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.     

Is portable monitoring for diagnosing obstructive sleep apnea syndrome suitable in elderly population?

Purpose

Obstructive sleep apnea syndrome (OSAS) is highly prevalent in the elderly. Unattended, at-home portable monitoring (PM) is a diagnostic alternative to polysomnography in adults with high clinical probability of OSAS. However, no studies have evaluated the diagnostic accuracy of PM in elderly population. The aim of our study was to evaluate the effectiveness of PM in elderly patients.

Methods

We selected patients aged over 65 years with suspected OSAS. Two-order randomized evaluations were performed: one night of at-home PM (PMhome) and one night of simultaneous PM and polysomnography (PSG) in the sleep lab (PSG+PM). We obtained three different apnea–hypopnea index (AHI): AHI from PSG (AHI PSG), AHI from at-home PM (AHI PMhome), and AHI from PM+PSG (AHI PM+PSG). Two technicians, blinded to the recording order, scored each sleep study.

Results

We studied a total of 43 patients. No difference between the AHI values for each of the different recordings was found (p?>?0.05). There was good correlation between AHI PSG and AHI PMhome (r?=?0.67) and AHI PSG+PM (r?=?0.84). The area under the receiver operator curve was above 0.83, indicating good sensitivity and a positive predictive value for AHI with cutoffs of 5, 15, and 30 and good specificity and negative predictive value for AHI values above 15. Correlation, accuracy, and agreement were greater when the recordings were made simultaneously.

Conclusions

PM was effective for diagnosing OSAS in the elderly and can be used as an alternative to PSG in elderly patients with a high clinical probability of OSAS.     

Optimal continuous positive airway pressure in patients with obstructive sleep apnoea: role of craniofacial structure

Although nasal continuous positive airway pressure (CPAP) is effective in improving nocturnal obstructive apnoea, daytime sleepiness and well-being in patients with obstructive sleep apnoea syndrome (OSAS), not all patients tolerate this treatment. Since optimal CPAP titration is essential to maintain compliance, it is important to elucidate the factors that help to determine the optimal pressure. However, the determinants of the optimal CPAP level are controversial. The subjects comprised 27 Japanese male patients with OSAS who underwent standard polysomnography (PSG), pulmonary function tests, arterial blood gas analysis, cephalometry and CPAP titration. Twenty normal controls also underwent cephalometric analysis. The apnoea-hypopnoea index (AHI), mean oxygen saturation (mean SaO2) and the lowest SaO2 during sleep were found to be 54.7+/-22.6, 89.0+/-5.6%, and 69.7+/-9.0%, respectively by PSG. The mean optimal CPAP was 9.6+/-1.8 cmH2O. The cephalometric angles (SNA, SNB and NSBa) were similar to those found in the control subjects. but MP-H, and PNS-P were significantly longer than those in the control subjects as shown by cephalometry. The optimal CPAP was correlated with the mean SaO2 (P<0.0001), neck circumference (P<0.05) and three cephalometric variables (NSBa: P<0.01, MP-H: P<0.05, PNS-P: P<0.05). Multiple, step-wise, regression analysis showed that the mean SaO2 and NSBa were independent variables that best predicted the optimal CPAP. These variables accounted for 57.5% of the total variance (R2=0.575, P<0.001). Optimal CPAP was closely correlated with oxygen desaturation during sleep. However, the craniofacial structure had additional effects such as an independent factor in determining the optimal CPAP level.     

Apnoeic–hypopnoeic episodes during obstructive sleep apnoea are associated with histological nonalcoholic steatohepatitis

Background: Nonalcoholic fatty liver disease (NAFLD) and obstructive sleep apnoea are associated with metabolic syndrome and atherosclerotic heart disease. This study evaluates the potential association between the NAFLD subtypes and a number of polysomnographical (PSG) parameters. Methods: This study included patients undergoing bariatric surgery with extensive clinical and histological data for whom complete PSG data before surgery were also available. Excess alcohol intake and other causes of liver disease were excluded. Apnoea, hypopnoea and apnoea–hypopnoea index (AHI) were calculated as described previously. Results: In this study, a total of 101 patients [77 nonalcoholic steatohepatitis (NASH) and 22 non‐NASH controls] with PSG data were included (age 42.9 ± 11.4 years, body mass index 51.6 ± 9.5 kg/m², fasting serum glucose 117.4 ± 53.4 mg/dl, fasting serum triglycerides 171.3 ± 82.9 mg/dl, 58% hypertension and 33% diabetes mellitus). Subjects with histological NASH had significantly lower lowest desaturation (77 vs. 85%, P=0.006), lower mean nocturnal oxygen saturation (91 vs. 93%, P=0.05), higher AHI (35 vs. 22, P=0.03), higher respiratory disturbance index (46 vs. 21, P=0.02) and higher alanine aminotransferase/aspartate aminotransferase ratio (1.4 vs. 1.3, P=0.05) compared with non‐NASH controls. In multivariate analysis, the lowest desaturation (P=0.04) was independently associated with histological NASH. Lowest desaturation and mean nocturnal oxygen saturation were significantly lower in subjects with fibrosis (76 vs. 85%, P=0.004 and 90.4 vs. 93.0%, P=0.02). Conclusions: Our results suggest that the frequent nocturnal hypoxic episodes in NAFLD patients may be a risk factor for developing NASH. Additional studies are needed to study the effect of optimizing sleep apnoea management on the outcomes of patients with NAFLD.     

自动持续正压系统对睡眠呼吸障碍的诊治

目的探索简便、临床易于推广应用的睡眠呼吸障碍疾患的诊治手段。方法对１１例睡眠呼吸障碍患者同步进行经典的多导睡眠图监测和自动持续正压系统监测，将监测结果进行比较；对２３例已确诊的阻塞性睡眠呼吸暂停综合征（ＯＳＡＳ）患者使用自动持续正压系统治疗，并对治疗效果进行评价。各监测指标比较采用ｔ检验。结果（１）自动持续正压系统与多导睡眠图相比较，自动持续正压系统虽无睡眠及心电记录，但可记录鼾声及上气道阻力；最高及最低血氧饱和度、最长呼吸暂停时间、呼吸暂停低通气（ＡＨＩ）指数等监测结果，两者相比，差异无显著性（Ｐ＞０．０５）；自动持续正压系统诊断ＯＳＡＳ的敏感性为７０％，特异性为１００％。（２）ＯＳＡＳ患者使用自动持续正压系统治疗后症状改善；ＡＨＩ显著减低，最低血氧饱和度显著升高（Ｐ＜０．００１）；此外，平均和最高压力与９５％可信压力比较差异有显著性。结论自动持续正压系统使用简便，并减轻了技术员监测时的劳动强度；在持续正压通气（ＣＰＡＰ）治疗时可采用９５％可信限所需的压力     

The role of nasal CPAP in obstructive sleep apnoea syndrome due to mandibular hypoplasia

Melnick Needles syndrome (MNS), Treacher Collins syndrome (TCS) and Pierre Robin syndrome (PRS) are congenital abnormalities with characteristic facial appearances that include micrognathia. A 20‐year‐old girl with MNS, a 16‐year‐old boy with TCS and a 12‐year‐old girl with PRS attended the sleep apnoea clinic at our institution at different times. Diagnostic sleep studies were initially performed on all three patients to confirm the diagnosis of obstructive sleep apnoea syndrome (OSAS). They subsequently commenced nasal CPAP (nCPAP) treatment and their progress was followed. A limited sleep study on the patient with MNS demonstrated moderate/severe OSAS with an AHI of 33 events/h. Commencement of nCPAP resulted in symptomatic improvement. Overnight oximetry in the patient with TCS showed repeated desaturation to SpO₂ <90%. Subsequent treatment by nCPAP almost completely abolished the desaturation events. Overnight polysomnography in the patient with PRS demonstrated severe OSAS with an AHI of 49 events/h. After 3 years of nCPAP therapy, this patient requested discontinuation of treatment. Subsequent polysomnography without nCPAP revealed an AHI of <5 events/h. The use of nCPAP in the patients with MNS and TCS resulted in effective control of their sleep abnormalities. Mandibular growth and enlargement of the posterior airway space led to resolution of OSAS in the patient with PRS. There is a definite role for nCPAP therapy in patients with congenital micrognathia and OSAS. The use of nCPAP may obviate the need for more invasive corrective surgery for OSAS and is not necessarily a life‐long requirement.     

阻塞性睡眠呼吸障碍患者频繁觉醒的原因探讨

目的探讨导致睡眠呼吸障碍患者睡眠中频繁发生觉醒的原因。方法对因有白天过度困倦而就诊的25例患者作全晚多导睡眠图(PSG)检查和呼吸模式分析,并与7名健康正常人对照。按国际标准人工判断觉醒。结果上气道阻力综合征(UARS)组10例,呼吸暂停／低呼吸指数(AHI)（2.5±1.4）次/h,动脉血氧饱和度(SaO2)<90%累计时间%(SLT90%)（0.1±0.1）%,觉醒指数(ArI)（30±16）次/h;阻塞性睡眠呼吸暂停综合征(OSAS)组15例,AHI（32.8±19.1）次/h,SLT90%（11.3±16.5）%,ArI（35±17）次/h;正常人组7名,AHI（5.9±4.4）次/h,SLT90%（0.2±0.4）%,ArI（13±5）次/h。OSAS和UARS组的ArI无统计学差异(H=0.49,P=0.48),均高于正常对照组的ArI(H分别为7.36和5.22,P值分别为0.001和0.02),但UARS组AHI、SLT90%明显低于OSAS组(H>5.00,P<0.05),与正常组相近(P>0.05)。结论睡眠时上气道吸气性阻力增高,是导致睡眠频繁觉醒的主要原因。     

Inter-observer agreement on apnoea hypopnoea index using portable monitoring of respiratory parameters

BACKGROUND: Although portable polygraphy or portable monitoring of respiratory parameters (PM) is commonly used to confirm obstructive sleep apnoea syndrome, agreement on apnoea hypopnoea index (AHI), the main measure of disease severity, has not been evaluated. The aim of this study was to assess the agreement on AHI among multiple observers as well as between individual observers and automated analysis. METHODS: A total of 88 ambulatory sleep recordings ("Embletta") were independently scored by 8 physicians (observers). Agreement on AHI, using intraclass correlation coefficient (ICC), was measured among observers. Bland Altman plots were built to compare individual observers with PM. RESULTS: Among observers, ICCs were .73 for agreement on AHI, .71 for hypopnoea index and .98 for desaturation index. Compared to visual analysis, automated analysis underestimated AHI by 5.1 events on average. When comparing individual observers with automated analysis, systematic bias varied from -1. to +1 .5 events/h on AHI. CONCLUSIONS: Among observers who used PM in a clinical setting, agreement on AHI was limited. When automated and individual visual analyses were compared, the systematic bias varied from almost zero to values sufficient to affect clinical diagnosis. Much of the discordance was due to different counts of hypopnoea, whereas agreement on apnoea and desaturation index was better. Efforts should be directed towards standardisation of visual analysis, improvement and quality control of ambulatory sleep studies.     

Prediction of the apnea-hypopnea index from overnight pulse oximetry

STUDY OBJECTIVE:s: To compare the relative usefulness of the different indexes derived from pulse oximetry in the diagnosis of obstructive sleep apnea (OSA), and to determine if a combination of these indexes improves the prediction of the apnea-hypopnea index (AHI) measured by polysomnography. DESIGN: Prediction model developed from 224 patients, validated prospectively in 101 patients from the same center (group 1) and in 191 patients from a different sleep center (group 2). SETTING: Two independent sleep clinics run by university sleep specialists. PARTICIPANTS: Patients who underwent polysomnography for suspicion of OSA. INTERVENTIONS: The following indexes were calculated from pulse oximetry recordings performed simultaneously during polysomnography: (1) Delta index, the average of the absolute differences of oxygen saturation between successive 12-s intervals; (2) desaturation events per hour to 2%, 3%, and 4% levels; and (3) cumulative time spent below 90%, 88%, 86%, 84%, 82%, and 80% saturation. MEASUREMENTS AND RESULTS: The best predictor was the Delta index, although desaturation events provided similar levels of diagnostic accuracy. An aggregation of multivariate models using combination of indexes reduced the prediction error (r(2) = 0.70) significantly (p < 0.05) compared to using the Delta index alone (r(2) = 0.60). The proportion of subjects from the validation groups within 95% confidence interval (CI) of the derivation group was 90% (95% CI, 83 to 95%) and 91% (95% CI, 86 to 95%) for groups 1 and 2, respectively. The overall likelihood ratios for the aggregated model in all patient groups were 4.2 (95% CI, 3.3 to 15.3), 3.4 (95% CI, 2.7 to 4.3), 3.0 (95% CI, 2.2 to 4.1), and 6.7 (95% CI, 4.9 to 9.2) for normal (AHI < 5/h), mild (AHI 5 to < 15/h), moderate (AHI 15 to < 30/h), and severe (AHI > or = 30/h) disease, respectively. CONCLUSIONS: The Delta index and oxygen desaturation indexes provided similar levels of diagnostic accuracy. The combination of indexes improved the precision of the predicted AHI and may offer a potentially simpler alternative to polysomnography.     

Metabolic syndrome in Japanese patients with obstructive sleep apnea syndrome.

We investigated the prevalence of metabolic syndrome in patients with obstructive sleep apnea syndrome (OSAS) referred to a tertiary university-based medical center. A cross-sectional study of patients with a definite diagnosis of OSAS was performed using new diagnostic criteria for metabolic syndrome that were designed for the Japanese population. Clinical features and comorbidities related to metabolic syndrome were compared between 819 patients with OSAS (719 men and 100 women) and 89 control subjects without OSAS. Metabolic syndrome was significantly more common in the patients with OSAS than in the controls (49.5% vs. 22.0% for men, p < 0.01; 32.0% vs. 6.7% for women, p < 0.01). Men with OSAS (apnea-hypopnea index [AHI] > or =5/h) had a higher risk of metabolic syndrome compared with controls (odds ratio [OR]: 3.47; 95% confidence interval [CI]: 1.84-6.53). There was a significantly increased risk of metabolic syndrome in men with moderate OSAS (AHI: 15-29.9/h) (OR: 2.83; 95% CI: 1.42-5.66) and men with severe OSAS (AHI > or =30/h) (OR: 5.09; 95% CI: 2.67-9.71). Women with OSAS (AHI> or =5/h) also had an increased risk of metabolic syndrome (OR: 6.59; 95% CI: 1.47-29.38), and the risk was significantly higher in women with severe OSAS (AHI > or =30/h) (OR 14.00; 95% CI: 2.93-66.82). Risk factors for metabolic syndrome differed by gender: in men, age, body mass index (BMI), and OSAS (AHI > or =15/h) were significantly associated with metabolic syndrome, whereas, in women, BMI was the only risk factor for metabolic syndrome. The increase of metabolic syndrome in Japanese OSAS patients suggests that this patient population is burdened with multiple risk factors for cardiovascular disease.     

The influence of patent foramen ovale on oxygen desaturation in obstructive sleep apnoea.

Obstructive sleep apnoea (OSA) is associated with oxygen desaturation to a varying degree. A patent foramen ovale (PFO) may allow interatrial right-to-left shunting. The hypothesis of the current study was that oxygen desaturation will occur more often, in proportion to the frequency of respiratory disturbances, in OSA subjects with PFO than in those without. In a group of 209 subjects diagnosed with OSA, the proportion of desaturation to respiratory events was calculated as the ratio of oxygen desaturation index (ODI)/apnoea-hypopnoea index (AHI). A total of 15 cases with high proportional desaturation (ODI/AHI >or=0.66) were individually matched with 15 controls with low proportional desaturation (ODI/AHI or=20 bubbles passed over from the right to the left atrium after a single injection. The prevalence of large PFO was nine out of 15 (60%) in the high proportional desaturation group versus two out of 15 (13%) in the low proportional desaturation group. The median number of passing bubbles was positively correlated to minimum oxygen saturation among those with PFO. In conclusion, oxygen desaturation occurs more often, in proportion to the frequency of respiratory disturbances, in obstructive sleep apnoea subjects with a patent foramen ovale than in those without.     

Influence of movement arousal on circadian rhythm of blood pressure in obstructive sleep apnea syndrome

OBJECTIVE: To investigate the hypothesis that repeated arousals at the termination of apnea/hypopnea in obstructive sleep apnea syndrome (OSAS) are related to abnormal circadian rhythm of blood pressure (BP). DESIGN AND METHODS: We performed polysomnography (PSG) with pulse oximetry in 26 middle-aged patients with OSAS aged 42-58 years (mean age 51.8 years). The intensity of arousal on PSG was graded into two levels: grade 1 (EEG arousal, EA), an abrupt shift in EEG frequency, and grade 2 (movement arousal, MA), EEG arousal with an increase in electromyogram activity lasting at least 3 s. The number of apnea/hypopneas per hour (apnea/hypopnea index, AHI), and length of time during which nocturnal oxygen saturation decreased below 90% (oxygen desaturation time, ODT) were also evaluated. Percentage EA and %MA were assessed by the ratio of the number of apneas and hypopneas with EA or MA to the number of apneas and hypopneas in total. The 24 h systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured noninvasively. Multiple regression analysis was performed among AHI, ODT, %EA and %MA or among age, body mass index and %MA. RESULTS: The %MA was the most significant factor contributing to the elevated 24 h SBP (r= 0.46, P< 0.05); oxygen desaturation (r= 0.44, P< 0.05) was the next most important contributing factor. The level and pattern of 24 h BP differed significantly between the patients with %MA 85% and %MA < 85% (mean 24 h SBP: 147 +/- 16.8 versus 125 +/- 19.6 mmHg, P< 0.01; mean 24 h DBP: 97.5 +/- 14.3 versus 85.6 +/- 14.6 mmHg, P< 0.01), and also differed between those with severe OSAS, i.e. ODT > or = 130 min, and mild to moderate OSAS, i.e. ODT < 130 min, (mean 24 h SBP: 149 +/- 15.8 versus 132 +/- 20.6 mmHg, P < 0.01; mean 24 h DBP: 100 +/- 14.1 versus 87.4 +/- 14.0 mmHg, P < 0.01). CONCLUSION: Our findings suggest that MA and oxygen desaturation in OSAS make an important contribution to abnormal circadian rhythm of BP. We conclude that repeated end-apneic arousal and/or hypoxic asphyxia and the subsequent sleep fragmentation may contibute to nocturnal and diurnal elevation of BP.     

QT interval dispersion in obstructive sleep apnoea syndrome patients without hypertension.

QT interval dispersion (QT(d)) reflects inhomogeneity of repolarisation. Delayed cardiac repolarisation leading to the prolongation of the QT interval is a well-characterised precursor of arrhythmias. Obstructive sleep apnoea syndrome (OSAS) can cause cardiovascular complications, such as arrhythmias, myocardial infarction, and systemic and pulmonary hypertension. The aim of this study was to assess QT(d) in OSAS patients without hypertension. A total of 49 subjects without hypertension, diabetes mellitus, any cardiac or pulmonary diseases, or any hormonal, hepatic, renal or electrolyte disorders were referred for evaluation of OSAS. An overnight polysomnography and a standard 12-lead ECG were performed in each subject. According to the apnoea-hypopnoea index (AHI), subjects were divided into control subjects (AHI <5, n = 20) and moderate-severe OSAS patients (AHI > or =15, n = 29). QT(d) (defined as the difference between the maximum and minimum QT interval) and QT-corrected interval dispersion (QT(cd)) were calculated using Bazzet's formula. In conclusion, the QT(cd) was significantly higher in OSAS patients (56.1+/-9.3 ms) than in controls (36.3+/-4.5 ms). A strong positive correlation was shown between QT(cd) and AHI. In addition, a significantly positive correlation was shown between QT(cd) and the desaturation index (DI). The AHI and DI were significantly related to QT(cd) as an independent variable using stepwise regression analysis. The QT-corrected interval dispersion is increased in obstructive sleep apnoea syndrome patients without hypertension, and it may reflect obstructive sleep apnoea syndrome severity.     

Obstructive sleep apnoea syndrome, plasma adiponectin levels, and insulin resistance

OBJECTIVE: To investigate whether sleep-disordered breathing and/or plasma adiponectin levels are associated with insulin resistance independent of obesity or fat distribution in obstructive sleep apnoea syndrome (OSAS). DESIGN: Cross-sectional clinical study. PATIENTS: Two-hundred and thirteen Japanese patients with OSAS aged 27-80 years were divided into three groups: 30 with mild OSAS [apnoea-hypopnoea index (AHI) = 10.3 +/- 0.9 episodes/h, minimum oxygen saturation (min SpO2) = 87.3 +/- 0.9%], 98 with moderate OSAS (AHI = 28.9 +/- 0.6 episodes/h, min SpO2 = 82.1 +/- 0.7%), and 85 with severe OSAS (AHI = 68.1 +/- 2.8 episodes/h, min SpO2 = 72.3 +/- 1.6%). Twenty-one patients undergoing diabetic treatments (two mild, nine moderate and 10 severe) were excluded from the assessment of insulin resistance and plasma adiponectin measurements. MEASUREMENTS: Fat distribution [evaluated according to visceral (V) and subcutaneous (S) fat areas using computed tomography scanning at the umbilical level], blood pressure, metabolic parameters and hormones including insulin and adiponectin were measured. After full polysomnography, venous blood was collected between 0600 and 0700 h. RESULTS: Severe OSAS patients were more hypertensive than mild and moderate OSAS. Fasting plasma glucose (FPG) and fasting plasma insulin and homeostasis model assessment of insulin resistance (HOMA-IR) levels were all higher in severe OSAS than mild and moderate OSAS patients. HOMA-IR was correlated not only with obesity [body mass index (BMI), V and S areas] but also with apnoea (AHI, min SpO2 and desaturation time). Additionally, HOMA-IR was correlated positively with haemoglobin (Hb)A1c, systolic (SBP) and diastolic blood pressure (DBP), triglycerides and free fatty acids (FFA), and negatively with high density lipoprotein (HDL)-cholesterol, suggesting that insulin resistance is a key component of the metabolic syndrome in OSAS. Plasma adiponectin levels were not different between mild, moderate and severe OSAS groups. Plasma adiponectin levels were correlated with HOMA-IR and V area, but not AHI or min SpO2. Stepwise multiple regression analysis, however, revealed that BMI, AHI and plasma adiponectin were independently associated with HOMA-IR. CONCLUSION: Sleep-disordered breathing was associated with insulin resistance independent of obesity. Although plasma adiponectin was also an independent determinant of HOMA-IR in OSAS patients, plasma adiponectin was more closely related to obesity than to sleep apnoea. Although treatment of sleep-disordered breathing with nasal continuous positive airway pressure reportedly improves insulin sensitivity, our findings suggest that treatment of obesity is also essential in ameliorating insulin resistance at least through increased plasma adiponectin levels in OSAS.     

Low Level of IGF-1 in Obesity May Be Related to Obstructive Sleep Apnea Syndrome

The aim of this study was to compare serum insulin-like growth factor (IGF-1) levels in patients with obstructive sleep apnea syndrome (OSAS) with those of nonapneic controls and to determine the risk factors of low IGF-1 levels in patients with OSAS. The study included 39 newly diagnosed moderate-to-severe OSAS patients and 36 nonapneic controls. Overnight polysomnography (PSG) was performed in all patients. The circulating levels of IGF-1 in the OSAS group were significantly lower than those of the control group (p < 0.05). There was a significant negative correlation between IGF-1 and logarithmic transformation (Ln) of the apnea-hypopnea index (AHI), duration of apnea-hypopnea, arousal index, average desaturation, and oxygen desaturation index (ODI). The result of stepwise regression analyses showed that OSAS (p = 0.001) was a risk factor for a low IGF-1 level, independent of age, gender, and body mass index (BMI). Our findings demonstrated that there was a significant negative correlation between IGF-1 and Ln AHI and that OSAS reduced the circulating levels of IGF-1.     

Validation of ApneaLink Ox™ for the diagnosis of obstructive sleep apnea

Objective

The aim of the study was to validate the automatic and manual analysis of ApneaLink Ox? (ALOX) in patients with suspected obstructive sleep apnea (OSA).

Methods

All patients with suspected OSA had a polysomnography (PSG) and an ALOX performed in the sleep laboratory. For automatic analysis, hypopnea was defined as a decrease in airflow ≥30 % of baseline for at least 10 s plus oxygen desaturation ≥3 or 4 %. While for the manual analysis, hypopnoea was considered when a reduction of airflow ≥30 % of ≥10 s plus oxygen desaturation ≥3 % or increase in cardiac rate ≥5 beats/min were identified or, when only a reduction of airflow ≥50 % was observed. OSA was defined as a respiratory disturbance index (RDI) ≥5. The apnea/hypopnea automatic index (AHI3-a, AHI4-a) and manual index were estimated. Receiver operating characteristics (ROC) analysis and the agreement between ALOX and PSG were performed.

Results

Fifty-five patients were included (38 men; mean age, 48.2; median, RDI 15.1; median BMI, 30 Kg/m²). The automatic analysis of ALOX under-estimated the RDI from PSG, mainly for the criterion of oxygen desaturation ≥4 % (AHI3-a–RDI, ?3.6?±?10.1; AHI4-a–RDI, ?6.5?±?10.9, p?<?0.05). The autoscoring from ALOX device showed a better performance when it was set up to identify hypopneas with an oxygen desaturation criterion of ≥3 % than when it was configured with an oxygen desaturation criterion of ≥4 % (area under the receiver operator curves, 0.87 vs. 0.84). Also, the manual analysis was found to be better than the autoscoring set up with an oxygen desaturation of ≥3 % (0.923 vs. 0.87). The manual analysis showed a good interobserver agreement for the classification of patients with or without OSA (k?=?0.81).

Conclusion

The AHI obtained automatically from the ApneaLink Ox? using oxygen desaturation ≥3 % as a criterion of hypopnea had a good performance to diagnose OSA. The manual scoring from ApneaLink Ox? was better than the automatic scoring to discriminate patients with OSA.     

Twenty-four-hour ambulatory oxygen desaturation and electrocardiographic recording in obstructive sleep apnea syndrome

Background: Although nocturnal pulseoximetry is routinely performed in obstructive sleep apnea syndrome (OSAS), pulseoximetry over a 24-h period has not been studied. Hypothesis: The purpose of the study was to determine whether simultaneous 24-h oxygen desaturation and electrocardiographic (ECG) recording might be used to screen for daytime sleep sequelae in patients with OSAS. Methods: Simultaneous recording of arterial oxygen saturation (SpO2) and ECG was conducted over a 24-h period in 18 male patients with OSAS (mean age 51.3 years) who were diagnosed by standard polysomnography (PSG), and in 15 agematched healthy subjects (mean age 52.7 years) as controls to evaluate circadian variation of these parameters. The measures of heart rate variability (HRV) were calculated from 24-h ambulatory ECGs. Seventeen patients with OSAS showed excessive daytime sleepiness (EDS). We calculated the duration in which SpO₂ decreased to <90% (duration of SpO₂ > 90%). The number of apnea/hypopneas per hour (AHI) during sleep was investigated with Apnomonitors (Chest MI, Co., Tokyo) on the same day as the SpO₂ recordings. Results: Controls showed no episodes of oxygen desaturation. in patients with OSAS, driving (33.3% of patients with OSAS) was the most common activity in which SpO₂ decreased to <90%, followed by daytime napping (27.8%) and resting after meals (22.2%). The duration of SpO₂ < 90% over a 24-h period correlated significantly with the duration levels recorded during sleep (r = 0.99, p < 0.05) and in the afternoon (r = 0.62, p <0.05), and with the AHI (r = 0.55, p>0.05), but not with the duration of SpO²> 90% in the morning. The number of ventricular premature beats correlated significantly with the duration of SpO²>90% for a 24-h period, but not with measures of HRV. Ventricular tachycardia was found in two (11.1 %) and ST-T depression in three patients (16.6%) with underlying cardiac diseases. Conclusion: Our results suggest that daytime sleep attacks accompanied by oxygen desaturation in patients with moderate to severe OSAS may contribute to the occurrence of traffic or cardiovascular accidents. We conclude that 24-h ambulatory recordings of SpO² and ECG are useful for screening for daytime sleep sequelae associated with the potential risk of this pathology in OSAS during social activities.     

老年心血管疾病患者阻塞性睡眠呼吸暂停综合征的评价

目的 评价老年心血管疾病患者阻塞性睡眠呼吸暂停综合征(OSAS)的患病情况和特点,为临床决策提供参考. 方法 采用便携式睡眠监测仪对入住在老年心内科的患者,进行睡眠呼吸监测,了解其阻塞性睡眠呼吸暂停(OSA)的患病情况. 结果 共监测了317例老年心血管疾病患者的夜间睡眠呼吸紊乱情况,得出符合OSA[睡眠呼吸紊乱指数(AHI)≥5]的有281例,占88.6%;符合阻塞性睡眠呼吸暂停综合征(OSAS)[AHI≥5,Epworth量表(ESS)≥9分]的有47例,占14.8%.多元回归分析结果 提示,以OSA严重程度作为因变量,对它影响有显著性意义的是最低血氧饱和度和血氧饱和度下降指数(简称氧减指数),而年龄、习惯性打鼾、嗜睡评分、体质指数(BMI)、血氧饱和度平均值和低于90%的时间对其影响无显著性意义. 结论 老年心血管疾病患者中OSAS具有高的患病率,而且无白天嗜睡症状的OSA的老年人患病率更高.对睡眠呼吸暂停严重程度的独立预测因子是最低血氧饱和度氧减指数,而老年人的年龄、BMI、是否经常打鼾、是否白天嗜睡与OSA的严重程度关系不密切.     

Role of nocturnal hypoxaemia in the genesis of systemic hypertension

Two groups of patients with nocturnal arterial oxygen desaturation were compared. The degree of nocturnal oxygen desaturation, as reflected by the percentage of total sleep time spent with an oxygen saturation less than 90 and 80%, was similar in patients with the obstructive sleep apnoea syndrome (OSAS) and in those with nocturnal hypoventilation (NH) secondary to restrictive chest wall disease. Systemic hypertension was present in 16 of the 24 OSAS patients but in only 6 of the 24 with NH (p less than 0.005). Multiple regression analysis demonstrated that this difference remained significant even after adjustment for age, sex, weight and history of smoking. It is likely that factors other than nocturnal hypoxaemia are important in the aetiology of systemic hypertension in patients with sleep-related breathing disorders.     

Cardiovascular risk factors in patients with obstructive sleep apnoea syndrome.

Cardiovascular disorders are common in patients with obstructive sleep apnoea syndrome (OSAS) but there is debate as to whether OSAS is an independent risk factor for their development, since OSAS may be associated with other disorders and risk factors that predispose to cardiovascular disease. In an effort to quantify the risk of OSAS patients for cardiovascular disease arising from these other factors, the authors assessed the future risk for cardiovascular disease among a group of 114 consecutive patients with established OSAS prior to nasal continuous positive airway pressure therapy, using an established method of risk prediction employed in the Framingham studies. Patients were 100 males, aged (mean+/-SD) 52+/-9.0 yrs, and 14 females, aged 51+/-10.4 yrs, with an apnoea/hypopnoea index of 45+/-22 x h(-1). Based on either a prior diagnosis, or a mean of three resting blood pressure recordings >140 mmHg systolic and/or 90 diastolic, 68% of patients were hypertensive. Only 18% were current smokers, while 16% had either diabetes mellitus or impaired glucose tolerance, and 63% had elevated fasting cholesterol and/or triglyceride levels. The estimated 10-yr risk of a coronary heart disease (CHD) event in males was (mean+/-SEM) 13.9+/-0.9%, 95% confidence interval (95% CI) 12.1-16.0, and for a stroke was 12.3+/-1.4%; 95% CI 9.4-15.1, with a combined 10 yr risk for stroke and CHD events of 32.9+/-2.7%; 95% CI 27.8-38.5 in males aged >53 yrs. These findings indicate that obstructive sleep apnoea syndrome patients are at high risk of future cardiovascular disease from factors other than obstructive sleep apnoea syndrome, and may help explain the difficulties in identifying a potential independent risk from obstructive sleep apnoea syndrome.