Complex sleep apnea unmasked by the use of a mandibular advancement device

The prevalence of treatment-emergent central sleep apnea with mandibular advancement device therapy

STUDY OBJECTIVES

Treatment-emergent central sleep apnea (TECSA) describes the appearance or persistence of central sleep apnea while undergoing treatment for obstructive sleep apnea. TECSA is well studied in continuous positive airway pressure therapy with an estimated prevalence of 8%. Based on a few case reports, mandibular advancement devices (MAD) may also provoke TECSA. This study aims to gain insight into the prevalence of TECSA with MAD therapy.

METHODS

This retrospective study includes a total of 129 patients with moderate to severe obstructive sleep apnea who were treated with a custom-made titratable MAD. Baseline and follow-up sleep studies were compared to identify patients with TECSA. Since different diagnostic criteria to define TECSA are used in literature, prevalence was calculated according to three definitions (TECSA-1, -2, and -3). Demographics, MAD treatment variables, and findings of the diagnostic polysomnography were compared between TECSA and non-TECSA patients to identify possible predictors.

RESULTS

Depending on the definition used, TECSA was found in 3.1%-7.8% of patients undergoing MAD therapy. TECSA patients had a higher apnea index (9.2 vs 2.0 events/h, P = .042), central apnea-hypopnea index (4.1 vs 0.2 events/h, P = .045) and oxygen desaturation index (23.9 vs 16.3 events/h, P = .018) at baseline compared to non-TECSA patients. No differences were found in demographics and treatment variables.

CONCLUSIONS

These findings demonstrate that TECSA also occurs in patients starting MAD treatment. Patients with TECSA had a higher apnea index, central apnea-hypopnea index, and oxygen desaturation index at baseline compared to non-TECSA patients.

CITATION

Hellemans S, Van de Perck E, Braem MJ, Verbraecken J, Dieltjens M, Vanderveken OM. The prevalence of treatment-emergent central sleep apnea with mandibular advancement device therapy. J Clin Sleep Med. 2023;19(12):2035-2041.

Non-invasive positive pressure ventilation for central sleep apnoea in adults

BACKGROUND

Central sleep apnoea (CSA) is characterised by abnormal patterns of ventilation during sleep due to a dysfunctional drive to breathe. Consequently, people with CSA may present poor sleep quality, sleep fragmentation, inattention, fatigue, daytime sleepiness, and reduced quality of life.

OBJECTIVES

To assess the effectiveness and safety of non-invasive positive pressure ventilation (NIPV) for the treatment of adults with CSA.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and Scopus on 6 September 2021. We applied no restrictions on language of publication. We also searched clinical trials registries for ongoing and unpublished studies, and scanned the reference lists of included studies to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) reported in full text, those published as abstract only, and unpublished data.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data, and assessed risk of bias of the included studies using the Cochrane risk of bias tool version 1.0, and the certainty of the evidence using the GRADE approach. In the case of disagreement, a third review author was consulted.

MAIN RESULTS

We included 15 RCTs with a total of 1936 participants, ranging from 10 to 1325 participants. All studies had important methodological limitations. We assessed most studies (11 studies) as at high risk of bias for at least one domain, and all studies as at unclear risk of bias for at least two domains. The trials included participants aged > 18 years old, of which 70% to 100% were men, who were followed from one week to 60 months. The included studies assessed the effects of different modes of NIPV and CSA. Most participants had CSA associated with chronic heart failure. Because CSA encompasses a variety of causes and underlying clinical conditions, data were carefully analysed, and different conditions and populations were not pooled. The findings for the primary outcomes for the seven evaluated comparisons are presented below.  Continuous positive airway pressure (CPAP) plus best supportive care versus best supportive care in CSA associated with chronic heart failure In the short term, CPAP plus best supportive care may reduce central apnoea hypopnoea index (AHI) (mean difference (MD) -14.60, 95% confidence interval (CI) -20.11 to -9.09; 1 study; 205 participants). However, CPAP plus best supportive care may result in little to no difference in cardiovascular mortality compared to best supportive care alone. The evidence for the effect of CPAP plus best supportive care on all-cause mortality is very uncertain. No adverse effects were observed with CPAP, and the results for adverse events in the best supportive care group were not reported. Adaptive servo ventilation (ASV) versus CPAP in CSA associated with chronic heart failure The evidence is very uncertain about the effect of ASV versus CPAP on quality of life evaluated in both the short and medium term. Data on adverse events were not reported, and it is not clear whether data were sought but not found. ASV versus bilevel ventilation in CSA associated with chronic heart failure In the short term, ASV may result in little to no difference in central AHI. No adverse events were detected with ASV, and the results for adverse events in the bilevel ventilation group were not reported. ASV plus best supportive care versus best supportive care in CSA associated with chronic heart failure In the medium term, ASV plus best supportive care may reduce AHI compared to best supportive care alone (MD -20.30, 95% CI -28.75 to -11.85; 1 study; 30 participants). In the long term, ASV plus best supportive care likely increases cardiovascular mortality compared to best supportive care (risk ratio (RR) 1.25, 95% CI 1.04, 1.49; 1 study; 1325 participants). The evidence suggests that ASV plus best supportive care may result in little to no difference in quality of life in the short, medium, and long term, and in all-cause mortality in the medium and long term. Data on adverse events were evaluated but not reported. ASV plus best supportive care versus best supportive care in CSA with acute heart failure with preserved ejection fraction Only adverse events were reported for this comparison, and no adverse events were recorded in either group. ASV versus CPAP maintenance in CPAP-induced CSA In the short term, ASV may slightly reduce central AHI (MD -4.10, 95% CI -6.67 to -1.53; 1 study; 60 participants), but may result in little to no difference in quality of life. Data on adverse events were not reported, and it is not clear whether data were sought but not found. ASV versus bilevel ventilation in CPAP-induced CSA In the short term, ASV may slightly reduce central AHI (MD -8.70, 95% CI -11.42 to -5.98; 1 study; 30 participants) compared to bilevel ventilation. Data on adverse events were not reported, and it is not clear whether data were sought but not found.

AUTHORS' CONCLUSIONS

CPAP plus best supportive care may reduce central AHI in people with CSA associated with chronic heart failure compared to best supportive care alone. Although ASV plus best supportive care may reduce AHI in people with CSA associated with chronic heart failure, it likely increases cardiovascular mortality in these individuals. In people with CPAP-induced CSA, ASV may slightly reduce central AHI compared to bilevel ventilation and to CPAP. In the absence of data showing a favourable impact on meaningful patient-centred outcomes and defining clinically important differences in outcomes in CSA patients, these findings need to be interpreted with caution. Considering the level of certainty of the available evidence and the heterogeneity of participants with CSA, we could draw no definitive conclusions, and further high-quality trials focusing on patient-centred outcomes, such as quality of life, quality of sleep, and longer-term survival, are needed to determine whether one mode of NIPV is better than another or than best supportive care for any particular CSA patient group.

Abnormal Sleep-Related Breathing Related to Heart Failure

Sleep-disordered breathing (SDB) is highly prevalent in patients with heart failure (HF). Untreated obstructive sleep apnea (OSA) and central sleep apnea (CSA) in patients with HF are associated with worse outcomes. Detailed sleep history along with polysomnography (PSG) should be conducted if SDB is suspected in patients with HF. First line of treatment is the optimization of medical therapy for HF and if symptoms persist despite optimization of the treatment, positive airway pressure (PAP) therapy will be started to treat SDB. At present, there is limited evidence to prescribe any drugs for treating CSA in patients with HF. There is limited evidence for the efficacy of continuous positive airway pressure (CPAP) or adaptive servo-ventilation (ASV) in improving mortality in patients with heart failure with reduced ejection fraction (HFrEF). There is a need to perform well-designed studies to identify different phenotypes of CSA/OSA in patients with HF and to determine which phenotype responds to which therapy. Results of ongoing trials, ADVENT-HF, and LOFT-HF are eagerly awaited to shed more light on the management of CSA in patients with HF. Until then the management of SDB in patients with HF is limited due to the lack of evidence and guidance for treating SDB in patients with HF.

Treatment-emergent central sleep apnea associated with non-positive airway pressure therapies in obstructive sleep apnea patients: A systematic review

This systematic review summarizes the prevalence of treatment-emergent central sleep apnea (TECSA) occurring with therapies other than positive airway pressure (PAP) for the management of obstructive sleep apnea (OSA). We describe its natural course as well as the proposed underlying pathophysiological mechanisms and the clinical management of affected patients. A systematic search of PubMed, Embase, Web of science, and the Cochrane Library was performed until June 2020. Eighteen studies (n = 284 patients) were included. TECSA was observed in 31 patients with the use of four different medical devices (mandibular advancement device, hypoglossal nerve stimulation, tongue stabilizing device and nasal expiratory PAP) and after three different types of surgical treatments (tracheostomy, maxillofacial surgery and oro-nasal surgery). Due to the paucity of data available, it was not possible to establish a clear prevalence rate of TECSA for each alternative treatment. After the initiation of non-PAP treatments, a systematic reassessment of the treatment efficacy with follow-up sleep studies will be helpful to identify TECSA. A spontaneous resolution over time was described as well as a persistence of TECSA. In this case, treatment should focus on patients' specific underlying pathophysiology. Overall, the limited current literature suggests that this phenomenon is rare (<4%).

Treatment-emergent central sleep apnea: a unique sleep-disordered breathing

Treatment-emergent central sleep apnea (TECSA) is a specific form of sleep-disordered breathing, characterized by the emergence or persistence of central apneas during treatment for obstructive sleep apnea. The purpose of this review was to summarize the definition, epidemiology, potential mechanisms, clinical characteristics, and treatment of TECSA. We searched for relevant articles up to January 31, 2020, in the PubMed database. The prevalence of TECSA varied widely in different studies. The potential mechanisms leading to TECSA included ventilatory control instability, low arousal threshold, activation of lung stretch receptors, and prolonged circulation time. TECSA may be a self-limited disorder in some patients and could be resolved spontaneously over time with ongoing treatment of continuous positive airway pressure (CPAP). However, central apneas persist even with the regular CPAP therapy in some patients, and new treatment approaches such as adaptive servo-ventilation may be necessary. We concluded that several questions regarding TECSA remain, despite the findings of many studies, and it is necessary to carry out large surveys with basic scientific design and clinical trials for TECSA to clarify these irregularities. Further, it will be vital to evaluate the baseline demographic and polysomnographic data of TECSA patients more carefully and comprehensively.

Treatment emergent obstructive sleep apnea after Chiari surgery: A case report

Patients with Chiari type I malformation may also present with sleep disordered breathing mainly central sleep apnea. Here, we report a patient with Chiari I malformation referred to our clinic because of snoring and sleep disordered breathing. He was a 28-year-old man referred to us for evaluation of snoring. An overnight polysomnography revealed central sleep apnea. On further evaluation of central sleep apnea, the patient found to have Chiari malformation type I on brain MRI. The patient developed obstructive sleep apnea after surgery for Chiari malformation. Accordingly, pap titration was performed for the patient's obstructive sleep apnea. In patients with central sleep apnea comprehensive evaluation of predisposing causes is required. Lesions of central nervous system including Chiari malformation should not be overlooked. Furthermore, after treatment of central sleep apnea follow up PSG is warranted to confirm newly emerged sleep breathing disorder such as obstructive sleep apnea.

Emergence of Central Sleep Apnea Events After Maxillomandibular Advancement Surgery for Obstructive Sleep Apnea

PURPOSE

Central sleep apnea (CSA) can develop after the treatment of obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP). No studies have identified whether treatment of OSA with maxillomandibular advancement surgery (MMA) can result in CSA. The purpose of our study was to determine the incidence and clinical significance of CSA emerging after MMA surgery to treat OSA.

PATIENTS AND METHODS

A retrospective review was conducted of all patients who had undergone MMA surgery for OSA at the Department of Oral and Maxillofacial Surgery at the QEII Health Sciences Centre (Halifax, NS, Canada) from 1996 through 2016. All patients with preoperative level 1 polysomnography and follow-up level 1 study results available at least 6 months postoperatively were included the present study. The pre- and postoperative central apnea index (CAI) results were compared.

RESULTS

A total of 113 patients (84 men and 29 women) with an average age of 44.0 years were included in the present study. In 35 patients (31.0%), the emergence of CSA events were recorded on postoperative polysomnograms. Only 2 of the 113 patients experienced the emergence of clinically significant postoperative CSA (CAI >5). In our patient cohort, gender (P = .085), patient age (P = .238), and preoperative (P = .716) and postoperative (P = .209) Apnea-Hypopnea Index (AHI) results correlated with the postoperative development of CSA events after MMA surgery. The mean AHI values had decreased from 41.4 to 8.7 in all patients treated with MMA in our study.

CONCLUSIONS

The emergence of CSA events occurred in 31% of patients after OSA treatment with MMA surgery. The rate of clinically significant CSA events emerging after MMA surgery in our study was 1.8%. These findings help to support the use of MMA surgery for OSA as a reasonable treatment alternative for patients unable to tolerate CPAP.

Tongue Stabilizing Device-Emergent Central Sleep Apnea: A Case Report

ABSTRACT

Treatment-emergent central sleep apnea is a phenomenon that has been reported after many obstructive sleep apnea treatment modalities. We present a case of demonstrating treatment-emergent central sleep apnea while using the tongue stabilizing device therapy. This case adds to the evidence that showed the effect of the supine position on the severity of central sleep apnea and shows the advantage of polysomnography follow-up after oral appliance therapy for central apnea assessment.

[Complex sleep apnea syndrome]

Complex sleep apnea syndrome (Comp-SAS) is the term used to describe a specific form of sleep disordered breathing characterized by the arise of central sleep apnea in patient with previous obstructive sleep apnea syndrome (OSAS) treated with continuous positive airway pressure devices (CPAP). The mechanisms of its occurrence are not well understood, but partly it seems to be a consequence of increased carbon dioxide elimination under positive airway pressure treatment and related improvement of pulmonary ventilation. The prevalence of Comp-SAS ranges from 5% to 20% of OSAS patient getting CPAP therapy with no significant predictors in comparison with simple obstructive sleep apnea, but more likely to happened in older males with more severe OSAS and accompanying cardiovascular pathology such as ischemic heart disease, atrial fibrillation and heart failure. In most cases of Comp-SAS, central apnea events are transient and disappear after continuous CPAP therapy use for 1 to 2 months. Novel treatment options like adaptive servo-ventilation or BiPAP-ST are available for such non-responders to CPAP but contra-indicated to patients with systolic heart failure. From the other hand, still not clear is it mandatory to treat all affected individuals with Comp-SAS if the disease is uncomplicated and patient is asymptomatic.

Mandibular Advancement Device-Emergent Central Sleep Apnea Can Resolve Spontaneously: A Case Report

ABSTRACT

The development of treatment emergent central sleep apnea (CSA) has been described after almost all obstructive sleep apnea (OSA) therapies. While the course of positive airway pressure (PAP) emergent CSA, is better established; little is known about the natural course of mandibular advancement device (MAD) emergent CSA. Previous reports failed to comment on its natural course or report treatment with advanced ventilator modes such as adaptive servoventilation. We describe spontaneous resolution of MAD emergent CSA in a patient with moderate OSA who refused PAP. We also highlight the need for follow up polysomnography (PSG) after maximal advancement with a MAD and the possible association between MAD emergent CSA and atrial fibrillation. The exact pathophysiology of this phenomenon remains unclear but may relate to high loop gain of the respiratory system resulting in ventilatory overshoot after treatment and atrial fibrillation associated increased susceptibility to periodic ventilation.

Pathogenesis of central and complex sleep apnoea

Central sleep apnoea (CSA) - the temporary absence or diminution of ventilatory effort during sleep - is seen in a variety of forms including periodic breathing in infancy and healthy adults at altitude and Cheyne-Stokes respiration in heart failure. In most circumstances, the cyclic absence of effort is paradoxically a consequence of hypersensitive ventilatory chemoreflex responses to oppose changes in airflow, that is elevated loop gain, leading to overshoot/undershoot ventilatory oscillations. Considerable evidence illustrates overlap between CSA and obstructive sleep apnoea (OSA), including elevated loop gain in patients with OSA and the presence of pharyngeal narrowing during central apnoeas. Indeed, treatment of OSA, whether via continuous positive airway pressure (CPAP), tracheostomy or oral appliances, can reveal CSA, an occurrence referred to as complex sleep apnoea. Factors influencing loop gain include increased chemosensitivity (increased controller gain), reduced damping of blood gas levels (increased plant gain) and increased lung to chemoreceptor circulatory delay. Sleep-wake transitions and pharyngeal dilator muscle responses effectively raise the controller gain and therefore also contribute to total loop gain and overall instability. In some circumstances, for example apnoea of infancy and central congenital hypoventilation syndrome, central apnoeas are the consequence of ventilatory depression and defective ventilatory responses, that is low loop gain. The efficacy of available treatments for CSA can be explained in terms of their effects on loop gain, for example CPAP improves lung volume (plant gain), stimulants reduce the alveolar-inspired PCO₂ difference and supplemental oxygen lowers chemosensitivity. Understanding the magnitude of loop gain and the mechanisms contributing to instability may facilitate personalized interventions for CSA.

A systematic review on prevalence and risk factors associated with treatment- emergent central sleep apnea

INTRODUCTION:

Treatment-emergent central sleep apnea (TECSA) is the appearance of central apneas and hypopneas after significant resolution of the obstructive events has been attained using positive airway pressure (PAP) therapy. The aim of the study was to determine the prevalence of TECSA and to understand what factors are associated with its development.

METHODS:

PubMed, MEDLINE, Scopus, Web of Science and Cochran Library databases were searched with Mesh headings to locate studies linking TECSA and obstructive sleep apnea (OSA).

RESULTS:

Nine studies were identified that reported the prevalence of TECSA ranging from 5.0% to 20.3%. Prevalence of TECSA for studies using only full night titration was between 5.0% and 12.1% where as it was between 6.5% and 20.3% for studies using split-night polysomnogram. The mean effective continuous PAP (CPAP) setting varied between 7.5 cm and 15.2 cm of water for patients in TECSA group and between 7.4 cm and 13.6 cm of water for the group without TECSA.

CONCLUSIONS:

The aggregate point prevalence of TECSA is about 8% with the estimated range varying from 5% to 20% in patients with untreated OSA. The prevalence tends to be higher for split-night studies compared to full night titration studies. TECSA can occur at any CPAP setting although extremely high CPAP settings could increase the likelihood. Male gender, higher baseline apnea-hypopnea index, and central apnea index at the time of diagnostic study could be associated with the development of TECSA at a subsequent titration study.

Complex sleep apnea associated with use of nasal expiratory positive airway (nEPAP) device

Complex sleep apnea syndrome (CompSAS) is characterized by predominant obstructive sleep disordered breathing with evolution of central disordered breathing following exposure to nasal continuous positive airway pressure (CPAP) therapy in obstructive sleep apnea (OSA) patients. We report a case of CompSAS associated with use of a nasal expiratory positive airway (nEPAP, Provent) device. We therefore recommend obtaining objective sleep data to confirm treatment effectiveness of the nEPAP device for OSA prior to long-term prescription. Further research is warranted to understand the underlying pathophysiological mechanisms and risk factors associated with CompSAS.

Complex sleep apnea

OPINION STATEMENT

Complex sleep apnea currently refers to the emergence and persistence of central apneas and hypopneas following the application of positive airway pressure therapy in patients with obstructive sleep apnea. However, this narrow definition is an "outcome" and does not capture the spectrum of pathological activation of the respiratory chemoreflex in sleep apnea. The International Classification of Sleep Disorders - 3rd edition recognizes the phenomenon of Treatment-Related Central Sleep Apnea, but the phenotype is usually evident prior to onset of therapy. The key polysomnographic characteristics of chemoreflex modulated and mediated sleep apnea are nonrapid eye movement (NREM) dominance of respiratory events, short (<30 seconds) or long (>60 seconds) cycle time with a self-similar metronomic timing, and spontaneous improvement during rapid eye movement (REM) sleep. Thus, the majority of chemoreflex effects go unrecognized due to the bias toward obstructive sleep apnea's current scoring criteria. Any treatment of apparently obstructive sleep apnea, including surgery and oral appliances, can expose chemoreflex-driven instabilities. As both sleep fragmentation and a narrow CO2 reserve or increased loop gain drive the disease, sedatives (to induce longer periods of stable NREM sleep and reduce the destabilizing effects of arousals in NREM sleep) and CO2-based stabilization approaches are logical. Adaptive ventilation reduces mean hyperventilation yet can induce ventilator-patient desynchrony, while enhanced expiratory rebreathing space (EERS, dead space during positive pressure therapy) and CO2 manipulation directly stabilize respiratory control by moving CO2 above the apnea threshold. Carbonic anhydrase inhibition can provide further adjunctive benefits. Novel pharmacological approaches may target mediators of carotid body hypoxic sensitization, such as the balance between gas neurotransmitters. In complex apnea patients, single mode therapy is unlikely to be successful, and the power of multi-modality therapy should be harnessed for optimal outcomes.

Randomized controlled trial of noninvasive positive pressure ventilation (NPPV) versus servoventilation in patients with CPAP-induced central sleep apnea (complex sleep apnea)

STUDY OBJECTIVES

To compare the treatment effect of noninvasive positive pressure ventilation (NPPV) and anticyclic servoventilation in patients with continuous positive airway pressure (CPAP)-induced central sleep apnea (complex sleep apnea).

DESIGN

Randomized controlled trial.

SETTING

Sleep center.

PATIENTS

Thirty patients who developed complex sleep apnea syndrome (CompSAS) during CPAP treatment.

INTERVENTIONS

NPPV or servoventilation.

MEASUREMENTS AND RESULTS

Patients were randomized to NPPV or servo-ventilation. Full polysomnography (PSG) was performed after 6 weeks. On CPAP prior to randomization, patients in the NPPV and servoventilator arm had comparable apnea-hypopnea indices (AHI, 28.6 ± 6.5 versus 27.7 ± 9.7 events/h (mean ± standard deviation [SD])), apnea indices (AI,19 ± 5.6 versus 21.1 ± 8.6 events/h), central apnea indices (CAI, 16.7 ± 5.4 versus 18.2 ± 7.1 events/h), oxygen desaturation indices (ODI,17.5 ± 13.1 versus 24.3 ± 11.9 events/h). During initial titration NPPV and servoventilation significantly improved the AHI (9.1 ± 4.3 versus 9 ± 6.4 events/h), AI (2 ± 3.1 versus 3.5 ± 4.5 events/h) CAI (2 ± 3.1 versus 2.5 ± 3.9 events/h) and ODI (10.1 ± 4.5 versus 8.9 ± 8.4 events/h) when compared to CPAP treatment (all P < 0.05). After 6 weeks we observed the following differences: AHI (16.5 ± 8 versus 7.4 ± 4.2 events/h, P = 0.027), AI (10.4 ± 5.9 versus 1.7 ± 1.9 events/h, P = 0.001), CAI (10.2 ± 5.1 versus 1.5 ± 1.7 events/h, P < 0.0001)) and ODI (21.1 ± 9.2 versus 4.8 ± 3.4 events/h, P < 0.0001) for NPPV and servoventilation, respectively. Other sleep parameters were unaffected by any form of treatment.

CONCLUSIONS

After 6 weeks, servoventilation treated respiratory events more effectively than NPPV in patients with complex sleep apnea syndrome.

Treatment of complex sleep apnea syndrome

Complex sleep apnea syndrome (CompSAS) describes the coexistence or appearance and persistence of central apneas or hypopneas in patients with obstructive sleep apnea upon successful restoration of airway patency. We review data on treatment of CompSAS with CPAP, bilevel positive airway pressure, and adaptive servoventilation and discuss evidence for the addition of medications (analgesics, hypnotics, acetazolamide) and gases (oxygen, CO2) to positive airway pressure therapy. Future research should focus on defining outcomes in patients with CompSAS and allow for more accurate tailoring of therapy to the pathophysiology present in the individual patient.

Clinical heterogeneity of patients with complex sleep apnea syndrome

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.

Complex sleep apnea syndrome

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.

The appearance of central sleep apnea after treatment of obstructive sleep apnea

Patients with a primary diagnosis of obstructive sleep apnea frequently demonstrate central sleep apnea that emerges during treatment with CPAP. Although a number of mechanisms for this finding have been hypothesized, the pathophysiology is not definitively known. Controversy exists as to whether the concomitant appearance of the two phenomena represents a distinct meaningful entity. Regardless, the coincidence of these diseases may have important clinical implications. Herein, we review the proposed mechanisms for obstructive sleep apnea complicated by central sleep apnea. Future research is needed to elucidate the relative importance and susceptibility to intervention of the various pathophysiologic mechanisms responsible for this phenomenon, and whether a treatment approach distinct from that of pure obstructive apnea is justified.

The emergence of central sleep apnea after surgical relief of nasal obstruction in obstructive sleep apnea

By the current definition, complex sleep apnea (CompSA) refers to the emergence of central sleep apnea (CSA) during the treatment of obstructive sleep apnea (OSA) with continuous positive airway pressure (CPAP). However, new-onset CSA has been described with use of other treatments for OSA, including tracheostomy, maxillofacial surgery, and mandibular advancement device. We present a patient with CSA beginning after endoscopic sinus and nasal surgery for nasal obstruction in the setting of mild OSA. This case highlights the importance of non-PAP mechanisms in the pathogenesis of CompSA.