Trials of bilevel positive airway pressure—spontaneous in patients with complex sleep apnea


Patients with complex sleep apnoea (CompSAS) have obstructive sleep apnoea and experience persistent central apnoeas when exposed to positive airway pressure. Elevated loop gain is one of the postulated mechanisms of CompSAS. We speculated that bilevel positive airway pressure - spontaneous (BPAP-S), by producing relative hyperventilation, may more readily produce CompSAS activity than continuous positive airway pressure (CPAP). If found to do so, a trial of BPAP-S might be a simple way of identifying patients with elevated loop gain who are at risk for CompSAS.
Thirty-nine patients with complex sleep apnoea were included in the study. Segments of NREM sleep on CPAP and BPAP-S matched for body position and expiratory airway pressure (comparison pressure) were retrospectively analysed. Correlations between clinical and demographic variables and polysomnographic response to CPAP and BPAP-S were sought.
There was no difference in any of the polysomnographic indices on CPAP and BPAP-S. In 19 patients the use of CPAP was associated with lower AHI at the comparison pressure; in 20 patients the opposite was true. No clinical variables correlated to the differential response to CPAP vs. BPAP-S.
BPAP-S was not more effective than CPAP in stimulating complex sleep apnoea activity.

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    • "Central apneas were more likely to worsen with bi-level PAP than with CPAP. Other research included 39 patients with CompSAS and found that there was no difference in any of the polysomnographic indices on CPAP and bi-level PAP.49 However, Morgenthaler et al7 reported that bi-level PAP was effective in normalizing breathing and sleep parameters. "
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    ABSTRACT: Complex sleep apnea syndrome (CompSAS) is a distinct form of sleep-disordered breathing characterized as central sleep apnea (CSA), and presents in obstructive sleep apnea (OSA) patients during initial treatment with a continuous positive airway pressure (CPAP) device. The mechanisms of why CompSAS occurs are not well understood, though we have a high loop gain theory that may help to explain it. It is still controversial regarding the prevalence and the clinical significance of CompSAS. Patients with CompSAS have clinical features similar to OSA, but they do exhibit breathing patterns like CSA. In most CompSAS cases, CSA events during initial CPAP titration are transient and they may disappear after continued CPAP use for 4~8 weeks or even longer. However, the poor initial experience of CompSAS patients with CPAP may not be avoided, and nonadherence with continued therapy may often result. Treatment options like adaptive servo-ventilation are available now that may rapidly resolve the disorder and relieve the symptoms of this disease with the potential of increasing early adherence to therapy. But these approaches are associated with more expensive and complicated devices. In this review, the definition, potential plausible mechanisms, clinical characteristics, and treatment approaches of CompSAS will be summarized.
    Full-text · Article · Jul 2013 · Patient Preference and Adherence
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    • "Since the first description of complex sleep apnea by Gilmartin et al [1, 22], the sheer existence, definition, and treatment of this syndrome is debated [23, 24]. In our opinion, clinical utility of “CompSAS” designation lies in differences in acute and subacute response to PAP treatments of patients with “typical” OSA and CompSAS patients: while CPAP is highly effective in OSA, its acute effectiveness in much lower in CompSAS [25]. "
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    ABSTRACT: Background: The definition of complex sleep apnea (CompSAS) encompasses patients with obstructive sleep apnea (OSA) who develop central apnea activity upon restitution of airway patency. Presence of arterial hypertension (HTN), coronary artery disease (CAD) and heart failure (HF) have been proposed as risk factors for CompSAS among OSA patients. Using our database of patients with CompSAS, we examined the prevalence of these risk factors and defined other clinical characteristics of patients with CompSAS. Methods: Through retrospective search of the database, we examined the medical and clinical characteristics of consecutive patients diagnosed with CompSAS between 11/1/2006 and 6/30/2011 at NorthShore University HealthSystem. Results: One hundred and fifty patients with CompSAS were identified. Among patients included in the study, 97 (64.7 %) had at least one risk factor for CompSAS, while 53 (35.3 %) did not have any of them. Prevalence of low left ventricular ejection fraction and hypocapnia were low. Therapeutic interventions consisted of several positive airway pressure therapies, mainly adaptive servo ventilation. A hundred and ten patients (73.3 %) complied with recommended therapy and improved clinically. Conclusions: Although most patients with CompSAS have cardiac comorbidities, about one third of patients do not have any risk factors of CompSAS prior to sleep testing. Further research on factors involved in development of CompSAS will allow for better tailoring of therapy to pathophysiology involved in an individual case.
    Full-text · Article · Feb 2013 · Sleep And Breathing
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    ABSTRACT: Complex sleep apnoea syndrome (CompSAS) is a type of central apnoea characterised by the development or persistence of central apnoeas or hypopnoeas during application of continuous positive airway pressure (CPAP; central apnoea index ≥5 events·h-1). These patients present with predominantly obstructive apnoeas during diagnostic sleep studies. No clinical characteristics have been identified which can distinguish them from patients with a normal response during CPAP titration. Probably, this pattern is provoked by the application of high CPAP pressures in obstructive sleep apnoea syndrome patients with enhanced chemoreceptor sensitivity, or in patients with pronounced sleep fragmentation. Negative feedback is sent to the respiratory centre, via the Hering-Breuer reflex, which can lead to central apnoea. However, these explanations remain hypothetical at present. In a broader perspective, any occurrence of significant central apnoea activity during attempts to restore airway patency could be classified as CompSAS. Treatment modalities consist of prevention on the one hand (avoidance of high pressures and permissive flow limitation), and advanced ventilation techniques (adaptive servo ventilation) on the other hand.
    Full-text · Article · Sep 2013 · Breathe