Complex Sleep Apnea Research Articles

New modalities for non-invasive positive pressure ventilation: A review article.

Efficiency of non-invasive positive pressure ventilation in the treatment of respiratory failure has been shown in many published studies. In this review article, we introduced new modalities of non-invasive ventilation (NIV), clinical settings in which NIV can be used and a practical summary of the latest official guidelines published by the European Respiratory Clinical Practice. Clinical trials and review articles in four databases up to 25 February 2018 about new modalities of non-invasive positive pressure ventilation were reviewed. Commonly used modalities for treatment of respiratory failure include: CPAP (continuous positive airway pressure) and BiPAP (bilevel positive airway pressure) or NIPSV (noninvasive pressure support ventilation). The limitations of the BiPAP method are the trigger and cycle asynchrony, inadequate volume delivery and increased respiratory rate. Newer methods, such as adaptive servo-ventilation, have been developed to treat central and complex sleep apnea and the NAVA (neutrally adjusted ventilatory assist) to improve the trigger and cycle asynchrony. In the proportional assist ventilation, unlike the pressure support ventilation, with increased patient effort (flow) the tidal volume increases and it prevents the increase in the respiratory rate and respiratory distress. High-flow nasal cannula is a non-invasive technique that does not provide respiratory support, but provides a mixture of oxygen to the patient. The use of non-invasive pursed-lip breathing ventilation in chronic obstructive pulmonary disease (COPD) patients reduces dyspnea (decreases respiratory rate) and increases blood oxygen saturation. New modalities of NIV improve patient comfort and patient–ventilator interactions, and are recommended in patients with respiratory failure.

Complex Sleep Apnea

The term complex sleep apnea syndrome (Comp-SAS) refers to a specific variant of respiratory impairment during sleep characterized by the appearance or significant increases in the number of episodes of central apnea and hypopnea after starting CPAP therapy for obstructive sleep apnea syndrome (OSAS). The mechanisms producing Comp-SAS are not fully understood. It is possible that respiration with positive pressure and elimination of pharyngeal obstruction in some patients lead to increases in pulmonary ventilation and decreases in PaCO2 to below the individual threshold required for stimulating respiration. The prevalence of Comp-SAS is 5–20% of patients with OSAS receiving CPAP therapy. Significant clinical predictors for Comp-SAS have not been established, though this respiratory disorder is known to occur more frequently in male patients, older patients, those with severe OSAS, and those with cardiovascular diseases such as ischemic heart diseases, atrial fibrillation, or chronic heart failure (CHF). In most cases, Comp-SAS settles spontaneously after 1–2 months of regular CPAP therapy. If positive pressure treatment has no effect, other contemporary treatment methods can be used, such as adaptive servo ventilation or BPAP treatment with controlled respiratory frequency, though these are contraindicated in systolic heart failure. The question of whether treatment of patients with Comp-SAS is obligatory when the course of illness is straightforward and symptom-free remains open.

0545 Comparison of Performance of Four Adaptive Servo Ventilation Devices In Patients With Complex Sleep Apnea

0545 Comparison of Performance of Four Adaptive Servo Ventilation Devices In Patients With Complex Sleep Apnea

1158 Can Combination Conservative Therapy with Both Internal Nasal Dilator and Supine Avoidance Improve Complex Sleep Apnea?

1158 Can Combination Conservative Therapy with Both Internal Nasal Dilator and Supine Avoidance Improve Complex Sleep Apnea?

Estimation of adaptive ventilation success and failure using polysomnogram and outpatient therapy biomarkers

Adaptive servo-ventilation (ASV) devices provide anticyclic pressure support for the treatment of central and/or complex sleep apnea, including heart failure patients. Variability in responses in the clinic and negative clinical trials motivated assessment of standard and novel signal biomarkers for ASV efficacy. Multiple clinical databases were queried to assess potential signal biomarkers of ASV effectiveness, including the following: (1) attended laboratory adaptive ventilation titrations: 108, of which 66 had mainstream ETCO2 measurements; (2) AirView data in 98 participants, (3) complete data, from diagnostic polysomnogram (PSG) through review and prospective analysis of on-therapy data using SleepyHead freeware in 44 participants; and (4) hemodynamic data in the form of beat-to-beat blood pressure during ASV titration, using a Finometer in five participants. Signal biomarkers of reduced ASV efficacy were noted as follows: (1) an arousal index which markedly exceeded the respiratory event index during positive pressure titration; (2) persistent pressure cycling during long-term ASV therapy, visible in online review systems or reviewing data using freeware; (3) the ASV-associated pressure cycling induced arousals, sleep fragmentation, and blood pressure surges; and (4) elevated ratios of 95th percentile to median tidal volume, minute ventilation, and respiratory rate were associated with pressure cycling. High intraclass coefficients (>0.8) for machine apnea-hypopnea index and other extractable metrics were consistent with stability of patterns over multiple nights of use. Global clinical outcomes correlated negatively with pressure cycling. Potential polysomnographic- and device-related signal biomarkers of ASV efficacy are described and may allow improved estimation of therapeutic effectiveness of adaptive ventilation.

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

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. 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. 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). 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.

Adaptive Servo‐Ventilation (ASV) therapy improves long‐term prognosis in patients with complex sleep apnea syndrome (Comp SAS) better than cheyne‐stokes respiration (CSR)‐central sleep apnea (CSA)

Adaptive Servo‐Ventilation (ASV) therapy improves long‐term prognosis in patients with complex sleep apnea syndrome (Comp SAS) better than cheyne‐stokes respiration (CSR)‐central sleep apnea (CSA)

Positional Complex Sleep Apnea: Not So Complex

Complex sleep apnea (CxSA) is commonly seen during PAP therapy and it is often difficult to treat. Here we are reporting a case of positional complex sleep apnea in which CxSA was more prominent in supine position and it was treated with Bilevel PAP-S/T mode along with position therapy. This case highlights that postural therapy can be tried along with basic PAP modes in management of CxSA in setting of resource limitations before moving to costlier therapies like Adaptive servo ventilation.

0508 SLEEP APNEA AND ATRIAL FIBRILLATION - PHENOTYPE AND OUTCOMES

Sleep apnea, especially central (CSA), is associated with atrial fibrillation (AF). We hypothesized that AF patients are at high risk for treatment-emergent/complex apnea, and residual disease during long-term therapy with positive airway pressure. The sleep laboratory database at the Beth Israel Deaconess Medical center and affiliated services was queried, focusing on patients with AF, to extract polysomnographic information. The BIDMC Online Medical Records was used to collect co-morbid information. Residual apnea and related information was extracted from the EnocreAnywhere database; at the BIDMC, tracking is life-long, enabling assessment of outcomes beyond 6 months. Three hundred and eighteen patients had complete clinical/polysomnographic data, and 212 were reviewed in EncoreAnywhere. Split night was 31%. Summary statistics: age 68.3 ± 11.1 years, 69.1% male, BMI 33.6 ± 8 Kg/M2, ejection fraction 53.5 ± 10.8 (22% less than 50%), hypertension 68.6%. Baseline total sleep time (TST): 181.4 ± 116.3 minutes, sleep efficiency 62.9 ± 19.3 %, N1 24.3 ± 21.5% TST, N3: 9.7 ± 13.9 % TST, RDI: 39.4 ± 21.7, AHI4% 8.2 ± 11.9, minimum saturation 81.8 ± 10 %. Titration data: TST: 242 ± 98.9 minutes, sleep efficiency 66.9 ± 19.8 %, N1: 18 ± 15.2 %, RDI 27 ± 21.6, AHI4% 5 ± 8.5, minimum saturation 85.4 ± 6.9 %. CSA was noted in 4% on baseline, and treatment-emergent/complex apnea in 30%. The mean duration of use of positive airway pressure (93% continuous) was 21 ± 3 months, mean use 4.1 ± 2.1 hours. Residual AHI-flow was 11.6 ± 7.8 / hour of use, and periodic breathing of at least 10 minutes duration on visual waveforms inspection in 76.4 %. Patients with AF have highly fragmented sleep during diagnostic and titration polysomnograms. Complex sleep apnea is common, as is residual sleep apnea and periodic breathing on waveforms. This likely reflects persistently elevated loop gain. AF patients with sleep apnea are at high risk for reduced treatment effectiveness, and may require a dedicated phenotype-driven clinical pathway for optimal management. Beth Israel Deaconess Medical Center Chief Academic Officer’s Innovation Grant.

1235 Complex Sleep Apnea Refractory to Positive Airway Pressure (PAP) Therapy While on Baclofen that Responded to Continuous Positive Airway Pressure (CPAP) Therapy upon Cessation of Baclofen

1235 Complex Sleep Apnea Refractory to Positive Airway Pressure (PAP) Therapy While on Baclofen that Responded to Continuous Positive Airway Pressure (CPAP) Therapy upon Cessation of Baclofen

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.

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.

Residual Events during Use of CPAP: Prevalence, Predictors, and Detection Accuracy.

To assess the frequency, severity, and determinants of residual respiratory events during continuous positive airway therapy (CPAP) for obstructive sleep apnea (OSA) as determined by device output. Subjects were consecutive OSA patients at an American Academy of Sleep Medicine accredited multidisciplinary sleep center. Inclusion criteria included CPAP use for a minimum of 3 months, and a minimum nightly use of 4 hours. Compliance metrics and waveform data from 217 subjects were analyzed retrospectively. Events were scored manually when there was a clear reduction of amplitude (≥ 30%) or flow-limitation with 2-3 larger recovery breaths. Automatically detected versus manually scored events were subjected to statistical analyses included Bland-Altman plots, correlation coefficients, and logistic regression exploring predictors of residual events. The mean patient age was 54.7 ± 14.2 years; 63% were males. All patients had a primary diagnosis of obstructive sleep apnea, 26% defined as complex sleep apnea. Residual flow measurement based apnea-hypopnea index (AHIFLOW) > 5, 10, and 15/h was seen in 32.3%, 9.7%, and 1.8% vs. 60.8%, 23%, and 7.8% of subjects based on automated vs. manual scoring of waveform data. Automatically detected versus manually scored average AHIFLOW was 4.4 ± 3.8 vs. 7.3 ± 5.1 per hour. In a logistic regression analysis, the only predictors for a manual AHIFLOW > 5/h were the absolute central apnea index (CAI), (odds ratio [OR]: 1.5, p: 0.01, CI: 1.1-2.0), or using a CAI threshold of 5/h of sleep (OR: 5.0, p: < 0.001, CI: 2.2-13.8). For AHIFLOW > 10/h, the OR was 1.14, p: 0.03 (CI: 1.1-1.3) per every CAI unit of 1/hour. Residual respiratory events are common during CPAP treatment, may be missed by automated device detection and predicted by a high central apnea index on the baseline diagnostic study. Direct visualization of flow data is generally available and improves detection.

Sleep apnea in Chiari I malformation

A 36-year-old non-obese woman consulted her physician for recent excessive daytime sleepiness (EDS) with Epworth sleepiness scale (ESS) at 13/24, morning headache and heavy snoring. Polysomnography revealed moderate mixed sleep apnea syndrome with an Apnoea–Hypopnoea Index (AHI) of 23/h (Figure 1). Despite adequate continuous positive airway pressure (CPAP) therapy, the patient reported an aggravation of EDS and headache. A second polysomnography with CPAP, conclude to moderate complex sleep apnea syndrome by revealing the persistence of numerous central sleep apnea (AHI of 21/h) but no evidence of obstructive events. The patient reported a sensation of unrefreshing sleep and EDS (ESS at 17/24) with no symptoms suggesting cardiac failure, periodic limb movement disorder or narcolepsy. Physical examination, including neurologic and cardiac examinations, was normal. Routine blood tests, arterial blood gas analysis and echocardiography were performed and showed no significant abnormalities.

Clinical Use of Loop Gain Measures to Determine Continuous Positive Airway Pressure Efficacy in Patients with Complex Sleep Apnea. A Pilot Study.

Measures of unstable ventilatory control (loop gain) can be obtained directly from the periodic breathing duty ratio on polysomnography in patients with Cheyne-Stokes respiration/central sleep apnea and can predict the efficacy of continuous positive airway pressure (CPAP) therapy. In this pilot study, we aimed to determine if this measure could also be applied to patients with complex sleep apnea (predominant obstructive sleep apnea, with worsening or emergent central apneas on CPAP). We hypothesized that loop gain was higher in patients whose central events persisted 1 month later despite CPAP treatment versus those whose events resolved over time. We calculated the duty ratio of the periodic central apneas remaining on the CPAP titration (or second half of the split night) while patients were on optimal CPAP with the airway open (obstructive apnea index < 1/h). Loop gain was calculated by the formula: LG = 2π/[(2πDR - sin(2πDR)]. Patients were followed on CPAP for 1 month. Post-treatment apnea-hypopnea index and compliance data were recorded from smart cards. Thirty-two patients with complex sleep apnea were identified, and 17 patients had full data sets. Eight patients continued to have a total of more than five events per hour (11.8 ± 0.5/h) (nonresponders). The remaining nine patients had an apnea-hypopnea index less than 5/h (2.2 ± 0.4/h) (responders). Loop gain was higher in the nonresponders versus responders (2.0 ± 0.1 vs. 1.7 ± 0.2, P = 0.026). Loop gain and the residual apnea-hypopnea index 1 month after CPAP were associated (r = 0.48, P = 0.02). CPAP compliance was similar between groups. In this pilot study, loop gain was higher for patients with complex sleep apnea in whom central apneas persisted after 1 month of CPAP therapy (nonresponders). Loop gain measurement may enable an a priori determination of those who need alternative modes of positive airway pressure.

Complex sleep apnea at auto-titrating CPAP initiation: prevalence, significance and predictive factors.

Obstructive sleep apnea (OSA) patients may develop central respiratory events under continuous positive airway pressure (CPAP), referred to as complex sleep apnea (CompSA). We aimed to assess prevalence and predictive factors of complex apnea and to evaluate treatment response to CPAP. Within a retrospective cohort study, we assessed clinical data of OSA patients, attending the sleep lab during a 15-months period. Included participants underwent two consecutive polysomnographies; baseline diagnosis and treatment trial. Complex apnea patients, defined by a central apnea index ≥ 5 per hour during pressure auto-titration, were compared to remainders. Among 263 included patients, the prevalence of complex apnea was 9.1%. The mean apnea hypopnea index only dropped from 52.7 to 39.9 per hour in CompSA patients, while it improved from 40.9 to 7.3 in patients without CompSA. Although a decreased sleep-fragmentation under CPAP was observable in both groups, the enhancement of Non-REM sleep was superior in patients without CompSA. The CompSA patients showed higher median apnea-hypopnea, mixed apnea and central apnea indices at baseline and displayed higher rates of comorbid heart failure and obstructive pulmonary disease, but no higher severity of associated daytime fatigue and sleepiness symptoms. Despite evidenced partial improvement of obstructive events, nocturnal hypoxemia and sleep fragmentation, the occurrence of complex apnea presented here as a clear therapeutic failure of auto-titrating CPAP and was associated with heart failure, COPD and higher central and mixed apnea indices at baseline.

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

PurposeTo 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. MethodsWe 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. ResultsOne 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. ConclusionsSevere 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.

Prevalence of central sleep apnea during continous positive airway pressure (CPAP) titration in subjects with obstructive sleep apnea syndrome at an altitude of 2640 m

BackgroundThe occurrence of central apneas when applying positive pressure (CPAP) to patients with obstructive sleep apnea syndrome (OSAS) is called complex sleep apnea (CompSA). This causes poor adherence to CPAP and persistence of symptoms. In Bogota, a city located at an altitude of 2640 m above sea level, chronic hypoxemia can generate certain instability of the respiratory system during sleep which could increase the presence of central apnea. The aim was to establish the prevalence of central apnea (central apnea index >5/h) in adults with moderate or severe OSAS during CPAP titration, and the factors associated with this. MethodPatients over 18 years old with OSAS were referred to the Fundacion Neumologica Colombiana Sleep Center, from January 2008 to June 2010. Polysomnogram (PSG) for CPAP titration was performed according to the American Academy of Sleep Medicine criteria. The prevalence was calculated and the clinical and baseline PSG factors associated with the CompSA were analyzed. ResultsWe included 988 patients, 58% men. CompSA prevalence was 11.6%. Factors associated with CompSA were: central apneas in the baseline PSG (OR: 5.34 [3.49–8.16]), history of heart failure (OR: 2.53 [1.58–4.07]), and male sex (OR: 1.68 [1.06–2.69]). ConclusionThe prevalence of complex sleep apnea in Bogota (11.6%) was intermediate compared to the reported in lower altitudes. The factors associated with the development of CompSA were male sex, heart failure, and the presence of central apnea in the baseline PSG.

Absence of Typical Symptoms and Comorbidities in Patients with Central Sleep Apnea.

Sleep apnea is characterized by pauses in breathing during sleep. There are three forms: central, obstructive, and complex, or mixed sleep apnea. Central sleep apnea, a manifestation of respiratory instability in many clinical conditions and with a variety of causes, is the result of a temporary cessation of breathing in which the inhibitory influences favoring the instability predominate over excitatory influences favoring stable breathing. In contrast to central sleep apnea, according to the published data from previous studies, an association exists between obstructive sleep apnea and various comorbidities, especially chronic obstructive pulmonary disease. This article examines retrospectively the possible association of central sleep apnea with special sleep-related symptoms and various co-morbidities. Data of all patients with different types of central sleep apnea were collected from our hospital charts within the Department of Pneumology, HELIOS Clinic, University of Witten/Herdecke, Wuppertal, Germany, within the study period of January 1, 2011 to September 19, 2014. After clinical examination, all patients underwent polysomnography in our sleep laboratory. We identified a total of 60 (3.5 %) patients with central sleep apnea from 1722 patients with assumed sleep disordered breathing of the mean age of 68.2 ± 13.7 years (44 males - 73.3 %, 95 % CI 0.6-0.9 and 16 females - 26.7 %, 95 % CI 0.2-0.4). Typical symptoms of sleep-disordered breathing were not observed. A relation to co-morbidities was not found. Central sleep apnea was often diagnosed in the elderly. A direct association between central sleep apnea and symptoms of sleep-disordered breathing and various co-morbidities was not detected. This is in direct contrast to the obstructive sleep apnea syndrome.

P296 Effectiveness Of Adaptive Servo Ventilation In The Treatment Of Central Sleep Apnea

Background Adaptive Servo Ventilation (ASV) was developed to treat Central Sleep Apnea in patients with heart failure, which is usually associated with a low or normal PaCO2. The aim of ASV is to stabilise rather than increase overall ventilation. Evidence is limited regarding the use of ASV not only in heart failure patients but central sleep apnea of other aetiologies. The current study therefore explored this therapy in a regional sleep centre in the UK. Method A retrospective review of the outcomes of 42 patients who were treated with ASV between January 2012 and December 2013, either following conventional positive airway pressure (PAP) or as an initial therapy. Measurements included the Apnea Hypopnea Index (AHI), compliance (measured by hours of machine use/night) and subjective sleep quality, pre and post ASV. Results All patients demonstrated evidence of central sleep apnea with a reduced or normal transcutaneous CO2 during daytime spontaneous ventilation. Seven patients (16%) met the criteria for complex sleep apnea. 16 (38%) had evidence of heart failure whilst opioids were in use in six patients (14%). The majority of patients, (n = 36, 86%), were on PAP prior to ASV (mean duration 2.4 years), 22 patients (53%) were on Bi-level and 14 (33%) were on CPAP. Six patients (14%) had ASV as an initial therapy. The mean AHI improved from 31.7/h (range 2–84/h) to 5.1/h (Range 0–50/h) with ASV [Figure 1]. Compliance improved from 5.2 h/night to 6.4 h/night with ASV. 22 patients (52%) reported a subjective improvement in their sleep quality using ASV. Conclusion ASV appeared superior to traditional PAP in improving AHI, compliance and sleep quality for patients with central sleep apnea of various aetiologies.