Treatment of complex sleep apnea syndrome: a retrospective comparative review

Influence of Obstructive Apnea Index on Persistent Left Ventricular Dysfunction in Patients with ST-Segment Elevation Myocardial Infarction

Background: We retrospectively investigated the effects of the severity and classification of sleep-disordered breathing (SDB) on left ventricular (LV) function in patients with ST-segment elevation myocardial infarction (STEMI). Methods: A total of 115 patients with STEMIs underwent a sleep study using a multichannel frontopolar electroencephalography recording device (Sleep Profiler) one week after STEMI onset. We evaluated LV global longitudinal strain (LV-GLS) using two-dimensional echocardiography at one week and seven months. Patients were classified as no SDB (AHI < 5 events/h), obstructive SDB (over 50% of apnea events are obstructive), and central SDB (over 50% of apnea events are central). Due to the device's limitations in distinguishing obstructive from central hypopnea, SDB classification was based on apnea index percentages. Results: The obstructive apnea index (OAI) was significantly associated with LV-GLS at one week (r = 0.24, p = 0.027) and seven months (r = 0.21, p = 0.020). No such correlations were found for the central apnea index and SDB classification. Multivariable regression analysis showed that the OAI was independently associated with LV-GLS at one week (β = 0.24, p = 0.002) and seven months (β = 0.20, p = 0.008). Conclusions: OAI is associated with persistent LV dysfunction assessed by LV-GLS in STEMI.

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.

[Treatment-Emergent Central Sleep Apnea - Detection and Treatment]

Treatment-Emergent Central Sleep Apnea - Detection and Treatment Abstract. In treatment-emergent central sleep apnea (TECSA), affected patients with obstructive sleep apnea newly develop central sleep apnea (AHI central ≥5/h) under therapy with positive pressure ventilation which cannot be explained by other causes. The pathophysiology of TECSA is incompletely understood. PaCO2 and the associated apnea threshold seem to play a central role. The incidence of TECSA varies (1.8-20%), and in about 2/3 of cases it is self-limiting in the course of the therapy. If persistence or new onset occurs later in the course of positive pressure therapy, a further evaluation (e.g., echocardiography, neurologic examination, medication history) is indicated. Effective treatment options include a change in ventilation therapy (adaptive servoventilation or bilevel ventilation with back-up frequency) or additional nocturnal oxygen supplementation; these options should be decided case by case.

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 Central Apnea: Physiologic Mechanisms Informing Clinical Practice

The purpose of this review was to describe our management approach to patients with treatment-emergent central sleep apnea (TECSA). The emergence of central sleep apnea during positive airway pressure therapy occurs in approximately 8% of titration studies for OSA, and it has been associated with several demographic, clinical, and polysomnographic factors, as well as factors related to the titration study itself. TECSA shares similar pathophysiology with central sleep apnea. In fact, central and OSA pathophysiologic mechanisms are inextricably intertwined, with ventilatory instability and upper airway narrowing occurring in both entities. TECSA is a "dynamic" process, with spontaneous resolution with ongoing positive airway pressure therapy in most patients, persistence in some, or appearing de novo in a minority of patients. Management strategy for TECSA aims to eliminate abnormal respiratory events, stabilize sleep architecture, and improve the underlying contributing medical comorbidities. CPAP therapy remains a standard therapy for TECSA. Expectant management is appropriate given its transient nature in most cases, whereas select patients would benefit from an early switch to an alternative positive airway pressure modality. Other treatment options include supplemental oxygen and pharmacologic therapy.

Natural history of treatment-emergent central sleep apnea on positive airway pressure: A systematic review

INTRODUCTION:

Treatment-emergent central sleep apnea (TECSA) 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. The objective of this study was to systematically review the literature for studies describing the natural history of TECSA.

METHODS:

PubMed, Medline, Scopus, Web of Science, and Cochran Library databases were searched through June 29, 2017.

RESULTS:

Five studies were identified that discussed the natural history of TECSA. TECSA developed in 3.5%–19.8% of PAP-treated patients. Treatment-persistent central sleep apnea (TPCSA), representing protracted periods of PAP therapy-related central apneas, was noted in 14.3%–46.2% of patients with TECSA. Delayed-TECSA (D-TECSA) represents an anomalous TECSA entity appearing weeks to months after initial PAP therapy. D-TECSA was observed in 0.7%–4.2% of OSA patients undergoing PAP treatment (after at least 1 month). In patients with TECSA, a higher apnea–hypopnea index (AHI) and central apnea index at their baseline study or a higher residual AHI at their titration study may be associated with an increased likelihood of conversion to TPCSA.

CONCLUSIONS:

Overall, TECSA developed in 3.5%–19.8% of PAP-treated patients with OSA. The vast majority will experience complete resolution of central apneas over a few weeks to months. Unfortunately, about a third of patients with TECSA may continue to exhibit persistence of central sleep apnea on reevaluation. A small proportion may experience D-TECSA after few weeks to several months of initial exposure to PAP therapy.

Complex sleep apnea after full-night and split-night polysomnography: the Greek experience

PURPOSE

Treatment-emergent central sleep apnea (TE-CSA) is defined as the emergence or persistence of central respiratory events during the initiation of positive airway pressure (PAP) without a back-up rate in obstructive sleep apnea (OSA) patients and after significant resolution of obstructive events. Previous studies have estimated a prevalence from 0.56 to 20.3%. The aim of this study was to establish the prevalence of TE-CSA in a Greek adult population.

METHODS

One thousand fifty nine patients with newly diagnosed OSA, who were referred to the Sleep Disorders Center of Evangelismos Hospital of Athens over an 18-month period, were included in this study. A split-night polysomnography (PSG), or two formal overnight PSGs (diagnostic and continuous PAP (CPAP) titration study), were performed.

RESULTS

Patients with OSA were divided in two groups; the first group included 277 patients, who underwent two separate studies (diagnostic and CPAP titration study), and the second group 782 patients, who underwent split-night studies. The prevalence of TE-CSA in the first group was 2.53% (7 patients), and in the second group was 5.63% (44 patients).

CONCLUSIONS

The prevalence of TE-CSA in Greece was lower compared to most previous reported studies. The significant variation in the prevalence of TE-CSA between different centers throughout the world is mainly associated with the used diagnostic criteria as well as methodological and technical aspects.

Sleep-Disordered Breathing and Excessive Daytime Sleepiness

Sleep-related breathing disorders include obstructive sleep apnea (OSA), central sleep apnea, sleep-related hypoventilation, and sleep-related hypoxemia. Excessive daytime sleepiness (EDS) is frequently reported by patients with OSA but is not invariably present. The efficacy of positive airway pressure therapy in improving EDS is well established for OSA, but effectiveness is limited by suboptimal adherence. Non-OSA causes of sleepiness should be identified and treated before initiating pharmacotherapy for persistent sleepiness despite adequately treated OSA. Further research on the identification of factors that promote EDS in the setting of OSA is needed to aid in the development of better treatment options.

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.

Clinical predictors of central sleep apnea evoked by positive airway pressure titration

PURPOSE

Treatment-emergent central sleep apnea (TECSA), also called complex apnea, occurs in 5%-15% of sleep apnea patients during positive airway pressure (PAP) therapy, but the clinical predictors are not well understood. The goal of this study was to explore possible predictors in a clinical sleep laboratory cohort, which may highlight those at risk during clinical management.

METHODS

We retrospectively analyzed 728 patients who underwent PAP titration (n=422 split-night; n=306 two-night). Demographics and self-reported medical comorbidities, medications, and behaviors as well as standard physiological parameters from the polysomnography (PSG) data were analyzed. We used regression analysis to assess predictors of binary presence or absence of central apnea index (CAI) ≥5 during split-night PSG (SN-PSG) versus full-night PSG (FN-PSG) titrations.

RESULTS

CAI ≥5 was present in 24.2% of SN-PSG and 11.4% of FN-PSG patients during titration. Male sex, maximum continuous positive airway pressure, and use of bilevel positive airway pressure were predictors of TECSA, and rapid eye movement dominance was a negative predictor, for both SN-PSG and FN-PSG patients. Self-reported narcotics were a positive predictor of TECSA, and the time spent in stage N2 sleep was a negative predictor only for SN-PSG patients. Self-reported history of stroke and the CAI during the diagnostic recording predicted TECSA only for FN-PSG patients.

CONCLUSION

Clinical predictors of treatment-evoked central apnea spanned demographic, medical history, sleep physiology, and titration factors. Improved predictive models may be increasingly important as diagnostic and therapeutic modalities move away from the laboratory setting, even as PSG remains the gold standard for characterizing primary central apnea and TECSA.

Clinical, polysomnographic, and CPAP titration features of obstructive sleep apnea: Mixed versus purely obstructive type

PURPOSE

To determine whether obstructive sleep apnea syndrome (OSAS) patients with mixed sleep apnea (MSA) have different clinical, polysomnographic, and continuous positive airway pressure (CPAP) titration findings compared to OSAS patients without MSA.

METHODS

We retrospectively reviewed the records of OSAS patients who had undergone CPAP titration and categorized them into pure-OSA and mixed-OSA groups. Demographic features, daytime sleepiness, and apnea severity were compared between the two groups using univariate and multivariate analyses. CPAP titration findings were also compared between the two groups.

RESULTS

One hundred and ninety-five subjects (n=126 pure-OSA; n=69 mixed-OSA) were included in the analysis. Compared to the pure-OSA group, the mixed-OSA group had a higher percentage of males (p=0.003) and a higher body mass index (p=0.044), Epworth Sleepiness Scale score (p=0.028), and apnea-hypopnea index (AHI) (p<0.001). In logistic regression analysis, older age, male sex, and higher body mass index were independently associated with mixed-OSA before PSG study. When using AHI as a covariable, the higher AHI with older age, male sex, and daytime sleepiness was independently related to mixed-OSA. The mixed-OSA group had a higher percentage of patients with complex sleep apnea, a lower percentage of patients with optimal titration, and a higher titrated pressure than the pure-OSA group.

CONCLUSIONS

Severe OSA, older age, male sex, obesity, and daytime sleepiness were related to mixed-OSA. Complex sleep apnea, less optimal titration, and a higher titrated CPAP were also associated with MSA in OSAS patients.

Clinical impact of adaptive servoventilation compared to other ventilatory modes in patients with treatment-emergent sleep apnea, central sleep apnea and Cheyne-Stokes respiration

INTRODUCTION

Adaptive servoventilation is a recent ventilatory mode initially designed to treat Cheyne-Stokes respiration (CSR). Recently, the efficacy of ASV has been discussed for the treatment of central sleep apnea (CSA) and treatment-emergent central sleep apnea (treatment-emergent CSA) where other forms of traditional positive airway pressure (PAP) may be insufficient.

OBJECTIVES

To compare the clinical impact of ASV with other forms of PAP in treating patients with treatment-emergent CSA, CSA and CSR.

METHODS

Medical data of all the patients who underwent polysomnography (PSG) with ASV titration were evaluated. The patients were divided into two groups according to the mode of ventilation reimbursed: ASV and PAP (AutoCPAP/CPAP/BIPAP). All patients had a minimal follow-up of 6 months. Both groups were compared in terms of symptoms, apnea hypopnea index, compliance, cardiac function and cardiovascular events.

RESULTS

ASV titration was performed in 33 patients (30M/3F) with a mean age of 69±8 years. The majority (58%) present a treatment-emergent SA and 42% a CSA and or CSR. The median initial diagnostic AHI was 46±22events/h. After the initial diagnosis, 28 patients were treated with PAP and 5 with servoventilation. All of the patients treated with PAP were posteriorly submitted to PSG and ASV titration because of suboptimal response to PAP. Despite a clear indication for ASV, due to differences in reimbursement, 15 patients continued treatment with PAP (12 with AutoCPAP, 1 with BIPAP and 2 with CPAP) and 16 changed to ASV. Two patients were lost in follow-up. In both groups, most of patients present a treatment-emergent SA (53% in ASV group vs. 67% in PAP group) or a CSA/CSR (29.4% in ASV group vs. 20% in PAP). After ASV titration, the mean follow-up was 25±14 months. Both groups (ASV vs. PAP) were similar in terms of compliance (77±23% vs.88±14%) and in terms of Epworth sleepiness scale score (6±5 vs. 7±5). There was a statistical difference in terms of residual AHI: mean AHI was 4±3 in ASV group and 9±3 in PAP group (P=0.005). We found no differences in terms of left ventricular fractional shortening (ASV 33±10% vs. PAP 32±10%). Although no difference was observed between the 2 groups in terms of non-fatal cardiovascular events (3 events in each group), 2 fatal cardiovascular events occurred in the PAP group (sudden death).

CONCLUSIONS

These data confirm that ASV is an efficient treatment in patients with treatment-emergent CSA, CSA/CSR significantly decreasing residual AHI. In both groups, compliance rate was high and sleepiness improved. It is relevant that the 2 patients who died of sudden death were treated with PAP.

The complex sleep apnea resolution study: a prospective randomized controlled trial of continuous positive airway pressure versus adaptive servoventilation therapy

INTRODUCTION

Prior studies show that adaptive servoventilation (ASV) is initially more effective than continuous positive airway pressure (CPAP) for patients with complex sleep apnea syndrome (CompSAS), but choosing therapies has been controversial because residual central breathing events may resolve over time in many patients receiving chronic CPAP therapy. We conducted a multicenter, randomized, prospective trial comparing clinical and polysomnographic outcomes over prolonged treatment of patients with CompSAS, with CPAP versus ASV.

METHODS

Qualifying participants meeting criteria for CompSAS were randomized to optimized CPAP or ASV treatment. Clinical and polysomnographic data were obtained at baseline and after 90 days of therapy.

RESULTS

We randomized 66 participants (33 to each treatment). At baseline, the diagnostic apnea-hypopnea index (AHI) was 37.7 ± 27.8 (central apnea index [CAI] = 3.2 ± 5.8) and best CPAP AHI was 37.0 ± 24.9 (CAI 29.7 ± 25.0). After second-night treatment titration, the AHI was 4.7 ± 8.1 (CAI = 1.1 ± 3.7) on ASV and 14.1 ± 20.7 (CAI = 8.8 ± 16.3) on CPAP (P ≤ 0.0003). At 90 days, the ASV versus CPAP AHI was 4.4 ± 9.6 versus 9.9 ± 11.1 (P = 0.0024) and CAI was 0.7 ± 3.4 versus 4.8 ± 6.4 (P < 0.0001), respectively. In the intention-to-treat analysis, success (AHI < 10) at 90 days of therapy was achieved in 89.7% versus 64.5% of participants treated with ASV and CPAP, respectively (P = 0.0214). Compliance and changes in Epworth Sleepiness Scale and Sleep Apnea Quality of Life Index were not significantly different between treatment groups.

CONCLUSION

Adaptive servoventilation (ASV) was more reliably effective than CPAP in relieving complex sleep apnea syndrome. While two thirds of participants experienced success with CPAP, approximately 90% experienced success with ASV. Because both methods produced similar symptomatic changes, it is unclear if this polysomnographic effectiveness may translate into other desired outcomes.

CLINICAL TRIALS

Clinicaltrials.Gov NCT00915499.

Complex sleep apnea syndrome

Complex sleep apnea is the term used to describe a form of sleep disordered breathing in which repeated central apneas (>5/hour) persist or emerge when obstructive events are extinguished with positive airway pressure (PAP) and for which there is not a clear cause for the central apneas such as narcotics or systolic heart failure. The driving forces in the pathophysiology are felt to be ventilator instability associated oscillation in PaCO2 arterial partial pressure of Carbon Dioxide, continuous cositive airway pressure (CPAP) related increased CO2 carbon dioxide elimination, and activation of airway and pulmonary stretch receptors triggering these central apneas. The prevalence ranges from 0.56% to 18% with no clear predictive characteristics as compared to simple obstructive sleep apnea. Prognosis is similar to obstructive sleep apnea. The central apnea component in most patients on followup using CPAP therap, has resolved. For those with continued central apneas on simple CPAP therapy, other treatment options include bilevel PAP, adaptive servoventilation, permissive flow limitation and/or drugs.

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.

Effective sleep apnoea treatment improves cardiac function in patients with chronic heart failure

BACKGROUND

Sleep disordered breathing (SDB) is highly prevalent in patients with chronic heart failure (CHF) and is associated with adverse effects on cardiac geometry and function. Continuous positive airway pressure (CPAP) has been proved an effective treatment modality for obstructive sleep apnoea (OSA), whereas adaptive servoventilation (ASV) is more effective in patients with central sleep apnoea (CSA). The impact of selection of therapy and effective apnoea alleviation on cardiac performance and reverse left ventricular remodelling (r-LVR) has not yet been evaluated.

METHODS

Eighty five patients with stable CHF were screened for SDB and underwent polysomnography and treatment according to the type of SDB. Clinical evaluation and a comprehensive echocardiographic study was performed before initiation of therapy and after six months of effective treatment (ventilator use >5h/day with AHI <5 events/h).

RESULTS

Seventeen compliant patients under effective treatment were included in the analysis (8 OSA under Autoset CPAP and 9 CSA under ASV). In both groups, a significant improvement in all measured, conventional and TDI LV systolic indexes was recorded, including LVEF (32% ± 6% vs. 27% ± 6%, p<0.001). A decrease in LV end-systolic volume (189 ± 94 ml vs. 211 ± 88 ml, p=0.015, difference >10%) was indicative of r-LVR. Furthermore, RV systolic parameters were also increased (TAPSE, p<0.001; systolic TDI wave from lateral tricuspid annular aspect, p=0.001), whereas right heart dimensions and areas were diminished, indicating better pulmonary haemodynamics. Moreover, a significant improvement in patients' clinical status, as evaluated by New York Heart Association Class was also documented at the end of six months follow-up.

CONCLUSIONS

Effective alleviation of SDB in CHF patients is associated with significant improvements in LV and RV systolic function and r-LVR. Longitudinal studies are needed to evaluate effects on morbidity and mortality.

Treatment of complex sleep apnea syndrome

Patients with complex sleep apnea syndrome (CompSAS) present with features of obstructive sleep apnea syndrome but demonstrate not only instability of upper airway tone (leading to classic obstructive apneas and hypopneas) but also unstable, chemosensitive ventilatory control leading to repetitive central apneas or periodic breathing during sleep. The central apneas often become most apparent after application of continuous positive airway pressure (CPAP) to alleviate upper airway obstruction; patients continue to have fragmented sleep and repetitive desaturations as a result of central apneas and hypopneas. In some patients, central apneas appear to abate over time as a result of some form of adaptation to CPAP. How often this occurs is uncertain, however, and many patients with CompSAS require treatment that combines stabilization of the upper airway obstruction with treatment of respiratory center dysfunction. Adaptive servo-ventilation, which provides both a minimum pressure to hold the airway open and a precisely calculated ventilatory assist to minimize cyclic hypoventilation and hyperventilation, has emerged as a leading treatment. Noninvasive ventilation using bilevel positive airway pressure in the spontaneous-timed mode also may regulate ventilation in some patients with CompSAS. There is anecdotal evidence that CompSAS may be successfully treated using combined PAP therapy with oxygen, carbon dioxide, or the addition of dead space, but data are not sufficient to routinely recommend these methods.

A systematic review of CPAP adherence across age groups: clinical and empiric insights for developing CPAP adherence interventions

Continuous positive airway pressure (CPAP) is a highly efficacious treatment for obstructive sleep apnea (OSA) but adherence to the treatment limits its overall effectiveness across all age groups of patients. Factors that influence adherence to CPAP include disease and patient characteristics, treatment titration procedures, technological device factors and side effects, and psychological and social factors. These influential factors have guided the development of interventions to promote CPAP adherence. Various intervention strategies have been described and include educational, technological, psychosocial, pharmacological, and multi-dimensional approaches. Though evidence to date has led to innovative strategies that address adherence in CPAP-treated children, adults, and older adults, significant opportunities exist to develop and test interventions that are clinically applicable, specific to sub-groups of patients likely to demonstrate poor adherence, and address the multi-factorial nature of CPAP adherence. The translation of CPAP adherence promotion interventions to clinical practice is imperative to improve health and functional outcomes in all persons with CPAP-treated OSA.

Continuous positive airway pressure intolerance associated with elevated nasal resistance is possible mechanism of complex sleep apnea syndrome

PURPOSE

Complex sleep apnea syndrome (CompSAS) is diagnosed after an elimination of obstructive events with continuous positive airway pressure (CPAP), when a central apnea index ≥5/h or Cheyne-Stokes respiration pattern emerges in patients with obstructive sleep apnea syndrome (OSAS). However, the pathophysiology of CompSAS remains controversial.

METHODS

Of the 281 patients with suspected OSAS, all of whom underwent polysomnography conducted at Nagoya University Hospital, we enrolled 52 patients with apnea-hypopnea index ≥15/h (age 51.4 ± 13.3 years). The polysomnographic findings, left ventricular ejection fraction (LVEF), and nasal resistance were compared between the CompSAS patients and OSAS patients.

RESULTS

Forty-three patients were diagnosed with OSAS and nine patients with central sleep apnea syndrome by natural sleep PSG. Furthermore, 43 OSAS patients were classified into the OSAS patients (OSAS group, n = 38) and the CompSAS patients (CompSAS group, n = 5) by the night on CPAP PSG. The nasal resistance was significantly higher in CompSAS group than in OSAS group (0.30 ± 0.10 vs. 0.19 ± 0.07 Pa/cm(3)/s, P = 0.004). The arousal index, percentage of stage 1 sleep, and oxygen desaturation index were significantly decreased, and the percentage of stage REM sleep was significantly increased in the OSAS group with the initial CPAP treatment, but not in the CompSAS group. In addition, the patients with CompSAS showed normal LVEF.

CONCLUSION

CPAP intolerance secondary to an elevated nasal resistance might relate to frequent arousals, which could presumably contribute to an increase in central sleep apnea. Further evaluation in a large study is needed to clarify the mechanism of CompSAS.

Differences in breathing patterning during wakefulness in patients with mixed apnea-dominant vs obstructive-dominant sleep apnea

BACKGROUND

Mixed apneas share both central and obstructive components and are often treated as if they are obstructive events. The hypothesis is that patients with obstructive sleep apnea syndrome (OSAS) who exhibit a majority of mixed apneas will differ in ventilatory control from those with predominantly obstructive apneas during wakefulness; moreover, this difference could affect nasal continuous positive airway pressure (CPAP) adherence.

METHODS

In a retrospectively derived case-control study, 5 min of respiratory inductance plethysmography signals during wakefulness prior to sleep onset were extracted from a diagnostic polysomnogram in these groups: (1) mixed apnea-dominant OSAS (mix-OSAS) (n = 36), (2) obstructive apnea-dominant OSAS (pure-OSAS) (n = 20), (3) central apnea-dominant sleep apnea syndrome (pure-CSAS) (n = 6), and (4) control subjects (n = 10). Breathing patterning was compared between the groups using the coefficient of variation (CV) for breath-to-breath inspiration time (TI), expiration time (TE), TI + TE (Ttot), and tidal volume, and an information theory-based metric of signal pattern variability (sample entropy). Subsequent CPAP adherence over 12 months was determined in OSAS groups.

RESULTS

Breath-to-breath CV parameters and sample entropy in the mix-OSAS group were significantly greater as compared with the pure-OSAS and control groups. In a subanalysis, CV and sample entropy were similar in the mix-OSAS and the pure-CSAS groups. CPAP adherence was significantly poorer in mix-OSAS compared with pure-OSAS.

CONCLUSIONS

During wakefulness, both breath patterning and sample entropy in mix-OSAS are similar to pure-CSAS and more variable than in pure-OSAS. In addition, CPAP adherence was decreased in patients with mix-OSAS, which may be related to basic differences in respiratory control.

Prevalence and treatment of central sleep apnoea emerging after initiation of continuous positive airway pressure in patients with obstructive sleep apnoea without evidence of heart failure

BACKGROUND

This study aimed to assess the prevalence of complex sleep apnoea (CompSA), defined as central sleep apnoea (CSA) emerging after the initiation of continuous positive airway pressure (CPAP) therapy for obstructive sleep apnoea (OSA), in patients with normal brain natriuretic peptide (BNP) levels, along with assessing the prevalence of CSA persisting in such patients after the onset of CPAP therapy. We hypothesised that the prevalence of CompSA and persistent CSA after CPAP initiation would be low in patients with OSA and normal BNP levels.

MATERIAL AND METHODS

Between April 2004 and July 2007, CPAP was initiated for all patients with OSA for two nights using a standardised protocol. The prevalence of CompSA syndrome (CompSAS) and persisting CSA [central apnoea index (CAI) >5/h and apnoea-hypopnoea index (AHI) >15/h with >50% central events during CPAP therapy] was prospectively assessed in patients with normal BNP levels. Patients with CompSAS or persisting CSA upon CPAP treatment received adaptive servoventilation (ASV).

RESULTS

Of 1,776 patients with OSA receiving CPAP, 28 patients (1.57%) had CSA at the time of CPAP therapy and normal BNP levels. Additionally, 10 patients had CompSAS (0.56%) and 18 patients (1.01%) had persisting CSA. In patients with CompSA or persisting CSA, the AHI was significantly lower with CPAP therapy than at the time of diagnosis (34 ± 15/h vs. 47 ± 20/h, p = 0.005). The CAI increased from 10 ± 10/h to 18/h ± 13/h (p = 0.009) upon initiation of CPAP therapy. ASV reduced the AHI to 6 ± 12/h (p < 0.001) during the first night of use.

CONCLUSION

The prevalence of CompSA or persisting CSA in patients with OSA and normal BNP levels who are receiving CPAP therapy is low (1.57%). ASV is an effective treatment for these patients.

Treatment options in Cheyne-Stokes respiration

About half of the patients suffering from heart failure present with sleep-disordered breathing. In most cases obstructive and central breathing disturbances (including Cheyne-Stokes respiration [CSR]) coexist. CSR is defined by a waxing and waning pattern of the tidal volume. While its pathophysiology has not been elucidated completely, increased ventilatory sensitivity for CO2 and therefore an imbalance of the respiratory drive and effort, a chronic hyperventilatory state, and changes of the apnoeic threshold are considered to play a relevant role. However, CSR in heart failure impairs survival and quality of life of the patients and is therefore a major challenge of respiratory sleep medicine. If CSR persists despite optimal medical and interventional therapy of the underlying cardiac disorder, oxygen supply, continuous positive airway pressure (CPAP), and bilevel pressure are often trialled. However, there is insufficient evidence to recommend oxygen or bilevel treatment. CPAP has proven to improve left ventricular function. In addition, retrospective analyses suggested a reduction of mortality under CPAP in heart failure patients with CSR. However, these findings could not be reproduced in the prospective controlled CanPAP trial. More recently, adaptive servoventilation (ASV) has been introduced for treatment of CSR or coexisting sleep-related breathing disorders. ASV devices aim at counterbalancing the ventilatory overshoot and undershoot by applying variable pressure support with higher tidal volume (TV) during hypoventilation and reduced TV during hyperventilation. ASV has proven to be superior to CPAP but the long-term efficacy and the influences on cardiac parameters and survival are still under investigation.

Combined adaptive servo-ventilation and automatic positive airway pressure (anticyclic modulated ventilation) in co-existing obstructive and central sleep apnea syndrome and periodic breathing

BACKGROUND

The co-existence of obstructive and central sleep apnea/hypopnea syndrome (OSAS) and periodic breathing is common in patients with and without underlying heart diseases. While automatic continuous positive airway pressure (APAP) has proven to effectively treat OSAS, the adaptive servo-ventilation (ASV) sufficiently improves periodic breathing. This is the first trial on a device which combines both treatment modes.

METHODS

Pilot study on a two-week treatment in patients with co-existing obstructive and central and periodic breathing disturbances during sleep. Twelve consecutive patients (9 male, 3 female, age 56.9+/-10.6 years, BMI 32.4+/-5.5 kg/m(2)) were treated with a new algorithm which combines APAP and ASV (also called anticyclic modulated ventilation (ACMV), SOMNOventCR, Weinmann, Hamburg, Germany). Seven suffered from arterial hypertension, coronary heart disease and mitral regurgitation, none from congestive heart failure.

RESULTS

The total apnea-hypopnea index (AHI) improved from 43.8+/-24.0/h to 2.1+/-2.4 (p<0.01), the obstructive AHI from 12.8+/-14.3/h to 0.3+/-0.6/h (p<0.01) and the central AHI from 31.0+/-17.5/h to 1.7+/-2.0/h (p<0.01). Moreover, there was a significant improvement in the total number of arousals, respiratory induced arousals, oxygen saturation and sleep profile.

CONCLUSION

The algorithm combining automatic continuous positive airway pressure (CPAP) and ASV normalizes all types of co-existing obstructive and central apnea/hypopnea and periodic breathing.

Characteristics of Japanese patients with complex sleep apnea syndrome: a retrospective comparison with obstructive sleep apnea syndrome

OBJECTIVE

The prevalence of complex sleep apnea syndrome (CompSAS) among Asian patients with obstructive sleep apnea syndrome (OSAS) has not yet been reported. Distinguishing CompSAS from pure OSAS is difficult using only diagnostic polysomnography (PSG). We examined the prevalence of CompSAS in Japanese patients with OSAS and the possibility to distinguish CompSAS from pure OSAS by analyzing the severity of respiratory events based on either sleep body position or sleep stage using a diagnostic PSG.

PATIENTS AND METHODS

A retrospective chart review of 297 consecutive Japanese patients who were 15 years of age or older with a primary diagnosis of OSAS who were referred for CPAP titration (AHI> or =20 events/hr).

RESULTS

Seventeen patients (5.7%) out of the 297 patients who had an obstructive apnea hypopnea index (AHI) of 20 or higher showed adverse increases in central apnea index (CAI) by the treatment with CPAP whereas obstructive apnea index (OAI) and mixed apnea index (MAI) were significantly decreased. In the results, the AHI on the PSG for CPAP titration reached only approximately half of the values on the diagnostic PSG. In these CompSAS patients, both the total CAI and the CAI in the supine position during NREM sleep on the diagnostic PSG were significantly higher than those in the OSAS group. The sleep body position did not so strongly affect the AHI, OAI and MAI in the CompSAS group. Multiple, stepwise, and logistic regression analyses revealed that the CAI in the supine position during NREM (p=0.026) was a significant variable to distinguish CompSAS from OSAS statistically although the variables were within the normal range.

CONCLUSION

The prevalence of CompSAS in Japanese OSAS patients may be lower when compared with Caucasian patients. The increase of CAI in the supine position during NREM sleep on diagnostic PSG may be a characteristic feature in CompSAS.

Natural course of complex sleep apnea--a retrospective study

Patients with complex sleep apnea syndrome (CompSAS) have obstructive sleep apnea but develop troublesome central sleep apnea activity or Cheyne-Stokes breathing when provided continuous positive airway pressure (CPAP) therapy. We examined whether CompSAS activity persists with long-term CPAP treatment. We retrospectively identified all patients with CompSAS who underwent two therapeutic polysomnograms (PSGs) separated by at least 1 month during 2003-2005. We compared PSG findings between the initial and follow-up study and noted clinical responses to therapy. We identified 13 CompSAS patients meeting criteria. Most follow-up PSGs were ordered after an abnormal overnight oximetry on CPAP or because of CPAP intolerance after 195 (49-562) days. The residual apnea-hypopnea index (AHI) on CPAP decreased from 26 (23-40) on the first PSG to 7 (3-21.5) on the follow-up PSG. Only seven patients reached AHI < 10 and 6 had AHI > or = 10 ("CPAP nonresponders") at follow-up. "CPAP nonresponders" were sleepier (Epworth Sleepiness Score 13 [12.5-14] vs 9 [6-9.5], p = 0.03) and trended toward lower body mass index (29.7 [28.6-31.6] vs 34.3 [32.5-35.1], p = 0.06). Both groups were equally compliant with CPAP therapy. Although the AHI tends to improve over time in CompSAS patients treated with CPAP, in this retrospective study nearly half-maintained a persistently elevated AHI. A prospective trial is merited to determine the optimal treatment for these patients.

Prevalence of complex sleep apnea among Japanese patients with sleep apnea syndrome

Sleep apnea syndrome (SAS) is basically divided into two types: obstructive and central SAS. Recently, the concept of complex SAS has been advocated. Complex SAS is defined as SAS that initially manifests as primarily obstructive SAS, but is characterized by the frequent central apneas after the removal of upper airway obstruction. To determine the prevalence and clinical significance of complex SAS among Japanese patients with SAS, 1,312 patients with SAS were enrolled in this study. Diagnosis of central SAS was made based on diagnostic polysomnography, and differentiation of obstructive SAS from complex SAS was made from polysomnographic findings for treatment with continuous positive airway pressure, which resolved upper airway obstruction. As a result, obstructive SAS was found in 1,232 of 1,312 patients with SAS (93.9%) and central SAS was found in 14 patients (1.1%). The overall prevalence of complex SAS was 5.0% (n = 66). The prevalence of complex SAS among 1,218 male and 94 female patients with SAS were 5.3% and 1.1%, respectively. Patients with complex SAS had significantly higher apnea/hypopnea indices than patients with either obstructive or central SAS, but were similar in both mean age and average body mass index to obstructive SAS patients. There were no significant between-group differences in numbers of patients with clinical complications including hypertension, cardiac diseases, or cerebrovascular diseases. In conclusion, the prevalence of complex SAS in Japanese SAS patients is 5.0%, which is lower than previously reported prevalence of complex SAS in the USA and Australia.

Efficacy of adaptive servoventilation in treatment of complex and central sleep apnea syndromes

BACKGROUND

Complex sleep apnea syndrome (CompSAS) is recognized by the concurrence of mixed or obstructive events with central apneas, the latter predominating on exposure to continuous positive airway pressure (CPAP). Treatment of CompSAS or central sleep apnea (CSA) syndrome with adaptive servoventilation (ASV) is now an option, but no large series exist describing the application and effectiveness of ASV.

METHODS

Retrospective chart review of the first 100 patients who underwent polysomnography using ASV at Mayo Clinic Sleep Center.

RESULTS

ASV titration was performed for CompSAS (63%), CSA (22%), or CSA/Cheyne Stokes breathing patterns (15%). The median diagnostic sleep apnea hypopnea index (AHI) was 48 events per hour (range, 24 to 62). With CPAP, obstructive apneas decreased, but the appearance of central apneas maintained the AHI at 31 events per hour (range, 17 to 47) [p = 0.02]. With bilevel positive airway pressure (BPAP) in spontaneous mode, AHI trended toward worsening vs baseline, with a median of 75 events per hour (range, 46 to 111) [p = 0.055]. BPAP with a backup rate improved the AHI to 15 events per hour (range, 11 to 31) [p = 0.002]. Use of ASV dramatically improved the AHI to a mean of 5 events per hour (range, 1 to 11) vs baseline and vs CPAP (p < 0.0001). ASV also resulted in an increase in rapid eye movement sleep vs baseline and CPAP (18% vs 12% and 10%, respectively; p < 0.0001). Overall, 64 patients responded to the ASV treatment with a mean AHI < 10 events per hour. Of the 44 successful survey follow-up patients contacted, 32 patients reported some improvement in sleep quality.

CONCLUSION

The ASV device appears to be an effective treatment of both CompSAS and CSA syndromes that are resistant to CPAP.