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Internal Medicine

Central sleep apnoea (CSA)

Cessation in airflow of 10 or more seconds in the absence of any inspiratory effort.

  • CSA is diagnosed when ≥ 50% of events are central.

Classification

International Classification of Sleep Disorders, 2nd edition (ICSD-2):

  1. Primary (idiopathic) CSA
  2. Cheyne-Stokes breathing (CSB) pattern
  3. CSA due to high-altitude periodic breathing
  4. CSA due to drug/substance
  5. Primary sleep apnoea of infancy 

Complex sleep apnoea (complex SA):

Primarily OSA/mixed apnoeas who develop central apnoeas on positive airway pressure (PAP) treatment (treatment-emergent central apnoeas) or have significant persistent central apnoeas on PAP treatment (treatment-persistent CSAs).

Hypocapnic CSA:

  • Normal/low wake PaCO2 and do not develop sleep hypercapnoea.
  • Includes:
    • Primary (idiopathic) CSA (ICSA)
    • Cheyne-Stokes breathing (CSB) pattern
    • Complex CSA

Hypercapnic CSA:

  • High normal/elevated wake PaCO2 (may rise further in sleep)

  • Includes:
    • CSA due to drug/substance
    • Primary CSA of infancy
    • Hypoventilation syndromes: Obesity hypoventilation syndrome, thoracic cage disorders, neuromuscular disorders and others

Aetiology

Drugs:

  • Opium: depress respiratory center in a dose-dependent manner.
  • Barbiturates: cause respiratory depression in high doses
  • Gelsemium: This is an ergot-type alkaloid and is a CNS depressant. With large doses, paralysis and death from respiratory failure can occur.

Complications

Heart failure:

nihms-671923-f0002
Pathophysiologic Consequences of CSA in Heart Failure: The repeated episodes of apnea, hypoxia, reoxygenation, and arousal throughout the night are the factors leading to the pathophysiologic consequences of central sleep apnea (CSA). These pathologic effects are multiple, and include sympathetic nervous system activation, oxidative stress, systemic inflammation, and endothelial dysfunction. All contribute to worsening heart failure. RAAS = renin-angiotensin aldosterone system. | Costanzo, M. R., Khayat, R., Ponikowski, P., Augostini, R., Stellbrink, C., Mianulli, M., & Abraham, W. T. (2015). Mechanisms and clinical consequences of untreated central sleep apnea in heart failure. Journal of the American College of Cardiology, 65(1), 72–84. https://doi.org/10.1016/j.jacc.2014.10.025

Diagnosis

Polysomnography: multi-parametric test and includes:

  • EEG
  • Eye movements (EOG)
  • Skeletal muscle activation (EMG)
  • ECG
  • Respiratory airflow and respiratory effort indicators
  • Peripheral pulse oximetry
  • Sleep latency
  • Sleep efficiency
  • Arousal index
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Polysomnogram of CSA in a Patient With Heart Failure: Overnight polysomnography performed in a sleep laboratory remains the gold standard for diagnosing sleep-disordered breathing. The image highlights characteristic findings of central sleep apnea (CSA) on a polysomnogram. | Costanzo, M. R., Khayat, R., Ponikowski, P., Augostini, R., Stellbrink, C., Mianulli, M., & Abraham, W. T. (2015). Mechanisms and clinical consequences of untreated central sleep apnea in heart failure. Journal of the American College of Cardiology, 65(1), 72–84. https://doi.org/10.1016/j.jacc.2014.10.025

Management

Continuous Positive Airway Pressure (CPAP):

  • Haemodynamic effects:
    • ↑ right atrial pressure
    • ↓ cardiac pre-load
    • ↑ oxygenation
    • ↓ catecholamines
    • ↓ ventricular wall tension/after-load
    • Improved mitral regurgitation
    • ↓ pleural pressure required for inspiration by improving lung compliance
    • Improved right-ventricular after-load through ↓ pulmonary vasoconstriction from hypoxemia and catecholamines

Cheyne-Stokes breathing (CSB) pattern: Adaptive servo-ventilation (ASV) 

  • Form of closed-loop mechanical ventilation, pressure preset, and volume or flow cycled. Alleviates central sleep apnea due to CSBP by providing dynamic (breath-by-breath) adjustment of inspiratory pressure support with a back-up rate to normalize breathing patterns relative to a predetermined target. Specifically, ASV mitigates hyperventilation and associated hypocapnia by delivering preset minute ventilation.

Csa secondary to heart failure: Nocturnal oxygen therapy

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Practical CSA Management in Patients With Heart Failure: Current treatment strategies for central sleep apnea (CSA) focus on either improving heart failure (HF) or reducing CSA itself. ACE-I = angiotensin-converting enzyme inhibitor; OSA = obstructive sleep apnea; SDB = sleep-disordered breathing; Sxs = symptoms. | Costanzo, M. R., Khayat, R., Ponikowski, P., Augostini, R., Stellbrink, C., Mianulli, M., & Abraham, W. T. (2015). Mechanisms and clinical consequences of untreated central sleep apnea in heart failure. Journal of the American College of Cardiology, 65(1), 72–84. https://doi.org/10.1016/j.jacc.2014.10.025

 

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