Nov
Central Sleep Apnea (CSA) occurs when the brain fails to send proper signals to the muscles responsible for breathing. This condition is typically seen in infants, particularly those born prematurely, and in adults with underlying conditions such as heart disease, cerebrovascular disorders, or congenital abnormalities. It may also be triggered by certain medications or high-altitude environments.
Central Sleep Apnea in Infants
CSA may affect both premature infants (born before 37 weeks of gestation) and full-term infants. It is defined as apneic episodes lasting longer than 20 seconds, often accompanied by a slowed heart rate, reduced blood oxygen levels, or hypotonia (a generalized relaxation of muscle tone). These infants often require the use of an apnea monitor, which sounds an alarm when an apneic episode occurs.
It is important to note that central sleep apnea in infants is not the same as sudden infant death syndrome (SIDS).
Mechanism of Breathing Control
Under normal circumstances, the brain continuously monitors oxygen and carbon dioxide levels in the blood to regulate breathing. When oxygen levels drop or carbon dioxide levels rise, the brain increases the rate and depth of breathing to correct the imbalance.
In individuals with chronic heart or lung disease, carbon dioxide levels may remain elevated over time. In such cases, the brain becomes desensitized to oxygen levels and relies primarily on carbon dioxide levels to regulate breathing. However, when someone breathes more deeply or rapidly—“blowing off” too much carbon dioxide—the brain slows the respiratory drive. As carbon dioxide builds up again, the brain eventually signals to increase breathing once more.
This delayed response creates a cyclical breathing pattern, known as Cheyne-Stokes respiration, characterized by alternating periods of rapid breathing, slow breathing, and apnea. Although this pattern may occur both during wakefulness and sleep, it tends to be more pronounced and problematic during sleep.
Cheyne-Stokes respiration is particularly common in patients with heart failure, and it is frequently associated with central sleep apnea.
Diagnosis and Treatment
Central sleep apnea is most often seen in adults with underlying medical conditions, and in infants with prematurity or congenital disorders. In both populations, the condition is usually identified by a primary care provider or pediatrician. Diagnosis is confirmed through a sleep study (polysomnography) or continuous overnight monitoring in a hospital setting.
- In Infants: Treatment typically involves the use of an apnea monitor that uses sensors to detect breathing irregularities and sounds an alarm during apnea events. The alarm not only alerts caregivers but often wakes the infant, resuming normal breathing. Most infants outgrow CSA as they mature, and monitoring can eventually be discontinued. However, those with congenital conditions may require longer-term monitoring.
- In Adults: Treatment focuses on addressing the underlying cause, such as optimizing management of heart disease, adjusting medications, or mitigating the effects of high altitude. In some cases, specific therapies like adaptive servo-ventilation (ASV) may be used to stabilize breathing patterns during sleep.