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Complex OSA
The Disorder
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Complex sleep apnea is also referred to as treatment-emergent central sleep apnea.
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Complex sleep apnea occurs when someone who previously had obstructive sleep apnea develops central sleep apnea due to treatment with continuous positive airway pressure (CPAP) (1).
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This phenomenon (sometimes called “treatment-emergent CSA”) can be observed once the upper airway has been made patent with treatment, such as CPAP therapy.
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Approximately 10% of patients with obstructive sleep apnea (OSA) also clinically demonstrate CSA during CPAP titration studies, which can contribute to poor adherence to therapy (2).
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Common risk factors for CSA include systolic heart failure, atrial fibrillation, cerebrovascular diseases, and the use of opioid drugs, which may also be the risk factors associated with complex OSA (1).
1.Wang J, Wang Y, Feng J, Chen BY, Cao J. Complex sleep apnea syndrome. Patient preference and adherence. 2013;7:633.
2.Roberts EG, Raphelson JR, Orr JE, LaBuzetta JN, Malhotra A. The Pathogenesis of Central and Complex Sleep Apnea. Current Neurology and NeuroscieCommon risk factors for CSA include systolic heart failure, atrial fibrillation, cerebrovascular diseases, and use of opioid drugs, which may also be the risk factors associated with CompSAS.nce Reports. 2022 May 19:1-8.
Consequences
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Complex OSA exerts a number of acute deleterious effects including intermittent hypoxia, arousals from sleep, and swings in negative intrathoracic pressure, which in turn lead to chronic physiologic consequences such as autonomic dysregulation, endothelial dysfunction, and cardiac remodelling.
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These underlying pathophysiological mechanisms provide a framework for understanding why OSA and CSA may predispose to cardiovascular diseases like ischemic heart disease and stroke (3).
3. Leung RS, Comondore VR, Ryan CM, Stevens D. Mechanisms of sleep-disordered breathing: causes and consequences. Pflügers Archiv-European Journal of Physiology. 2012 Jan;463(1):213-30.
Risk Factors
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Common risk factors for central sleep apnoea include systolic heart failure, atrial fibrillation, cerebrovascular diseases, and the use of opioid drugs, which may also be the risk factors associated with Complex OSA (1).
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Complex OSA phenotype has been described in patients with congestive heart failure and Cheyne–Stokes breathing patterns with up to 18 % of CHF patients exhibiting Complex OSA activity.
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The presence of arterial hypertension and coronary artery disease has been associated with Complex OSA (4).
4. Kuźniar TJ, Kasibowska-Kuźniar K, Ray DW, Freedom T. Clinical heterogeneity of patients with complex sleep apnea syndrome. Sleep and Breathing. 2013 Dec;17(4):1209-14.
Screening and Diagnosis
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Respiratory polygraphy (either in a hospital or at home) is recommended to establish the presence and severity of Complex OSA and nocturnal hypoventilation and to help determine the most suitable treatment (such as CPAP).
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Complex OSA is observed in some patients when they are treated with positive airway pressure (PAP) after significant resolution of the preexisting obstructive events in patients with obstructive sleep apnea.
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Most of the patients with Complex OSA show gradual resolution of central apneas over weeks to months.
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However, some patients appear to experience central apneas for protracted periods of time.
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For these patients, CPAP use may be associated with dyspnea or air hunger as well as inadvertent CPAP mask removal during the night.
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All this can lead to the persistence or worsening of sleep-disordered breathing as well as poor sleep quality at night (5).
5. Nigam G, Riaz M, Chang ET, Camacho M. Natural history of treatment-emergent central sleep apnea on positive airway pressure: a systematic review. Annals of Thoracic Medicine. 2018 Apr;13(2):86.
Treatment
Patients with Complex OSA represent a treatment challenge and the optimal therapeutic approaches remain to be defined.
They have more problems adapting to CPAP with large residual AHI/CAI events similar to the situation with CSA patients.
In most Complex OSA cases, CSA events during initial CPAP titration are transient and they disappear after continued CPAP use.
Because Complex OSA patients have a poor initial experience with CPAP, they may be nonadherent with continued therapy.
Treatment options like Adapto servo ventilation (ASV are available that may rapidly resolve the disorder and relieve the symptoms of this disease with the potential of increasing early adherence to therapy.
But not all Complex OSA patients need an expensive and complicated device.
