Central sleep apnea (CSA) is a sleep-related breathing disorder characterized by apneas or a cessation of breathing during sleep. In people with central sleep apnea, the brain does not properly deliver signals to the muscles that control a person’s breathing.
What is Central Sleep Apnea?
Central sleep apnea is a type of sleep-related breathing disorder that involves apneas, or breathing interruptions, during sleep. It’s characterized by apneas or cessation of breathing while sleeping that is frequently associated with underlying cardiovascular and neurological disorders. Central sleep apnea is seen more frequently during NREM sleep and is linked to a number of health conditions involving the heart and brain.
Symptoms of Central Sleep Apnea:
- Abrupt nighttime awakenings
- Shortness of breath that is relieved by sitting up
- Daytime fatigue
- Mood changes
- Lack of focus and concentration
Causes and Types of Central Sleep Apnea
Central sleep apnea is primarily caused by a dysfunction between the brain and the muscles involved with breathing. At its most basic definition, central sleep apnea is a disorder of hyperventilation (rapid, frequent breathing) or hypoventilation (underbreathing, slow breathing). Both of these occurrences can alter the amount of carbon dioxide within the body which ultimately affects how the brainstem (the region of the brain that controls breathing) signals the muscles for breathing to function.
Cheyne-Stokes breathing: This form of central sleep apnea is frequently paired with congestive heart failure or stroke. Cheyne-Stokes breathing is a very recognizable pattern consisting of a gradual increase then gradual decrease in breathing effort and airflow followed by complete cessation or apnea before repeating the pattern again.
Drug-induced apnea: Use of particular medications such as opioids may cause irregularities in breathing consistent with central apnea due to their effects on the brain’s signaling process.
High-altitude periodic breathing: A pattern of breathing similar to Cheyne-Stokes appears when exposed to high altitudes. Due to the change in available oxygen at higher altitudes, changes in breathing occur varying between rapid breathing (hyperventilation) and underbreathing (hypoventilation).
Medical condition-induced: Medical conditions that occur and may cause central sleep apnea not associated with Cheyne-Stokes.
Primary central sleep apnea: Uncommon, cause is unknown.
Primary central sleep apnea of infancy: Most commonly seen in infants born prematurely and is thought to be caused by a developmental issue as a result of an immature brainstem or as a secondary problem from another medication condition.
Treatment-emergent: This kind of central sleep apnea is often called complex sleep apnea and is a combination of central and obstructive sleep apnea. Patients can develop central apnea while using CPAP or continuous positive airway pressure for treatment of their obstructive apnea and may require alternative forms of treatment.
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Central Sleep Apnea vs. Obstructive Sleep Apnea
Central sleep apnea differs from obstructive sleep apnea. Obstructive sleep apnea as the name implies, is caused by airway obstruction during sleep. It is a mechanical issue; the brain is emitting signals to breathe but due to excessive tissue in the airway airflow is obstructed. Effort to breathe remains intact.
In central sleep apnea, the area of the brain that controls breathing does not emit the signal to breathe. It is a wiring issue; without the proper signal, the muscles involved in breathing do not function. The end result is in an apnea. Effort to breathe does not occur due to the lack of proper signaling.
Central sleep apnea is less common than obstructive sleep apnea. Assessments of the population having central sleep apnea vary, but it is estimated that central sleep apnea represents around 20% of all sleep apnea diagnoses. Certain neurological or cardiovascular conditions are often associated in conjunction with central sleep apnea.
What Causes Central Sleep Apnea?
In central sleep apnea, the brain’s control of nighttime breathing is impaired, so the brain can’t signal the muscles that control breathing. Conditions affecting the brainstem, the region of the brain that controls breathing, make CSA more likely. These include stroke, certain spinal conditions and severe obesity.
The use of some narcotic pain relievers may increase the risk of central sleep apnea. Narcotic pain relievers work by binding to brain receptors, and may influence the brain’s signaling process. These pain relievers include: Codeine, Morphine, Oxycodone, Fentanyl, Hydrocodone, Hydromorphone, Meperidine, Tramadol.
Diagnosis of central sleep apnea is often done by a board certified sleep medicine physician in collaboration with other medical specialists such as cardiologists or neurologists. The sleep physician reviews past medical history, comorbidities or other health related disorders and the results of a diagnostic or split-night sleep study or polysomnogram.
A diagnostic overnight sleep study or polysomnogram includes a stay in a sleep facility where specially trained technicians apply a multitude of electrodes for monitoring purposes. The technician observes the patient throughout the night paying close attention to brain activity, heart rate, oxygen levels as well as possible respiratory events such as apnea. Additionally the technician monitors any muscle movements that may occur during sleep.
A split-night sleep study or polysomnogram consists of both a diagnostic portion and a treatment portion. It is essentially two studies in one night, just shortened versions of each. The sleep technician monitors the patient for half of the night as they would for a regular diagnostic study but then applies the appropriate form of treatment if central apnea is observed consistently.
Treatment for central sleep apnea can be complex due to the nature of origin or additional conditions such as heart failure or neurological complications.
Physicians often begin by treating underlying conditions as a means to lower the risk of central sleep apnea from occurring. In addition, a decreased use of opioid medications can also serve to lower the risk of central apnea.
Traditional pressure-based treatments such as CPAP (Continuous Positive Airway Pressure) may be utilized. If the central apnea persists BiPAP (BiLevel Positive Airway Pressure) is an alternative to CPAP. Rather than use a fixed, single pressure, BiLevel treatment uses a lower pressure for the patient during exhalation and a higher pressure during inhalation. The lower pressure serves to eliminate the central events that may be occurring.
For more severe cases of central sleep apnea or those that do not respond well to BiLevel pressure settings, adaptive servo-ventilation or ASV may be an alternative. During an ASV titration, the device delivering the pressure monitors the patient’s breathing pattern and responds accordingly based on when the patient has a respiratory event. The sleep technician sets basic parameters on the machine that allows for variability. As the patient sleeps, minor adjustments can be made to ensure the patient’s breathing becomes more uniform and consistent; eliminating central respiratory events. ASV treatment is not recommended for patients with particular kinds of heart failure.
Supplemental oxygen is another form of treatment that may be used for central sleep apnea. Supplemental oxygen increases the oxygen levels in the blood and can be used in conjunction with PAP treatment or without depending on the severity of central apnea.