Cheyne-Stokes Respiration (CSR) is an abnormal breathing pattern characterized by a distinct cyclical fluctuation in depth and rate, most often appearing during sleep. This pattern is a serious clinical sign pointing to underlying medical instability. It involves periods of deep, rapid breathing alternating with periods of minimal or absent breathing. The presence of CSR is highly associated with severe health conditions affecting the heart and brain.
Defining the Cheyne-Stokes Pattern
The pattern is described using a “crescendo-decrescendo” model, where breathing depth waxes and wanes cyclically. A cycle begins with the crescendo phase (increasing depth and rate/hyperventilation), followed by the decrescendo phase (breathing becomes shallower and slower).
The cycle culminates in apnea (cessation of breathing) or hypopnea (extremely shallow breathing). Cycles typically last between 45 and 90 seconds before the crescendo phase begins again. These interruptions prevent restorative sleep and can lead to excessive daytime sleepiness and fatigue.
The physiological mechanism involves an unstable feedback loop in the respiratory control system, regulated by carbon dioxide (\(\text{CO}_2\)) levels. The brain’s respiratory center is highly sensitive to \(\text{CO}_2\), the main stimulus for breathing. When hyperventilation drives \(\text{CO}_2\) too low, the brain overcorrects and temporarily shuts down breathing, causing the apnea phase.
During the apnea, \(\text{CO}_2\) levels slowly build back up until they exceed the threshold that triggers the respiratory center, leading to the sudden, deep breaths of the next crescendo phase. A prolonged circulation time delays the \(\text{CO}_2\) signal reaching the brain. This delay destabilizes the system and perpetuates the cyclical pattern.
Primary Underlying Conditions
CSR is linked to severe medical conditions that compromise circulatory or neurological function. The most common cause is moderate to severe congestive heart failure (CHF), where the heart struggles to pump blood efficiently. Between 30% and 50% of people with heart failure experience CSR.
In CHF, the slow movement of blood exacerbates the signaling delay, causing the brain to receive outdated information about \(\text{CO}_2\) levels. This circulatory lag creates the unstable breathing feedback loop. The presence of CSR is considered a marker of a poor outlook and increased risk of sudden cardiac death.
Another primary cause involves damage to the central nervous system. Damage to the brainstem, which houses the respiratory control center, directly impairs the ability to regulate breathing rhythm. This neurological compromise leads to increased sensitivity to \(\text{CO}_2\) fluctuations.
CSR can also occur acutely in otherwise healthy individuals exposed to high altitudes. The low oxygen environment causes hyperventilation, which lowers \(\text{CO}_2\) and triggers the unstable feedback loop. This form is typically temporary and non-pathological.
Diagnosis and Monitoring
Diagnosing CSR relies on clinical observation and specialized sleep testing, as the pattern is most pronounced during sleep. A healthcare provider may initially notice the characteristic waxing and waning of breathing depth. For a definitive diagnosis, nocturnal polysomnography (a sleep study) is required.
During the sleep study, sensors monitor brain waves, heart rate, oxygen saturation, and breathing effort throughout the night. CSR is diagnosed when episodes of at least three consecutive central apneas or hypopneas are separated by the crescendo-decrescendo pattern.
Pulse oximetry measures blood oxygen saturation. This device shows recurrent dips in oxygen levels corresponding to the apneic phases, followed by recovery during the hyperventilation phase. These diagnostic tools help determine the severity of the disorder, quantified by the Apnea-Hypopnea Index (AHI).
Treatment Approaches
Treatment for CSR primarily focuses on addressing the underlying medical condition, typically heart failure. Optimal management involves standard medications (such as beta-blockers and diuretics) which improve the heart’s pumping function. Improving cardiac output reduces the circulatory lag time, thereby stabilizing the respiratory control loop.
When the underlying disease is optimally managed but the breathing pattern persists, specific respiratory interventions are used. Adaptive Servo-Ventilation (ASV) is an advanced form of positive airway pressure therapy designed specifically for CSR. The ASV device monitors breathing in real-time and delivers variable pressure support.
The machine provides higher pressure support during the shallow breathing or apneic phases and reduces pressure during the hyperventilation phase. This stabilization suppresses the cycle of apnea and hyperventilation by preventing \(\text{CO}_2\) levels from dropping too low. Supplemental oxygen therapy can also be used to improve oxygen saturation levels.
Pharmacological options are sometimes considered, such as acetazolamide, which induces a mild metabolic acidosis that stimulates the respiratory drive. Acetazolamide helps increase the baseline \(\text{CO}_2\) level, making the breathing pattern more stable. However, ASV use in patients with heart failure and a severely reduced ejection fraction is approached with caution due to studies suggesting increased cardiovascular mortality.