Sleep Disorders: Central Sleep Apnea
Central sleep apnea (CSA) is a disorder where the brain tells the body to stop breathing periodically. Breathing slowly returns and increases to where the breaths are very long and then slowly decreases until, once again, breathing stops. This goes on over and over throughout the night. This is much less common than obstructive sleep apnea and is usually caused by heart failure, diseases of the brain such as a tumor or a stroke, exposure to high altitude or sometimes by chronic narcotic use. Rarely there is no obvious cause at all; it is just that some patients are predisposed to developing this for no real reason, in which case it is called “idiopathic.”
What are the signs and symptoms?
These include daytime drowsiness, chronic fatigue, morning headaches, as well as frequent arousals from sleep for which the patient receives no clear reason.
What are the risk factors and triggers?
Risk factors include congestive heart failure, stroke, brain tumor, high altitude exposure and chronic narcotic use. Occasionally, it can occur in otherwise normal patients for no clear reason other than that the patient is predisposed to it.
How is it diagnosed?
Overnight polysomnography, or a sleep study done in a sleep laboratory, is the gold standard. Sleep studies done at home are very good for diagnosing obstructive sleep apnea but not for central sleep apnea. If a patient has central sleep apnea risk factors, the study should always be done in a sleep laboratory.
What is the treatment?
When a narcotic causes central sleep apnea, then the narcotic should be discontinued if possible. If it is caused by high altitude exposure, then the patient should return to low altitude. If that is not possible, then using oxygen during sleep can help.
If a person has central apnea because of a stroke, a brain tumor or is on a narcotic that cannot be stopped, then they can sometimes be treated with a CPAP machine. If that doesn’t work, they can be treated with an adaptive servo ventilator. This looks like a standard CPAP machine but is a lot more complicated on the inside. This device can sense whenever the brain tells the body to stop breathing and gives a series of breaths to overcome that and eliminate central sleep apnea.
However, an adaptive servo ventilator cannot be used on a patient with heart failure due to a weak heart (said to have a low “ejection fraction”). For reasons that are not clear, this sort of device has been shown to increase the death rate for such patients, even though it’s perfectly safe to use when heart function is normal. The best way to treat a patient with central sleep apnea due to this sort of heart failure is to improve the heart failure with medical or surgical therapy. If that doesn’t work, then sometimes using a standard CPAP machine can help. Sometimes, using oxygen at night as well as certain medications may also help.