Validation of a portable recording device (ApneaLink) for identifying patients with suspected obstructive sleep apnoea syndrome

Background: Polysomnography (PSG) is currently the standard diagnostic procedure for sleep apnoea. This study evaluates the diagnostic accuracy of a portable recording device, ApneaLink (AL; ResMed, Poway, CA, USA) for detection of sleep apnoea in comparisons against PSG.
Methods: The AL device is a three-channel screening tool that measures airflow through a nasal pressure transducer, oximetry and pulse, providing an apnoea–hypopnoea index (AHI) based on recording time. Nocturnal PSG (Alice 4; Healthdyne, Atlanta, GA, USA), with airflow measured by a nasal pressure transducer (ProTech PTAF2; ProTech, Woodinville, WA, USA) and AL recordings were carried out simultaneously in consecutive patients with suspected obstructive sleep apnoea syndrome (OSAS). The PSG recordings were analysed manually by a blinded investigator. The oxygen desaturation index of AL was also compared against the AHI based on PSG.
Results: Fifty consecutive subjects with symptoms of OSAS were recruited with mean age of 50 years and body mass index of 27.9 kg/m². The AHI obtained by the AL device correlated closely to that obtained by PSG (Pearson correlation, r = 0.978, P < 0.001), whereas the correlation between PSG AHI and oxygen desaturation index by AL was also strong ( r = 0.895, P < 0.001). Comparison of AHI based on the AL against the PSG demonstrated high sensitivity and specificity at AHI ≥10/h (sensitivity 0.977 and specificity 1.0) and at AHI ≥20/h (sensitivity 0.969 and specificity 1.0).
Conclusion: The AL portable monitoring device is highly sensitive and specific in quantifying the apnoea–hypopnoea index when compared against hospital based polysomnography in patients with suspected OSAS. The simple device may be useful for screening and diagnostic purpose when access to PSG is limited.     

Validation of Embletta portable diagnostic system for identifying patients with suspected obstructive sleep apnoea syndrome (OSAS)

Background and objectives: This study aimed to evaluate the diagnostic accuracy of Embletta portable diagnostic system (PDS, Medcare, Reykjavik, Iceland) for the screening of sleep apnoea in clinical practice. Methods: The Embletta PDS is a digital three‐channel recording device that measures airflow through a nasal cannula connected to a pressure transducer, oxygen saturation plus both respiratory and abdominal movements via built‐in effort and body position sensors. An AHI is determined based on recording time. Nocturnal polysomnography (Alice 4, Healthdyne, Atlanta, USA), with airflow measured by a nasal pressure transducer (PTAF2, Pro‐Tech, Woodinville, WA, USA)) and Embletta PDS recordings, was performed simultaneously in consecutive patients with suspected OSA syndrome. The PSG recordings were analysed manually by a blinded investigator. Results: Ninety subjects were recruited and 10 failed Embletta PDS studies due to measurement failure. Among the remaining 80 subjects, 63 were males. The mean age (SD) was 51.4 (11.9) years old, BMI 27.1(4.2) kg/m², neck circumference 38.6 (3.6) cm and Epworth Sleepiness Score 9.7 (5.3). The AHI obtained by the Embletta PDS correlated closely with that obtained by PSG (Pearson correlation, r = 0.979, P < 0.001). Comparison of AHI based on the Embletta PDS against the PSG demonstrated high sensitivity at AHI ≥ 5/h (sensitivity 0.924 and specificity 0.857) and high specificity at AHI ≥ 20/h (sensitivity 0.853 and specificity 0.957). Conclusions: The Embletta PDS is a highly sensitive and specific screening device in quantifying AHI when compared against PSG in patients with suspected OSA syndrome.     

Comparison of empirical continuous positive airway pressure (CPAP) treatment versus initial portable sleep monitoring followed by CPAP treatment for patients with suspected obstructive sleep apnoea

Background: Polysomnography is labour‐intensive for diagnosing obstructive sleep apnoea (OSA). We compared two algorithms for initiating continuous positive airway pressure (CPAP) treatment for patients with suspected OSA. Methods: Symptomatic OSA patients were randomised into either algorithm I or II. Algorithm I consisted of an empirical CPAP trial whereas algorithm II utilised an Apnea Risk Evaluation System, a wireless device applied on the forehead, for establishing a diagnosis before a CPAP trial for 3 weeks. Primary outcome was success of CPAP trial, defined as CPAP usage > 4 h/night and willingness to continue CPAP. Subjective usefulness of CPAP, accuracy of Apnea Risk Evaluation System versus polysomnography and CPAP adherence at 6 months were secondary end‐points. Results: Altogether 138 patients in algorithm I and 110 patients in algorithm II completed the CPAP trial. There were no significant differences between these algorithms with respect to the primary end‐point. The sensitivity and specificity of algorithm I versus II as a diagnostic test for OSA were 0.3, 0.8 versus 0.31, 1.00 respectively. In predicting CPAP adherence at 6 months, the likelihood ratio positive for algorithms I and II was 2.7 and 5.27 respectively. The mean (SE) time taken from the first consultation to the end of CPAP trial in algorithm I and algorithm II was 60 (2) and 98 (5) days, respectively, P < 0.01. Conclusion: An ambulatory approach with portable sleep monitoring for diagnosing OSA before a CPAP trial can identify more patients who would adhere to CPAP at 6 months than empirical CPAP treatment alone.     

Neurocognitive impairment in Chinese patients with obstructive sleep apnoea hypopnoea syndrome

Background and objective: Sleep‐disordered breathing is known to be associated with impairment in cognitive function. The aim of this study was to characterize neurocognitive impairment in a cohort of Chinese patients with varying severities of obstructive sleep apnoea hypopnoea syndrome (OSAHS), and to develop a sensitive instrument for routine screening of cognitive impairment. Methods: Eligible patients (n = 394) were categorized into a primary snoring group, and mild, moderate and severe OSAHS groups, based on assessment of AHI. The Montreal Cognitive Assessment (MoCA) and the Mini‐Mental State Examination (MMSE) questionnaires were administered to assess cognitive function, and the correlations between questionnaire scores and clinical and polysomnographic parameters were further evaluated by stepwise multivariate regression. Results: MoCA scores decreased progressively across the spectrum from primary snoring to severe OSAHS. Importantly, mild neurocognitive impairment as defined by a MoCA score <26 was more common in the moderate (38.6%) and severe (41.4%) OSAHS groups than in the mild OSAHS (25.0%) and primary snoring (15.2%) groups. In contrast, MMSE scores were largely normal and comparable among all four groups. Evaluation of MoCA subdomains further revealed selective reduction in memory/delayed recall, visuospatial and executive function, and attention span in the severe OSAHS group compared with the other groups. Stepwise multivariate regression analysis demonstrated that MoCA scores correlated significantly with lowest oxygen saturation (L‐SaO₂) and years of education. Conclusions: Neurocognitive impairment is common in patients with OSAHS. The MoCA is a brief and sensitive tool for the assessment of cognitive impairment in OSAHS patients, whose performance on the MMSE is in the normal range.     

New acoustic method for detecting upper airway obstruction in patients with sleep apnoea

Background and objective: OSA is a common disorder resulting in health and economic burdens. Currently identifying OSA in patients involves expensive techniques that require overnight studies in a laboratory setting with qualified staff. This paper tests a new acoustic device (AirwayClear (AC)) for assessing upper airway patency in human subjects with OSA. We hypothesize that obstructive apnoeas would be detected equally well with AC and polysomnography (PSG). Methods: Twenty‐three patients with severe OSA underwent an overnight CPAP titration study. We introduced pseudorandom noise (600–1200 Hz) using AC to the patient's nasal mask during 1 h of subtherapeutic CPAP. AC determined a measure of airway patency based on the level of pseudorandom noise reaching a sternal notch sensor. The ability of AC to detect obstructive respiratory events was compared with standard PSG. Results: Three hundred and twenty‐two obstructive events (obstructive and mixed apnoeas) were identified by PSG. AC scored 80% as complete obstructions and 16% as partial obstructions. Conversely, AC detected 281 complete obstructions. PSG recognized 84% as apnoeas and scored 11% as hypopnoeas. Of the 204 hypopnoeas identified with PSG, AC indicated the airway was partially or completely obstructed in 69% of patients. A Bland–Altman analysis for the apnoeas from the two measures showed a mean difference of 2.3 events/h and 95% confidence intervals of ±15.5 events/h. Conclusions: We conclude that AC is able to track airway patency and to identify airway closure in patients with OSA.     

Craniofacial abnormalities in Japanese patients with severe obstructive sleep apnoea syndrome

Objective: To clarify that factors besides obesity play an important role in the development of obstructive sleep apnoea syndrome (OSAS) in Japanese patients, we compared craniofacial structures in patients with severe OSAS with those of normal controls.
Methodology: The craniofacial structures of 60 Japanese patients with severe OSAS and 30 normal controls were evaluated using standard cephalometric analysis. Patients were stratified according to body mass index (BMI): non-obese, BMI < 25; moderately obese, BMI = 25–30, severely obese, BMI > 30.
Results: The SNA (sella to nasion to subspinale angle) was significantly smaller in the patient groups than in the controls. The SNB (sella to nasion to supramentale angle) and NSBa (cranial base flexure) were significantly smaller in the non-obese and moderately obese patients than in controls. The MP-H (distance from the mandibular plane to the hyoid bone) and the PNS-P (distance from the posterior nasal spine to the tip of the soft palate) were significantly longer in the patient groups than in the controls. The PNS-P was significantly longer in the severely obese patients than in the non-obese patients.
Conclusions: Japanese patients with severe OSAS have enlargement of the soft tissues and palate as well as craniofacial bony structural abnormalities. This is particularly apparent in non-obese patients.     

Obstructive sleep apnoea is independently associated with an increased prevalence of metabolic syndrome.

AIMS: Obstructive sleep apnoea (OSA) is associated with increased cardiovascular morbidity and mortality. Although it was previously assumed that this was due to its relation with obesity, recent data suggest that OSA is independently associated with the cardiovascular risk factors that comprise metabolic syndrome, including hypertension, insulin resistance, impaired glucose tolerance, and dyslipidaemia. However, as previous studies have only considered these variables individually, it has not been possible to determine the overall association of OSA with this syndrome. METHODS AND RESULTS: We recruited 61 male subjects with OSA and 43 controls. Glucose, insulin, lipids, and blood pressure (BP) were measured following an overnight fast. Insulin resistance was estimated using homeostasis model assessment (HOMA). Metabolic syndrome was diagnosed according to National Cholesterol Education Program (NCEP) criteria. Subjects with OSA were more obese, had higher BP and fasting insulin, were more insulin resistant, had lower HDL cholesterol, and an increased incidence of metabolic syndrome (87% vs. 35%, p<0.0001). In order to determine whether these associations were independent of obesity and other known covariates, a regression analysis adjusted for age, BMI, smoking, and alcohol consumption was performed. This demonstrated that OSA was independently associated with increased systolic and diastolic blood pressure, higher fasting insulin and triglyceride concentrations, decreased HDL cholesterol, increased cholesterol:HDL ratio, and a trend towards higher HOMA values. Metabolic syndrome was 9.1 (95% confidence interval 2.6, 31.2: p<0.0001) times more likely to be present in subjects with OSA. CONCLUSIONS: OSA is independently associated with an increase in the cardiovascular risk factors that comprise the metabolic syndrome and its overall prevalence. This may help explain the increased cardiovascular morbidity and mortality associated with this condition.     

Predicting optimal continuous positive airway pressure in Japanese patients with obstructive sleep apnoea syndrome

Background and objective: Several algorithms that predict the optimal CPAP have been developed for Caucasian patients with OSA syndrome, but these algorithms do not allow for racial differences in craniofacial anatomy. We investigated whether an equation that included data on craniofacial structure, physique and severity of OSA could more accurately predict the optimal CPAP for Japanese patients with OSA syndrome. Methods: In 170 Japanese patients with OSA syndrome, the optimal CPAP was determined by manual titration during polysomnography. An equation predicting the optimal pressure was derived from anthropometric, polysomnographic and cephalometric data. This equation was validated in another 110 Japanese patients with OSA syndrome. Results: Stepwise multiple regression analysis identified AHI, BMI, mean SaO₂ and a cephalometric parameter: the angle between a line from point B to the menton (Me) and a line from Me to the hyoid bone (H) (BMeH), as independent predictors of optimal CPAP. The following equation was constructed to predict the optimal CPAP: 27.78 + (0.041 × BMeH) + (0.141 × BMI) + (0.040 × AHI) ? (0.312 × mean SaO₂). This equation accounted for 47% of the variance in optimal pressure (R² = 0.47, P < 0.0001). The measured optimal pressure and the pressure calculated using this equation were very similar in the other 110 patients with OSA syndrome (9.5 ± 3.0 and 9.2 ± 2.1 cmH₂O, respectively). Conclusion: Optimal CPAP was more accurately predicted by combining a cephalometric parameter with BMI and polysomnographic data in Japanese patients with OSA, suggesting that craniofacial structure may be important in the pathogenesis of OSA syndrome among Asians.     

Diagnostic accuracy of a questionnaire and simple home monitoring device in detecting obstructive sleep apnoea in a Chinese population at high cardiovascular risk

Background and objective: OSA is a common condition associated with cardiovascular (CV) morbidity. It remains underdiagnosed globally in part due to the limited availability and technical requirements of polysomnography (PSG). The aim of this study was to test the accuracy of two simple methods for diagnosing OSA. Methods: Consecutive subjects identified from a community register with high CV risk were invited to complete the Berlin Sleep Questionnaire and undergo simultaneous, home, overnight PSG and ApneaLink device oximetry and nasal pressure recordings. The relative accuracies of the Berlin Questionnaire, oximetry and nasal pressure results in diagnosing PSG‐defined moderate‐severe OSA were assessed. Results: Of 257 eligible high CV risk subjects enrolled, 190 completed sleep studies and 143 subjects' studies were of sufficient quality to include in final analyses. Moderate‐severe OSA was confirmed in 43% of subjects. The Berlin Questionnaire had low overall diagnostic accuracy in this population. However, ApneaLink recordings of oximetry and nasal pressure areas had high diagnostic utility with areas under the receiver operating characteristic curves of 0.933 and 0.933, respectively. At optimal diagnostic thresholds, oximetry and nasal pressure measurements had similar sensitivity (84% vs 86%) and specificity (84% vs 85%). Technical failure was lower for oximetry than nasal pressure (5.8% vs 18.9% of tests). Conclusions: In patients with high CV risk overnight single‐channel oximetry and nasal pressure measurements may provide high diagnostic accuracy and offer an accessible alternative to full PSG.     

Ambulatory models of care for obstructive sleep apnoea: Diagnosis and management

The high prevalence of obstructive sleep apnoea (OSA) and increasing awareness of its potential health consequences has placed significant pressure on laboratory‐based sleep services leading to growing waiting lists and delays in diagnosis and treatment. Consequently, there has been increasing interest in the use of simplified, ambulatory models of care involving clinical prediction tools, portable sleep monitoring and home autotitrating continuous positive airway pressure. Researchers are also exploring the potential role for a wider range of health‐care providers, including trained nurses and general practitioners, in the primary management of OSA. Recent randomized, controlled studies evaluating the clinical effectiveness of ambulatory management strategies versus traditional laboratory‐based care for patients with OSA have consistently demonstrated that comparable patient outcomes can be achieved. The cost‐effectiveness of these strategies is currently being debated, and further research examining the long‐term economic implications of ambulatory models of care is needed.     

老年阻塞性睡眠呼吸暂停综合征睡眠障碍特点与认知损害相关性分析

目的 分析老年阻塞性睡眠呼吸暂停综合征(obstructive sleep apnea syndrome,OSAS)的睡眠障碍特点与认知损害相关性. 方法 受检老年人36例,分为OSAS组(18例),对照组(18例),均进行多导睡眠图(polysomnography,PSG)家庭睡眠监测、匹兹堡睡眠质量指数(Pittsburgh sleep quality index,PSQI)、爱泼沃斯思睡量表(Epworth sleepiness scale,ESS)测试,检测简易智力状态(mini-mental state examination,MMSE)、记忆商(MQ)并进行画钟测验、词表学习、符号数字测验等认知功能评估. 结果 (1)OSAS组Delta睡眠比例减少、最低和平均血氧饱和度明显减少、呼吸暂停及低通气指数(apnea and hypopnea index,AHI)及氧减指数明显增加(P＜0.05).(2)OSAS组MMSE、MQ、符号数字测验、画钟测验成绩较差(P＜0.05).(3)OSAS组MMSE评分与年龄呈负相关(r=-0.533,P＜0.05),与平均血氧水平呈正相关(r=0.409,P＜0.05).MQ与MMSE、入睡潜伏期、氧减指数相关(r分别为0.726,0.495,0.645,P均＜0.05). 结论 老年OSAS以深睡眠减少、血氧饱和度降低等为其睡眠障碍特点,可能是引起记忆、视空间、操作学习等认知功能损害的重要原因.     

A high prevalence of sleep disordered breathing in men with mild symptomatic chronic heart failure due to left ventricular systolic dysfunction

BACKGROUND: Sleep disordered breathing (SDB) is common in severe chronic heart failure (CHF) and is associated with increased morbidity and mortality. The prevalence of SDB in mild symptomatic CHF is unknown. AIM: The aim of this study was to determine the prevalence and characteristics of SDB in male patients with NYHA class II symptoms of CHF. METHODS AND RESULTS: 55 male patients with mild symptomatic CHF underwent assessment of quality of life, echocardiography, cardiopulmonary exercise, chemoreflex testing and polysomnography. 53% of the patients had SDB. 38% had central sleep apnoea (CSA) and 15% had obstructive sleep apnoea. SDB patients had steeper VE/VCO(2) slope [median (inter-quartile range) 31.1 (28-37) vs. 28.1 (27-30) respectively; p=0.04], enhanced chemoreflexes to carbon dioxide during wakefulness [mean+/-sd: 2.4+/-1.6 vs. 1.5+/-0.7 %VE Max/mmHg CO(2) respectively; p=0.03], and significantly higher levels of brain natriuretic peptide and endothelin-1 compared to patients without SDB. No differences in left ventricular ejection fraction, percent predicted peak oxygen uptake, or symptoms of SDB were observed. CONCLUSIONS: A high prevalence of SDB was found in men with mild symptomatic CHF. Patients with SDB could not be differentiated by symptoms or by routine cardiac assessment making clinical diagnosis of SDB in CHF difficult.     

无创正压通气对慢性阻塞性肺疾病合并睡眠呼吸暂停综合征的治疗效应

目的观察无创正压通气（NPPV）在慢性阻塞性肺疾病（COPD）合并睡眠呼吸暂停综合征（SAS）所致Ⅱ型呼吸衰竭中的治疗价值。方法对比分析NPPV对COPD合并SAS与单纯COPD所致Ⅱ型呼吸衰竭的治疗效应。COPD合并SAS组21例,COPD组33例。观察NPPV治疗前,治疗2 h,治疗第2 d、第3 d、第5 d和出院前的动脉血气分析变化。结果在COPD合并SAS组在应用NPPV治疗后及出院时各时间点pH值显著改善（P〈0.05）,PaCO2显著下降（P〈0.05）,PaO2显著升高（P〈0.05）。在COPD组应用NPPV治疗后各时间点和出院前PaCO2均显著下降（P〈0.05）,pH值显著改善（P〈0.05）;PaO2在应用NPPV治疗第2 d、第3 d、第5 d和出院前显著升高（P〈0.05）。结论 NPPV对COPD合并SAS和COPD所致的Ⅱ型呼吸衰竭均有较好的治疗效果。     

急性脑梗死合并睡眠呼吸暂停低通气综合征的初步筛查

目的初步探讨急性脑梗死患者睡眠呼吸暂停低通气综合征（SAHS）的患病情况。方法对2008年1月至2008年12月我科收治的急性脑梗死患者200例进行初步筛查,对配合的40例经知情同意后进行多导睡眠呼吸监测（PSG）检查,并随机抽取40例同期收治的EWW嗜睡自评不符合SAHS的急性脑梗死患者做对照,比较患者年龄、体重指数（BMI）、睡眠打鼾史、高血压史、糖尿病史、吸烟史、AHI、最低动脉血氧饱和度（SaO2）及梗死部位与症状。结果急性脑梗死合并SAHS者占急性脑梗死患者的20%,其中以阻塞型及混合型睡眠呼吸暂停居多;45～60岁组患病率最高,占60%;AHI〉20者占70%,病变累及脑干或出现吞咽困难、饮水呛咳等球麻痹症状者SASH较严重。结论急性脑梗死出现球麻痹者常合并较严重的阻塞型睡眠呼吸暂停,睡眠呼吸暂停是脑梗死的独立危险因素,BMI及上气道周围组织功能异常是引起阻塞型睡眠呼吸暂停的重要因素。     

老年阻塞性睡眠呼吸暂停综合征患者睡眠监测及临床特点分析

目的分析老年阻塞性睡眠呼吸暂停综合征（obstructive sleep apnea syndrome OSAS）患者的多导睡眠监测特点。方法比较中青年组72例、老年组42例的多导睡眠监测（polysomnography，PSG）资料及临床资料。结果老年组呼吸暂停低通气指数（apnea hypopnea index，AHI）、微觉醒指数（arousal index，ArI）与中青年组相比均较低，最低血氧饱和度（SaO2）与中青年相比却较高，睡眠结构两组类似，差异无显著性，P〉0．05；老年OSAS中打鼾、夜间憋醒、觉醒时头痛、白天困倦等症状与中青年患者比较较轻，但各系统并发症较多，差异有显著性。结论老年组OSAS患者呼吸紊乱及缺氧程度较轻，临床症状较轻但睡眠结构紊乱的程度与中青年组基本接近。     

Clinical characteristics of Japanese patients with familial obstructive sleep apnoea syndrome

Background and objective: Craniofacial structure and body fat are key factors that predispose to upper airway obstruction while asleep, and these phenotypes can be genetically inherited. Neither the clinical characteristics of familial obstructive sleep apnoea syndrome (OSAS) nor the definitive morphological factors responsible for familial occurrence have been well identified. This study compared the clinical and cephalographic characteristics of Japanese patients with familial OSAS, non‐familial OSAS and healthy controls, to clarify the mechanisms underlying familial OSAS. Methods: The study recruited 28 patients with familial OSAS, comprising 14 index cases and 14 first‐degree relatives affected with OSAS, and compared these with age‐ and sex‐matched patients with non‐familial OSAS (n = 32) and healthy subjects (n = 33). Data on clinical status were collected, including the presence of hypertension, BMI and daytime sleepiness measured on the Epworth sleepiness scale. Respiratory function was evaluated by the AHI, % periods in which SpO₂ fell 90% or below and lowest value of SpO₂ on polysomnograms. Information on the first witnessed age of habitual snoring during sleep was collected via interview with patients and/or their family members. A detailed cephalometric assessment was made of each study subject. Results: Patients with familial OSAS had lower mean BMI than did patients with non‐familial OSAS. The first witnessed age of habitual snoring was younger in the familial cases than the non‐familial cases. Cephalometric variables showed that the posterior airway space and the distance between the gonion and the gnathion were significantly smaller in the familial group than in the other two groups. Conclusions: Familial OSAS occurred at a younger age than non‐familial OSAS due to minor anomalies of craniofacial morphology.