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Study Objectives:Apnea-hypopnea index (AHI) is the main polysomnographic measure to diagnose obstructive sleep apnea (OSA). We aimed to evaluate the effect of three standard hypopnea definitions on the prevalence of OSA and its association with cardiometabolic outcomes in the general population.Methods:We analyzed data from the HypnoLaus study (Lausanne, Switzerland), in which 2,162 participants (51% women, 57 ± 19 years) underwent in-home full polysomnography. AHI was calculated using three hypopnea definitions: AASM1999 (≥ 50% decrease in airflow or lower airflow reduction associated with oxygen desaturation ≥ 3% or an arousal), AASM2007 (≥ 30% airflow reduction associated with ≥ 4% oxygen desaturation), and AASM2012(≥ 30% airflow reduction associated with ≥ 3% oxygen desaturation or an arousal). Participants underwent clinical assessment for hypertension, diabetes, and metabolic syndrome.Results:Median AHI of AASM1999, AASM2007 and AASM2012 criteria were 10.9, 4.4, and 10.1 events/h, respectively. OSA prevalence defined as AHI ≥ 5, ≥ 15, and ≥ 30 events/h was 74.5%, 39.3%, and 16.3% using AASM1999; 46.9%, 18.8%, and 6.8% using AASM2007; and 72.2%, 36.6%, and 14.9% using AASM2012. Different AHI thresholds derived from AASM1999, AASM2007, and AASM2012 criteria, respectively, were associated with hypertension (11.5, 4.8, 10.7 events/h), diabetes (15.7, 7.1, 14.4 events/h), and metabolic syndrome (12.8, 5.5, 11.8 events/h).Conclusions:Hypopnea definition has a major effect on AHI and on OSA prevalence in the general population and, hence, important implications for public health policies. There is a twofold difference in the threshold above which an association with diabetes, hypertension, and metabolic syndrome is observed using AASM2007 compared to AASM1999 or AASM2012 criteria.Citation:Hirotsu C, Haba-Rubio J, Andries D, Tobback N, Marques-Vidal P, Vollenweider P, Waeber G, Heinzer R. Effect of three hypopnea scoring criteria on OSA prevalence and associated comorbidities in the general population. J Clin Sleep Med 2019;15(2):183–194.

This paper aims to present a unified overview of the main Very Large-Scale Integration (VLSI) implementation solutions of forward and inverse discrete sine transforms using systolic arrays. The main features of the most important solutions to implement the forward and inverse discrete sine transform (DST) using systolic arrays are presented. One of the central ideas presented in the paper is to emphasize the advantages of using regular and modular systolic array computational structures such as cyclic convolution, circular correlation, and pseudo-band correlation in the VLSI implementation of these transforms. The use of such computational structures leads to architectures well adapted to the features of VLSI technologies, with an efficient use of the hardware structures and a reduced I/O cost that helps avoiding the so-called I/O bottleneck. With the techniques presented in this review, we have developed a new VLSI implementation of the DST using systolic arrays that allow efficient hardware implementation with reduced complexity while maintaining high-speed performances. Using a new restructuring input sequence, we have been able to efficiently reformulate the computation of the forward DST transform into a special computational structure using eight short quasi-cycle convolutions that can be computed with low complexity and where some of the coefficients are identical. This leads to a hardware structure with high throughput. The new restructuring sequence is the use of the input samples in a natural order as opposed to previous solutions, leading to a significant reduction of the hardware complexity in the pre-processing stage due to avoiding a permutation stage to reverse the order. Moreover, the proposed VLSI architecture allows an efficient incorporation of the obfuscation technique with very low overheads.

Study Objectives Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia associated with neurodegenerative synucleinopathies. Its prevalence is largely unknown. This study determined the prevalence and characteristics of RBD in the general population using gold-standard polysomnography. Methods Full polysomnographic data from 1,997 participants (age = 59 ± 11.1 years, 53.6% women) participating in a population-based study (HypnoLaus, Lausanne, Switzerland) were collected. Sleep-related complaints and habits were investigated using various sleep measures including the Munich Parasomnia Screening (MUPS) questionnaire, which includes two questions evaluating complex motor behaviors suggestive of RBD. Full polysomnography was performed at home. For participants screening positive for RBD, muscle activity during REM sleep was quantified to diagnose RBD. Results Three hundred sixty-eight participants endorsed dream-enactment behavior on either of the two MUPS questions, and 21 fulfilled polysomnographic criteria for RBD, resulting in an estimated prevalence of 1.06% (95% CI = 0.61–1.50), with no difference between men and women. Compared with RBD− participants, RBD+ took more frequently antidepressants and antipsychotics (23.8% vs. 5.4%, p = .005; 14.3% vs. 1.5%, p = .004, respectively) and were more frequently smokers or ex-smokers (85% vs. 56.6%, p = .011). On polysomnography, RBD+ had more stage N2 sleep (52 ± 11.5% vs. 46.3 ± 10.2%, p = .024) and less REM sleep (18 ± 6.4% vs. 21.9 ± 6.2%, p = .007), lower apnea–hypopnea index in REM sleep (3.8 ± 5.2 vs. 8.9 ± 13/hour, p = .035), and lower autonomic arousal index (31 ± 14.9 vs. 42.6 ± 19.5/hour, p = .002). Conclusions In our middle-to-older age population-based sample, the prevalence of RBD was 1.06%, with no difference between men and women. RBD was associated with antidepressant and antipsychotic use and with minor differences in sleep structure.

Background and Purpose Sleep disordered breathing (SDB) is frequent in acute stroke patients and is associated with early neurologic worsening and poor outcome. Although continuous positive airway pressure (CPAP) effectively treats SDB, compliance is low. The objective of the present study was to assess the tolerance and the efficacy of a continuous high-flow-rate air administered through an open nasal cannula (transnasal insufflation, TNI), a less-intrusive method, to treat SDB in acute stroke patients. Methods Ten patients (age, 56.8 ± 10.7 years), with SDB ranging from moderate to severe (apnea–hypopnea index, AHI, >15/h of sleep) and on a standard sleep study at a mean of 4.8 ± 3.7 days after ischemic stroke (range, 1–15 days), were selected. The night after, they underwent a second sleep study while receiving TNI (18 L/min). Results TNI was well tolerated by all patients. For the entire group, TNI decreased the AHI from 40.4 ± 25.7 to 30.8 ± 25.7/h ( p  = 0.001) and the oxygen desaturation index >3% from 40.7 ± 28.4 to 31 ± 22.5/h ( p  = 0.02). All participants except one showed a decrease in AHI. The percentage of slow-wave sleep significantly increased with TNI from 16.7 ± 8.2% to 22.3 ± 7.4% ( p  = 0.01). There was also a trend toward a reduction in markers of sleep disruption (number of awakenings, arousal index). Conclusions TNI improves SDB indices, and possibly sleep parameters, in stroke patients. Although these changes are modest, our findings suggest that TNI is a viable treatment alternative to CPAP in patients with SDB in the acute phase of ischemic stroke.

RationaleLimited-channel portable monitors (PMs) are increasingly used as an alternative to polysomnography (PSG) for the diagnosis of obstructive sleep apnoea (OSA). However, recommendations for the scoring of PM recordings are still lacking. Pulse-wave amplitude (PWA) drops, considered as surrogates for EEG arousals, may increase the detection sensitivity for respiratory events in PM recordings.ObjectivesTo investigate the performance of four different hypopnoea scoring criteria, using 3% or 4% oxygen desaturation levels, including or not PWA drops as surrogates for EEG arousals, and to determine the impact of measured versus reported sleep time on OSA diagnosis.MethodsSubjects drawn from a population-based cohort underwent a complete home PSG. The PSG recordings were scored using the 2012 American Academy of Sleep Medicine criteria to determine the apnoea–hypopnoea index (AHI). Recordings were then rescored using only parameters available on type 3 PM devices according to different hypopnoea criteria and patients-reported sleep duration to determine the ‘portable monitor AHIs’ (PM-AHIs).Main results312 subjects were included. Overall, PM-AHIs showed a good concordance with the PSG-based AHI although it tended to slightly underestimate it. The PM-AHI using 3% desaturation without PWA drops showed the best diagnostic accuracy for AHI thresholds of ≥5/h and ≥15/h (correctly classifying 94.55% and 93.27% of subjects, respectively, vs 80.13% and 87.50% with PWA drops). There was a significant but modest correlation between PWA drops and EEG arousals (r=0.20, p=0.0004).ConclusionInterpretation of PM recordings using hypopnoea criteria which include 3% desaturation without PWA drops as EEG arousal surrogate showed the best diagnosis accuracy compared with full PSG.

Introduction Current home sleep test (HST) devices are limited by an absence of EEG, or by being too cumbersome to use. We developed a wireless PSG system (Onera Health, NL) consisting of four disposable patches to record EEG, EOG, EMG, SaO2, ECG, bioimpedance derived respiratory airflow and effort, airflow via nasal cannula, snoring sounds, body position, actigraphy, and leg movements. Signals are stored on reusable electronic modules attached to each patch. Methods We measured PSG hook-up time in 15 healthy laypersons (6 male, 9 female, age 18-to-70 yrs, BMI 29.7±5.2 kg/m2). We also enrolled 6 additional asymptomatic healthy volunteers (2 male, 4 female, age 27-to-33 yrs, BMI 24.3±5.7 kg/m2) with history of occasional snoring, on which we scored the apnea-hypopnea index (AHI) using data from our patch-based PSG system recorded at home. We evaluated scoring using the 2016 AASM rules for hypopneas in comparison to the 2007 AASM rules requiring a greater than 3% fall in SaO2 for obstructive hypopneas. Results Mean hook-up time for applying all four patches and electronic modules was 4:42 ± 1:20 min. Mean home sleep efficiency was 89.5 SE 1.9% with an average REM% of 20 SE 6.7%. When comparing the 2016 vs 2007 AASM rules for scoring hypopneas, the AHI increased more than threefold during NREM (9.0 SE 2.0/h vs 2.7 SE 0.8/h; p<0.03) and minimally during REM (11.7 SE 2.3/h and 7.1/h SE 1.8/h; p<0.01), implying an overall increase in the AHI from 3.7 SE 0.8/h to 9.9 SE 1.9/h; p<0.02. One subject changed AHI category from normal to mild (3.6 to 14.4/h), another from mild to moderate (12.7 to 26.3/h) using the 2016 AASM rules. Conclusion Our wireless patch-based PSG system is an easy solution for sleep studies at home or in the sleep lab, lowering the burden to conduct large scale epidemiologic sleep studies. The presence of standard EEG signals allows to determine NREM and REM statistics, respiratory and non-respiratory arousal indices, AHI and RERA’s by sleep stages. Preliminary study results show that using cortical arousal criteria for hypopneas, the AHI increase is more pronounced in NREM compared to REM sleep. Support (if any):

Study Objectives:To determine the prevalence and clinical associations of respiratory effort-related arousals (RERA) in a general population sample.Methods:A total of 2,162 participants (51.2% women, 58.5 ± 11.0 years old, body mass index [BMI] 25.6 ± 4.2 kg/m2) of a general population-based cohort (HypnoLaus, Switzerland) underwent full polysomnography at home. Each subject with a RERA index ≥ 5 events/h was compared with an age-, sex- and apnea-hypopnea index (AHI)-matched control without RERA.Results:A RERA index ≥ 5 events/h was present in 84 participants (3.8%; 95% confidence interval: 3.2–4.8%). In 17 participants (0.8%; 95% confidence interval: 0.5–1.3%), RERAs were the predominant sleep breathing disorder and only one of them complained of excessive daytime sleepiness. Compared to matched controls, subjects with a RERA index ≥ 5 events/h were similar in terms of BMI (26.5 ± 3.5 versus 26.3 ± 4.8 kg/m2, P = .73), neck circumference (38.5 ± 3.3 versus 37.6 ± 3.7 cm, P = .10) and Epworth Sleepiness Scale score (6.7 ± 3.7 versus 6.0 ± 3.7, P = .22). Also, no differences were found for hypertension (21.4% versus 27.4%, P = .47), diabetes (7.1% versus 7.1%, P = 1.00), or metabolic syndrome (31.0% versus 23.8%, P = .39).Conclusions:In a middle-aged population-based cohort, the prevalence of a RERA index ≥ 5 events/h was low (3.8%) and was not associated with negative clinical outcomes when using the currently recommended scoring criteria of the American Academy of Sleep Medicine.Citation:Ogna A, Tobback N, Andries D, Preisig M, Vollenweider P, Waeber G, Marques-Vidal P, Haba-Rubio J, Heinzer R. Prevalence and clinical significance of respiratory effort-related arousals in the general population. J Clin Sleep Med. 2018;14(8):1339–1345.

REM sleep behavior disorder (RBD) is a parasomnia associated with neurodegenerative synucleinopathies. Its prevalence is largely unknown. This study determined the prevalence and characteristics of RBD in the general population using gold-standard polysomnography. Full polysomnographic data from 1997 subjects (age=59±11.1 years, 53.6% women) participating in a population-based study (HypnoLaus, Lausanne, Switzerland) were collected. Sleep-related complaints and habits were investigated using various sleep measures including the Munich Parasomnia Screening (MUPS) questionnaire, which includes two questions evaluating complex motor behaviors suggestive of RBD. Full polysomnography was performed at home. For subjects screening positive for RBD, muscle activity during REM sleep was quantified to diagnose RBD. 368 participants endorsed dream-enactment behavior on either of the two MUPS questions, and 21 fulfilled polysomnographic criteria for RBD, resulting in an estimated prevalence of 1.06% (95% CI=0.61-1.50), with no difference between men and women. Compared to RBD- participants, RBD+ took more frequently antidepressants and antipsychotics (23.8% vs. 5.4%, p=0.005; 14.3% vs. 1.5%, p=0.004, respectively), and were more frequently smokers/ex-smokers (85% vs. 56.6%, p=0.011). On polysomnography, RBD+ had more stage N2 sleep (52±11.5% vs. 46.3±10.2%, p=0.024) and less REM sleep (18±6.4% vs. 21.9±6.2%, p=0.007), lower AHI in REM sleep (3.8±5.2 vs. 8.9±13/h, p=0.035) and lower autonomic arousal index (31±14.9 vs. 42.6±19.5/h, p=0.002). In our middle-to-older age population-based sample, the prevalence of RBD was 1.06%, with no difference between men and women. RBD was associated with antidepressant and antipsychotic use and with minor differences in sleep structure.

In this study we assess the impact of corporate governance on the risk investment behavior of firms and its implications on firms' growth rate. Using a sample of non-financial companies from 10 countries over a period leading to the recent global financial crisis, we documented that the corporate governance has a nonlinear (inverted U-shape) impact on the companies' investment risk, meaning that the investment risk is increasing up to a level of corporate governance of 0.61 (as measured by our comprehensive index), while at higher levels of corporate governance the investment risk is decreasing. For the models of sales growth and assets growth it is shown that predicted investment risk has a positive effect on firms' growth measures. Moreover, the two growth models are not moving independently and a shock to one of the growth measures (sales or assets) affects the other growth measure in the same direction. Additionally, we evaluated the effect of financial crisis on both the growth measures and the risk measure. The effect of financial crisis was captured in both measures in 2009, with higher impact on the growth of sales.

Winter windstorms are among the most significant natural hazards in Europe linked to fatalities and substantial damage. However, projections of windstorm impact in Europe under climate change are highly uncertain. This study combines climate projections from 30 general circulation models participating in Phase 6 of the Coupled Model Intercomparison Project (CMIP6) with the climate risk assessment model CLIMADA to obtain projections of windstorm-induced damage over Europe in a changing climate. We conduct an uncertainty–sensitivity analysis and find large uncertainties in the projected changes in the damage, with climate model uncertainty being the dominant factor of uncertainty in the projections. We investigate the spatial patterns of the climate change-induced modifications in windstorm damage and find an increase in the damage in northwestern and northern central Europe and a decrease over the rest of Europe, in agreement with an eastward extension of the North Atlantic storm track into Europe. We combine all 30 available climate models in an ensemble-of-opportunity approach and find evidence for an intensification of future climate windstorm damage, in which damage with return periods of 100 years under current climate conditions becomes damage with return periods of 28 years under future SSP585 climate scenarios. Our findings demonstrate the importance of climate model uncertainty for the CMIP6 projections of windstorms in Europe and emphasize the increasing need for risk mitigation due to extreme weather in the future.