Sleep Apnea (cont.)
How common is obstructive sleep apnea?
Obstructive sleep apnea (OSA) is estimated to affect
about 4% of men and 2% of women. In one study of people over 18 years of age,
obstructive sleep apnea was estimated to develop in 1.5 % of people per year
over the 5 year study. It is probably more common than either of these numbers
because the population is becoming more obese, and obesity worsens obstructive sleep apnea. More shocking is the
estimate that only 10% of people with obstructive sleep apnea are currently receiving treatment.
Some groups are more likely to develop obstructive sleep apnea.
- Men are more likely to have obstructive sleep apnea
than women before age 50.
- After age 50, the risk is the same in men and women.
- Among obese patients, 70% have obstructive sleep
apnea. Obstructive sleep apnea worsens in severity and prevalence with
increasing obesity.
- Among cardiac patients, 30-50% have obstructive sleep
apnea, and among patients with strokes, 60% have obstructive sleep apnea.
- A recent study estimated that 14% of NFL football
players and 34% of NFL linemen have obstructive sleep apnea.
- African-Americans have a 2.5 times greater risk of obstructive sleep
apnea than Caucasians. In India, 7.5% of males have obstructive sleep apnea. Chinese males have
a 4% prevalence and Chinese females a 2% prevalence of obstructive sleep apnea. This is interesting
because the prevalence is similar to American Caucasians, but the Chinese
population is generally smaller and less obese than the general American
population. Therefore, something besides obesity must be the explanation for
Chinese obstructive sleep apnea. We do not understand the reasons for these differences, but studies
are ongoing to better define the risks.
What are obstructive sleep apnea symptoms?
Obstructive sleep apnea has many well-studied consequences. First, as you would expect, it
disrupts sleep. Patients with disrupted sleep cannot concentrate, think, or
remember as well during the day. This has been shown to cause more accidents in
the work place and while driving. Thus, people with obstructive sleep apnea have
a three-fold greater risk of a car accident than the general population (there aren't many diseases that can kill the patient AND the people in the car
next to him or her!).
High blood pressure
Sleep apnea causes high blood pressure and heart
problems. Stopping breathing frequently during the night (every 1-4 minutes) can
cause increased stress on the heart. As the oxygen saturation in the blood
decreases and the apnea continues, the sympathetic system ("Fight or Flight"
response) is activated. This sends nerve signals and adrenaline signals to the blood vessels to
constrict and to the heart to work harder. When the vessels constrict, more
blood is sent to the brain and muscles. However, this increases the blood
pressure, which requires the heart to work harder to pump blood through the
smaller vessels. That, combined with the signal for the heart to work harder and
the lower available oxygen in the blood, causes increased stress on the heart
throughout the night. During sleep is the time when the heart usually has less
work to do and can "rest."
Among patients with obstructive sleep apnea that do not
have high blood pressure, 45% will develop high blood pressure within 4 years.
If you look at patients who have hard-to-control blood pressure, that is, taking
more than one medicine for control, 80% have obstructive sleep apnea. When the
obstructive sleep apnea is treated, the high blood pressure comes down. For
more, please read the High Blood
Pressure
article.
Heart complications
The risk for congestive heart failure increases by 2.3 times and the risk of
stroke by 1.5 times with obstructive sleep apnea. For more, please read the
Congestive Heart Failure article.
Obstructive sleep apnea can complicate atrial
fibrillation treatment. Atrial
fibrillation is a condition in which the upper
part of the heart (atrium) is beating out of coordination with the lower part
(ventricle).
The treatment is to cardiovert the heart, which resets the atrium and allows it
to synchronize with the ventricle. After cardioversion, 50% of
patients have a recurrence of atrial fibrillation, but patients with obstructive
sleep apnea have an 80% recurrence. Finally, obstructive sleep apnea can
increase the risk of sudden death. For more, please read the Atrial Fibrillation
article.
Obstructive sleep apnea has many consequences, some of which can kill patient
and their loved ones. Again, it is estimated that only 10% of people with
obstructive sleep apnea are being treated. Just treating the obstructive sleep
apnea would improve
many other areas of their lives.
Next: How is obstructive sleep apnea diagnosed and evaluated? »
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