By Robert Preidt
Friday, September 1, 2006
FRIDAY, Sept. 1 (HealthDay News) -- Mayo Clinic researchers
say they've identified a new type of sleep apnea called "complex
sleep apnea" that may be resistant to standard treatment
such as continuous positive airway pressure (CPAP).
"All of us in our sleep lab have observed
for years that there are patients who appear to have obstructive
sleep apnea, but the CPAP doesn't make them all that much better
-- they still have moderate to severe sleep apnea even with
our best treatment and subjectively don't feel they're doing
very well," study lead investigator Dr. Timothy Morgenthaler,
a sleep medicine specialist and pulmonologist, said in a prepared
statement.
Until now, obstructive sleep apnea and central
sleep apnea have been the two known types of apnea. Obstructive
sleep apnea, which is most common, occurs when the throat muscles
relax and the airway narrows, which momentarily cuts off breathing
and causes loud snoring. In central sleep apnea, the brain fails
to send the proper signals to the muscles that control breathing.
Complex sleep apnea is a combination of both obstructive
and central sleep apnea, according to the Mayo researchers.
Their findings were published in the September issue of the
journal Sleep.
The study of 223 patients referred to the Mayo
Clinic Sleep Disorder Center found that 15 percent of the patients
had complex sleep apnea, 84 percent had obstructive sleep apnea
and 0.4 percent had central sleep apnea. Males are more likely
to have complex sleep apnea.
At first, patients with complex sleep apnea appear
to have obstructive sleep apnea and stop breathing 20 to 30
times per hour each night. However, unlike people with typical
obstructive sleep apnea, the breathing problems in patients
with complex sleep apnea aren't completely relieved by a CPAP
machine, which keeps a patient's airway open during sleep.
"When they put on a CPAP machine, they start
to look like central sleep apnea syndrome patients. This phenomenon
has been observed for years, but this study is the first to
attempt to categorize these people," he said.
There are no known risk factors for complex sleep
apnea, and an effective treatment for the condition has not
yet been identified, Morgenthaler said.
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