Complex Sleep Apnoea

What Is Complex Sleep Apnoea?

Complex Sleep Apnoea – also known as treatment-emergent central sleep apnoea (CSA) – occurs when a patient with obstructive sleep apnoea (OSA) begins to develop central apnoeas during treatment with CPAP.

This phenomenon emerges after the upper airway is opened with CPAP, revealing central breathing disturbances not previously seen. Around 10% of OSA patients demonstrate CSA during CPAP titration, which can contribute to therapy intolerance or non-adherence.

Consequences

Complex OSA can result in:

  • Intermittent hypoxia

  • Frequent sleep arousals

  • Negative swings in intrathoracic pressure

These disturbances may lead to chronic complications such as autonomic dysregulation, endothelial dysfunction, and cardiac remodelling. The combined impact of OSA and CSA is thought to increase the risk of cardiovascular disease, including stroke and ischaemic heart disease.

Risk Factors

Complex OSA often overlaps with conditions linked to central sleep apnoea, such as:

  • Systolic heart failure

  • Atrial fibrillation

  • Cerebrovascular disease

  • Opioid use

Up to 18% of patients with congestive heart failure (CHF) may demonstrate a Complex OSA phenotype, particularly in those with Cheyne–Stokes respiration. Other associated conditions include arterial hypertension and coronary artery disease.

Screening & Diagnosis

Diagnosis is typically made via respiratory polygraphy, performed either in a hospital setting or at home. Key considerations include:

  • Most central apnoeas observed in Complex OSA resolve gradually over time with continued CPAP use

  • Some patients experience persistent central apnoeas that contribute to poor sleep quality and discomfort, including air hunger and mask removal during sleep

  • Long-term central events may worsen therapy outcomes without additional intervention

In all cases, a clear diagnostic process and follow-up are critical to guide the appropriate treatment pathway.

Treatment

Managing Complex OSA can be challenging, particularly due to:

  • Poor adaptation to CPAP

  • High residual AHI/CAI during initial titration

  • Reduced therapy adherence from early discomfort

In many cases, the central events disappear with ongoing CPAP therapy. However, for patients whose symptoms persist, adaptive servo-ventilation (ASV) may offer relief by rapidly resolving CSA events and improving comfort.

ASV has shown potential in increasing early adherence and reducing symptom burden, but treatment must always be tailored to the individual patient and monitored closely.

References

    • Wang J, et al. Complex sleep apnoea syndrome. Patient Prefer Adherence. 2013;7:633.

    • Roberts EG, et al. The Pathogenesis of Central and Complex Sleep Apnoea. Curr Neurol Neurosci Rep. 2022.

    • Leung RS, et al. Mechanisms of sleep-disordered breathing: causes and consequences. Pflügers Arch. 2012;463(1):213–30.

    • Kuźniar TJ, et al. Clinical heterogeneity of patients with complex sleep apnea syndrome. Sleep Breath. 2013;17(4):1209–14.

    • Nigam G, et al. Natural history of treatment-emergent CSA on PAP: a systematic review. Ann Thorac Med. 2018;13(2):86.

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