Conditions That Cause Central Sleep Apnea
Central sleep apnea (CSA) is caused by six main categories of conditions according to the International Classification of Sleep Disorders: heart failure (most commonly presenting with Cheyne-Stokes respiration), medications/substances (particularly opioids), other medical disorders, treatment-emergent CSA from CPAP therapy, high altitude exposure, and primary/idiopathic CSA. 1
Primary Categories of CSA Etiologies
1. Heart Failure (Most Common Clinical Cause)
- CSA with Cheyne-Stokes respiration is the most frequently encountered form in clinical practice
- Occurs in up to 50-60% of patients with heart failure 2, 3
- Associated with increased mortality and hospitalization rates 1
- Characterized by prolonged circulation time and increased CO2 sensitivity 3
- The sudden development of CSA in a chronic CPAP user may indicate new-onset atrial fibrillation 4
2. Medication or Substance-Induced CSA
- Opioid analgesics are the primary culprit 1
- Unique pathophysiology: occurs with depressed central respiratory drive and decreased chemosensitivity, unlike other CSA types that have increased chemosensitivity 1
- Chronic opioid use is one of the most common causes at sea level 4
3. Treatment-Emergent CSA
- Develops in approximately 5% of patients initiating CPAP for obstructive sleep apnea 4
- Represents unmasking of central breathing instability during OSA treatment 1
4. Medical Disorders Without Cheyne-Stokes
Key conditions include:
- Chronic kidney disease (CKD): CSA is prevalent but often under-recognized; may impact morbidity and mortality through intermittent hypoxia effects on kidney pathology 5
- Stroke: Post-stroke CSA is an established entity 2
- Acromegaly: Significant prevalence of CSA 5
- Hypothyroidism: Lesser extent but documented 5
- Chronic renal failure 6
- Neurological conditions 3
5. High Altitude
- Altitude-induced CSA has a distinct pathophysiology 1
- Recent evidence suggests it may be adaptive rather than detrimental, reducing work of breathing while maintaining gas exchange 4
6. Primary (Idiopathic) CSA
- Diagnosis of exclusion after ruling out cardiac, neurological, and endocrine causes 4
- Rare in the general population (0.9-1.5% prevalence) 3
Key Pathophysiological Mechanism
The final common pathway for most CSA involves posthyperventilation hypocapnia leading to central apnea 1. During non-REM sleep, the wakefulness "drive to breathe" is removed, making respiration critically dependent on PaCO2 and unmasking the hypocapnic apneic threshold 1.
Important Clinical Pitfalls
- Mixed presentations are common: Patients frequently present with both obstructive and central events, making classification challenging 1
- Diagnostic limitations: When respiratory events are predominantly hypopneas, distinguishing central from obstructive etiology without esophageal pressure monitoring can be difficult 1
- Multiple etiologies may coexist: A patient may have CSA from more than one cause simultaneously (e.g., heart failure patient on opioids)
Risk Factors to Assess
When evaluating for CSA causes, specifically assess:
- Gender (male predominance)
- Age (increases with age)
- Heart failure status and ejection fraction
- Opioid medication use (dose and duration)
- History of stroke
- Chronic kidney disease
- Endocrine disorders (acromegaly, hypothyroidism)
- Recent altitude exposure
- Current CPAP therapy for OSA 6