What is Central Sleep Apnea?
Central sleep apnea, or CSA, is characterized by symptoms of frequent starts and stops of breathing during sleep, which leads to regular nighttime awakening. Typically, the episodes last for 10-30 seconds (or longer) and can be intermittent in nature or happen in cycles throughout the night.
CSA is associated with lower oxygen saturation levels, a condition called hypoxia or hypoxemia, which can lead to serious health complications like confusion, rapid heart rate, shortness of breath, cough, and wheezing.
Causes and Description of Central Sleep Apnea
There are several potential causes of CSA. These include heart problems, brain disorders, medications, other substances, and idiopathic causes.
Carbon dioxide and oxygen levels should stay fairly constant when the body is at rest. Inhalation causes oxygen levels to increase and carbon dioxide levels to decrease, while exhalation does the opposite, causing carbon dioxide to increase and oxygen to decrease. Regular respirations allow the body to remove excess, harmful carbon dioxide from the lungs and bloodstream.
There are chemoreceptors in the body, which are governed by oxygen and carbon dioxide levels in the bloodstream. These chemoreceptors send signals to the brain to tell it when to open the throat and other breathing airways, as well as to move the muscles associated with respiratory efforts.
The body’s need for oxygen/carbon dioxide balance is so great that the brain will automatically signal respiration if either of the levels is out of balance.
In CSA, however, the respiratory control centers in the brain are dysfunctional during sleep, so they fail to give the signal to inhale, leading the individual to miss several cycles of breath and an increase in carbon dioxide levels.
The brain and heart normally work together to keep a balanced level of oxygen and carbon dioxide in the bloodstream. In CSA, the heart and brain differ in what each organ considers normal inhalation and exhalation cycles. In this condition, the neurological centers in the brain that are responsible for breathing cycles fail to react fast enough to keep the respiratory rate even and unlabored.
This causes the rate to fluctuate between apnea and hypopnea episodes throughout the night.
During the breathing pauses, the individual makes no efforts to start breathing again, the chest does not move, and the muscles do not relax or contract. Individuals will wake up and not being able to immediately start breathing again, leading to a feeling of panic and cognitive dysfunction. These symptoms are associated with excess carbon dioxide levels in the blood.
Symptoms of Central Sleep Apnea
Five primary categories could lead to symptoms of CSA:
- Primary CSA
- Cheyne-Stokes respirations
- Non-Cheyne-Stokes Medical Condition
- Drug or Substance Use Related
- High-Altitude Breathing Patterns
Cheyne-Stokes respirations are characterized by periodic breathing with regular episodes of alternating between apnea and rapid breathing, causing extreme fluctuations in oxygen and carbon dioxide levels in the bloodstream. This is a condition found in patients with congestive heart failure and does not always happen only in sleep, but during waking hours as well. It is also common in patients with kidney failure and stroke.
It is believed that treatment of the failing organ leads to a resolution of Cheyne-Stokes respirations.
Signs and symptoms that may mean you have central sleep apnea include:
- Lack of muscle movement or use in the thoracic and abdominal cavities for 10 or more seconds during sleep
- Inability to complete exhalation
- Inability to start the breathing cycle upon waking
- Waking up with an urgent need to breathe
- Sleep paralysis (not present in every individual)
Sleep apnea will often lead to daytime symptoms like fatigue, irritability, headaches, restless sleep, changes in voice, weakness, problems swallowing, and shortness of breath.
Diagnostic Tests for Central Sleep Apnea
A licensed physician diagnoses sleep apnea. It first requires an examination, which generally includes the individual staying overnight in a sleep laboratory to receive a sleep study, or polysomnography.
Periods of breathing cessation are measured in frequency during the sleep study, which will allow the technician to help delineate what type of sleep apnea is present.
In central sleep apnea, the interruption in breathing is associated with physically being unable to restart the cycle. A polysomnogram will be able to look at the relation between the cessation of airflow through the nose and mouth, as well as the absence of muscle movement in the rib cage and abdominal area.
Since central sleep apnea is frequently associated with heart, lung, or kidney diseases, there are other tests that are done with polysomnography, including:
- Lung function tests
- MRI of head, spine, or neck
Treatment Options for Central Sleep Apnea
After diagnosis, the physician will provide a few different options for treatment.
Generally, treating the cause of CSA is the first step.
Continuous positive airway pressure (CPAP) treatment is usually reserved for those with obstructive sleep apnea (OSA) rather than CSA. The patient wears a face mask that is connected to a machine, which provides pressured airflow into the breathing passages. The device compresses the room air at a constant level so that the airway does not collapse, which is typical in OSA cases. While it is usually at a higher level, it stays low enough so that the individual can easily exhale on their own.
BiLevel positive airway pressure (BiPAP) is much more common in CSA instances. It differs from CPAP in that it is not at a constant high pressure, but is set at two separate pressure settings: IPAP (for inhalation) and EPAP (for exhalation). This allows the breather to have a more normal respiratory rhythm by inflating the lungs at a regular interval, which is a measurement including the duration of a single breath and their normal breathing rate. The BiPAP levels are programmed by the diagnosing provider.
Adaptive Servo Ventilation (ASV) is a newer technology that is being used to treat CSA. ASV is similar to CPAP, but uses a different algorithm.
This is more of a lifestyle change, rather than a treatment, but recent studies have shown that positional changes at night may have an impact on the severity of one type of CSA: Cheyne-Stokes.
Positional changes are known to affect the severity of obstructive sleep apnea; however, recent research has looked at how these changes may affect central sleep apnea patients as well. Symptoms of Cheyne-Stokes respirations were improved by the changing body’s position during sleep.
There was increased severity of Cheyne-Stroke respirations when patients were in the supine position (lying on their back).
Otherwise, patients with CSA and no known cardiac conditions were not seen to have any symptom changes related to position during sleep.
A highly experimental process, adding a pacemaker to the diaphragm has shown improvement in CSA symptoms and helping patients overcome the condition.
- Central sleep apnea. (n.d.). Retrieved July 19, 2016, from https://en.wikipedia.org/wiki/Central_sleep_apnea
- Blaivas, A. J., DO, & Zieve, D., MD. (n.d.). Central sleep apnea: MedlinePlus Medical Encyclopedia. Retrieved July 19, 2016, from https://medlineplus.gov/ency/article/003997.htm
- Zaharna M; Rama A; Chan R; Kushida C. A case of positional central sleep apnea. J Clin Sleep Med 2013;9(3):265-268.
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Apneas are defined as pauses in breathing of more than 10 seconds while asleep. These occur at regular intervals throughout the night. The subject is rarely aware of their difficulty breathing even upon awakening, and the condition may go undetected for years until spotted by someone else, or detected during a sleep study. Central sleep apnea differs from obstructive sleep apnea in that there is no ‘central’ attempt made to breath, whereas in OSA, the breaths are hampered by a physical blockage. In mixed sleep apnea, there is a transition between both forms.
Central sleep apnea is largely caused by an imbalance in the brain and central nervous system during sleep. The brain monitors all blood oxygen levels, and in most people this function ensures consistent intake of oxygen and outtake of carbon dioxide. In central sleep apnea, the brain does not react quickly enough to changes in these levels in the body while sleeping, and is forced to overcompensate afterwards, resulting in long missed breaths, followed by short rapid breaths.
In extreme cases where the apneas are long enough to severely lower the level of oxygen in the blood stream, central sleep apnea can lead to brain damage or even sudden death. Central sleep apnea can also exacerbate other disorders. People suffering epilepsy may be prone to seizures due to hypoxia (a lack of oxygen in the blood stream), even if taking medication to control seizures. Seizures may also occur in subjects without epilepsy. Increased carbon dioxide levels (hypercapnia) over a long period of undetected central sleep apnea can raise the pH balance of the blood enough to lead to metabolic acidosis. Hypoxia can also lead to heart attacks, angina or arrhythmias in subjects with coronary heart disease.
A sub class of central sleep apnea is Cheyne-Stokes respiration. This is similar to central sleep apnea in that the brain reacts slowly to changes in the blood oxygen level, and must rapidly compensate after. This condition is typically found in subjects with congestive heart failure, strokes or brain tumours. It can also occur with people with no prior history of the problem when sleeping at high altitudes, and is a signal of altitude sickness.
Detecting CSA in the absence of a bed partner should be centered on recognizing common symptoms and warning signs of CSA. Common symptoms include poor sleep with consistent awakenings, occasional shortness of breath when waking, difficulty falling asleep, and excessive sleepiness during the day. Those with a bed partner should be able to detect CSA much easier, as the partner will be able to easily detect the apneas, which can last as long as 15-20 seconds.
Daytime sleepiness will be common for anyone suffering with CSA. Apneas will often cause short awakenings which the subject likely won’t be aware of. This can happen as many as 100 times a night, and severely disrupts sleep, often preventing the individual from attaining deep, regenerative sleep.
If suspected, a sleep specialist should be consulted, and an overnight sleep study obtained. The polysomnogram will clearly show the frequency and duration of the apneas, as well as the corresponding drop or rise in oxygen and carbon dioxide levels. This will not only identify the problem, but also give immediate feedback to the doctors on how serious the condition is, and what methods of treatment should be implemented. Other conditions that may be causing the central sleep apnea may also come to light during this process, so care should be given to ensure all avenues are explored.
Treatment of central sleep apnea is often determined by the cause of the events. One popular treatment is positive airway pressure (PAP). Continuous PAP (CPAP) or Bilevel PAP may be used. A relatively new PAP, adaptive servo ventilation (ASV) has recently demonstrated beneficial response for patients with central sleep apnea.
If drugs or drug abuse is causing the CSA, a switch in medications and/or a refrain from drug use may be necessary.