position in which the person is sleeping is also monitored as position-dependent sleep apnea does exist, whereby a person could have apnea if they are sleeping on their back but not have apnea if they are sleeping on their side.
Part of the challenge with diagnosis, and one of the main reasons that only an estimated 10 percent of all sleep apnea cases are diagnosed, is that undergoing the sleep study is uncomfortable and overwhelming for some. Realizing this, Amatoury is looking into ways to enhance the technologies and therapies required for diagnosis. He is also studying how current treatments function in terms of their mechanisms in order to improve their efficacy. “In the end," Amatoury says, “the idea is that it all comes down to the balance between the forces that want to keep the airway open and the forces that want to close the airway. We want to tip the scale in favor of those that keep it open!"