Treatment-Emergent Central Apnea: Physiologic Mechanisms Informing Clinical Practice

Treatment-emergent central sleep apnea resolves with lower inspiratory pressure

STUDY OBJECTIVES

Treatment-emergent central sleep apnea (TECSA) is an important problem during therapy with continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea. We tested a device designed to improve CPAP comfort through reducing inspiratory positive airway pressure (IPAP; V ˙ -Com ) to determine whether such a reduction in IPAP could eliminate central apneas in patients with TECSA. Because increasing tidal volume (potentially via IPAP increments) has been suggested as a possible mechanism contributing to TECSA onset, our hypothesis was that reducing IPAP would yield a drop in the central apnea index.

METHODS

The addition of a known resistance (V ˙ -Com device) that reduces IPAP was implemented into the CPAP circuit during the second half of CPAP titrations in a cohort of community-dwelling patients who developed TECSA during a split-night CPAP titration. Central apnea index was quantified from the sleep periods without and with V ˙ -Com in place.

RESULTS

A total of 1,613 patients underwent CPAP titration, with 19 of them developing TECSA during the titration. The addition of V ˙ -Com resulted in complete resolution of TECSA in all patients with adequate sleep data under all conditions (n = 13), yielding a significant reduction in the central apnea index (17.3 ± 11.0 vs 1.5 ± 1.7 events/h without and with V ˙ -Com , respectively; P < .001).

CONCLUSIONS

V ˙ -Com virtually resolved all instances of TECSA, suggesting that reducing IPAP could be an effective strategy for managing the occurrence of central respiratory events in patients with obstructive sleep apnea using CPAP.

CITATION

Noah WH, Messineo L, Hete B, et al. Treatment-emergent central sleep apnea resolves with lower inspiratory pressure. J Clin Sleep Med. 2025;21(3):559-564.

Insights, recommendations, and research priorities for central sleep apnea: report from an expert panel

Central sleep apnea (CSA) is commonly encountered among patients with sleep-disordered breathing; however, its clinical consequences are less well-characterized. The senior author (A.M.) therefore convened an expert panel to discuss the common presentations of CSA, as well as challenges and knowledge gaps in the diagnosis and management of CSA. The panel identified several key research priorities essential for advancing our understanding of the disorder. Within the diagnostic realm, panel members discussed the utility of multinight assessments and importance of the development and validation of novel metrics and automated assessments for differentiating central vs obstructive hypopneas, such that their impact on clinical outcomes and management may be better evaluated. The panel also discussed the current therapeutic landscape for the management of CSA and agreed that therapies should primarily aim to alleviate sleep-related symptoms, after optimizing treatment to address the underlying cause. Most importantly, the panel concluded that there is a need to further investigate the clinical consequences of CSA, as well as the implications of therapy on clinical outcomes, particularly among those who are asymptomatic. Future research should focus on endo-phenotyping central events for a better mechanistic understanding of the disease, validating novel diagnostic methods for implementation in routine clinical practice, as well as the use of combination therapy and comparative effectiveness trials in elucidating the most efficacious interventions for managing CSA.

CITATION

Kundel V, Ahn A, Arzt M, et al. Insights, recommendations, and research priorities for central sleep apnea: report from an expert panel. J Clin Sleep Med. 2025;21(2):405-416.

OSA pathophysiology: a contemporary update

Defined as an elevated frequency of obstructive respiratory events in sleep, obstructive sleep apnoea (OSA) is driven by a combination of four pathophysiologic mechanisms: elevated upper airway collapsibility, unstable ventilatory control, impaired upper airway dilator muscle responsiveness and decreased arousal threshold. Established therapies such as continuous positive airway pressure (CPAP) and oral appliance therapy (OAT) work chiefly through targeting elevated collapsibility, which affects the majority of OSA patients. However, many patients respond poorly or do not tolerate these 'anatomic' therapies. The emerging field of 'precision sleep medicine' seeks to determine if novel treatment approaches specifically targeting the other, 'non-anatomic' mechanisms will improve treatment efficacy and acceptance. In this review, we consider the concepts underlying each pathophysiologic mechanism, the predisposing factors, and the potential implications for established and future OSA treatments.

Central sleep apnea: emphasizing recognition and differentiation

INTRODUCTION

Central sleep apnea (CSA) is a sleep-related breathing disorder in which the effort to breathe is intermittently diminished or absent. CSA is a common disorder among patients with different cardiovascular disorders, including heart failure. In addition, a growing number of medications have been shown to induce CSA and CSA can emerge after initiation of treatment for obstructive sleep apnea. Accumulating evidence shows that CSA is a heterogeneous disorder with individual differences in clinical and biological characteristics and/or underlying pathophysiological mechanisms.

AREAS COVERED

This narrative review offers an overview of the diagnostic aspects and classification of CSA, with an emphasis on heart failure patients, patients with CSA due to a medication and treatment-emergent CSA. The importance of evaluation of prognostic biomarkers in patients with different types of CSA is discussed. This narrative review synthesizes literature on CSA sourced from the PubMed database up to February 2024.

EXPERT OPINION

CSA presents a remarkably diverse disorder, with treatment modalities exhibiting potentially varied efficacy across its various phenotypes. This highlights the imperative for tailored management strategies that are rooted in phenotype classification.

Central sleep apnea: pathophysiologic classification

Central sleep apnea is not a single disorder; it can present as an isolated disorder or as a part of other clinical syndromes. In some conditions, such as heart failure, central apneic events are due to transient inhibition of ventilatory motor output during sleep, owing to the overlapping influences of sleep and hypocapnia. Specifically, the sleep state is associated with removal of wakefulness drive to breathe; thus, rendering ventilatory motor output dependent on the metabolic ventilatory control system, principally PaCO2. Accordingly, central apnea occurs when PaCO2 is reduced below the "apneic threshold". Our understanding of the pathophysiology of central sleep apnea has evolved appreciably over the past decade; accordingly, in disorders such as heart failure, central apnea is viewed as a form of breathing instability, manifesting as recurrent cycles of apnea/hypopnea, alternating with hyperpnea. In other words, ventilatory control operates as a negative-feedback closed-loop system to maintain homeostasis of blood gas tensions within a relatively narrow physiologic range, principally PaCO2. Therefore, many authors have adopted the engineering concept of "loop gain" (LG) as a measure of ventilatory instability and susceptibility to central apnea. Increased LG promotes breathing instabilities in a number of medical disorders. In some other conditions, such as with use of opioids, central apnea occurs due to inhibition of rhythm generation within the brainstem. This review will address the pathogenesis, pathophysiologic classification, and the multitude of clinical conditions that are associated with central apnea, and highlight areas of uncertainty.

Practice recommendations for the role of physiotherapy in the management of sleep disorders: the 2022 Brazilian Sleep Association Guidelines

This clinical guideline supported by the Brazilian Sleep Association comprises a brief history of the development of Brazilian sleep physiotherapy, outlines the role of the physiotherapist as part of a sleep health team, and describes the clinical guidelines in respect of the management of some sleep disorders by the physiotherapist (including sleep breathing disorders, i.e., obstructive sleep apnea, central sleep apnea, upper airway resistance syndrome, hypoventilation syndromes and overlap syndrome, and pediatric sleep breathing disorders; sleep bruxism; circadian rhythms disturbances; insomnia; and Willis-Ekbom disease/periodic limb movement disorder. This clinical practice guideline reflects the state of the art at the time of publication and will be reviewed and updated as new information becomes available.

Exacerbation of ventricular arrhythmias by continuous positive airway pressure treatment in idiopathic dilated cardiomyopathy

Continuous positive airway pressure (CPAP) therapy can be beneficial in patients with obstructive sleep apnea (OSA) and cardiovascular diseases, reducing arrhythmia frequency and improving cardiac function. We describe a case of moderate OSA with idiopathic dilated cardiomyopathy, in which the frequency of premature ventricular contraction (PVC) and non-sustained ventricular tachycardia (NSVT) increased immediately after initiating CPAP therapy. Although PVC and NSVT are benign cardiac arrhythmias, they are associated with an increased risk of sustained lethal ventricular tachyarrhythmias. Therefore, when initiating CPAP therapy, the possibility of increased arrhythmia should be considered.

Brazilian Thoracic Association Consensus on Sleep-disordered Breathing

Sleep is essential for the proper functioning of all individuals. Sleep-disordered breathing can occur at any age and is a common reason for medical visits. The objective of this consensus is to update knowledge about the main causes of sleep-disordered breathing in adult and pediatric populations, with an emphasis on obstructive sleep apnea. Obstructive sleep apnea is an extremely prevalent but often underdiagnosed disease. It is often accompanied by comorbidities, notably cardiovascular, metabolic, and neurocognitive disorders, which have a significant impact on quality of life and mortality rates. Therefore, to create this consensus, the Sleep-Disordered Breathing Department of the Brazilian Thoracic Association brought together 14 experts with recognized, proven experience in sleep-disordered breathing.

Treatment-emergent central sleep apnoea managed by CPAP with adjunctive acetazolamide: A case report

Treatment-emergent central sleep apnoea (TECSA) refers to the emergence of central apnoea during treatment for obstructive sleep apnoea (OSA), most commonly continuous positive airway pressure (CPAP). It has been reported in 8% of OSA patients treated with CPAP and spontaneous resolution rate varies between 60% and 80%. Management options include watchful waiting with continuation of CPAP, bi-level positive pressure ventilation, adaptive servo-ventilation and CPAP with supplemental oxygen. Acetazolamide has been shown to be effective in other forms of central sleep apnoea; its use as adjunct to CPAP in TECSA is sparsely reported. We report a 74-year-old man with severe OSA who developed moderate central apnoea upon CPAP initiation. Subsequent addition of acetazolamide led to gratifying resolution of the TECSA. In TECSA patients with significant symptoms and high central apnoea index, treatment with acetazolamide as adjunct to CPAP may be considered, particularly in patients in whom CPAP adherence is imperative.

Central sleep apnea

Central apnea syndrome is a disorder with protean manifestations and concomitant conditions. It can occur as a distinct clinical entity or as part of another clinical syndrome. The pathogenesis of central sleep apnea (CSA) varies depending on the clinical condition. Sleep-related withdrawal of the ventilatory drive to breathe is the common denominator among all cases of central apnea, whereas hypocapnia is the final common pathway leading to apnea in the majority of central apnea. Medical conditions most closely associated with CSA include heart failure, stroke, spinal cord injury, and opioid use, among others. Nocturnal polysomnography is the standard diagnostic method, including measurement of sleep and respiration. The latter includes detection of flow, measurement of oxyhemoglobin saturation and detection of respiratory effort. Management strategy incorporates clinical presentation, associated conditions, and the polysomnographic findings in an individualized manner. The pathophysiologic heterogeneity may explain the protean clinical manifestations and the lack of a single effective therapy for all patients. While research has enhanced our understanding of the pathogenesis of central apnea, treatment options are extrapolated from treatment of obstructive sleep apnea. Co-morbid conditions and concomitant obstructive sleep apnea influence therapeutic approach significantly. Therapeutic options include positive pressure therapy, pharmacologic therapy, and supplemental Oxygen. Continuous positive airway pressure (CPAP) is the initial standard of care, although the utility of other modes of positive pressure therapy, as well as pharmacotherapy and device-based therapies, are currently being investigated.