While asleep, there may be pauses in breathing, which are called apnoeas. Up to 5 brief apnoeas an hour may be seen in normal adults. For people with central sleep apnea (CSA), the apnoeas last longer and occur more frequently. The body does not make an attempt to breathe during these pauses. This is different to the more common sleep disorder obstructive sleep apnoea (OSA). Patients with OSA struggle to breathe against a blocked airway. For patients with CSA, the airway is not blocked, there is just a pause in breathing efforts. About 10% of people with breathing problems during sleep have CSA. This affects the quality of sleep and they feel sleepy during the day.
CSA can be caused as the brain may be slow to respond to changes in oxygen and carbon dioxide levels in the blood when breathing slows down. This may occur in people who have had sleep apnea for a long time. This is due to blunting of the breathing reflex. CSA may also be due to a slow circulation from heart failure having an effect on the normal breathing reflex pathway.
CSA can only be diagnosed through a thorough evaluation of all the possible causes and also a sleep study.
CPAP can help many forms of CSA and sleep hypoventilation responds well to bilevel ventilatory assistance (BIPAP). Where heart failure is a factor, treatment of this with medications is important.