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This review aimed to examine the relationship between surgical weight loss and obstructive sleep apnoea (OSA) severity (i.e., apnoea-hypopnoea index [AHI]), and how this relationship is altered by the various respiratory events scoring (RES) criteria used to derive the AHI. A systematic search of the literature was performed up to December 2017. Before-and-after studies were considered due to a paucity of randomised controlled trials (RCTs) available to be reviewed in isolation. Primary outcomes included pre- and post-surgery AHI and body mass index (BMI). Secondary outcomes included sleep study type and RES criteria. Meta-analysis was undertaken where possible. Overall, surgical weight loss resulted in reduction of BMI and AHI, however, OSA persisted at follow-up in the majority of subjects. There was high between-study heterogeneity which was largely attributable to baseline AHI and duration of follow-up when analysed using meta-regression. There was insufficient data to evaluate the impact of different RES criteria on OSA severity. Therefore, more RCTs are needed to verify these findings given the high degree of heterogeneity and future studies are strongly encouraged to report the RES criteria used to enable fair and uniform comparisons of the impact of any intervention on OSA severity., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Lifetime lung function is related to quality of life and longevity. Over the lifespan, individuals follow different lung function trajectories. Identification of these trajectories, their determinants, and outcomes is important, but no study has done this beyond the fourth decade., Methods: We used six waves of the Tasmanian Longitudinal Health Study (TAHS) to model lung function trajectories measured at 7, 13, 18, 45, 50, and 53 years. We analysed pre-bronchodilator FEV 1 z-scores at the six timepoints using group-based trajectory modelling to identify distinct subgroups of individuals whose measurements followed a similar pattern over time. We related the trajectories identified to childhood factors and risk of chronic obstructive pulmonary disease (COPD) using logistic regression, and estimated population-attributable fractions of COPD., Findings: Of the 8583 participants in the original cohort, 2438 had at least two waves of lung function data at age 7 years and 53 years and comprised the study population. We identified six trajectories: early below average, accelerated decline (97 [4%] participants); persistently low (136 [6%] participants); early low, accelerated growth, normal decline (196 [8%] participants); persistently high (293 [12%] participants); below average (772 [32%] participants); and average (944 [39%] participants). The three trajectories early below average, accelerated decline; persistently low; and below average had increased risk of COPD at age 53 years compared with the average group (early below average, accelerated decline: odds ratio 35·0, 95% CI 19·5-64·0; persistently low: 9·5, 4·5-20·6; and below average: 3·7, 1·9-6·9). Early-life predictors of the three trajectories included childhood asthma, bronchitis, pneumonia, allergic rhinitis, eczema, parental asthma, and maternal smoking. Personal smoking and active adult asthma increased the impact of maternal smoking and childhood asthma, respectively, on the early below average, accelerated decline trajectory., Interpretation: We identified six potential FEV 1 trajectories, two of which were novel. Three trajectories contributed 75% of COPD burden and were associated with modifiable early-life exposures whose impact was aggravated by adult factors. We postulate that reducing maternal smoking, encouraging immunisation, and avoiding personal smoking, especially in those with smoking parents or low childhood lung function, might minimise COPD risk. Clinicians and patients with asthma should be made aware of the potential long-term implications of non-optimal asthma control for lung function trajectory throughout life, and the role and benefit of optimal asthma control on improving lung function should be investigated in future intervention trials., Funding: National Health and Medical Research Council of Australia; European Union's Horizon 2020; The University of Melbourne; Clifford Craig Medical Research Trust of Tasmania; The Victorian, Queensland & Tasmanian Asthma Foundations; The Royal Hobart Hospital; Helen MacPherson Smith Trust; and GlaxoSmithKline., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

This review aimed to determine the effectiveness of positional modification techniques in preventing supine sleep, sleep-disordered breathing and other clinically important outcomes in patients with supine obstructive sleep apnea (OSA). Randomized controlled trials comparing positional modification techniques with any other therapy or placebo were included. Electronic searches of databases including CENTRAL, MEDLINE, CINAHL, Embase, and Web of Science up to April 2016 were performed. Meta-analysis was undertaken where possible. This comprehensive meta-analysis found benefit for positional modification techniques in those with supine OSA in terms of reduction in apnea-hypopnea index (AHI) and time spent supine. Whilst positional modification techniques were effective in terms of a reduction in AHI, continuous positive airway pressure (CPAP) was more effective than these techniques. A reliable diagnosis of supine OSA should be considered, and further research is required on patient-centred outcomes including comfort, barriers to adherence, cost-analysis, and long term outcomes including the effect on cardiovascular disease, the metabolic syndrome, and insulin resistance., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Rationale: Obstructive sleep apnea (OSA) is associated with impaired renal function, but uncertainty exists over whether OSA treatment can influence renal outcomes., Objectives: To determine the effects of continuous positive airway pressure (CPAP) on renal function in subjects with coexisting OSA and cardiovascular disease., Methods: This was a substudy of the international SAVE (Sleep Apnea Cardiovascular Endpoints) trial, in which 2,717 patients with moderate to severe OSA and established coronary or cerebrovascular disease were randomized to receive either CPAP plus usual care or usual care alone. Renal function and adverse renal events were compared between the CPAP (n = 102) and usual care (n = 98) groups. Glomerular filtration rate was estimated at randomization and at the end of follow-up, and the urinary albumin-to-creatinine ratio was measured at study exit., Measurements and Main Results: In 200 substudy participants (mean age, 64 yr; median, 4% oxygen desaturation index; 20 events/h; mean estimated glomerular filtration rate at baseline, 82 ml/min/1.73 m 2 ), the median (interquartile range) changes in estimated glomerular filtration rate (ml/min/1.73 m 2 /yr) were -1.64 (-3.45 to -0.740) in the CPAP group and -2.30 (-4.53 to -0.71) in the usual care group (P = 0.21) after a median of 4.4 years. There were no between-group differences in end-of-study urinary albumin-to-creatinine ratio or in the occurrence of serious renal or urinary adverse events during the trial. The level of CPAP adherence did not influence the findings., Conclusions: CPAP treatment of OSA in patients with cardiovascular disease does not alter renal function or the occurrence of renal adverse events. Clinical trial registered with www.clinicaltrials.gov (NCT00738179).

We aimed to systematically review the Berlin questionnaire as a screening tool for obstructive sleep apnea. We systematically searched PubMed, Embase, and Scopus databases, reviewed articles reporting the Berlin questionnaire's diagnostic utility as measured against type-1 polysomnography, and performed meta-analyses where possible. Thirty five eligible articles showed that the Berlin questionnaire's diagnostic utility varied by study population, definition of hypopnea used, and apnea-hypopnea index threshold used. It had good sensitivity and specificity for detecting clinically relevant obstructive sleep apnea as well as any obstructive sleep apnea in the sleep clinic population. Despite limited evidence, it showed modest to high sensitivity for detecting clinically relevant obstructive sleep apnea or any obstructive sleep apnea in other clinical and general population subgroups. Its specificity was relatively low. Possible reasons for variability in reported diagnostic utility of the Berlin questionnaire are multifaceted. We conclude that the Berlin questionnaire is useful as a clinical screening test and epidemiological tool in the sleep clinic population. Despite limited evidence, it likely has potential clinical and research utility in other populations. Adopting more consistent methodological definitions and focussing more on the general population and specific clinical populations to determine its usefulness as a clinical or epidemiological screening tool are recommended., (Copyright © 2017. Published by Elsevier Ltd.)

Study Objective: Continuous Positive Airway Pressure (CPAP) is considered to be the gold standard treatment for obstructive sleep apnoea (OSA). CPAP monitoring systems allow tracking of patient CPAP adherence and treatment efficacy, by measuring residual sleep-disordered breathing, hours of CPAP use, and mask leak etc. The American Thoracic Society (ATS) published a position paper in 2013 highlighting issues of interpreting CPAP data such as a lack of consistency between CPAP manufacturers data algorithms, legal implications of CPAP data and implications for CPAP adherence. This paper extends on this work by investigating these issues in an Australasian context., Method: A review of current literature on CPAP monitoring systems, privacy and security of CPAP data for major Australasian CPAP providers, and CPAP adherence was undertaken. A legal review was also commissioned for issues related to privacy and security of CPAP data., Results: CPAP manufacturers' utilize different algorithms for respiratory event detection and clinicians need to be aware the implications for interpreting CPAP data. Australasian CPAP manufacturers have created security/privacy policies with the intent to follow relevant legislation to protect patients' CPAP data, however they do need to be constantly reviewed and updated to avoid data breaches and changes to agreements. No guarantees can be provided by the Australasian Sleep Association on CPAP manufacturers' compliance with these policies and there is the potential for some degree of liability for physicians and CPAP providers associated with CPAP data. Lastly, providing patients with feedback on their CPAP usage and OSA management appears to have positive influence CPAP adherence., Conclusions: CPAP data provides many opportunities to increase OSA patient care and to help patients self-manage this chronic condition. However, issues relating to lack of standardization of CPAP parameters, privacy, security, and legal implications will need to be managed in this changing technologic and clinical environment., (Copyright © 2017 Elsevier B.V. All rights reserved.)

With this systematic review we aimed to determine the prevalence of obstructive sleep apnea (OSA) in adults in the general population and how it varied between population sub-groups. Twenty-four studies out of 3807 found by systematically searching PubMed and Embase databases were included in this review. Substantial methodological heterogeneity in population prevalence studies has caused a wide variation in the reported prevalence, which, in general, is high. At ≥5 events/h apnea-hypopnea index (AHI), the overall population prevalence ranged from 9% to 38% and was higher in men. It increased with increasing age and, in some elderly groups, was as high as 90% in men and 78% in women. At ≥15 events/h AHI, the prevalence in the general adult population ranged from 6% to 17%, being as high as 49% in the advanced ages. OSA prevalence was also greater in obese men and women. This systematic review of the overall body of evidence confirms that advancing age, male sex, and higher body-mass index increase OSA prevalence. The need to a) consider OSA as having a continuum in the general population and b) generate consensus on methodology and diagnostic threshold to define OSA so that the prevalence of OSA can be validly compared across regions and countries, and within age-/sex-specific subgroups, is highlighted., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Study Objectives: Upper airway collapsibility is a key determinant of obstructive sleep apnea (OSA) which can influence the efficacy of certain non-continuous positive airway pressure (CPAP) treatments for OSA. However, there is no simple way to measure this variable clinically. The present study aimed to develop a clinically implementable tool to evaluate the collapsibility of a patient's upper airway., Methods: Collapsibility, as characterized by the passive pharyngeal critical closing pressure (Pcrit), was measured in 46 patients with OSA. Associations were investigated between Pcrit and data extracted from patient history and routine polysomnography, including CPAP titration., Results: Therapeutic CPAP level, demonstrated the strongest relationship to Pcrit (r2=0.51, p < .001) of all the variables investigated including apnea-hypopnea index, body mass index, sex, and age. Patients with a mildly collapsible upper airway (Pcrit ≤ -2 cmH2O) had a lower therapeutic CPAP level (6.2 ± 0.6 vs. 10.3 ± 0.4 cmH2O, p < .001) compared to patients with more severe collapsibility (Pcrit > -2 cmH2O). A therapeutic CPAP level ≤8.0 cmH2O was sensitive (89%) and specific (84%) for detecting a mildly collapsible upper airway. When applied to the independent validation data set (n = 74), this threshold maintained high specificity (91%) but reduced sensitivity (75%)., Conclusions: Our data demonstrate that a patient's therapeutic CPAP requirement shares a strong predictive relationship with their Pcrit and may be used to accurately differentiate OSA patients with mild airway collapsibility from those with moderate-to-severe collapsibility. Although this relationship needs to be confirmed prospectively, our findings may provide clinicians with better understanding of an individual patient's OSA phenotype, which ultimately could assist in determining which patients are most likely to respond to non-CPAP therapies., (© Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.)

The objective of this systematic review is to synthesize the evidence on prevalence, polysomnographic findings and clinical outcomes of co-morbid obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) - known as the "overlap syndrome". We systematically searched PubMed on 1 December 2015 using appropriate medical subject headings (MeSH) and text words to capture prevalence studies and comparative studies of any observational design examining the clinical outcomes in patients with co-existent COPD and OSA. We reviewed 591 articles and included 27 in the final review. In total, 21 observational studies (n = 29,341 participants) provided prevalence estimates. Overlap syndrome is not common in the general and hospital population (range: 1.0-3.6%), but is highly prevalent in patients diagnosed with either obstructive sleep apnea (range: 7.6-55.7%) or COPD (range: 2.9-65.9%). Overlap syndrome patients have been shown to have greater nocturnal oxygen desaturation (NOD) (i.e., reduced mean peripheral capillary oxygen saturation (SpO 2 ) and increased sleep time spent with SpO 2  < 90% (T90)) and worse sleep quality than patients with only OSA. It is associated with more frequent cardiovascular morbidity, poorer quality of life (QoL), more frequent COPD exacerbation and increased medical costs. This systematic review on overlap syndrome highlights the limitations and knowledge gaps of its prevalence, etiology and underlying pathophysiologic mechanisms related to increased morbidity and mortality., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Obstructive sleep apnoea (OSA) and obesity are two common conditions affecting the Australian population; obesity is the major risk factor for OSA., Objective: The objectives of this article are to review the interactions between obesity and OSA, including the increased cardiovascular risk, and highlight the importance of using OSA diagnosis as a critical time to address obesity itself and other cardiovascular risk factors., Discussion: Snoring and symptoms of OSA frequently worsen during periods of rapid weight gain. Obesity and metabolic factors (eg hypertension, hyperlipidaemia, insulin resistance) are commonly present at the time of OSA diagnosis. Severe OSA is an independent risk factor for cardiovascular disease and stroke. Continuous positive airway pressure (CPAP) treatment is safe and effective, reduces sleepiness, and improves mood and quality of life; however, the cardiovascular benefits of CPAP are uncertain. Weight loss leads to variable improvement in OSA, is most effective in milder OSA, and has a greater benefit on cardiovascular risk than CPAP.

Cheyne-Stokes respiration (CSR) foretells deleterious outcomes in patients with heart failure. Currently, the size of therapeutic intervention is not guided by the patient's underlying pathophysiology. In theory, the intervention needed to resolve CSR, as a control system instability (loop gain >1), can be predicted knowing the baseline loop gain and how much it falls with therapy.In 12 patients with heart failure, we administered an inspiratory carbon dioxide fraction of 1-3% during CSR (n=95 interventions) as a means to reduce loop gain. We estimated the loop gain on therapy (LG therapy ), using the baseline loop gain (using hyperpnoea length/cycle length) and its expected reduction (18% per 1% inspired carbon dioxide), and tested the specific hypothesis that LG therapy predicts CSR persistence (LG therapy >1) versus resolution (LG therapy <1).As predicted, when LG therapy >1.0, CSR continued during therapy in 23 out of 25 (92%) trials. A borderline loop gain zone (0.8therapy <1) yielded an unpredictable outcome, while LG therapy <0.8 consistently yielded CSR resolution (37 out of 37 trials). A threshold of LG therapy =0.9 determined outcome in 76 out of 95 (80%) trials.We establish proof-of-concept that control theory provides predictive insight into CSR resolution in heart failure. Thus, we now have a means to calculate the size of interventions needed to ameliorate CSR on a patient-by-patient basis., (Copyright ©ERS 2016.)

Currently there is no method to predict which treatments for obstructive sleep apnea will have the best outcomes in individual patients. Given that there is increasing interest in a personalized medicine approach to the treatment of a variety of disorders, this review describes the personalized approaches that are currently available for the treatment of obstructive sleep apnea as well as future directions for individualized obstructive sleep apnea treatment., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The most striking feature of obstructive respiratory events is that they are at their most severe and frequent in the supine sleeping position: indeed, more than half of all obstructive sleep apnea (OSA) patients can be classified as supine related OSA. Existing evidence points to supine related OSA being attributable to unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses. The role of arousal threshold and ventilatory control instability in the supine position has however yet to be defined. Crucially, few physiological studies have examined patients in the lateral and supine positions, so there is little information to elucidate how breathing stability is affected by sleep posture. The mechanisms of supine related OSA can be overcome by the use of continuous positive airway pressure. There are conflicting data on the utility of oral appliances, while the effectiveness of weight loss and nasal expiratory resistance remains unclear. Avoidance of the supine posture is efficacious, but long term compliance data and well powered randomized controlled trials are lacking. The treatment of supine related OSA remains largely ignored in major clinical guidelines. Supine OSA is the dominant phenotype of the OSA syndrome. This review explains why the supine position so favors upper airway collapse and presents the available data on the management of patients with supine related OSA., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Purpose: Obstructive sleep apnea (OSA) may be associated with increased energy expenditure (EE) during sleep. As actigraphy is inaccurate at estimating EE from body movement counts alone, we aimed to compare a multiple physiological sensor with polysomnography for determination of sleep and wake, and to test the hypothesis that OSA is associated with increased EE during sleep., Methods: We studied 50 adults referred for routine overnight polysomnography. In addition to polysomnography, the SenseWear Pro3 Armband(TM) (Bodymedia Inc.) was placed on the upper right arm. Epoch-by-epoch agreement rate between the measures of sleep versus wake was calculated. Linear regression analyses were performed for EE against apnea-hypopnea index (AHI), 3% oxygen desaturation index (ODI), body mass index (BMI), waist-hip ratio (WHR), gender, age, and average heart rate during sleep., Results: The epoch-by-epoch agreement rate was high (79.9 ± 1.6%) and the ability of the SenseWear to estimate sleep was very good (sensitivity, 88.7 ± 1.5%). However, it was less accurate in determining wake (specificity 49.9 ± 3.6%). Sleep EE was associated with AHI, 3% ODI, BMI, WHR, and male gender (p < 0.001 for all). Stepwise multiple linear regression however revealed that BMI, male gender, age, and average heart rate during sleep were independent predictors of EE (Model R (2) = 0.78)., Conclusions: The SenseWear armband provides a reasonable estimation of sleep but a poor estimation of wake. Furthermore, in a selected population of OSA patients, increasing OSA severity is associated with increased EE during sleep, although primarily through an association with increased BMI. However, as our data are not adjusted for fat-free mass and the SenseWear has yet to be validated for EE in OSA patients, these data should be interpreted with caution.