Also called: Sleep Disordered Breathing, Apnea, Obstructive Sleep Apnea-Hypopnea, SDB
Sleep apnea is a condition in which a person’s breathing stops and starts many times during sleep. These interruptions in breathing last at least 10 seconds and sometimes as long as 2 minutes. These frequent disruptions have a number of side effects. By depriving the body of oxygen repeatedly, even for short periods, and disturbing valuable sleep time, there is increased risk of symptoms such as poor concentration, daytime fatigue, headaches and even organ damage. Furthermore, there is some evidence that sleep apnea may be related to high blood pressure(hypertension), abnormal heart rhythms and pulmonary hypertension.
There are three types of sleep apnea: obstructive, central and mixed. Obstructive sleep apnea, which accounts for about 90 percent of cases, is a mechanical problem in which relaxed muscles at the back of the throat block the air passage. Central sleep apnea is a neurological problem in which the brain fails to signal the lungs to breathe. Mixed sleep apnea is a combination of both problems.
Mild sleep apnea may be relieved through weight loss, regular exercise (under the supervision of a physician for those out of shape), avoiding alcohol and refraining from sleeping on one’s back. More serious cases may require the use of medical devices or even surgery.
About sleep apnea
Although the condition has been recognized since at least the 19th century, sleep apnea was first diagnosed in 1965. This condition is characterized by frequent sleep interruption because the person has temporarily stopped breathing. Sleep apnea was originally called “Pickwickian syndrome,” after a Charles Dickens character. The character, named Fat Joe, had a condition that caused him to fall asleep while standing up. Its current name comes from “apnea” – the Greek word for “want of breath.”
There are three types of sleep apnea:
- Obstructive sleep apnea (OSA) or hypopnea. This is the most common form of sleep apnea and can occur in all age groups. Soft tissue in the back of the throat can fall back into the airway when a person breathes. Muscles in this area normally work to keep the throat open, but the airway can become blocked if the muscles relax during sleep. When the brain detects a drop in oxygen from not breathing, it quickly sends a signal to the chest muscles and diaphragm to gulp in air. As a result, the sleeper makes a gasping or snorting sound and partially awakens, although he or she may not remember doing so. Snoring – sometimes very loud snoring – is associated with OSA. The risk of OSA increases with stress, obesity, smoking, alcohol and sedatives. Obesity has been noted in as many as 40 percent of cases. Physical characteristics can also play a role. For example, people with large tonsils and tongues, and relatively small lower jaws, are more prone to OSA.
- Central sleep apnea. This is a less common form of sleep apnea. It occurs when the brain does not signal the chest muscles and diaphragm to breathe. The air passage remains open, but the diaphragm and chest muscles do not function until the person wakes up. This is a neurological, rather than mechanical, malfunction and is rarely seen in people under the age of 60. It is not associated with snoring.
- Mixed apnea. As its name suggests, this is a combination of the first two disorders.
Sleep apnea is a common condition. Estimates range from 4.5 million Americans to about 18 million Americans suffering from the condition. In the 1990s alone, there was a 12-fold increase in the diagnosis of sleep apnea. This increase is explained by increased clinical awareness of sleep apnea. Men are affected twice as often as women. A person is considered to have significant sleep apnea if episodes occur at least five times an hour. If they occur 10 or more times an hour, the apnea is considered severe.
Although most of the symptoms associated with sleep apnea are relatively minor, there is a definite link between apnea-induced sleepiness and car accidents. Because apnea is so common, this represents a major health problem.
Sleep apnea is the most common type of condition classified as “sleep-disordered breathing” (SBD). Other types of SBD include:
- Hypoventilation. Continuous but very shallow breathing that gradually leads to low levels of oxygen and high levels of carbon dioxide.
- Snoring. Forceful, noisy breathing that indicates an obstruction in the airway during sleep. Exceptionally loud and vibrating snoring has also been shown to be a risk factor for sleep apnea. Among women, it has been associated with significant medical risks, including cardiovascular disease and high blood pressure(hypertension).
Impact of sleep apnea on heart health
Sleep apnea results in periods of higher blood pressure(hypertension) because the heart tries to counter the build-up of carbon dioxide by pumping harder. Numerous studies have attempted to link sleep apnea to elevated blood pressure that occurs during waking hours. At this time, the link between sleep apnea and high blood pressure remains murky.
Early studies seemed to definitively link sleep apnea to high blood pressure. However, these studies frequently failed to take into account other risk factors for hypertension, most notably obesity, which occurs in almost half of sleep apnea cases. More recently, several large population studies have demonstrated a link between sleep apnea and elevated waking blood pressure. However, other studies that controlled for factors such as age, smoking, alcohol consumption and other risk factors have contradicted these findings.
Similarly, researchers have been working to establish a link between pulmonary hypertension, or elevated blood pressure in the lungs, and sleep apnea. Because breathing is stopped, it makes logical sense that pulmonary hypertension would follow. Once again, it has been difficult to determine a direct relationship between sleep apnea and pulmonary hypertension because of the significant overlap between risk factors for both, particularly obesity.
While the association between these conditions and sleep apnea remains murky, researchers have uncovered a number of conclusive links that may one day help us better understand how sleep apnea affects cardiovascular health. For instance, sleep apnea is associated with increased risk of type 2 diabetes, independent of obesity. Similarly, apnea has been associated with lowered levels of HDL “good” cholesterol. Both of these are considered risk factors for coronary artery disease.
Some studies have also linked sleep apnea to increased risk for transient ischemic attack and stroke. A study that accounted for overlapping risk factors found that people with untreated severe sleep apnea have three times greater risk of cardiovascular events, such as heart attack and stroke. There is a well-established link between sleep apnea and certain forms of abnormal heart rhythms. The most common rhythm disturbance connected to sleep apnea is a slow heartbeat (bradycardia). Sleep apnea has also been linked with increased risk of atrial fibrillation among patients who have already experienced atrial fibrillation.
Signs and symptoms of sleep apnea
All types of sleep apnea lead to excessive sleepiness during waking hours. In some cases, this sleepiness may have gone unnoticed by the patient because it took years to develop. They may not remember what normal alertness is anymore. However, under careful questioning, certain patterns may emerge, including embarrassing episodes of sleep (e.g., at religious services), habitual drowsiness during periods of boredom and trouble focusing while driving.
The other major symptom of sleep apnea is loud snoring, often accompanied by frequent audible pauses in breathing followed by gasping, snorting and frequent movements in bed. Because apneic people don’t always awaken during their episodes, they may be unaware of their nighttime struggle. In many cases, initial visits to the physician are prompted by frustrated bed partners who are unable to sleep through the snoring and gasping of their partner.
Other symptoms include:
- Morning headaches
- Poor ability to concentrate
- Poor motor skills
- Erectile dysfunction
- Morning dry mouth or sore throat
Diagnosis methods for sleep apnea
Patients suspected of having sleep apnea often undergo a sleep study, which may be conducted overnight at a hospital, an accredited sleep center or in the home using special equipment that monitors sleep. Prior to the sleep study, a medical history and a family history will be taken by the physician. During the history, the patient should tell the physician of any medication being taken. In addition, the patient should keep a record of periods of daytime fatigue, morning headaches and other symptoms associated with sleep apnea before and after the sleep study.
The physician may also check for the physical characteristics associated with obstructive sleep apnea, such as a large neck, enlarged tonsils and/or enlarged tongue. An electrocardiogram (EKG) may also be used to detect abnormal heart rhythms (arrhythmias) that have been associated with sleep apnea.
In an in-office sleep study, about two hours before going to sleep, the patient will be hooked up to several monitoring devices to record various measures of sleep, including pulse, airflow and air saturation. Together, these tests are called polysomnography. The tests are painless and noninvasive. In-office polysomnography is the gold standard sleep test. Its major drawback is the cost and inconvenience of the study (e.g., it must be conducted away from home and usually attended by a specially trained technician).
Hoping to make this test more economical, there has been a trend in recent years toward performing a “split” test over the course of a single night. This approach combines a traditional sleep test in the first half of the night with continuous positive airway pressure (CPAP) therapy in the second half of the sleep period. This allows physicians to both confirm a diagnosis and simultaneously calibrate CPAP therapy, which normally requires another night in the sleep clinic.
Because of the cost associated with polysomnography studies, and the increasing frequency of sleep apnea, a number of in-home devices have been designed that allow sleep studies to be conducted while the patient sleeps in his or her own bed. These devices have the obvious advantage of being cheaper and more convenient. However, they tend to measure fewer parameters than in-office equipment, and there is some controversy surrounding the use of in-home technologies versus established sleep center studies.
Currently, researchers are still gathering and analyzing data on the use of portable sleep monitors. So far, these devices are still not recommended to make a stand-alone diagnosis of sleep apnea but can help confirm a diagnosis. In addition, they are not recommended for use in patients with additional conditions, such as obesity or established heart disease.
A multiple sleep latency test (MSLT) may also conducted to record the time it takes for a person to fall asleep in a quiet room during the day. People with sleep apnea can fall asleep within five minutes. Normally, a person can fall asleep in 10 to 20 minutes.
Treatment and prevention for sleep apnea
People with relatively mild obstructive sleep apnea may be able to reduce episodes by sleeping on their sides. To keep from rolling onto the back, the patient might sew a pocket on the back of his or her pajamas and place a ball into it. Another way to reduce symptoms is to use over-the-counter nasal strips.
Lifestyle changes can also help. Losing weight, quitting smoking and avoiding alcohol for at least four hours before going to sleep may help. Sleeping pills and tranquilizers should be avoided because they cause the throat tissue to sag, which inhibits breathing.
If lifestyle change are ineffective, the most common treatment for obstructive sleep apnea is called nasal continuous positive airflow pressure (CPAP), in which a bedside machine delivers air continuously through a plastic mask over the nose. The predetermined air pressure acts as a splint to keep the airway open, while still allowing the person to exhale. CPAP is currently the most widely used treatment. However, although CPAP makes inhalation easier, it also makes exhalation more difficult and can lead to dryness in the mouth. Many people find the device inconvenient and obtrusive, which has led to problems with patients not completing this treatment as directed.
This form of treatment can be applied using different delivery methods. For instance, an oral positive airway pressure machine delivers pressure through the mouth only. More recently, equipment has been introduced that senses a person’s need for pressure and delivers only what is required to keep the airway open. Other types of equipment deliver pressure gradually. The initial pressure is low to allow a person to fall asleep, and slowly rises to the full prescribed pressure.
Recent studies have found that using CPAP in the treatment of obstructive sleep apnea improved heart failure and heart enlargement and decreased the overall risk of cardiovascular disease. Another study found CPAPs less helpful among patients with heart failure and central sleep apnea, the less common form of the condition. More studies need to be conducted to investigate the link between CPAP treatments, heart failure and heart enlargement.
Surgery is also an option, but the patient should discuss with his or her physician whether surgery is the answer to the particular problem. One of the most common techniques is a procedure called uvulopalatopharyngoplasty (UPPP). In this procedure, a laser or surgical instruments are used to either remove or reduce the size of the uvula, tonsils and portions of the soft palate.
Other techniques and strategies include:
- Tongue reduction surgery. The tongue is reduced in size and sutured to prevent it from falling back into the airway.
- Genioglossus tongue advancement. The airway behind the base of the tongue is improved by moving the tongue forward slightly.
- Maxillomandibular advancement. The bones of the upper and lower jaw are cut and moved forward to open the airway behind the palate as well as from behind the base of the jaw.
People can reduce their risk of sleep apnea (particularly obstructive sleep apnea) by reducing the factors that can lead to heart disease. Getting or staying in shape, quitting or refraining from smoking, and moderating alcohol consumption are all ways to reduce the risk.
Questions for your doctor about sleep apnea
Preparing questions in advance can help patients have more meaningful discussions with their doctor. Patients may wish to ask their physicians the following questions related to sleep apnea:
- What type of sleep apnea do I have?
- Can any of my heart problems be attributed to sleep apnea?
- Are there medications to treat sleep apnea?
- Will treating sleep apnea improve my blood pressure?
- Are there treatment options other than breathing devices?
- Can I die if I stop breathing because of sleep apnea?
- If I lose weight will I still need to use a breathing device for sleep apnea?
- I don’t notice any sleep problems. How can you be sure I have sleep apnea?
- Will a sleep study identify problems other than sleep apnea? Can I use a home-based portable sleep monitor?
- Now that I have been diagnosed with sleep apnea, how do you monitor the condition?