What is sleep apnea?
Sleep apnea is a serious sleep disorder that happens when a person's breathing is interrupted during sleep. People with untreated sleep apnea stop breathing repeatedly during their sleep, sometimes hundreds of times during the night.
If it’s not treated, sleep apnea can cause a number of health problems, including hypertension (high blood pressure), stroke, cardiomyopathy (enlargement of the muscle tissue of the heart), heart failure, diabetes and heart attacks. Untreated sleep apnea can also be responsible for job impairment, work-related accidents and motor vehicle crashes, as well as underachievement in school in children and adolescents.
There are two types of sleep apnea, obstructive and central:
- Obstructive sleep apnea is the more common of the two. Obstructive sleep apnea occurs as repetitive episodes of complete or partial upper airway blockage during sleep. During an apneic episode, the diaphragm and chest muscles work harder as the pressure increases to open the airway. Breathing usually resumes with a loud gasp or body jerk. These episodes can interfere with sound sleep, reduce the flow of oxygen to vital organs, and cause heart rhythm irregularities.
- In central sleep apnea, the airway is not blocked but the brain fails to signal the muscles to breathe due to instability in the respiratory control center. Central apnea is related to the function of the central nervous system.
Who gets sleep apnea?
Sleep apnea occurs in about 25% of men and nearly 10% of women. Sleep apnea can affect people of all ages, including babies and children and particularly people over the age of 50 and those who are overweight.
Certain physical traits and clinical features are common in patients with obstructive sleep apnea. These include excessive weight, large neck and structural abnormalities reducing the diameter of the upper airway, such as nasal obstruction, a low-hanging soft palate, enlarged tonsils or a small jaw with an overbite.
What happens when you stop breathing?
When you stop breathing, your heart rate also tends to drop the longer your body is deprived of oxygen. Then, your involuntary reflexes cause you to startle awake at the end of that period of not breathing. When this occurs, your heart rate tends to accelerate quickly and your blood pressure rises.
These are changes that take place acutely when you stop breathing. However, your body starts to experience chronic effects if you experience frequent apnea. Data suggests increased risk, particularly when you stop breathing roughly 30 times or more per hour. But there is likely a risk at even lower frequency rates.
For example, your blood pressure tends to go up, your heart walls thicken due to increased workload and the structure of your heart changes. It tends to become stiffer and less flexible because there are more fibrous cells growing in between the muscle cells.
All of those things increase the risk that you can have either atrial or ventricular arrhythmias. They also tend to reduce the function of the heart so that it’s less efficient at pumping blood.
Symptoms and Causes
What causes sleep apnea?
Obstructive sleep apnea is caused by a blockage of the airway, usually when the soft tissue in the rear of the throat collapses during sleep. Central sleep apnea is usually observed in patients with central nervous system dysfunction, such as following a stroke or in patients with neuromuscular diseases like amyotrophic lateral sclerosis (ALS, Lou Gehrig’s disease). It is also common in patients with heart failure and other forms of heart, kidney or lung disease.
What are the symptoms of sleep apnea?
Often the first signs of OSA are recognized not by the patient, but by the bed partner. Many of those affected have no sleep complaints. The most common signs and symptoms of OSA include:
- Daytime sleepiness or fatigue.
- Restlessness during sleep, frequent nighttime awakenings.
- Sudden awakenings with a sensation of gasping or choking.
- Dry mouth or sore throat upon awakening.
- Cognitive impairment, such as trouble concentrating, forgetfulness or irritability.
- Mood disturbances (depression or anxiety).
- Night sweats.
- Frequent nighttime urination.
- Sexual dysfunction.
People with central sleep apnea more often report recurrent awakenings or insomnia, although they may also experience a choking or gasping sensation upon awakening.
Symptoms in children may not be as obvious and include:
- Poor school performance.
- Sluggishness or sleepiness, often misinterpreted as laziness in the classroom.
- Daytime mouth breathing and swallowing difficulty.
- Inward movement of the ribcage when inhaling.
- Unusual sleeping positions, such as sleeping on the hands and knees, or with the neck hyper-extended.
- Excessive sweating at night.
- Learning and behavioral disorders (hyperactivity, attention deficits).
Diagnosis and Tests
How is sleep apnea diagnosed?
If your doctor determines that you have symptoms suggestive of sleep apnea, you may be asked to have a sleep evaluation with a sleep specialist or may order an overnight sleep study to objectively evaluate for sleep apnea.
- Testing includes an overnight sleep study called a polysomnogram (PSG). A PSG is performed in a sleep laboratory under the direct supervision of a trained technologist. During the test, a variety of body functions, such as the electrical activity of the brain, eye movements, muscle activity, heart rate, breathing patterns, air flow, and blood oxygen levels are recorded at night during sleep. After the study is completed, the number of times breathing is impaired during sleep is tallied and the severity of the sleep apnea is graded.
- For adults, a Home Sleep Test (HST) can sometimes be performed instead. This is a modified type of sleep study that can be done in the comfort of home. It records fewer body functions than PSG, including airflow, breathing effort, blood oxygen levels and snoring to confirm a diagnosis of moderate to severe obstructive sleep apnea.
An HST is not appropriate to be used as a screening tool for patients without symptoms. It’s not used for patients with significant medical problems (such as heart failure, moderate to severe cardiac disease, neuromuscular disease or moderate to severe pulmonary disease). It’s also not used for patients who have other sleep disorders (such as central sleep apnea, restless legs syndrome, insomnia, circadian rhythm disorders, parasomnias or narcolepsy) in addition to the suspected obstructive sleep apnea.
Management and Treatment
What are the treatments for sleep apnea?
Conservative treatments: In mild cases of obstructive sleep apnea, conservative therapy may be all that is needed.
- Overweight persons can benefit from losing weight. Even a 10% weight loss can reduce the number of apneic events for most patients. However, losing weight can be difficult to do with untreated obstructive sleep apnea due to increased appetite and metabolism changes that can happen with obstructive sleep apnea.
- Individuals with obstructive sleep apnea should avoid the use of alcohol and certain sleeping pills, which make the airway more likely to collapse during sleep and prolong the apneic periods.
- In some patients with mild obstructive sleep apnea, breathing pauses occur only when they sleep on their backs. In such cases, using a wedge pillow or other devices that help them sleep in a side position may help.
- People with sinus problems or nasal congestion should use nasal sprays or breathing strips to reduce snoring and improve airflow for more comfortable nighttime breathing. Avoiding sleep deprivation is important for all patients with sleep disorders.
Mechanical therapy: Positive Airway Pressure (PAP) therapy is the preferred initial treatment for most people with obstructive sleep apnea. With PAP therapy, patients wear a mask over their nose and/or mouth. An air blower gently forces air through the nose and/or mouth. The air pressure is adjusted so that it is just enough to prevent the upper airway tissues from collapsing during sleep. PAP therapy prevents airway closure while in use, but apnea episodes return when PAP is stopped or if it is used improperly. There are several styles, and types of positive airway pressure devices depending on specific needs of patients. Styles and types include:
- CPAP (Continuous Positive Airway Pressure) is the most widely used of the PAP devices. The machine is set at one single pressure.
- Bi-Level PAP uses one pressure during inhalation (breathing in), and a lower pressure during exhalation (breathing out). There is a criterion that must be met before health insurance will cover the bi-level. This usually means that the CPAP machine must be tried first with no success and these results documented before insurance will pay for a bi-level.
- Auto CPAP or Auto Bi-Level PAP uses a range of pressures that self-regulates during use depending on pressure requirements detected by the machine.
- Adaptive Servo-Ventilation (ASV) is a type of non-invasive ventilation that is used for patients with central sleep apnea, which acts to keep the airway open and delivers a mandatory breath when needed.
Mandibular advancement devices: These are devices for patients with mild to moderate obstructive sleep apnea. Dental appliances or oral mandibular advancement devices that help to prevent the tongue from blocking the throat and/or advance the lower jaw forward can be made. These devices help keep the airway open during sleep. A sleep specialist and dentist (with expertise in oral appliances for this purpose) should jointly determine if this treatment is best for you.
Hypoglossal nerve stimulator: A stimulator is implanted under the skin on the right side of the chest with electrodes tunneled under the skin to the hypoglossal nerve in the neck and to intercostal muscles (between two ribs) in the chest. The device is turned on at bedtime with a remote control. With each breath, the hypoglossal nerve is stimulated, the tongue moves forward out of the airway and the airway is opened.
Surgery: Surgical procedures may help people with obstructive sleep apnea and others who snore but don’t have sleep apnea. Among the many types of surgeries done are outpatient procedures. Surgery is for people who have excessive or malformed tissue obstructing airflow through the nose or throat, such as a deviated nasal septum, markedly enlarged tonsils or small lower jaw with an overbite that causes the throat to be abnormally narrow. These procedures are typically performed after sleep apnea has failed to respond to conservative measures and a trial of CPAP. Types of surgery include:
- Somnoplasty is a minimally invasive procedure that uses radiofrequency energy to reduce the soft tissue in the upper airway.
- Tonsillectomy is a procedure that removes the tonsillar tissue in the back of the throat which is a common cause of obstruction in children with sleep apnea.
- Uvulopalatopharyngoplasty (UPPP) is a procedure that removes soft tissue on the back of the throat and palate, increasing the width of the airway at the throat opening.
- Mandibular/maxillary advancement surgery is a surgical correction of certain facial abnormalities or throat obstructions that contribute to obstructive sleep apnea. This is an invasive procedure that is reserved for patients with severe obstructive sleep apnea with head-face abnormalities.
- Nasal surgery includes correction of nasal obstructions, such as a deviated septum.
What are the effects of sleep apnea?
If left untreated, sleep apnea can result in a number of health problems including hypertension, stroke, arrhythmias, cardiomyopathy (enlargement of the muscle tissue of the heart), heart failure, diabetes, obesity and heart attacks.
It’s likely that sleep apnea can cause arrhythmias and heart failure because if you have sleep apnea, you tend to have higher blood pressure. In fact, sleep apnea occurs in about 50% of people with heart failure or atrial fibrillation.
This is because sleep apnea can cause:
- Repeated episodes of oxygen lowering (what doctors call hypoxia).
- Changes in carbon dioxide levels.
- Direct effects on the heart due to pressure changes within the chest.
- Increased levels of markers of inflammation.
With the high prevalence of sleep apnea in cardiac arrhythmias and heart failure (essentially a coin flip as to whether the patient has it), experts recommend that you don’t delay in seeking the advice of your physician.