Sleep-Related Breathing Disorders
Sleep-related breathing disorders make up a large group of disorders related to abnormal breathing during sleep with sleep apnea being the most common.
Overview
Sleep apnea causes intermittent pauses in breathing during sleep. These intermittent pauses in breathing result in brief repetitive arousals from sleep, intermittent drops in oxygenation, elevations in heart rate and blood pressure, and can result in daytime fatigue from fragmented sleep.
Sleep apnea can be caused by obstructive factors as well as abnormalities in ventilatory control. Obstructive factors include any condition that causes the upper airway to intermittently collapse, such as obesity or enlarged tonsils. Conditions associated with reduced muscle tone, such as aging, hypothyroidism, or menopause, can also contribute to obstruction and collapse of the upper airway.
Abnormalities in ventilatory control are characterized by a respiratory pattern that overshoots or undershoots desired ventilation. Conditions associated with abnormalities in ventilatory control include heart disease, such as congestive heart failure and stroke, although some healthy individuals can be prone to this pattern as well.
Obstructive sleep apnea (OSA) describes sleep apnea with primarily obstructive features. Central sleep apnea (CSA) describes sleep apnea where abnormalities in ventilatory control are the main feature. Complex sleep apnea describes sleep apnea comprised of features from both.
Sleep-related breathing disorders also include conditions such as nocturnal hypoventilation and obesity-related hypoventilation. Individuals with sleep apnea are unable to adequately ventilate or eliminate their carbon dioxide (CO2). Typically, individuals who have difficulty with ventilation have co-existing medical conditions that make it difficult for them to breathe.
Symptoms
Common symptoms of sleep apnea include frequent arousals from sleep, unrefreshing sleep, gasping arousals, frequent urination, fatigue, and changes in memory and concentration. Individuals with primarily obstructive sleep apnea may also describe loud snoring, waking with heart burn or headaches, motor restlessness, and excessive daytime sleepiness. Risk factors for sleep apnea include obesity, high blood pressure, heart disease, diabetes, atrial fibrillation and stroke. Alcohol use and certain sedatives increase the likelihood of OSA while opioid pain medications increase the likelihood of CSA.
Diagnosis
A sleep study is required to diagnose sleep apnea. A sleep study can be conducted either in a sleep laboratory or at home using an at-home sleep testing device. An in-laboratory sleep study is typically recommended when either complex or central sleep apnea is suspected. An at-home sleep test is typically recommended when obstructive sleep apnea is suspected or if required as an initial test by insurance.
Treatment
Treatments for sleep apnea depend on the underlying contributing factors and severity of sleep apnea. In patients with primarily obstructive sleep apnea, the following interventions can be very helpful, especially in mild cases: weight loss, avoidance of alcohol, avoidance of sleeping in the supine position, and treatment of any nasal congestion.
Individuals with severe symptoms related to sleep apnea, or moderate to severe obstructive sleep apnea, are better served by positive airway pressure therapy or dental appliance therapy. Continuous positive airway pressure (CPAP) is a very effective treatment for obstructive sleep apnea. This device alleviates obstruction by providing air pressure through a mask to keep the upper airway open during sleep. Dental appliances are sometimes used to prevent the tongue from collapsing into the airway by holding the jaw and tongue forward.
A variety of upper airway surgical procedures have been used to treat obstructive sleep apnea. However, most surgical interventions have a mediocre success rate and are reserved for select candidates when other treatment options have failed. Gastric bypass and other bariatric procedures that cause major weight loss can significantly improve sleep apnea. Hypoglossal nerve stimulation (Inspire therapy) uses an implant to keep the tongue pushed forward and the airway open in individuals with predominantly obstructive sleep apnea.
In patients with either central or complex sleep apnea, those treatment options are often considered insufficient. Additional measures are often required to help stabilize breathing. Such measures include using a device that relies on pressure support to target an individual’s average ventilation or use of supplemental oxygen which stabilizes ventilatory drive. Off-label therapies are also available to address ventilatory instability including interventions that modulate CO2 and/or medications that stabilize breathing. Phrenic nerve stimulation (Remede therapy) is an implanted device which paces the diaphragm to provide consistent respiratory effort and ventilation in individuals with predominantly central sleep apnea.
In individuals with nocturnal hypoventilation or obesity-related hypoventilation, advanced ventilator modes are utilized to stabilize breathing, improve ventilation, and increase elimination of CO2.
Sleep Disorders Center
The Sleep Disorders Center at BIDMC is one of the largest academic sleep centers in New England. This multi-disciplinary center includes neurologists, pulmonologists and psychologists who treat adult patients with the full range of sleep disorders, ranging from sleep apnea to insomnia, narcolepsy to restless leg syndrome.