What is Sleep Apnea?
Sleep apnea is a serious, potentially life-threatening condition that is far more common than generally
understood. First described in 1965, sleep apnea is a breathing disorder characterized by brief
interruptions of breathing during sleep. It owes its name to a Greek word, apnea, meaning "want of
breath." There are two types of sleep apnea: central and obstructive. Central sleep apnea, which is
less common, occurs when the brain fails to send the appropriate signals to the breathing muscles to
initiate respiration. Obstructive sleep apnea is far more common and occurs when air cannot flow into
or out of the person's nose or mouth although efforts to breathe continue. In a given night, the number
of involuntary breathing pauses or "apneic events" may be as high as 100 per hour. These breathing
pauses are almost always accompanied by snoring between apnea episodes, although not everyone
who snores has this condition. Sleep apnea can also be characterized by choking sensations. The
frequent interruptions of deep, restorative sleep often lead to early morning headaches and excessive
daytime sleepiness. Early recognition and treatment of sleep apnea is important because it may be
associated with irregular heartbeat, high blood pressure, heart attack, and stroke.
Who gets Sleep Apnea?
Sleep apnea occurs in all age groups and both sexes but is more common in men (it may be under
diagnosed in women) and possibly young African Americans. It has been estimated that as many as
18 million Americans have sleep apnea. Four percent of middle-aged men and 2 percent of
middle-aged women have sleep apnea along with excessive daytime sleepiness. People most likely to
have or develop sleep apnea include those who snore loudly and also are overweight, or have high
blood pressure, or have some physical abnormality in the nose, throat, or other parts of the upper
airway. Sleep apnea seems to run in some families, suggesting a possible genetic basis.
What Causes Sleep Apnea?
Certain mechanical and structural problems in the airway cause the interruptions in breathing during
sleep. In some people, apnea occurs when the throat muscles and tongue relax during sleep and
partially block the opening of the airway. When the muscles of the soft palate at the base of the tongue
and the uvula (the small fleshy tissue hanging from the center of the back of the throat) relax and sag,
the airway becomes blocked, making breathing labored and noisy and even stopping it altogether.
Sleep apnea also can occur in obese people when an excess amount of tissue in the airway causes it
to be narrowed. With a narrowed airway, the person continues his or her efforts to breathe, but air
cannot easily flow into or out of the nose or mouth. Unknown to the person, this results in heavy
snoring, periods of no breathing, and frequent arousals (causing abrupt changes from deep sleep to
light sleep). Ingestion of alcohol and sleeping pills increases the frequency and duration of breathing
pauses in people with sleep apnea.
How is normal breathing restored during sleep?
During the apneic event, the person is unable to breathe in oxygen and to exhale carbon dioxide,
resulting in low levels of oxygen and increased levels of carbon dioxide in the blood. The reduction in
oxygen and increase in carbon dioxide alert the brain to resume breathing and cause an arousal. With
each arousal, a signal is sent from the brain to the upper airway muscles to open the airway; breathing
is resumed, often with a loud snort or gasp. Frequent arousals, although necessary for breathing to
restart, prevent the patient from getting enough restorative, deep sleep.
What are the effects of Sleep Apnea?
Because of the serious disturbances in their normal sleep patterns, people with sleep apnea often feel
very sleepy during the day and their concentration and daytime performance suffer. The consequences
of sleep apnea range from annoying to life-threatening. They include depression, irritability, sexual
dysfunction, learning and memory difficulties, and falling asleep while at work, on the phone, or driving.
It has been estimated that up to 50 percent of sleep apnea patients have high blood pressure.
Although it is not known with certainty if there is a cause and effect relationship, it appears that sleep
apnea contributes to high blood pressure. Risk for heart attack and stroke may also increase in those
with sleep apnea. In addition, sleep apnea is sometimes implicated in sudden infant death syndrome.
When should should Sleep Apnea be suspected?
For many sleep apnea patients, their spouses are the first ones to suspect that something is wrong,
usually from their heavy snoring and apparent struggle to breathe. Coworkers or friends of the sleep
apnea victim may notice that the individual falls asleep during the day at inappropriate times (such as
while driving a car, working, or talking). The patient often does not know he or she has a problem and
may not believe it when told. It is important that the person see a doctor for evaluation of the sleep
problem.
How is Sleep Apnea diagnosed?
In addition to the primary care physician, paleontologists, neurologists, or other physicians with
specialty training in sleep disorders may be involved in making a definitive diagnosis and initiating
treatment. Diagnosis of sleep apnea is not simple because there can be many different reasons for
disturbed sleep. Several tests are available for evaluating a person for sleep apnea. Polysomnography
is a test that records a variety of body functions during sleep, such as the electrical activity of the brain,
eye movement, muscle activity, heart rate, respiratory effort, air flow, and blood oxygen levels. These
tests are used both to diagnose sleep apnea and to determine its severity. The Multiple Sleep Latency
Test (MSLT) measures the speed of falling asleep. In this test, patients are given several opportunities
to fall asleep during the course of a day when they would normally be awake. For each opportunity, time
to fall asleep is measured. People without sleep problems usually take an average of 10 to 20 minutes
to fall asleep. Individuals who fall asleep in less than 5 minutes are likely to require some treatment for
sleep disorders. The MSLT may be useful to measure the degree of excessive daytime sleepiness and
to rule out other types of sleep disorders. Diagnostic tests usually are performed in a sleep center, but
new technology has allowed some sleep studies to be conducted in the patient's home.
Sleep apnea treatments...
|
|
