New Type Of Sleep Apnea Discovered By Mayo Clinic Researchers

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New Type Of Sleep Apnea Discovered By Mayo Clinic Researchers

http://www.medicalnewstoday.com/medicalnews.php?newsid=51105

Researchers at Mayo Clinic have identified a new type of sleep apnea

they call " complex sleep apnea. " The findings will be published in

the September issue of the journal Sleep.

The two previously known types of sleep apnea include obstructive

sleep apnea and central sleep apnea. In obstructive sleep apnea, the

more common form, the throat muscles relax and the airway is

narrowed, momentarily cutting off breathing and resulting in noisy

snoring. With central sleep apnea, the brain does not send proper

signals to the muscles that control breathing. The newly discovered

type, complex sleep apnea, is a combination of both obstructive and

central sleep apneas.

Patients with complex sleep apnea at first appear to have obstructive

sleep apnea and stop breathing 20 to 30 times per hour each night.

But unlike typical obstructive sleep apnea patients, their breathing

problem is not completely alleviated by a CPAP (continuous airway

pressure) machine, which functions like a pneumatic splint to open a

patient's airway. Instead, once the CPAP is applied to complex sleep

apnea patients, the obstruction seems to dissipate, but still they do

not breathe properly. Symptoms of central sleep apnea then appear and

fragmented sleep results, due to frequent pauses in breathing.

" 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, " says Morgenthaler, M.D.,

Mayo Clinic sleep medicine specialist, pulmonologist and lead study

investigator. " 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 attempt to categorize

these people. "

The study involved a retrospective review of 223 patients

consecutively referred to the Mayo Clinic Sleep Disorders Center over

one month, plus 20 consecutive patients diagnosed with central sleep

apnea. The investigators found that complex sleep apnea comprised 15

percent of all sleep apnea patients, while 84 percent had obstructive

sleep apnea and 0.4 percent had central sleep apnea. They also

discovered that males have a higher tendency to have complex sleep

apnea. Dr. Morgenthaler says this may be due to less stable

respiratory control in males than females. The complex sleep apnea

patients had sleep and cardiovascular histories similar to the

obstructive sleep apnea patients. The complex sleep apnea patients

also had fewer complaints about waking up after initially falling

asleep than those with central sleep apnea (32 percent vs. 79

percent). The investigators found that complex sleep apnea could be

diagnosed based on patients' sleep patterns defined at their initial

diagnostic exams plus lack of response to CPAP.

According to Dr. Morgenthaler, no known factors influence risk for

complex sleep apnea. An effective treatment has not been identified,

but research continues to test breathing assistance machines to

alleviate this condition's symptoms