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.
Sleep apnea describes a form of sleep disorder characterized by disordered breathing. There are two primary types of sleep apnea: Central and Obstructive.
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.
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.
Implantable Electronic Devices
There are relatively new treatments that use programmed electrical impulse to stimulate the diaphragm for the treatment of central sleep apnea. They physically resemble cardiac pacemakers. However, they are attached to the phrenic nerve.
- 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.