Nightly variation in sleep-related respiratory disturbance in older adults

This study investigated variation in respiratory disturbance during sleep. Sixty-six healthy elderly subjects (mean age = 67.2) underwent two consecutive nights of polysomnography. Respiratory disturbance was assessed by Respiratory Disturbance Index (RDI), the number of events per hour of sleep. Results indicated an increase in RDI from Night 1 to Night 2. Fourteen subjects increased their RDI by over 2.5, and eight by over 5.0, events per hour on Night 2. The increase was not a function of increased REM on Night 2. Age was positively related to RDI on individual lab nights but unrelated to nightly variation in RDI. Subjects without complaints of insomnia were more likely to show increases in RDI, perhaps reflecting the sounder sleep of this group on the second laboratory night. This study suggests that a single night of polysomnography is likely to underestimate the absolute level of respiratory disturbance seen in a subsequent recording night. Studies placing prevalence of such disturbance in the elderly at approximately 30% are thus likely to be underestimates. Whether this "error" is important will depend ultimately upon the meaning of various absolute levels of respiratory disturbance in healthy older persons.     

Consistency of respiratory measurements from night to night during the sleep of elderly men

Fourteen healthy elderly men had polysomnography performed on two consecutive nights to assess the consistency of sleep and breathing from night to night. The reported first-night effect was seen on electroencephalographic sleep, leading to lighter or fitful sleep on the first night. Mean values for apneas, hypopneas, and oxygen desaturations did not change from night 1 to night 2. Five of 14 subjects would have changed classification from night to night if a cutoff of five apneas and hypopneas per hour were used to define normality. Because this numerical cutoff may not be valid in the elderly, the clinical significance of such a changing classification is not clear.     

Sleep-related respiratory disturbance and dementia in elderly females

Sleep-related respiratory disturbance was studied with a microprocessor-based portable monitoring system in female residents of a retirement village aged greater than or equal to 75 years. Comparisons were made between 29 demented subjects Mini-Mental State Examination Score (MMSE) less than 21 and 48 controls (MMSE greater than 25). Respiratory disturbance index (RDI, the number of episodes of apnea and hypopnea/hour of total sleep time) was higher in the demented subjects: mean RDI (+/- SD) 18.5 +/- 18.6 vs 7.3 +/- 10.8, p = .004. The number of minutes per hour of sleep spent with disturbed breathing was greater in demented subjects than in controls (p = .01). These differences between demented subjects and controls persisted after adjustment for age and relevant medical history. Other possible confounders, namely body mass index and use of sedatives, were not significant. We conclude that respiratory disturbance during sleep is more prevalent in elderly demented females than in controls.     

Sleep disordered breathing and cognitive function in a retirement village population.

Sleep disordered breathing (SDB) may be associated with cognitive dysfunction in non-demented elderly people. A random sample of 96 retirement village residents were given both neuropsychological assessment and overnight sleep monitoring with a portable microprocessor based system (Vitalog PMS-8). Respiratory disturbance index (RDI) was calculated as the number of apnoeas and hypopnoeas per hour of sleep. RDI was not associated with 'memory', 'verbal', and 'motor' factors identified from the analysis of cognitive tests, but was associated with the 'cerebral efficiency' factor (R2 = 0.21, p less than 0.0001). Seventy-three subjects had repeat neuropsychological tests, median time to follow-up being 17 months. Baseline RDI did not predict changes in scores on the two factors identified from the second analysis. We conclude that mild to moderate disturbance of breathing during sleep is not associated with cognitive dysfunction in non-demented subjects.     

Measurement of sleep-related breathing disturbances in epidemiologic studies. Assessment of the validity and reproducibility of a portable monitoring device

The feasibility and reliability of measuring sleep-related breathing disorders with a portable monitor (PM) were assessed in a heterogeneous population, consisting of 31 patients recruited from a sleep laboratory and pulmonary disease clinic, 16 participants in a genetic-epidemiologic study of sleep apnea, and four volunteers with no specific sleep complaints. The validity of measurements made by the PM was assessed with comparisons of respiratory parameters made with the PM to those determined with in-hospital polysomnography (PSG) (25 studies). Reproducibility was assessed in 29 subjects who underwent in-home monitoring on two occasions. There was a high level of agreement between the number of respiratory events (apneas or hypopneas) per hour of estimated sleep (respiratory disturbance index, RDI) recorded with the PM and PSG and log-transformed (r = 0.96). Using a RDI of greater than or equal to 10 to define "abnormality," 20 of the 21 subjects who would have been classified as abnormal with PSG were classified similarly with use of the PM. A similar high level of agreement was demonstrated for the log-transformed RDI determined with replicate in-home studies (r = 0.94). No evidence of a "first-night effect" for the RDI was suggested in studies performed with the PM; ie, RDI was 18.4 +/- 27.7 and 17.4 +/- 25.7 (mean +/- SD) for first and second night studies, respectively (p = 0.21). A second compared with an initial study with the PM would have resulted in reclassification of abnormality based on an RDI of greater than or equal to 10 in one subject. These findings suggest that measurement of the RDI with in-home monitoring provides a valid and highly reproducible index for assessment of sleep-related respiratory disturbances for use in epidemiologic studies of general populations.     

Follow-up assessment of CPAP efficacy in patients with obstructive sleep apnea using an ambulatory device based on peripheral arterial tonometry

This study aimed to assess the accuracy of a wrist-worn device based on peripheral arterial tonometry (Watch_PAT 100) to detect residual episodes of respiratory disturbance during continuous positive airway pressure (CPAP) therapy. Concurrent polysomnography was used as the reference standard to identify sleep disordered breathing (SDB) events. The study was conducted in three sleep laboratories affiliated with tertiary care academic medical centers. Seventy patients using CPAP to treat obstructive sleep apnea for at least 3 months, following an in-laboratory titration to determine the optimal therapeutic positive airway pressure, participated in this study. Symptoms indicating suboptimal therapy were not required for participation, but self-reported adherence to CPAP therapy was necessary for inclusion. Interventions are not applicable in this study. The accuracy of the PAT-derived respiratory disturbance index (PAT RDI scored by automated algorithm) to detect residual SDB on CPAP was assessed against polysomnography (PSG) using Bland–Altman analysis, receiver–operator characteristic (ROC) curves, and likelihood ratios for increasing (LR+) and decreasing (LR−) the probability of moderate–severe SDB in the study population. Respiratory events on the PSG were quantified using standard criteria for research investigations (“Chicago criteria”) to yield a PSG RDI.C. Based on the PSG results, 19% of the participants had moderate–severe SDB (PSG RDI.C>15 events per hour) on their prescribed pressure. For PAT RDI >15 events per hour, the area under the ROC curve was 0.95 (SE 0.03, p<0.0001, 95% CI 0.89 to 1.00), the LR+ was 8.04 (95% CI 3.64–17.7), and the LR− was 0.17 (95% CI 0.05–0.62). The mean difference between the PAT RDI and PSG RDI.C was three (2SD 14.5) events per hour. Therefore, residual moderate–severe SDB on CPAP was not uncommon in a multicenter population self-reporting adherence to CPAP therapy to treat obstructive sleep apnea. The Watch_PAT device accurately identified participants with moderate–severe SDB while using CPAP in the attended setting of a sleep laboratory.     

Evaluation of a portable device based on peripheral arterial tone for unattended home sleep studies

BACKGROUND: Diagnosis of obstructive sleep apnea syndrome (OSAS) by ambulatory systems is a growing practice in view of the large number of patients awaiting correct diagnosis. The Watch PAT100 (WP100) [Itamar Medical; Caesarea, Israel] is a portable device based on the peripheral arterial tone (PAT) signal, and is designed for unattended home sleep studies. OBJECTIVES: To evaluate the efficacy, reliability, and reproducibility of the WP100 device for the diagnosis of OSAS as compared to in-laboratory, standard polysomnographic-based manual scoring. Design and methods: One hundred two subjects (78 men; 69 patients with OSAS and 33 normal volunteers; mean +/- SD age, 41.4 +/- 15.2 years; body mass index, 26.8 +/- 5.5) underwent in-laboratory full polysomnography simultaneously with WP100 recording. Fourteen subjects also underwent two additional unattended home sleep studies with the WP100 alone. The polysomnography recordings were blindly scored for apnea/hypopnea according to the American Academy of Sleep Medicine criteria (1999), and the polysomnography respiratory disturbance index (RDI) [PSG-RDI] was calculated. The WP100 data were analyzed automatically for the PAT RDI (PRDI) by a proprietary algorithm that was previously developed on an independent group of subjects. RESULTS: Across a wide range of RDI levels, the PRDI was highly correlated with the PSG-RDI (r = 0.88, p < 0.0001), with an area under the receiver operating characteristic curve of 0.82 and 0.87 for thresholds of 10 events per hour and 20 events per hour, respectively. The PRDI scores were also highly reproducible, showing high correlation between home and in-laboratory sleep studies (r = 0.89, p < 0.001). CONCLUSION: The WP100 may offer an accurate, robust, and reliable ambulatory method for the detection of OSAS, with minimal patient discomfort.     

A 3-year longitudinal study of sleep disordered breathing in the elderly

Limited and controversial data exist on the natural evolution of sleep disordered breathing (SDB) in untreated individuals. This study examines the evolution of SDB over a 3-yr period in a community-based sample of elderly subjects. From the initial cohort of 854 healthy subjects aged mean±sd 68.4±0.8 yrs, 519 untreated subjects accepted clinical and instrumental follow-up 3.6±1.6 yrs later. SDB was defined as a respiratory disturbance index (RDI) >15 events·h(-1). At baseline, 202 (39%) subjects had an RDI ≤15 events·h(-1) and 317 (61%) had an RDI >15 events·h(-1). 3 yrs later, 280 (54%) subjects were non-SDB and 239 (46%) had SDB. Between evaluations, the RDI decreased from 22.3±16.2 to 16.4±13.0 events·h(-1), with a greater decrease in the number of cases with an RDI >30 events·h(-1) that in those with RDI ≥30 events·h(-1). In the non-SDB group, 81% had a stable RDI and 19% increased their RDI by a mean of 13.7 events·h(-1). In the SDB group, the RDI decreased to values ≤15 events·h(-1) in 36.6% of cases, 63.4% still having SDB. The RDI changes did not depend on weight changes. In healthy elderly subjects, the prevalence and severity of SDB did not show a tendency toward natural worsening, some cases having improvement or a remission independent of weight changes. These findings also suggest that in the elderly, natural SDB progression is still hypothetical.     

Factors associated with nightly variability in sleep-disordered breathing in the elderly

The purpose of this study was to evaluate factors associated with nightly variability in sleep-disordered breathing. In this study, variability in sleep-disordered breathing over two consecutive laboratory nights was evaluated in 71 aged volunteers with varying levels of sleep apnea. High variability (n = 13) and low variability (n = 58) groups were formed on the basis of an absolute two-night apnea/hypopnea index difference of a minimum ten events per hour. Results indicate high variability was related to longer soft palate measurements and the presence of nasal obstruction on physical examination. Within the high variability group, variation in sleep-disordered breathing occurred within identical gross body position over the two nights. The results suggest that local, anatomic factors affecting airway patency may not be constant from night to night.     

Short-term effects of cardiac resynchronization therapy on sleep-disordered breathing in patients with systolic heart failure

OBJECTIVES: We evaluated the short-term effect of cardiac resynchronization therapy (CRT) on sleep apnea in patients with systolic heart failure. BACKGROUND: Sleep-disordered breathing is common in patients with left ventricular systolic dysfunction. METHODS: Twelve patients (mean [+/-SE] age, 59.6+/-7.8 years; mean left ventricular ejection fraction, 28.0+/-2.8%) with an implanted atrial-synchronized biventricular pacemaker for the treatment of left ventricular systolic dysfunction were selected and studied. Each subject underwent polysomnography on 3 consecutive nights with CRT on the first night, CRT off the second night, and CRT on the third night. Echocardiography was performed prior to each polysomnogram. RESULTS: The central sleep event index (ie, the number of central sleep apneas [CSAs] and hypopneas per hour of sleep) score was lower with CRT compared to that without CRT (mean central sleep event index score with CRT on, 6.9+/-1.7 events per hour of sleep; mean central sleep event index score with CRT off, 14.3+/-2.9 events per hour of sleep; mean central sleep event index score with CRT on, 8.1+/-1.5 events per hour of sleep; p<0.001). Similarly, the cumulative duration of central sleep events (the number of minutes per hour of sleep during CRT) was one half that observed without CRT (CRT on, 2.8+/-0.7 min per hour of sleep; CRT OFF 6.2+/-1.2 min per hour of sleep; CRT ON 3.1+/-0.7 min per hour of sleep; p<0.001). There was a significant correlation between mitral regurgitant volume and central sleep event index on all three nights (r>or=0.77; p<0.01). CONCLUSIONS: CRT reduces CSA severity in the short term. This reduction correlated significantly with the CRT-mediated reduction of mitral regurgitation.     

Nightly variation of periodic leg movements in sleep in middle aged and elderly individuals

This study investigated night-to-night variation in periodic leg movements in sleep (PLMS). PLMS are common in the elderly, but their mechanism and significance are not understood. Forty-five aged individuals (means = 69.7 years) were studied polysomnographically for 2 or 3 nights with surface electrodes placed above the anterior tibialis. Results indicated that PLMS varied considerably from night to night within individuals, though there was not a significant difference between nights for the entire group. Some evidence indicated that individuals with less severe sleep complaints showed greater nightly variation. The nightly variation in PLMS was over four times as large as the nightly variation in breathing disturbance in sleep, another condition common in the sleep of the aged. These data suggest that studies relating PLMS to other key variables (e.g. symptoms of disturbed sleep) should rely on multiple nights of data or, if single night data are used, be particularly careful to replicate findings across samples.     

Comparison of respiratory polysomnographic parameters in matched cohorts of upper airway resistance and obstructive sleep apnea syndrome patients.

OBJECTIVE: To compare respiratory nocturnal polysomnography (NPSG) characteristics between matched cohorts of upper airway resistance syndrome (UARS) and obstructive sleep apnea syndrome (OSAS) patients. METHODS: All patients received 13-channel NPSG, including esophageal pressure (Pes) manometry. By definition, OSAS patients had an apnea-hypopnea index (AHI, number of apneas/hypopneas per hour total sleep time) > or = 15, and UARS patients had an AHI < 5. Respiratory effort-related arousal (RERA) was defined as the absence of apnea/hypopnea with > or = 10 s duration of progressive negative Pes, culminating in an arousal or microarousal. UARS patients, by definition, had > or = 15 RERAs per hour. Fifteen consecutively diagnosed UARS patients were matched with OSAS patients on the basis of body mass index (BMI) and gender. RESULTS: Respiratory disturbance index (sum of the AHI and RERA per hour) was the same for both cohorts: UARS, 36+/-4; OSAS, 42+/-6 (p = 0.34). There were no differences between cohorts for mean inspiratory Pes nadirs for each 30-s epoch of sleep compared for each sleep stage over an entire night. For randomly selected breaths from supine stage 2 sleep, the mean inspiratory Pes nadir was the same for the cohorts: UARS, -16.6+/-2 cm H2O; OSAS, -16.1+/-3 cm H2O (p = 0.30). Differences between cohorts for each parameter fell within respective 95% confidence intervals. CONCLUSION: With the exception of AHI, respiratory NPSG parameters were the same for UARS and OSAS patients when BMI and gender were controlled for.     

Prevalence of snoring and sleep-disordered breathing in a group of commercial bus drivers in Hong Kong

Objectives: To assess the prevalence of sleep‐­disordered breathing (SDB) and its associated symptoms in a group of commercial bus drivers in Hong Kong. Methods: Two hundred and sixteen of 410 bus drivers from three different shifts were interviewed with the Sleep & Health Questionnaire (SHQ) and the Epworth sleepiness scale (ESS) at a Hong Kong bus depot. Seventeen subjects from each shift were then randomly selected for at‐home sleep study using the Mesam IV device (Madaus Medizin?Elektronik, Freiburg, Germany). Results: There were 207 men and nine women (mean age 42.4 ± 7.5 years; body mass index (BMI) 25.4 ± 4.5 kg/m²; ESS 5.3 ± 4.2). From the SHQ it was discovered that: (i) daytime sleepiness was reported by 87 subjects (40%), (ii) snoring ≥ 3 times per week was reported by 80 subjects (37%), (iii) witnessed apnoea was reported by 17 subjects (7.9%) and (iv) 29 subjects (13.4%) reported having fallen asleep during driving. Among the 51 subjects who underwent the at‐home sleep study: (i) 31 subjects (61%) had respiratory disturbance index (RDI) ≥ 5 per hour of sleep, (ii) 21 subjects (41%) had RDI ≥ 10 per hour of sleep, (iii) 12 subjects (24%) had RDI ≥ 15 per hour of sleep and (iv) 35 subjects (68.6%) snored objectively ≥ 10% of the night. Ten subjects (20%) had RDI ≥ 5 and sleepiness at work, while five subjects (9.8%) had RDI ≥ 5 and ESS > 10. No significant differences were noted in the SHQ responses, ESS, objective snoring or RDI among the three groups. Multiple regression analysis showed that BMI and witnessed apnoea were the only positive independent predictors of RDI. Conclusions: This study showed a high prevalence of objective snoring and SDB in a group of commercial bus drivers. Neither self‐reported sleepiness nor the ESS could identify subjects with SDB. (Intern Med J 2002; 32: 149?157)     

The effect of hospitalization on the sleep pattern and on cortisol secretion of healthy elderly

The aim of this study was to verify whether polysomnography represents a stressful situation by assessing cortisol levels and the sleep pattern of healthy community-living elderly admitted to a sleep disorder center (SDC). Subjects slept for two sequential nights at the SDC for polysomnographic recordings. Blood was sampled at 0800 h, 1600 h, and 2300 h and 24-h urine was collected for cortisol determination. Three months later, subjects were visited at home for blood and urinary collections. Cortisol levels were higher in the SDC than at home at 0800 h but were lower at 2300 h and similar at 1600 h. No differences were observed in urinary cortisol. Polysomnographic recordings indicated a poorer sleep pattern in the first night. Our data indicate that a short-term stay of healthy elderly in a SDC disrupts sleep pattern in the first of 2 nights, without representing a stressful experience, as evaluated by cortisol levels.     

The Effect of Hospitalization on the Sleep Pattern and on Cortisol Secretion of Healthy Elderly

The aim of this study was to verify whether polysomnography represents a stressful situation by assessing cortisol levels and the sleep pattern of healthy community-living elderly admitted to a sleep disorder center (SDC). Subjects slept for two sequential nights at the SDC for polysomnographic recordings. Blood was sampled at 0800 h, 1600 h, and 2300 h and 24-h urine was collected for cortisol determination. Three months later, subjects were visited at home for blood and urinary collections. Cortisol levels were higher in the SDC than at home at 0800 h but were lower at 2300 h and similar at 1600 h. No differences were observed in urinary cortisol. Polysomnographic recordings indicated a poorer sleep pattern in the first night. Our data indicate that a short-term stay of healthy elderly in a SDC disrupts sleep pattern in the first of 2 nights, without representing a stressful experience, as evaluated by cortisol levels.     

Clinical associations between allergies and rapid eye movement sleep disturbances

Background

Allergic rhinitis, an immunoglobulin E inflammatory condition including nasal congestion, obstruction, sneezing, pruritus, and fatigue symptoms, has significant impact on quality of life and impairs sleep. Sleep‐disordered breathing (SDB) patients often have normal all‐night apnea‐hypopnea (AHI) or respiratory‐disturbance (RDI) indices on polysomnography (PSG). We hypothesized that the rapid eye motion–respiratory disturbance index (REM‐RDI) may be a novel predictor of allergic status.

Methods

A retrospective analysis of 100 patients compared REM‐RDI results in 67 allergen‐positive patients with 33 nonallergic patients who presented with nasal blockage. Subjects completed STOP‐Bang©, 22‐item Sino‐Nasal Outcome Test (SNOT‐22)©, and Epworth Sleepiness Scale© questionnaires and underwent skin‐prick testing (SPT) and PSGs including REM‐RDI values. Using multivariate logistic regression models, we evaluated relationships between allergic status and sleep parameters while controlling for possible confounders including body mass index (BMI).

Results

Using REM‐RDI as the outcome of interest, allergen‐positive patients were 3.92 times more likely to have REM‐RDI values in a moderate/severe range (≥15 events/hour); and patients with moderate/severe REM‐RDI values were more likely to be allergen positive (p < 0.05). Allergic status was not significantly related to all‐night AHI, RDI, or REM‐AHI. BMI was not significantly related to REM‐RDI. STOP‐Bang© was related to allergy status (p = 0.02) and REM‐RDI (p < 0.01). Allergic patients had increased REM latency and less total amount of REM.

Conclusion

We revealed significant bidirectional associations between allergen positivity and increased REM‐RDI values independent of BMI, AHI, RDI, and REM‐AHI. Allergic inflammation and REM‐RDI data may play important roles in diagnosing and treating fatigued SDB patients and as objective perioperative safety and outcomes measures.     

Systemic hypertension in sleep apnea syndrome. Relationship with sleep architecture and breathing abnormalities

To examine the possible relationship between systemic HT and SAS we compared 21 hypertensive (HT+) and 29 normotensive (HT-) patients for morphologic characteristics, sleep disturbances and respiratory events monitored during a full night polysomnography. There was no significant difference between HT+ and HT- patients with respect to age, weight, BMI, sleep stage distribution and disorganization, apnea-hypopnea index (number of episodes per hour of sleep) and duration (minutes per hour of sleep) nor O2 saturation indices: mean nocturnal and minimum O2 saturation. We conclude therefore that HT in SAS patients is not directly related to morphologic characteristics, sleep disturbances and breathing abnormalities.     

The effects of nasal anesthesia on breathing during sleep

Inability to breathe through the nose is an increasingly recognized cause of disordered breathing during sleep. To test the hypothesis that this respiratory dysrhythmia could result from loss of neuronal input to respiration from receptors located in the nose, we anesthetized the nasal passages of 10 normal men during sleep. Each subject spent 4 consecutive nights in the sleep laboratory while sleep stages, breathing patterns, respiratory effort, and arterial oxygen saturation were monitored. Night 1 was for acclimatization with Nights 3 and 4 being randomized to nasal spraying with either 4% lidocaine or placebo. On the lidocaine and placebo nights (Nights 3 and 4) the nasal passages were also sprayed with a decongestant to prevent increased nasal air-flow resistance resulting from mucosal swelling. To control for the possible effects of this decongestant, an additional night (Night 2) was included during which the nasal passages were sprayed with room air. Parallel studies conducted during wakefulness demonstrated low nasal resistance during the lidocaine-decongestant regimen. Because of the short duration of anesthesia with lidocaine, spraying was done at lights out and 2.5 and 5 h later. On the placebo night (decongestant plus saline) there were 6.4 +/- 1.8 (SEM) disordered breathing events (apneas plus hypopneas) per subject, whereas with lidocaine (plus decongestant) this increased fourfold to 25.8 +/- 7.8 events per subject (p less than 0.05). The majority of the disordered breathing events were apneas and were fairly evenly distributed between central and obstructive events. The magnitude of these changes is similar to that previously reported with complete nasal obstruction. These results suggest that nasal receptors sensitive to air flow may be important in maintaining breathing rhythmicity during sleep.     

Negative pressure ventilation. Effects on ventilation during sleep in normal subjects

Negative pressure ventilation (NPV) is used for ventilatory support of patients with respiratory failure due to neuromuscular disorders and thoracic deformities, and to provide ventilatory muscle rest for patients with severe chronic airflow limitation. To determine whether NPV would result in episodes of upper airway obstruction during sleep, we studied five normal subjects on two consecutive nights with the first night serving as a control and NPV being administered on the second night. Ventilators were adjusted so as to reduce the peak phasic diaphragm electromyogram signal by at least 50 percent. All subjects demonstrated an increase in the total number of apneas + hypopneas per hour on NPV control nights. Although differences were not significant, there was a tendency to develop decreased sleep efficiency, sleep fragmentation and altered sleep architecture with NPV. We conclude that nocturnal NPV can induce sleep apneas and impair sleep quality in normal subjects.