PERFORMANCE OF SIX SCREENING SCORES FOR OBSTRUCTIVE SLEEP APNOEA IN AN AFRICAN POPULATION.

Introduction: A screening tool for obstructive sleep apnoea (OSA) is useful in low-income countries where it may be difficult to access sleep recordings. The objective of this study was to assess the performance of six screening scores compared with objective sleep recording in an African population sample. Methods: This analysis is based on the "Benin Sleep and Society" (BeSAS) populational study in which respiratory polygraphy (PG) was performed using a type III device and OSA screening questionnaires (STOP, STOP-Bang, Berlin, NOSAS [≥ 8 and ≥ 5), No-Apnea, GOAL) were administered to participants. PG-defined OSA severity categories were defined according to the apnoea-hypopnoea index (AHI): mild (AHI 5 to <15/h), moderate (AHI 15 to <30/h) or severe (AHI≥30/h), and these were compared to score findings. Results: A total of 1810 subjects (mean age 45.4±14.6 years; 57.3% women) were included. For moderate to severe OSA, the area under the receiving operating characteristic (ROC) curve was greatest for GOAL and No-Apnea (0.70), followed by NoSAS5 (0.69). The highest sensitivity values were for NoSAS5 (0.73), No-Apnea (0.72), and GOAL (0.69), while NoSAS8 had the highest specificity (0.91), followed by Berlin (0.88) and GOAL (0.71). All scores performed poorly with respect to the positive predictive value (PPV), which was highest with NoSAS8 (0.38). Conclusion: This study provides the first comparison of the performance of screening scores for OSA in an African population. Although still low, PPV was highest with NoSAS8. Hence, NoSAS8 would be the screening method of choice for OSA in resource-constrained settings where formal sleep recordings are not accessible.

EVALUATION OF A MODIFIED EPWORTH SLEEPINESS SCALE TO RELIABLY ASSESS EXCESSIVE DAYTIME SLEEPINESS IN LOW-INCOME COUNTRIES: RESULTS FROM THE BENIN SOCIETY AND SLEEP (BESAS) STUDY.

Background: The Epworth Sleepiness Scale (ESS) is a tool widely used to assess excessive daytime sleepiness. Unfortunately, it is not reliable in low-income countries where situations such as reading a book, watching TV or driving a car are not common. The aim of this study was thus to assess the performance of a modified version of the Epworth scale in a low-income country. Methods: We used data from the Benin Society and Sleep (BeSAS) study where the ESS and a modified ESS (mESS) were administered to participants. In the mESS, questions four questions over eight were redesigned to reflect common living situations in Benin. The internal coherence of the mESS was assessed using the Cronbach alpha coefficient (CAC). The discriminatory ability of the scale was assessed by comparing the mean scores according to reported sleep quality, insomnia complaints and apnea-hypopnea index (AHI). Results: A total of 2909 participants were recruited, 1129 were male (38.9%) with a mean age (SD) of 44.7 (14.5) y. Overall, 52.4% (1526) completed all the mESS questions while 453 (15.6%) completed the standard ESS. The CAC of the mES was 0.86 showing good internal coherence. Concerning the discriminatory ability, mean scores for mESS were 7.8 for participants with ISI < 8 vs 9.2 for participants with ISI≥8 (p<0.001), 7.8 for participants withPSQI<5 vs 8.3 for participants with PSQI≥5 (p=0.03). No difference was found when comparing the participants participants using different cut-offs of AHI (15 and 30). Conclusion: The mES is more reliable than ES in the Beninese population. mESS shows good internal coherence and differentiates between insomniacs vs non-insomniacs and between good and poor sleepers. Although the mES is not a perfect score, it appears more relevant in the Benin population than the original Epworth scale but needs further validation/improvement in other low-income countries.

Obstructive sleep apnea, circulating microRNAs, and risk of cardiovascular disease.

OBJECTIVE: while obstructive sleep apnea is strongly associated with incident cardiovascular diseases (CVD), the underlying mechanisms remain to be elucidated. This study aimed to compare the patterns of microRNAs expression between OSA and control patients with and without incident CVD. METHODS: 218 matched adult participants with and without OSA and with and without incident CVD were selected from two independent community-based prospective cohorts in France and Switzerland, and 168 microRNAs on average were detected per sample. OSA was diagnosed using the validated Berlin questionnaire in one study (Paris Prospective Study 3) and during a full-night polysomnography in the second study (HypnoLaus Study). RESULTS: there were 78 OSA patients (39 with and 39 without CVD) and 140 controls (70 with and 70 without CVD). Participants were male in 54.6% (n = 119) and mean age was 58.7 years (±9.2). Of the 183 miRNAs screened, a mean 168 assays were detected per sample, and 129 in all samples. There was no pattern of blood microRNAs expression that discriminated OSA patients with and without CVD events. CONCLUSIONS: this binational study failed to find any association between a large panel of microRNAs and OSA patients with and without incident CVD.

SAS CARE 1: Sleep architecture changes in a cohort of patients with Ischemic Stroke/TIA.

OBJECTIVE: Changes in sleep architecture following ischemic stroke have been poorly investigated. Our objective was to explore changes of sleep structure in patients with ischemic stroke or transient ischemic attack in order to verify a possible predictive value of sleep with respect to clinical outcome. METHODS: Patients recruited in the prospective SAS-CARE study received two polysomnographies (PSG) in the acute and chronic phases after stroke/TIA. Sleep parameters were compared between the two time-points and matched with a non-stroke population randomly selected from the HypnoLaus cohort. RESULTS: Of the 169 patients investigated with PSG in the acute phase, 104 were again studied 3 months after stroke symptom onset and compared with 162 controls. The acute phase of stroke/TIA was associated with sleep disruption, which significantly improved in the chronic phase, but remained worse than controls (total sleep time improve from 318.8 ± 90.8 to 348.4 ± 81.5 min, compared to 388.2 ± 71.3 in controls, sleep latency from 49.9 ± 58.4 to 27.9 min, compared to 20.2 ± 22 in controls, sleep efficiency from 58.2 ± 18.1% to 27.9 ± 36.4 min, compared to 83.4 ± 10.3% in controls, wakefulness after sleep onset percentage from 36.5 ± 17.3 to 29.3 ± 15.6, compared to 13.2 ± 9.2 in controls). The percentage of REM sleep was negatively associated with stroke severity, whereas stroke topography did not correlate with sleep parameters. CONCLUSIONS: This study confirmed a severe sleep disruption in the acute phase of stroke. Although a significant improvement of sleep quality was observed during the three months after stroke, sleep architecture did not normalize. In particular, sleep efficiency and REM sleep seem to be particularly affected by stroke in the acute phase, with a relative preservation of NREM sleep. We suggest that these sleep architecture changes represent a persistent marker of brain damage due to stroke. Further studies are needed to assess the relationship with stroke topographic and outcome.

Impact of short-acting vs. standard anaesthetic agents on obstructive sleep apnoea: a randomised, controlled, triple-blind trial.

Sleep apnoea is associated with negative outcomes following general anaesthesia. Current recommendations suggest using short-acting anaesthetic agents in preference to standard agents to reduce this risk, but there is currently no evidence to support this. This randomised controlled triple-blind trial tested the hypothesis that a combination of short-acting agents (desflurane-remifentanil) would reduce the postoperative impact of general anaesthesia on sleep apnoea severity compared with standard agents (sevoflurane-fentanyl). Sixty patients undergoing hip arthroplasty under general anaesthesia were randomised to anaesthesia with desflurane-remifentanil or sevoflurane-fentanyl. Respiratory polygraphy was performed before surgery and on the first and third postoperative nights. The primary outcome was the supine apnoea-hypopnoea index on the first postoperative night. Secondary outcomes were the supine apnoea-hypopnoea index on the third postoperative night, and the oxygen desaturation index on the first and third postoperative nights. Additional outcomes included intravenous morphine equivalent consumption and pain scores on postoperative days 1, 2 and 3. Pre-operative sleep study data were similar between groups. Mean (95%CI) values for the supine apnoea-hypopnoea index on the first postoperative night were 18.9 (12.7-25.0) and 21.4 (14.2-28.7) events.h-1 , respectively, in the short-acting and standard anaesthesia groups (p = 0.64). Corresponding values on the third postoperative night were 28.1 (15.8-40.3) and 38.0 (18.3-57.6) events.h-1 (p = 0.34). Secondary sleep- and pain-related outcomes were generally similar in the two groups. In conclusion, short-acting anaesthetic agents did not reduce the impact of general anaesthesia on sleep apnoea severity compared with standard agents. These data should prompt an update of current recommendations.

Quantifying peripheral sympathetic activations during sleep by means of an automatic method for pulse wave amplitude drop detection.

Sudden drops in pulse wave amplitude (PWA) measured by finger photoplethysmography (PPG) are known to reflect peripheral vasoconstriction resulting from sympathetic activation. Previous work demonstrated that sympathetic activations during sleep typically accompany the occurrence of pathological respiratory and motor events, and their alteration may be associated with the arising of metabolic and cardiovascular diseases. Importantly, PWA-drops often occur in the absence of visually identifiable cortical micro-arousals and may thus represent a more accurate marker of sleep disruption/fragmentation. In this light, an objective and reproducible quantification and characterization of sleep-related PWA-drops may offer a valuable, non-invasive approach for the diagnostic and prognostic evaluation of patients with sleep disorders. However, the manual identification of PWA-drops represents a time-consuming practice potentially associated with high intra/inter-scorer variability. Since validated algorithms are not readily available for research and clinical purposes, here we present a novel automated approach to detect and characterize significant drops in the PWA-signal. The algorithm was tested against expert human scorers who visually inspected corresponding PPG-recordings. Results demonstrated that the algorithm reliably detects PWA-drops and is able to characterize them in terms of parameters with a potential physiological and clinical relevance, including timing, amplitude, duration and slopes. The method is completely user-independent, processes all-night PSG-data, automatically dealing with potential artefacts, sensor loss/displacements, and stage-dependent variability in PWA-time-series. Such characteristics make this method a valuable candidate for the comparative investigation of large clinical datasets, to gain a better insight into the reciprocal links between sympathetic activity, sleep-related alterations, and metabolic and cardiovascular diseases.

Prevalence of sleep-disordered breathing in the general population: the HypnoLaus study.

BACKGROUND: Sleep-disordered breathing is associated with major morbidity and mortality. However, its prevalence has mainly been selectively studied in populations at risk for sleep-disordered breathing or cardiovascular diseases. Taking into account improvements in recording techniques and new criteria used to define respiratory events, we aimed to assess the prevalence of sleep-disordered breathing and associated clinical features in a large population-based sample. METHODS: Between Sept 1, 2009, and June 30, 2013, we did a population-based study (HypnoLaus) in Lausanne, Switzerland. We invited a cohort of 3043 consecutive participants of the CoLaus/PsyCoLaus study to take part. Polysomnography data from 2121 people were included in the final analysis. 1024 (48%) participants were men, with a median age of 57 years (IQR 49-68, range 40-85) and mean body-mass index (BMI) of 25·6 kg/m(2) (SD 4·1). Participants underwent complete polysomnographic recordings at home and had extensive phenotyping for diabetes, hypertension, metabolic syndrome, and depression. The primary outcome was prevalence of sleep-disordered breathing, assessed by the apnoea-hypopnoea index. FINDINGS: The median apnoea-hypopnoea index was 6·9 events per h (IQR 2·7-14·1) in women and 14·9 per h (7·2-27·1) in men. The prevalence of moderate-to-severe sleep-disordered breathing (≥15 events per h) was 23·4% (95% CI 20·9-26·0) in women and 49·7% (46·6-52·8) in men. After multivariable adjustment, the upper quartile for the apnoea-hypopnoea index (>20·6 events per h) was associated independently with the presence of hypertension (odds ratio 1·60, 95% CI 1·14-2·26; p=0·0292 for trend across severity quartiles), diabetes (2·00, 1·05-3·99; p=0·0467), metabolic syndrome (2·80, 1·86-4·29; p<0·0001), and depression (1·92, 1·01-3·64; p=0·0292). INTERPRETATION: The high prevalence of sleep-disordered breathing recorded in our population-based sample might be attributable to the increased sensitivity of current recording techniques and scoring criteria. These results suggest that sleep-disordered breathing is highly prevalent, with important public health outcomes, and that the definition of the disorder should be revised. FUNDING: Faculty of Biology and Medicine of Lausanne, Lausanne University Hospital, Swiss National Science Foundation, Leenaards Foundation, GlaxoSmithKline, Ligue Pulmonaire Vaudoise.

Prevalence of restless legs syndrome in female blood donors 1 week after blood donation.

BACKGROUND AND OBJECTIVE: Restless legs syndrome (RLS) is a frequent condition with a prevalence of 5-15% in the general population. Clinical and genetic observations have shown that iron deficiency, highly prevalent among blood donors, can be related to RLS. The objective of this study was to assess the prevalence of RLS in female blood donors 1 week after blood donation. METHODS: One week after blood donation, 291 female blood donors, aged <50 years, self-responded to all four RLS questions defined by the 1995 International RLS study group. Blood donation rate, fatigue, aerobic capacity, menstruation, mood disorder and quality of life were also assessed along with haemoglobin and ferritin blood concentrations. RESULTS: Prevalence of RLS in female blood donors 1 week after blood donation was 6·9% (CI 95% 4·2-10·4%). Female blood donors with RLS had a higher prevalence of hyper-menorrhaea (P = 0·033) and were significantly more tired (P = 0·001). We observed no associations between RLS and number of previous donations (P = 0·409), aerobic capacity (P = 0·476), mood disorder (P = 0·169), quality of life (P = 0·356), haemoglobin (P = 0·087), and serum ferritin level (P = 0·446). CONCLUSION: Restless legs syndrome prevalence in female blood donors is not as important as described in some other studies, which could reassure blood donors. The prevalence of hypermenorrhaea and fatigue is higher in RLS blood donors. Therefore, screening for fatigue and hypermenorrhaea could be considered as these symptoms are associated with RLS in female blood donors.

[Positional obstructive sleep apnea syndrome]. / Syndrome d'apnées du sommeil positionnel.

Obstructive sleep apnea (OSA) tends to worsen on the supine posture due to the effect of gravity on tongue position. In some cases, OSA is present exclusively on the supine posture (exclusive postural OSA). These patients may benefit from positional therapy (PT), which aim is to prevent sleep in the supine posture using different types of devices. Before opting for this therapeutic option, a sleep study with PT should be perform in order to confirm its efficacy and assess the patients' tolerance. Because the efficacy of PT is inferior to continuous positive airway pressure (CPAP), the latter treatment remains the first line of therapy. Also, the discomfort of the existing devices appears to limit the long term use of PT. Further studies assessing the long term effects of PT on metabolic and neurocognitive outcomes are needed.

Effect of added dead space on sleep disordered breathing at high altitude.

OBJECTIVE: Sleep disordered breathing with central apnea or hypopnea frequently occurs at high altitude and is thought to be caused by a decrease in blood CO(2) level. The aim of this study was to assess the effects of added respiratory dead space on sleep disordered breathing. METHODS: Full polysomnographies were performed on 12 unacclimatized swiss mountaineers (11 males, 1 female, mean age 39 ± 12 y.o.) in Leh, Ladakh (3500 m). In random order, half of the night was spent with a 500 ml increase in dead space through a custom designed full face mask and the other half without it. RESULTS: Baseline data revealed two clearly distinct groups: one with severe sleep disordered breathing (n=5, AHI>30) and the other with moderate to no disordered breathing (n=7, AHI<30). DS markedly improved breathing in the first group (baseline vs DS): apnea hypopnea index (AHI) 70.3 ± 25.8 vs 29.4 ± 6.9 (p=0.013), oxygen desaturation index (ODI): 72.9 ± 24.1/h vs 42.5 ± 14.4 (p=0.031), whereas it had no significant effect in the second group or in the total population. Respiratory events were almost exclusively central apnea or hypopnea. Microarousal index, sleep efficiency, and sleep architecture remained unchanged with DS. A minor increase in mean PtcCO(2) (n=3) was observed with DS. CONCLUSION: A 500 ml increase in dead space through a fitted mask may improve nocturnal breathing in mountaineers with severe altitude-induced sleep disordered breathing.

[Sleep disorders in patients with chronic renal insufficiency]. / Troubles du sommeil chez des patients présentant une insuffisance rénale chronique.

Sleep disorders, especially insomnia, daytime sleepiness, sleep apnea syndrome and restless legs syndrome are very frequently encountered in patients with chronic renal failure whether or not they undergo renal replacement therapy. The causes of sleep disorders are multifactorial and not only linked to the renal disease itself, but also to its treatment and its associated psychosocial factors. This article discusses the prevalence and physiopathology of the most frequently encountered sleep disorders in chronic renal failure patients, and highlights the actually available therapeutic options.

[HypnoLaus sleep cohort study]. / HypnoLaus: le sommeil sous la loupe.

Normal sleep patterns and prevalence of sleep disorders in the general population are largely unknown. The aim of HypnoLaus cohort study is to record sleep and analyze sleep characteristics in a large population-based sample, which had undergone comprehensive genetic, somatic, and psychiatric investigations. Full polysomnography has already been performed in more than 1100 middle aged men and women randomly selected from Lausanne general population (goal 2000-3000 sleep recordings). Over 4000 additional subjects from the same population have filled various questionnaires on their sleep habits and complaints. These results combined with genetic, cardiovascular, metabolic, and psychiatric data provide a unique opportunity to determine the interaction between sleep, its genetic determinants and cardiovascular, psychiatric, or metabolic diseases.

[Narcolepsy with cataplexy associated with H1N1 vaccination]. / Narcolepsie avec cataplexie après vaccination anti-H1N1.

INTRODUCTION: It has been suggested that the H1N1 vaccine may be a trigger for the onset of narcolepsy-cataplexy, a rare disease whose autoimmune origin is suspected. OBSERVATIONS: We report two patients (a 9-year-old boy and an 18-year-old man) with severe narcolepsy-cataplexy, in whom the illness appeared within 3-4 weeks after H1N1 vaccination. In both cases, symptoms developed unusually abruptly and they presented with severe daytime sleepiness and multiple daily cataplexy attacks. Other similar cases have been recently reported associated with H1N1 vaccine. CONCLUSION: Although no formal link can be established, the unusual characteristics of the reported cases and the striking temporal relationship suggests that narcolepsy may be the result of an autoimmune reaction triggered by H1N1 vaccination in susceptible individuals.

Trazodone increases arousal threshold in obstructive sleep apnoea.

A low arousal threshold is believed to predispose to breathing instability during sleep. The present authors hypothesised that trazodone, a nonmyorelaxant sleep-promoting agent, would increase the effort-related arousal threshold in obstructive sleep apnoea (OSA) patients. In total, nine OSA patients, mean+/-sd age 49+/-9 yrs, apnoea/hypopnoea index 52+/-32 events.h(-1), were studied on 2 nights, one with trazodone at 100 mg and one with a placebo, in a double blind randomised fashion. While receiving continuous positive airway pressure (CPAP), repeated arousals were induced: 1) by increasing inspired CO(2) and 2) by stepwise decreases in CPAP level. Respiratory effort was measured with an oesophageal balloon. End-tidal CO(2 )tension (P(ET,CO(2))) was monitored with a nasal catheter. During trazodone nights, compared with placebo nights, the arousals occurred at a higher P(ET,CO(2)) level (mean+/-sd 7.30+/-0.57 versus 6.62+/-0.64 kPa (54.9+/-4.3 versus 49.8+/-4.8 mmHg), respectively). When arousals were triggered by increasing inspired CO(2) level, the maximal oesophageal pressure swing was greater (19.4+/-4.0 versus 13.1+/-4.9 cm H(2)O) and the oesophageal pressure nadir before the arousals was lower (-5.1+/-4.7 versus -0.38+/-4.2 cm H(2)O) with trazodone. When arousals were induced by stepwise CPAP drops, the maximal oesophageal pressure swings before the arousals did not differ. Trazodone at 100 mg increased the effort-related arousal threshold in response to hypercapnia in obstructive sleep apnoea patients and allowed them to tolerate higher CO(2) levels.

Intra-observer and overall agreement in the radiological assessment of tuberculosis.

OBJECTIVE: To assess the intra-observer and overall agreement in the interpretation of chest X-rays (CXRs) performed for detecting tuberculosis (TB) among immigrants in Switzerland. METHOD: Four hundred digitalised CXRs from the files of immigrant registration centres were selected and read twice in random order by three readers. The readers had to assess (1) if the picture was normal or abnormal; (2) if an abnormality was suggestive of TB; and (3) if the suspicion of TB needed an immediate examination (potentially smear-positive TB). The intra-observer and overall agreements were expressed as kappa with standard error. RESULTS: Due to losses for technical reasons, 377 of the 400 pictures were analysed. The intra-observer agreement was 0.39-0.90 for any abnormality, and 0.60-0.82 for TB needing an urgent examination. The overall agreements were: 0.55 (all three readers) and 0.84 (two best readers) for any abnormality, and 0.64 (all three readers) and 0.80 (two best readers) for active TB. CONCLUSIONS: The intra-observer and overall agreements for the detection of abnormalities on digitalised CXRs and for the presence of possible active TB depend on the reader's experience. It was good between experienced readers and fair between and within the inexperienced reader.

Effect of increased lung volume on sleep disordered breathing in patients with sleep apnoea.

BACKGROUND: Previous studies have shown that changes in lung volume influence upper airway size and resistance, particularly in patients with obstructive sleep apnoea (OSA), and that continuous positive airway pressure (CPAP) requirements decrease when the lung volume is increased. We sought to determine the effect of a constant lung volume increase on sleep disordered breathing during non-REM sleep. METHODS: Twelve subjects with OSA were studied during non-REM sleep in a rigid head-out shell equipped with a positive/negative pressure attachment for manipulation of extrathoracic pressure. The increase in lung volume due to CPAP (at a therapeutic level) was determined with four magnetometer coils placed on the chest wall and abdomen. CPAP was then stopped and the subjects were studied for 1 hour in three conditions (in random order): (1) no treatment (baseline); (2) at "CPAP lung volume", with the increased lung volume being reproduced by negative extrathoracic pressure alone (lung volume 1, LV1); and (3) 500 ml above the CPAP lung volume(lung volume 2, LV2). RESULTS: The mean (SE) apnoea/hypopnoea index (AHI) for baseline, LV1, and LV2, respectively, was 62.3 (10.2), 37.2 (5.0), and 31.2 (6.7) events per hour (p = 0.009); the 3% oxygen desaturation index was 43.0 (10.1), 16.1 (5.4), and 12.3 (5.3) events per hour (p = 0.002); and the mean oxygen saturation was 95.4 (0.3)%, 96.0 (0.2)%, 96.3 (0.3)%, respectively (p = 0.001). CONCLUSION: An increase in lung volume causes a substantial decrease in sleep disordered breathing in patients with OSA during non-REM sleep.

Slow-wave activity in sleep apnea patients before and after continuous positive airway pressure treatment: contribution to daytime sleepiness.

STUDY OBJECTIVES: To estimate the course of slow-wave activity (SWA), its amount during the night, and its correlation with daytime sleepiness in sleep apnea syndrome (SAS) patients. This study also verified whether continuous positive airway pressure (CPAP) treatment also restores a normal pattern of SWA in severe SAS patients. PARTICIPANTS: Ten patients with a diagnosis of severe SAS who showed a good clinical response to CPAP after approximately 9 months of treatment were included in this study. These patients were matched for sex and age with 10 control subjects. DESIGN: All subjects underwent 1 night of polysomnography (PSG), followed by the multiple sleep latency test (MSLT) the next day. For the SAS patients only, the same procedure was repeated after 9 +/- 0.7 months of CPAP treatment. In addition to traditional scoring of sleep stages, apneas, hypopneas, and microarousals, the SWA, defined as the power in the 0.75- to 4.5-Hz frequency band, was evaluated. RESULTS: A positive correlation between SWA of the first cycle and the MSLT (r = 0.56; p = 0.045) was found before treatment. Moreover, SAS patients significantly increased their mean SWA after CPAP treatment in the first (p = 0.024) and second (p = 0.002) sleep cycles and restored a more physiologic decay of SWA across the night. CONCLUSIONS: These results suggest that daytime sleepiness in SAS patients may be the result of a lack of SWA during the first part of the night, and show that CPAP restores a more physiologic pattern of SWA across the night.