There are three forms of sleep apnea: central (CSA), obstructive (OSA), and complex or mixed sleep apnea (i.e., a combination of central and obstructive) constituting 0.4%, 84% and 15% of cases respectively.
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. Mixed or complex sleep apnea, is a combination of both obstructive and central sleep apneas.
According to UpToDate, Complex sleep apnea (CompSA, also called “treatment-emergent central sleep apnea”) is the emergence or increase of central apneas and hypopneas during the initiation of continuous positive airway pressure therapy (or bilevel positive airway pressure without a backup respiratory rate) for obstructive sleep apnea (OSA).
As per PMC Patients with complex sleep apnea exhibit OSA, but upon application of positive airway pressure, the patient exhibits persistent central sleep apnea. This central apnea is most commonly noted while on CPAP therapy, after the obstructive component has been eliminated. This has long been seen in sleep laboratories…
As per the results of a study conducted by researchers at Mayo Clinic, 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.
- Complex Sleep Apnea or CompSA is more common among men than women. “This may be due to less stable respiratory control in males than females”, says Timothy Morgenthaler, M.D., Mayo Clinic sleep medicine specialist, pulmonologist and lead study investigator.
- CompSA is also more common among patients with heart failure, among patients with severe OSA, and among patients with a mixture of obstructive and central apneas during initial polysomnography.
- Additional factors associated with CompSA include non-rapid eye movement sleep, use of higher levels of continuous positive airway pressure (ie, over-titration), use of a high pressure support level, high altitude, oral breathing, opioid narcotics, and, possibly, sleeping in a supine position.
The complex sleep apnea patients have fewer complaints about waking up after initially falling asleep than those with central sleep apnea. 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, an effective treatment for Complex Sleep Apnea has not been identified, but research continues to test breathing assistance machines to alleviate this condition’s symptoms.