Confounded by obesity and modulated by urinary uric acid excretion, sleep-disordered breathing indirectly relates to hyperuricaemia in males: A structural equation model.

Sleep-disordered breathing (SDB) causes hypoxic stress and can trigger uric acid (UA) overproduction. We comprehensively investigated whether SDB, interacting with components of metabolic syndrome, hepatic and renal dysfunctions, low physical fitness, sedentary lifestyle, disrupted sleep, and chronic systemic inflammation (CSI), is directly associated with hyperuricaemia. In 528 community-based males (mean [SD] age 46.2 [7.4] years), we cross-sectionally analysed measures of anthropometry; self-reported lifestyle habits; overnight sleep polysomnography data; cardiopulmonary exercise tests; and biomarkers of cardiometabolic, hepatic, and renal functions; and CSI, using structural equation modelling. Objective disrupted sleep, C-reactive protein, low physical fitness, and sedentary lifestyle were not related to UA levels in univariate analysis and were excluded. The latent variables (with corresponding manifest variables) obesity (body mass index, waist-hip ratio), hypertension (post-sleep systolic, diastolic blood pressure), dyslipidaemia (total cholesterol, triglyceride/high-density lipoprotein cholesterol), hepatic dysfunction (alanine aminotransferase, aspartate transaminase), and renal dysfunction (blood urea nitrogen, serum creatinine) were positively; and hyperglycaemia (fasting glucose, glycated haemoglobin) was negatively associated with hyperuricaemia (serum UA), except for SDB (Apnea-Hypopnea Index, percentage of oxygen saturation <90% period against total sleep time, oxygen desaturation index) in the one-stage influence model. In the two-stage model, SDB, closely interacting with obesity, was positively indirectly associated with hyperuricaemia through directly linked renal dysfunction and obesity-linked hypertension, inverse hyperglycaemia, dyslipidaemia, and hepatic dysfunction. In conclusion, structural equation modelling reveals that SDB closely interacts with obesity and is positively but indirectly related to hyperuricaemia in males. This suggests that urinary UA excretion modulates and obesity confounds the SDB-hyperuricaemia relationship.

Objectively Measured Disrupted Sleep Is Independently and Directly Associated With Low Exercise Capacity in Males: A Structural Equation Model.

STUDY OBJECTIVES: We investigated the interaction between objective sleep disturbance and obesity, sedentary lifestyle, and lung dysfunction and whether it is negatively associated with cardiorespiratory fitness. METHODS: In this community cohort study of 521 men (age 46.6 ± 7.5 years), measures of anthropometry, pulmonary function, overnight sleep polysomnography, and cardiopulmonary exercise testing were processed stepwise using structural equation modeling (SEM). RESULTS: A univariate correlation analysis was used to group the corresponding variables (in parentheses) into the following eligible latent variables for lower exercise capacity: obesity (body mass index, waist-to-hip ratio), irregular exercise, impaired lung function (predicted values of forced expiratory volume in the first second, forced vital capacity, maximal ventilatory volume, and lung diffusion capacity for carbon monoxide), disrupted sleep (total sleep time, percentage of slow-wave sleep, sleep efficiency), and sleep-disordered breathing (apnea-hypopnea index, lowest oxygen saturation, percentage of total period of oxygen saturation < 90%). Advanced SEM analyses produced a well-fitted final confirmatory model that obesity (direct strength ßd = .366, P < .001), irregular exercise (ßd = .274, P < .001), and impaired lung function (ßd = .152, P < .001), with their mutual interactions, as well as disrupted sleep (ßd = .135, P = .001) were independently and directly associated with low exercise capacity. By contrast, sleep-disordered breathing (ßd = 0, P = .215) was related to low exercise capacity indirectly through obesity into the mutual interaction cycle of obesity, irregular exercise, and impaired lung function. Sleep-disordered breathing was robustly and mutually correlated with obesity (mutual relationship index = .534, P < .001). CONCLUSIONS: Objectively measured disrupted sleep is directly and independently associated with low exercise capacity; however, sleep-disordered breathing is indirectly mediated by obesity and mutual interactions among obesity, lung dysfunction, and sedentary lifestyle and is linked to low exercise capacity. Our findings indicate that individuals with limited exercise capacity without definite causes should undertake a sleep study, particularly in those describing symptoms of sleep-disordered breathing or insomnia.

Objective Sleep Measures in Inpatients With Subacute Stroke Associated With Levels and Improvements in Activities of Daily Living.

OBJECTIVE: To investigate whether objective polysomnographic measures of prevalent sleep problems such as sleep-disordered-breathing (SDB) and insomnia are associated with activities of daily living levels in inpatients at rehabilitation units. DESIGN: Retrospective and observational study. SETTING: Single rehabilitation center. PARTICIPANTS: Inpatients with subacute stroke (N=123) (61.6±13.1 years; 23.8±3.4 kg/m2; 33% women; 90.5±36.7 days post-stroke) underwent a 1-night polysomnographic study and a 1-month inpatient rehabilitation program. MAIN OUTCOME MEASURES: Admission and discharge Barthel Index (BI) scores and its change scores. RESULTS: One hundred three (92%) patients had moderate-to-severe SDB (46.7±25.1 events/h in the apnea-hypopnea index), and 24 (19.5%) patients had acceptable continuous positive airway pressure adherence. Diverse values were found for total sleep time (259±71 min), sleep efficiency (69.5%±19.3%), sleep latency (24.3±30.9 min), and wakefulness after sleep onset (93.1±74.2 min). Admission BI scores and the BI change scores were 33.8±23.2 and 10.1±9.2, respectively. The National Institutes of Health Stroke Scale (NIHSS, 10.2±5.6), available in 57 (46%) patients, was negatively associated with admission levels and gains in BI change scores (P<.001, =0.002, respectively) in a univariate analysis. In regression models with backward selection, excluding NIHSS score, both age (P=.025) and wakefulness after sleep onset (P<.001) were negatively associated (adjusted R2=0.260) with admission BI scores. Comorbidity of hypertension; sleep latency percentage of stage 1, non-rapid eye movement sleep; and desaturation events ≥4% (P<.001, 0.001, 0.021, and 0.043, respectively; adjusted R2=0.252) were negatively associated with BI score gains. CONCLUSIONS: Based on objective sleep measures, insomnia rather than SDB in inpatients with subacute stroke was associated negatively with admission levels of activity of daily living and its improvement after a 1-month rehabilitation course.

Scaling exponent values as an ordinary function of the ratio of very low frequency to high frequency powers in heart rate variability over various sleep stages.

PURPOSE: To assess the physiological meanings of the detrended fluctuation analysis (DFA) slope α and its relationship to spectral measures in heart rate variability, this study investigated changes of α and its corresponding spectral measures over various night-sleep stages. METHODS: The overall DFA α and natural-logarithm-transformed power values of the spectral parameters ln[high-frequency (HF)], ln[low-frequency (LF)], and ln[very-low-frequency (VLF)], and their relationship from one 5-min proper electrocardiography segment in each of pre-sleep-wakefulness (AWK), non-rapid eye movement stage 2 (N2), slow-wave (N3), the first and the latest rapid-eye movement sleep (REM1, and REM2), were computed in 93 otherwise healthy males (44.1 ± 7.7 years.) with wide-ranged apnea-hypopnea, periodic-limb movement and arousal indices (19.0 ± 20.9, 4.7 ± 9.9, and 10.7 ± 18.2 h, respectively). RESULTS: While ln(HF) dipped from AWK, N2, and N3 to REM1 then rebounded to the origin level at REM2, ln(VLF) dipped from AWK to N2, N3 trough, and then surged to levels surpassing AWKs and N2s at REM1 and REM2. ln(LF/HF), ln(VLF/HF), and α dipped from AWK and N2 to N3 trough, surged to levels surpassing AWKs, and N2s at REM1 then became attenuated at REM2. By general linear modeling, the relationship between α and the corresponding spectral values can be seen over various stages as α = b 0 + 0.147 × ln(VLF/HF) (R (2) = 0.766), regardless of age and sleep-sympathoexcitatory episodes. CONCLUSION: The REM sleep attenuations appeared in ln(HF) and its derivatives, such as ln(LF/HF), ln(VLF/HF), and the overall DFA slope α values. The quantitative function of ln(VLF/HF) describes the α values constantly for overnight sleep stages, and it is not affected by age, LF, PLM, and AHI. Our findings therefore suggest that in sleep studies with spectral HRV measures, ln(VLF/HF) as a surrogate of the overall DFA slope α should be calculated at the same time.

Poor sleep quality measured by polysomnography in non-obese asthmatic children with or without moderate to severe obstructive sleep apnea.

BACKGROUND: The co-effect of asthma and obstructive sleep apnea (OSA) on sleep quality among children remained unclear. OBJECTIVE: To compare sleep quality and emotional/behavioral problems among asthmatic and non-asthmatic children with or without moderate to severe obstructive sleep apnea. METHOD: An AHI-range-matched BMI-range-matched cross-sectional design was used to examine polysomnographic evaluation and emotional/behavioral problems in 102 non-obese children aged between 6 and 12 years old, categorized as with or without asthma and sleep disordered breathing. RESULTS: Asthmatic children in AHI ≤ 5/h group revealed a significantly longer sleep latency, a greater leg movement index (LMI), and a lower ratio of slow wave sleep compared with non-asthmatic AHI ≤ 5/h group. Compared with non-asthmatic AHI > 5/h group, asthmatic children displayed a higher ratio of REM sleep, sleep stage 1 and 2, a lower ratio of slow wave sleep, as well as a greater respiratory arousal index and LMI. There was no significant difference in emotional/behavior problems among groups. CONCLUSION: Sleep disturbance exists in asthmatic children with or without moderate to severe obstructive sleep apnea. Non-obese asthmatic children had less slow wave sleep compared with non-asthmatic children. We might recommend that sleep quality could be noticed and evaluated in children with asthma.

Evaluation of candidate measures for home-based screening of sleep disordered breathing in Taiwanese bus drivers.

BACKGROUND: Sleepiness-at-the-wheel has been identified as a major cause of highway accidents. The aim of our study is identifying the candidate measures for home-based screening of sleep disordered breathing in Taiwanese bus drivers, instead of polysomnography. METHODS: Overnight polysomnography accompanied with simultaneous measurements of alternative screening devices (pulse oximetry, ApneaLink, and Actigraphy), heart rate variability, wake-up systolic blood pressure and questionnaires were completed by 151 eligible participants who were long-haul bus drivers with a duty period of more than 12 h a day and duty shifting. RESULTS: 63.6% of professional bus drivers were diagnosed as having sleep disordered breathing and had a higher body mass index, neck circumference, systolic blood pressure, arousal index and desaturation index than those professional bus drivers without evidence of sleep disordered breathing. Simple home-based candidate measures: (1) Pulse oximetry, oxygen-desaturation indices by ≥3% and 4% (r = 0.87~0.92); (2) Pulse oximetry, pulse-rising indices by ≥7% and 8% from a baseline (r = 0.61~0.89); and (3) ApneaLink airflow detection, apnea-hypopnea indices (r = 0.70~0.70), based on recording-time or Actigraphy-corrected total sleep time were all significantly correlated with, and had high agreement with, corresponding polysomnographic apnea-hypopnea indices [(1) 94.5%~96.6%, (2) 93.8%~97.2%, (3) 91.1%~91.3%, respectively]. Conversely, no validities of SDB screening were found in the multi-variables apnea prediction questionnaire, Epworth Sleepiness Scale, night-sleep heart rate variability, wake-up systolic blood pressure and anthropometric variables. CONCLUSIONS: The indices of pulse oximetry and apnea flow detection are eligible criteria for home-based screening of sleep disordered breathing, specifically for professional drivers.