Central Sleep Apnea (CSA) is a distinct disorder of sleep-disordered breathing that affects the respiratory control system. Unlike the far more common Obstructive Sleep Apnea (OSA), CSA is not caused by a physical blockage in the throat. Instead, it results from a neurological failure to signal the breathing muscles. Continuous Positive Airway Pressure (CPAP) therapy is the gold standard for treating OSA, leading many to question its effectiveness for this neurologically driven condition. This difference in underlying cause determines whether CPAP is the right tool or if specialized interventions are necessary.
Understanding Central Sleep Apnea
The fundamental difference between sleep apnea types lies in the cause of the breathing pause. Obstructive Sleep Apnea occurs when soft tissues in the upper airway relax during sleep, physically collapsing and blocking the passage of air. The brain attempts to breathe, but the effort is unsuccessful due to the obstruction. This mechanical issue causes the characteristic loud snoring associated with OSA.
Central Sleep Apnea (CSA), however, involves a breakdown in communication between the brain and the muscles responsible for respiration. The brainstem fails to send the signal to inhale, resulting in a period of no respiratory effort. Because there is no physical effort against a closed airway, CSA episodes are typically quieter than OSA and do not involve snoring. This absence of a mechanical blockage means treatments focused solely on keeping the airway open may not be effective.
Standard CPAP Efficacy and Limitations
Standard Continuous Positive Airway Pressure (CPAP) delivers a constant stream of pressurized air to hold the upper airway open, acting as a pneumatic splint. This mechanism is highly effective for preventing the tissue collapse that defines Obstructive Sleep Apnea. Since Central Sleep Apnea is caused by a lack of respiratory drive rather than an obstruction, CPAP is inherently limited in its ability to directly address the root problem.
CPAP can stabilize mild forms of CSA by improving oxygen levels and reducing breathing instability. Studies suggest CPAP may suppress central apneas in approximately 42% of patients with CSA related to heart failure. However, the constant pressure can paradoxically destabilize the respiratory control system, leading to treatment-emergent central sleep apnea. This occurs when CPAP resolves obstructive events but then unmasks or induces central events, requiring a shift to specialized therapy.
Advanced Positive Airway Pressure Therapies
When standard CPAP is ineffective, specialized Positive Airway Pressure (PAP) devices are utilized to manage Central Sleep Apnea (CSA).
Adaptive Servo-Ventilation (ASV)
ASV represents a significant advancement over CPAP, designed specifically to stabilize the irregular breathing patterns seen in CSA. The ASV device continuously monitors the patient’s breathing, adjusting pressure on a breath-by-breath basis. If the machine detects a drop in the patient’s own breathing effort, it automatically increases pressure support to maintain a target ventilation level. When the patient’s breathing recovers and becomes too fast or deep, the device reduces pressure support, dampening the large respiratory swings that characterize central apnea events. This dynamic pressure adjustment is effective for complex sleep apnea and central apneas not related to systolic heart failure. ASV is generally not recommended for patients with symptomatic heart failure and reduced left ventricular ejection fraction (HFrEF) due to concerns about increased cardiovascular mortality.
Bi-level Positive Airway Pressure (BiPAP)
BiPAP delivers two distinct pressure settings: a higher pressure for inhalation and a lower pressure for exhalation. For Central Sleep Apnea, certain BiPAP modes can be programmed with a timed breath rate to ensure the patient takes a minimum number of breaths per minute. BiPAP is frequently employed as an alternative for patients who do not respond to CPAP. It has shown effectiveness in suppressing central apneas, especially in those with heart failure where CPAP fails.
Non-PAP Treatment Approaches
Addressing the underlying medical cause of Central Sleep Apnea (CSA) is often the most direct non-PAP treatment strategy. Since CSA is frequently linked to conditions like heart failure, optimizing the medical management of that condition can lead to a significant reduction in central apnea events. CSA also occurs in patients using opioid medications, and reducing or discontinuing the narcotic dosage can resolve the breathing disorder.
Supplemental oxygen therapy is an accessible alternative, particularly for CSA associated with high altitude or heart failure. By reducing the severity of low oxygen levels, supplemental oxygen helps stabilize the ventilatory control loop, decreasing the frequency of central apneas. This approach is a viable option for those who cannot tolerate positive airway pressure devices.
Certain pharmacological agents are sometimes prescribed to stabilize the respiratory drive. Acetazolamide works by inducing a mild metabolic acidosis, which stimulates breathing and helps shift the body’s threshold for apnea. Theophylline has also been studied for its ability to attenuate central sleep disordered breathing. However, evidence supporting the long-term use of these medications remains limited, and they are generally reserved for specific types of CSA or when PAP therapy is unsuccessful.