Sex influences endothelial function in sleep-disordered breathing

BACKGROUND: The bases for the association between sleep-disordered breathing (SDB) and cardiovascular disease are poorly understood. Endothelial dysfunction, assessed with brachial artery ultrasonography, may predict cardiovascular risk and represent preclinical vascular disease. We determined whether flow-mediated dilation (FMD) and peak blood flow (PBF) increase after cuff occlusion is altered with SDB. METHODS: 193 participants (58% women) in a cohort study were studied with overnight polysomnography and subsequent brachial artery ultrasonography. SDB was quantified using the apnea-hypopnea index (AHI) and indexes of overnight desaturation and arousal frequency. Two-dimensional and Doppler-velocity measurements of the brachial artery were obtained at baseline and after 5 minutes of upper-arm cuff occlusion. FMD and PBF were defined as the percentage changes from baseline in brachial artery diameter and flow, respectively. RESULTS: In the entire sample, the AHI was inversely associated with both FMD (r = -0.30, P < .001) and PBF (r = -0.20, P < .001). However, sex-stratified univariate analyses showed that these relationships were exclusive to women. Specifically, FMD was significantly lower in women with an AHI > or = 15 than in women with lower AHI scores (P < .005), with no relationship between AHI and FMD in men. Additionally, PBF decreased significantly with increasing AHI (r = -0.29, P = .010) in women alone. Statistical modeling, adjusting for body mass index, age, and other covariates, similarly showed that SDB severity significantly influenced FMD and PBF, with significant interactions between sex and AHI, reinforcing that the associations between SDB severity and endothelial function were stronger in women than in men. CONCLUSIONS: Moderate levels of SBD are associated with impaired conduit and resistance endothelial function in women. Women with SDB may be more vulnerable to early SDB-related cardiovascular disease than are men.     

Comparison of sleep-disordered breathing among healthy elderly in the seventh, eighth, and ninth decades of life

We investigated the prevalence of sleep-disordered breathing (SDB) in healthy 80 year-old subjects (n = 38) as compared with healthy 70-(n = 33) and 60-year-old subjects (n = 34). The apnea-hypopnea index (AHI) increased significantly across decades: 39.5% (15 of 38) of 80 year olds, 33.3% (11 of 33) of 70 year olds, and 2.9% (1 of 34) of 60 year olds had an AHI greater than or equal to 5 (chi 2 = 14.0, p less than 0.001). The prevalence of SDB as measured by a more stringent apnea index criterion of greater than or equal to 5 was 18.9% of those in their 80s, 12.1% in their 70s, and 0% in their 60s (chi 2 = 6.63, p less than 0.05). Significant gender differences were noted in the proportion of subjects with AHI greater than or equal to 10: 22.4% of men versus 5.4% of women (chi 2 = 4.25, p less than 0.05). These data suggest that SDB increases with advancing age even in the healthy elderly and may be more marked in healthy men than women.     

The prognostic value of simulated snoring in awake patients with suspected sleep-disordered breathing: introduction of a new technique of examination

STUDY OBJECTIVE: A clinical examination of the upper airway in patients with suspected sleep-disordered breathing (SDB) is frequently performed before nighttime polysomnography. In recent years, the findings of "static" examinations, such as dorsalization of the tongue base, the Malampatti index, and Mueller maneuver, have been determined to be of low predictive value. DESIGN: We developed a new method of "dynamic" examination of the upper airway during simulated snoring in awake patients and analyzed the method in terms of the predictive value for suspected SDB. SETTING: N/A PATIENTS: One hundred thirty-one patients were examined prior to night-time polysomnography, and the results were correlated with the apneahypopnea-index (AHI). INTERVENTIONS: N/A RESULTS: A significant correlation was detected between an increased dorsal movement of the tongue base, as well as with pharyngeal collapse at the level of the tongue base and the AHI. Pharyngeal collapse at the level of the velum did not correlate with the AHI. The patient's body position during simulated snoring did not influence the results. The "static" examinations, such as the dorsalization of the tongue base, tonsil size, Malampatti index, and Mueller maneuver, did not correlate with the AHI. Patients with a high degree of pharyngeal collapse at the level of the tongue base, in combination with dorsal movement of the tongue base during simulated snoring, revealed a probability of 75% to have an AHI more than 10 and of 92% for an AHI more than 5. CONCLUSION: The "dynamic" examination of the upper airway under simulated snoring in awake patients is an easy-to-perform method to predict the probability of SDB prior to nighttime polysomnography.     

The association between sleep disordered breathing, academic grades, and cognitive and behavioral functioning among overweight subjects during middle to late childhood

Study Objectives:

(1) to determine the associations of sleep disordered breathing (SDB) with behavioral functioning, cognitive test scores, and school grades during middle- to late-childhood, an under-researched developmental period in the SDB literature, and (2) to clarify whether associations between SDB and school grades are mediated by deficits in cognitive or behavioral functioning.

Design:

Cross-sectional correlative study.

Setting:

Office/hospital, plus reported functioning at home and at school.

Participants:

163 overweight subjects aged 10-16.9 years were divided into 4 groups based upon their obstructive apnea+hypopnea index (AHI) during overnight polysomnography and parent report of snoring: Moderate-Severe OSA (AHI > 5, n = 42), Mild OSA (AHI = 1-5, n = 58), Snorers (AHI < 1 + snoring, n = 26), and No SDB (AHI < 1 and nonsnoring, n = 37).

Measurements:

Inpatient overnight polysomnography, parent- and self-report of school grades and sleep, parent- and teacher-report of daytime behaviors, and office-based neuropsychological testing.

Results:

The 4 groups significantly differed in academic grades and parent- and teacher-reported behaviors, particularly inattention and learning problems. These findings remained significant after adjusting for subject sex, race, socioeconomic status, and school night sleep duration. Associations with SDB were confined to reports of behavioral difficulties in real-world situations, and did not extend to office-based neuropsychological tests. Findings from secondary analyses were consistent with, but could not definitively confirm, a causal model in which SDB affects school grades via its impact on behavioral functioning.

Conclusions:

SDB during middle- to late-childhood is related to important aspects of behavioral functioning, especially inattention and learning difficulties, that may result in significant functional impairment at school.

Citation:

Beebe DW; Ris MD; Kramer ME; Long E; Amin R. The association between sleep disordered breathing, academic grades, and cognitive and behavioral functioning among overweight subjects during middle to late childhood. SLEEP 2010;33(11):1447-1456.     

Sleep-disordered breathing in a general heart failure population: relationships to neurohumoral activation and subjective symptoms

The aim of this study was to determine the prevalence of sleep-related breathing disorders (SDB) in a UK general heart failure (HF) population, and assess its impact on neurohumoral markers and symptoms of sleepiness and quality of life. Eighty-four ambulatory patients (72 male, mean (SD) age 68.6 (10) yrs) attending UK HF clinics underwent an overnight recording of respiratory impedance, SaO2 and heart rate using a portable monitor (Nexan). Brain natriuretic peptide (BNP) and urinary catecholamines were measured. Subjective sleepiness and the impairment in quality of life were assessed (Epworth Sleepiness Scale (ESS), SF-36 Health Performance Score). SDB was classified using the Apnoea/Hypopnoea Index (AHI). The prevalence of SDB (AHI > 15 events h(-1)) was 24%, increasing from 15% in mild-to-moderate HF to 39% in severe HF. Patients with SDB had significantly higher levels of BNP and noradrenaline than those without SDB (mean (SD) BNP: 187 (119) versus 73 (98) pg mL(-1), P = 0.02; noradrenaline: 309 (183) versus 225 (148) nmol/24 h, P = 0.05). There was no significant difference in reported sleepiness or in any domain of SF-36, between groups with and without SDB (ESS: 7.8 (4.7) versus 7.5 (3.6), P = 0.87). In summary, in a general HF clinic population, the prevalence of SDB increased with the severity of HF. Patients with SDB had higher activation of a neurohumoral marker and more severe HF. Unlike obstructive sleep apnoea, SDB in HF had little discernible effect on sleepiness or quality of life as measured by standard subjective scales.     

Behavioral correlates of sleep-disordered breathing in older women

STUDY OBJECTIVES: To examine the association between SDB and subjective measures of daytime sleepiness, sleep quality, and sleep related quality of life in a large cohort of primarily community-dwelling older women, specifically considering the relative importance of sleep duration in mediating these associations. DESIGN: Cross-sectional. The functional outcome measures of interest were daytime sleepiness (using the Epworth Sleepiness Scale, ESS), sleep-related symptoms (Pittsburgh Sleep Quality Index, PSQI), and sleep related quality of life (Functional Outcomes of Sleep Questionnaire, FOSQ). ANOVA and regression analyses examined the association between SDB severity (measured by indices of breathing disturbances and overnight oxygen saturation) and sleep time (by actigraphy) and these outcome measures. Regression models were adjusted for age, body mass index (BMI), and a medical comorbidity index. We specifically explored whether associations with indices of SDB were mediated by sleep deprivation by adjusting models for actigraphy-determined average total sleep time (TST) during the night. SETTING: Community-based sample examined in home and outpatient settings. PARTICIPANTS: 461 surviving older women from the multicenter Study of Osteoporotic Fractures were examined during Visit 8 from 2002-03. All participants underwent in-home overnight polysomnography for one night and wrist actigraphy for a minimum of 3 24-h periods and completed the above functional outcomes questionnaires. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Participants were aged 82.9 +/- 3.5 (mean +/- SD) years, had BMI of 27.9 +/- 5.1 kg/m2, and had an apnea-hypopnea index (AHI) of 15.7 +/- 15.1. AHI and TST demonstrated a weak correlation (r = -0.15). ESS score individually demonstrated a modest association with AHI, oxygen desaturation, and TST. The association of ESS score and AHI--but not oxygen desaturation-was attenuated to some extent by adjustment for TST. PSQI and FOSQ scores were not associated with measures of SDB severity or TST. CONCLUSIONS: After adjustment for TST, SDB severity in community-dwelling older women was not independently associated with self-reported daytime sleepiness, although there may be a modest association that is mediated through reduced TST. In older women, SDB severity was not associated with indices of sleep related symptoms or sleep related quality of life.     

Sleep-disordered breathing and cardiovascular disease in the Bay Area Sleep Cohort

STUDY OBJECTIVES: To examine the relationship between sleep-disordered breathing (SDB) and cardiovascular disease among community-dwelling older adults. Previous studies have suggested relatively stronger associations between SDB and such morbidity in middle-aged, relative to elderly, populations. DESIGN: Cross-sectional analysis of an elderly ambulatory, non-clinic-based cohort (Bay Area Sleep Cohort, BASC) SETTING: Community population studied in a sleep laboratory PARTICIPANTS: One hundred twenty-nine older adults (mean [+/- SD] age = 72.6 [8.3]) (78 women; 51 men). INTERVENTIONS: NA. MEASUREMENTS: Complete clinical history including list of current medications, physical examination, selected blood chemistries, multiple blood pressure measurements, 12-lead electrocardiogram, and 2 consecutive nights of polysomnography. RESULTS: Fifty-one individuals (40%) were taking 1 or more cardiovascular medications and 24 (19%) had an apnea-hypopnea index (AHI) of 10 or more per hour of sleep. Cardiovascular medication use was related to cardiac events or procedures, history of angina, higher systolic or diastolic blood pressure, and abnormal electrocardiogram. Logistic regression showed statistically significant association between cardiovascular medication use and AHI of 10 or greater per hour, independent of age, sex, and body mass index. Supplementary analyses indicated that rapid eye movement AHI of 10 or greater per hour was significantly associated with elevated diastolic blood pressure. CONCLUSIONS: The results suggest that sleep-disordered breathing may contribute to increased cardiovascular morbidity in older adults.     

Sleep-disordered breathing and its concomitants in a subclinical population

In order to evaluate possible deficits accompanying sleep-disordered breathing (SDB) in a subclinical population, the nocturnal respiration, health status, and sleep/wake cycle of 46 healthy, heavy-snoring men were measured. Sixty-two percent of these subjects had at least one episode of apnea/hypopnea, while 13% had high levels of apnea/hypopnea [apnea/hypopnea index (AHI) greater than or equal to 5]. Most events occurred in stages 1 or 2 or in REM sleep. Strong relationships between weight and SDB were observed, as were more modest relationships between age and SDB. Correlational procedures indicated relationships between SDB and higher blood pressure, subjective sleepiness, and napping. Because similar, but stronger, relationships involving these variables are observed in patients with a sleep apnea syndrome (SAS), it appears that a continuum exists between heavy-snoring men and patients with SAS. When these subjects were grouped by level of SDB, subjects with high levels of SDB (AHI greater than or equal to 5) had significantly lower nocturnal oxygenation parameters than the remaining subjects. However, there were no between-group differences in health or sleep/wake variables. It is concluded that while apnea/hypopnea events in subclinical populations may not be completely benign events, the level at which they may be considered frankly pathological is presently unclear.     

Longitudinal association of sleep-disordered breathing and nondipping of nocturnal blood pressure in the Wisconsin Sleep Cohort Study

STUDY OBJECTIVES: The association of sleep-disordered breathing (SDB) and blunting of normal nocturnal lowering of blood pressure (BP) (nondipping) has only been examined cross-sectionally. The purpose of this study is to investigate whether SDB is prospectively associated with nondipping. METHODS: The longitudinal association between SDB and incident nondipping was examined in a subsample of 328 adults enrolled in the Wisconsin Sleep Cohort Study who completed 2 or more 24-hour ambulatory BP studies over an average of 7.2 years of follow-up. SDB identified by baseline in-laboratory polysomnography was defined by apnea-hypopnea index (AHI) categories. Systolic and diastolic nondipping was defined by systolic and diastolic sleep-wake BP ratios > 0.9. All models were adjusted for age, sex, body mass index at baseline and follow-up, smoking, alcohol consumption, hypertension, sleep time, length of follow-up time, and antihypertensive medication use. RESULTS: There was a dose-response increased odds of developing systolic nondipping in participants with SDB. The adjusted odds ratios (95% confidence interval) of incident systolic nondipping for baseline AHI 5 to < 15 and AHI > or = 15, versus AHI < 5, were 3.1 (1.3-7.7) and 4.4 (1.2-16.3), respectively (P trend = 0.006). The adjusted odds ratios (95% confidence interval) of incident diastolic nondipping for corresponding SDB categories were not statistically significant: 2.0 (0.8-5.6) and 1.3 (0.2-7.1). CONCLUSIONS: Our longitudinal findings of a dose-response increase in development of systolic nondipping of BP with severity of SDB at baseline in a population-based sample provide evidence consistent with a causal link. Nocturnal systolic nondipping may be a mechanism by which SDB contributes to increased cardiovascular disease.     

Predictors of sleep-disordered breathing in children with a history of tonsillectomy and/or adenoidectomy.

STUDY OBJECTIVES: To identify predictors of sleep-disordered breathing (SDB) in children who have undergone self-reported tonsillectomy and/or adenoidectomy (TA). DESIGN: Observational study of pediatric participants in a longitudinal genetic-epidemiological cohort study of SDB. SETTING: Community-based; studies conducted at participants' homes PARTICIPANTS: 577 children age <18 (10.8+/-4.2 SD) years; 53% female; 48% Black; 76% with a family member identified with SDB. INTERVENTIONS: NA. MEASUREMENTS AND RESULTS: Medical history assessed by questionnaire. Physical measures made directly. SDB was assessed with overnight inhome cardio-respiratory monitoring. 10% of children (n=60) had had aTA 5.5+/-4.6 yrs previously. An Apnea-Hypopnea Index (AHI, events/hr) > or =5 was found in a higher proportion of children with a reported TA than in children with no history of out surgery (35% vs. 13.7%, p<.001). A TA was reported more frequently for non-Blacks than for Blacks (13.6% non-Blacks, 6.9% Blacks, p=.02). Among children who had a TA, significant predictors of SDB (AHI> or =5) were: Black ethnicity (SDB in 57% vs. 24% of Blacks vs. non-Blacks; adjusted odds ratio (OR): 3.85; 95% CI: 1.11, 13.33) and obesity (OR 3.98; 95% Cl: 1.05, 15.08). SDB also tended to be greater in children with a family member with SDB (OR 2.87; 95% CI: 0.65, 12.07). CONCLUSIONS: Black children were less likely to have undergone TA but more likely to have SDB after TA surgery. These findings underscore the need to follow children post-TA and for evidence-based studies that define the role of TA in the management of pediatric adenotonsillar disease.     

Prediction of sleep-disordered breathing by unattended overnight oximetry

Between January 1994 and July 1997, 793 patients suspected of having sleep-disordered breathing had unattended overnight oximetry in their homes followed by laboratory polysomnography. From the oximetry data we extracted cumulative percentage time at SaO2 < 90% (CT90) and a saturation variability index (delta Index, the sum of the differences between successive readings divided by the number of readings - 1). CT90 was weakly correlated with polysomnographic apnea/hypopnea index (AHI). (Spearman rho = 0.36, P < 0.0001) and with delta Index (rho = 0.71, P < 0.0001). delta Index was more closely correlated with AHI (rho = 0.59, P < 0.0001). In a multivariate model, only delta Index was significantly related to AHI, the relationship being AHI = 18.8 delta Index + 7.7. The 95% CI for the coefficient were 16.2, 21.4, and for the constant were 5.8, 9.7. The sensitivity of a delta Index cut-off of 0.4 for the detection of AHI > or = 15 was 88%, for detection of AHI > or = 20 was 90% and for the detection of AHI > or = 25 was 91%. The specificity of delta Index > or = 0.4 for AHI > or = 15 was 40%. In 113 further patients, oximetry was performed simultaneously with laboratory polysomnography. Under these circumstances delta Index was more closely correlated with AHI (rho = 0.74, P < 0.0001), as was CT90 (rho = 0.58, P < 0.0001). Sensitivity of delta Index > or = 0.4 for detection of AHI > or = 15 was not improved at 88%, but specificity was better at 70%. We concluded that oximetry using a saturation variability index is sensitive but nonspecific for the detection of obstructive sleep apnea, and that few false negative but a significant proportion of false positive results arise from night-to-night variability.     

Identifying sleep apnea from self-reports

An apnea score (AS) was developed as a potential screening tool for sleep apnea. This was based on self-report questionnaire responses of 76 sleep disorder center patients and 20 sleep survey volunteers. Twenty volunteers and 23 patients (group I) comprised the initial AS development group. Their questionnaire responses were compared to polysomnographic apnea indexes (AI) and apnea plus hypopnea indexes (AHI). Stepwise multivariate discriminant analysis was used to test whether or not selected group I questionnaire responses could be used to correctly classify respondents into apnea (AI or AHI greater than 5) or nonapnea (AI, AHI less than or equal to 5) groups. Self-reports of "stops breathing during sleep," "loud snoring," and history of adenoidectomy best discriminated normal (AI less than or equal to 5) from apnea (AI greater than 5) cases. The AS derived from group I responses to these three variables was then computed for group II (n = 53). After examination of the AS results, the AS was modified to include just "stops breathing" and "loud snoring" and the AI criterion was raised to 10 per hour. This revised AS correctly identified 100% of the cases with moderate-severe sleep apnea (AI or AHI greater than 40) and 70-76% of all sleep apnea cases with AI or AHI greater than 5. Predictive accuracy was 88% for AI greater than 10. The two questions that comprise the AS should be incorporated into risk appraisal instruments or interviews to screen for sleep apnea.     

Relationship between sleep-disordered breathing and markers of systemic inflammation in women from the general population

Sleep‐disordered breathing (SDB) is a risk factor for cardiovascular disease (CVD). The underlying pathogenesis is not clear. In patients with obstructive sleep apnoea syndrome (OSAS) elevated levels of inflammatory markers, such as C‐reactive protein (CRP), interleukin‐6 (IL‐6) and tumour necrosis factor α (TNFα) have been found. These markers have also been shown as independent markers of CVD in other populations. The aim of the study was to investigate the association between SDB and systemic inflammation in a population‐based cohort of women. From 6817 women who previously answered a questionnaire concerning snoring habits, 230 habitually snoring women and 170 women regardless of snoring status went through polysomnography, anthropometric measurements and blood sampling. Analyses were made for CRP, TNFα, IL‐6, myeloperoxidase (MPO) and lysozyme. The levels of CRP, IL‐6 and lysozyme were significantly higher in subjects with apnoea–hypopnoea index (AHI) ≥15 compared with women with lower AHI. All inflammatory markers except MPO correlated to AHI and oxygen desaturation measures, and to waist circumference. In multiple linear regressions adjusting for age, waist circumference and smoking, independent correlations between oxygen desaturation indices (ODI) and inflammation were found for IL‐6 (P = 0.03 for % sleep time with saturation <90%) and TNFα (P = 0.03 for ODI 3%). No significant correlations were found between AHI and inflammation. Also, for women from the general population there is an independent correlation between SDB and inflammation, even after adjusting for obesity. The results indicate that intermittent hypoxia, and not the AHI, is related to systemic inflammation seen in OSAS.     

The relationship between chronically disrupted sleep and healthcare use

STUDY OBJECTIVES: To determine whether chronic sleep deprivation, sleep disruption, sleepiness, insomnia, and OSA are associated with increased healthcare use in a community-based population. DESIGN: Cross-sectional study. SETTING/PARTICIPANTS: 6440 Sleep Heart Health Study (SHHS) participants recruited from ongoing cohort studies. Interventions: N/A MEASUREMENTS: Polysomnography results (Apnea Hypopnea Index (AHI), percent of sleep time with oxyhemoglobin saturation below 90% (CT90), arousal index) as well as data on sleep related symptoms, medication use, and chronic illness. The indirect measure of predicted healthcare utilization was the modified Chronic Disease Score (CDS) calculated from medication data. RESULTS: After adjustment for age, gender, BMI and study site, subjects in the highest quartiles of AHI, CT90 and Epworth score had CDS that were 6%-9% higher than the lowest quartiles. The adjusted mean CDS for subjects with sleep apnea was similar to that for subjects with hypertension, chronic bronchitis or asthma and 18% greater than the mean CDS for subjects without sleep apnea. Among subjects who did not have significant sleep-disordered breathing, complaints of insomnia, sleepiness, fatigue, and not getting enough sleep were associated with increased CDS. CONCLUSIONS: This study demonstrated an association between subjective complaints of daytime sleepiness, inadequate sleep time, insomnia as well as objective measures of severity of SDB, and an indirect measure of healthcare utilization in a community-based sample. Though the percent increases in healthcare utilization observed were modest, the prevalence of these factors in the general population is high, and may therefore be associated with a substantial cost burden to the healthcare system.     

Sleep-disordered breathing and psychomotor vigilance in a community-based sample

STUDY OBJECTIVE: Sleep-disordered breathing (SDB) has been associated with impaired psychomotor vigilance performance in patients with sleep apnea patients. A bias toward greater referral of sleep apnea patients with severely impaired performance could explain these findings. Furthermore, no studies on the association between SDB and vigilance performance in a large community-based sample have been reported that encompasses the full spectrum of SDB severity. This study investigated the association between SDB and psychomotor vigilance with cross-sectional data from the Wisconsin Sleep Cohort Study. SETTING AND PARTICIPANTS: Community-based sample of 265 women and 346 men, mean age of 53.0 +/- 7.9 (age range: 35-74) years was used. Within 6 months of completing an overnight polysomnography protocol for SDB assessment, participants completed a 10-minute psychomotor vigilance task (PVT) during a daytime protocol. MEASUREMENTS: Sleep-disordered breathing was indicated by the number of apneas and hypopneas; psychomotor vigilance task variables included (1) mean of 1/reaction time (RT), (2) number of lapses, (3) mean reciprocal of fastest 10% RTs, (4) mean reciprocal of slowest 10% RTs, (5) slope of linear regression line across the 10 minutes of the task fit to 1/RTs, and (5) number of false responses. RESULTS: Multiple regression analysis showed a significant negative association between the logarithmically transformed apnea-hypopnea index (LogAHI) and number of lapses, mean of the slowest 10%, and number of false responses from the psychomotor vigilance task, independent of sex and body mass index in participants aged 65 years and older. CONCLUSION: SDB in the community population is associated with impaired psychomotor vigilance in older men and women.     

Utility of home oximetry as a screening test for patients with moderate to severe symptoms of obstructive sleep apnea

OBJECTIVE: To determine the value of home oximetry as a screening test in patients with moderate to severe symptoms of obstructive sleep apnea (OSA). DESIGN: Retrospective, observational study. SETTING: The Sleep Unit of a tertiary referral, university hospital. PATIENTS: 116 patients referred for evaluation of moderate to severe symptoms of OSA in which both home oximetry and polysomnography (PSG) were performed. INTERVENTIONS: NA. RESULTS: Three numerical oximetry indices were evaluated: average of desaturations > or =4% and average of resaturations > or =3% per hour of analysis time (DI4% and RI3%, respectively); and cumulative percentages of time spent at saturations below 90% (CT90%). A qualitative assessment was also performed. Oximetry indices were compared with apnea/hypopnea index (AHI) by simple linear regression and Bland-Altman analyses. Optimal cut-off points, in terms of sensitivity and specificity, for the oximetry indices were searched using ROC analysis, at an AHI threshold of > or =10. The correlation between AHI and the desaturation indices was r = 0.50 for CT90%, r = 0.60 for DI4%, and r = 0.58 for RI3%. No bias was found between PSG and oximetry indices in Bland-Altman plots. Neither the numerical indices nor the qualitative analysis achieved an adequate (>0.8) area under the ROC curve. A CT90% <0.79 excluded OSA with 84% sensitivity. A DI4% > or =31.4 or a RI3% > or =40.5 diagnosed OSA with 97% specificity. Using these values, 38% of the patients would have been correctly classified by oximetry alone, 10% would have been incorrectly classified, and 50% could not have been classified with certainty. Eleven (15%) OSA patients would have been missed by oximetry. CONCLUSIONS: Correlation between home oximetry and PSG was not high. Oximetry was more useful to confirm than to exclude OSA in our study. Qualitative assessment was not better than numerical analysis. The greatest value of oximetry in this setting seems to be as a tool to rapidly recognize and treat more severe OSA patients in waiting list for PSG.     

Sleep‐disordered breathing in children is associated with impairment of sleep stage‐specific shift of cardiac autonomic modulation

We examined the effects of sleep stages and sleep‐disordered breathing (SDB) on autonomic modulation in 700 children. Apnea hypopnea index (AHI) during one 9 h night‐time polysomnography was used to define SDB. Sleep stage‐specific autonomic modulation was measured by heart rate variability (HRV) analysis of the first available 5 min RR intervals from each sleep stage. The mean [standard deviation (SD)] age was 112 (21) months (49% male and 25% non‐Caucasian). The average AHI was 0.79 (SD = 1.03) h^?1, while 73.0%, 25.8% and 1.2% of children had AHI <1 (no SDB), 1–5 (mild SDB) and ≥5 (moderate SDB), respectively. In the no SDB group, the high frequency (HF) and root mean square SD (RMSSD) increased significantly from wake to Stage 2 and slow wave sleep (SWS), and then decreased dramatically when shifting into rapid eye movement (REM) sleep. In the moderate SDB group, the pattern of HRV shift was similar to that of no SDB. However, the decreases in HF and RMSSD from SWS to REM were more pronounced in moderate SDB children [between‐group differences in HF (?24% in moderate SDB versus ?10% in no SDB) and RMSSD (?27% versus ?12%) were significant (P < 0.05)]. The REM stage HF is significantly lower in the moderate SDB group compared to the no SDB group [mean (standard error): 4.49 (0.43) versus 5.80 (0.05) ms², respectively, P < 0.05]. Conclusions are that autonomic modulation shifts significantly towards higher parasympathetic modulation from wake to non‐rapid eye movement sleep, and reverses to a less parasympathetic modulation during REM sleep. However, the autonomic modulation is impaired among children with moderate SDB in the directions of more reduction in parasympathetic modulation from SWS to REM sleep and significantly weaker parasympathetic modulation in REM sleep, which may lead to higher arrhythmia vulnerability, especially during REM sleep.     

C-reactive protein is associated with sleep disordered breathing independent of adiposity

STUDY OBJECTIVES: It is well established that medical conditions such as obesity and cardiovascular disease are associated with increased levels of inflammatory biomarkers such as C-reactive protein (CRP). Prior studies have produced inconsistent results regarding the association between sleep disordered breathing (SDB) and CRP, possibly due to the confounding effects of obesity or medical comorbidity. The present study examined the association between degree of SDB and level of CRP independent of prevalent medical conditions and obesity. DESIGN: Cross-sectional study. SUBJECTS AND SETTING: University-based clinical sample referred for diagnostic polysomnography. MEASUREMENTS AND RESULTS: The study sample consisted of 69 men (mean age 40 years; mean BMI of 31.2 kg/m2) free of prevalent medical conditions including hypertension, diabetes mellitus, and cardiovascular disease. Measurements of morning and evening CRP levels were performed along with full-montage polysomnography. Confounding due to obesity was assessed by adjustments for body mass index, waist circumference, and percent body fat. A strong association was found between degree of SDB and serum levels of CRP, with or without adjustment for age and several measures of adiposity. Between the lowest and highest quartiles of apnea-hypopnea index (AHI) the mean difference in adjusted level of CRP was 3.88 microg/ml (P < 0.001). Moreover, an independent association between serum CRP levels and nocturnal hypoxia was also observed, whereas no association was noted with parameters of sleep architecture. CONCLUSIONS: While more research is needed to elucidate causal pathways involving the effects of sleep-related hypoxia on low-grade systemic inflammation, the results of this study suggest that mechanisms other than adiposity per se could contribute to the inflammatory state seen in adults with SDB.     

Gender-related differences in symptoms of patients with suspected breathing disorders in sleep: a clinical population study using the sleep disorders questionnaire

BACKGROUND: Gender-related differences in the symptom profile of patients with suspected sleep disordered breathing (SDB) may be one explanation of the clinical underrecognition of SDB in women. STUDY OBJECTIVES: The aim of this study was to prospectively assess gender-related differences in presenting symptoms in a clinical sample of patients with suspected sleep disordered breathing. DESIGN: Administration of the Sleep Disorders Questionnaire prior to clinical and polysomnographic evaluation. Responses obtained from the questionnaire were used to construct 4 independent symptom scales: sleep apnea (SA), periodic limb movement syndrome (PLM), psychiatric sleep disorder (PSY), and narcolepsy (NAR). Analyses of variance were used to examine the effect of gender, AHI, and age on the symptom scales. Associations between gender and each diagnostic scale of the questionnaire were determined by multiple analyses of covariance. SETTING: Tertiary pulmonary referral center. PARTICIPANTS: 2739 men and 782 women with suspected SDB. All patients who were referred to the sleep laboratory underwent full-night polysomnography, irrespective of the likelihood of SDB. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Overall, men scored significantly higher on items related to worsening of snoring/breathing with alcohol (P < 0.001) and smoking history (P < 0.01) than women. Complaints such as witnessed apneas (P < 0.001) and worsening of snoring in supine position (P < 0.05), however, were more frequently reported by men with an apnea-hypopnea index (AHI) < 5/hr, compared with AHI-matched women. There were no significant differences in these items in patients with an AHI > 15/hr. In contrast, women complained significantly more often of insomnia, restless legs, depression, nightmares, palpitations at night, and hallucinations than men. As a result, women had significantly higher scores on the PLM, PSY, and NAR scales of the Sleep Disorders Questionnaire (P < 0.001, for all). After adjustments for age, body mass index, AHI, arousal index, oxygen saturation data, and smoking history, by means of multiple analyses of covariances, gender differences remained significant (P < 0.001, for all scales). CONCLUSIONS: We observed significant gender-related differences in presenting symptoms of patients with sleep disordered breathing at a tertiary level. These differences should be taken into consideration in clinical evaluation of women with suspected sleep disordered breathing.     

阻塞性睡眠呼吸暂停综合征的情绪状况

目的 探讨阻塞性睡眠呼吸暂停综合征（OSAS）患者情绪状况的改变。方法 对63例疑诊OSAS的患者行全夜多导睡眠图（PSG）检查，根据呼吸暂停低通气指数（AHI）分为OSAS组和对照组，对其进行抑郁和焦虑症状评定，比较两组中各指标的差异性。结果 OSAS患者SAS、SDS得分均升高。OSAS患者抑郁和焦虑的发生率分别为44．2％和32．6％，明显高于对照组，以抑郁尤为明显。结论 OSAS患者存在明显情绪障碍。