Sleep apnea is a condition that is characterized by repeated pauses in breathing during sleep. The span for which the breathing stops every time, is called an apnea. This time span or apnea may last anywhere between a few seconds to a few minutes. If the breathing stops for ten seconds or more (during sleep), then, it is considered as an apnea. Sleep apnea is classified into three types - obstructive, central and complex (a combination of obstructive and central forms).
What is Central Sleep Apnea
Sleep apnea is of three types. The most common among them is obstructive sleep apnea, which is caused by some physical obstruction (like relaxed throat muscles) of the airways. Studies show that almost 85% of sleep apnea is diagnosed with the obstructive form of the disease. Central sleep apnea is another form, which is caused by failure of the brain in sending proper signals to the muscles that are responsible for controlling breathing. This is the most uncommon form and as per statistics, this type of sleep apnea amounts to 0.5% of the total sleep apnea cases. The third type called complex sleep apnea, is a combination of obstructive and central sleep apnea and is found in 15% of people affected with sleep apnea.
As in case of other body functions, the brain has an active role to play in breathing. In normal cases, the brain sends signals to the muscles that control breathing. If the blood level of oxygen gets low with a simultaneous rise in carbon dioxide level, the brain sends signals to increase breathing. This will automatically resolve the problem. But, in people with high levels of carbon dioxide in the blood (mostly seen in those with diseases of the heart and lungs), the brain starts concentrating more on the carbon dioxide levels. At this stage, the organ starts ignoring the oxygen levels in the blood. As a result, breathing is more or less controlled on the basis of carbon dioxide levels. This slows down the whole process.
Once the carbon dioxide level is lowered with fast breathing, the process slows down. With slow breathing, carbon dioxide level rises again, resulting in deeper breaths. The brain may continue to signal for fast breathing, till the carbon dioxide level gets too low. This cycle of fast breathing and slow to almost no breathing (apnea) is technically termed as Cheyne-Stokes pattern of breathing. This pattern of breathing is commonly witnessed in those with central sleep apnea. So, this type of sleep apnea is also called Cheyne-Stokes breathing-central sleep apnea.
Other types may be associated with high-altitude periodic breathing, certain medical conditions and use of some types of medication. This condition may happen when the person is awake or during sleep, but the latter is more common. However, the basic cause for this sleep apnea is the failure of the brain to send proper signals to the muscles that control breathing. This condition is mostly seen in adult males.
Causes and Symptoms
This condition is commonly linked to Cheyne-Stokes breathing, as witnessed in people with congestive heart failure or stroke. Another cause is high altitude periodic breathing, which is somewhat similar to Cheyne-Stokes breathing. This is due to the changing barometric pressure in the atmosphere at higher altitudes (more than 15000 feet).
There are various medical conditions that can cause central sleep apnea. This include certain neurological conditions like Parkinson's disease and Alzheimer's disease, conditions that affect the brain stem (like bulbar poliomyelitis, encephalitis and trauma). Even conditions that affect the cervical spine may lead to this type of sleep apnea. This includes, radiation, injury, cervical surgery and severe arthritis. Drugs like painkillers with narcotics may also cause this type of sleep apnea. In some people, this sleep apnea may develop without any obvious cause and this condition is called idiopathic central sleep apnea.
The symptoms may vary from one person to another, on the basis of the underlying condition or cause. In general, the affected people will experience episodes of temporary pauses in breathing, during sleep. Other symptoms include frequent awakenings during sleep, daytime sleepiness, fatigue, difficulty concentrating, memory problems and morning headaches. Even though snoring is mostly associated with obstructive sleep apnea, minor snoring may be found in people with central sleep apnea too. The affected person may have other symptoms, according to the underlying cause.
How is it Treated
This type of sleep apnea is diagnosed with the help of physical symptoms and tests like polysomnogram (sleep study). The patient's heart rate, breathing pattern, activity of the brain, blood oxygen levels and various other factors are monitored during this test. This test may be followed by a multiple sleep latency test during the next day. On the basis of the results of these tests, the severity of the condition is detected. In case, there is any underlying cause, then, that condition will be treated.
As in case of obstructive sleep apnea, CPAP (continuous positive airway pressure) or BiPAP (bi-level positive airway pressure) may also be used in treating central sleep apnea. Even Adaptive servo-ventilation (ASV) devices are used for this purpose. While CPAP therapy ensures a constant pressurized air flow to the patient, thereby preventing any kind of airway blockage, BiPAP facilitates a pressurized air flow during inhalation and the pressure is lowered during exhalation. ASV ensures normal breathing pattern in the affected person, during sleep. Apart from these treatment methods, the patient is also advised to reduce weight (if they are obese), reduce the use of narcotic pain killers and other drugs that may contribute to this condition.
Central sleep apnea is a medical condition that may be associated with certain serious medical problems. So, early diagnosis and treatment is always recommended. It may also lead to severe complications, if left untreated. So, in case you experience any of the symptoms associated with this condition, contact your physician and get it diagnosed and treated at the earliest.