Clinical Definition

CSA occurs when the respiratory control center in the brain fails to send appropriate signals to the respiratory muscles. This results in:

  • Absent Respiratory Effort: No chest or abdominal movement during apneas
  • Central Apneas: Cessation of airflow with no respiratory effort for ≥10 seconds
  • Cheyne-Stokes Breathing: Cyclical breathing pattern with crescendo-decrescendo ventilation
  • Hypocapnia: Low carbon dioxide levels that can trigger central apneas

CSA is often associated with underlying medical conditions such as heart failure, stroke, or brainstem disorders. It can also occur at high altitudes or as a side effect of certain medications.

Etymology & History

Central sleep apnea was first described in the early 20th century, with the understanding of its neurological basis developing as knowledge of respiratory control mechanisms advanced. The condition was initially called "primary alveolar hypoventilation" or "Ondine's curse."

Reference Values & Interpretation

Normal Values

A normal central apnea index is < 5 events/hour. Some healthy individuals may have occasional central apneas, particularly during sleep transitions or at high altitudes.

Abnormal Values

CSA is diagnosed when the central apnea index is ≥ 5 events/hour with symptoms, or ≥ 15 events/hour regardless of symptoms. In heart failure patients, any significant central apneas may be considered abnormal.

How It's Measured

CSA is diagnosed through in-lab polysomnography, which measures respiratory effort using chest and abdominal belts. The absence of respiratory effort during apneas distinguishes central from obstructive events.

Role in Diagnosis

CSA diagnosis requires demonstration of central apneas on polysomnography along with evaluation for underlying causes. The pattern of central apneas (isolated vs. Cheyne-Stokes) helps identify the underlying etiology.

Role in Treatment

Treatment depends on the underlying cause and may include treating heart failure, adaptive servo-ventilation (ASV), BiPAP with backup rate, supplemental oxygen, or medications like acetazolamide. CPAP may worsen some forms of CSA.

Associated Conditions

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Clinical Guidelines

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Latest Research & Updates

AI-Updated Weekly

Recent research has focused on the role of loop gain in CSA pathophysiology and the development of targeted therapies. Studies are investigating the use of hypoglossal nerve stimulation and other novel treatments for CSA.