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Introduction: Excessive daytime sleepiness (EDS) is a frequent symptom with many possible causes, and many of these can be treated. EDS and its underlying causes have been associated with various negative health consequences. Recognition of EDS is thus an important public health concern. The concept of EDS is, however, not yet well defined, and different measures are used to diagnose EDS. The Epworth Sleepiness Scale (ESS) is the most widely used tool to assess daytime sleepiness in a broad range of populations. Its applicability in patients exhibiting physical or mental disabilities, like older multimorbid patients, is limited, since the ESS was not developed and validated in this patient group. Methods: Within an expert study with 35 sleep medicine experts and a pilot study with 52 geriatric in-patients, who frequently exhibit physical or mental disabilities, and patients' close relatives, we adapted the original ESS to develop an alternative version to assess daytime sleepiness in adults with physical or mental disabilities (ESS-ALT). Results: In this adapted version, items 3 (sitting inactively in a public place) and 8 (sleepy in traffic) were replaced by 2 new items (sitting in a waiting room, sitting and eating a meal) and an interview format was used. This ESS-ALT achieved fewer missing responses (23 vs. 73%) and a higher level of internal consistency (Cronbach's α = 0.64 vs. 0.23) than the original ESS while keeping its somnificity structure. Conclusion: The ESS-ALT achieves better psychometric properties than the original ESS for individuals with physical or mental disabilities. [ABSTRACT FROM AUTHOR]

Background: Sleep-related breathing disorders may promote cardiovascular (CV) diseases. A novel and differentiated approach to overnight photoplethysmographic pulse wave analysis, which includes risk assessment and measurement of various pulse wave characteristics, has been evaluated in obstructive sleep apnea (OSA). Objectives: The purpose of this study was to assess if and which of the differentiated pulse wave characteristics might be influenced by OSA treatment with positive airway pressure (PAP). Methods: The study included two protocols. In the case-control study (group A), pulse wave-derived CV risk indices recorded during PAP therapy were compared with those obtained in age, body mass index, and CV risk class-matched patients with untreated OSA (n = 67/67). In the prospective PAP treatment study (group B), 17 unselected patients undergoing a full-night sleep test at baseline and after 23 ± 19 weeks of treatment were analyzed. Results: In untreated OSA patients (group A), the overnight hypoxic load was increased (SpO 2 index 38.7 ± 17.5 vs. 24.0 ± 11.1, p < 0.001) and the pulse wave attenuation index (PWA-I) was lower (29.4 ± 9.2 vs. 33.5 ± 11.8, p = 0.022) than in treated patients. In group B, PAP therapy reduced the hypoxic load and increased the PWA-I significantly. The composite CV risk index was slightly but not significantly reduced. Conclusions: PAP therapy modified the hypoxic load and pulse wave-derived markers. The PWA-I - associated with sympathetic vascular tone - was most prominently modified by PAP. This novel approach to markers of CV function should be further evaluated in prospective studies. [ABSTRACT FROM AUTHOR]

Background: Expiratory pressure relief continuous positive airway pressure (pressure relief CPAP, C-Flex®) is known to be as effective in the treatment of obstructive sleep apnea (OSA) as conventional CPAP while improving overall patients’ adherence. However, the effects of C-Flex on ventilation during sleep have not been studied yet. Objective: This study investigates the effects of pressure relief CPAP on respiratory parameters and possible inspiratory flow limitation with increased difference between inspiratory and expiratory pressure compared with conventional CPAP. Methods: In total, 24 patients were investigated both during conventional CPAP and during three C-Flex pressure relief settings in randomized order during rapid-eye-movement (REM) and non-REM (NREM) sleep. Airflow was monitored with a pneumotachograph; inspiratory flow limitation was assessed by analyzing airflow and esophageal pressure swings. Results: Using higher C-Flex gains, expiratory time decreased in favor of the inspiratory duty cycle while there was no significant change in tidal volume. Analysis of inspiratory flow limitation showed no significant difference between conventional CPAP and the C-Flex gains studied. Conclusions: The increase in the inspiratory duty cycle with C-Flex might either indicate an increase in the work of breathing or a decrease in the work of breathing due to a lower peak end-expiratory pressure and consecutive alleviation of passive expiration. Both treatments appeared equivalent regarding the occurrence of inspiratory flow limitation. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea (OSA) is a recognized risk factor for cardiovascular disorders. Thus, an association between endothelin-1 (EDN1) and OSA can be assumed. We investigated a cohort of 364 consecutive patients (age 57 ± 10 years) with mild to severe OSA for the EDN1 variant Lys198Asn (G/T) and endothelin plasma levels and compared them with 57 controls. The Lys198Asn genotype was significantly associated with the apnea/hypopnea index (AHI) with a median of 30/h of sleep for GG, 27/h for GT and 59/h for TT genotype (p < 0.05). Further stratification of patients into 2 groups by body mass index (BMI) revealed a strong association between AHI and Lys198Asn polymorphism in 191 obese patients (p = 0.005), whereas in 173 nonobese patients, we observed no association. A substantial effect by BMI on OSA severity was seen with multiple linear regression (p < 0.001). However, this effect was modified by the Lys198Asn polymorphism and by gender: the AHI increase per unit of BMI was more pronounced in males than in females, and about 1.3 times greater in homozygous carriers of the mutant allele than in other carrier groups. EDN1 plasma levels of untreated OSA patients and of patients treated with nasal continuous positive airway pressure were not elevated compared with controls. Our results indicate that the Lys198Asn polymorphism is associated with the severity of OSA in obese subjects. The EDN1 plasma level cannot be used as a marker for OSA or its severity. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: The optimal approach to initiate positive-pressure therapy in patients with obstructive sleep apnea is still debated. Current options are autotitrating positive airway pressure (APAP) or manual titration with continuous positive airway pressure (CPAP). Procedures differ by parameters and by algorithms used for adapting pressure. Objectives: To evaluate the efficacy of attended automatic titration in a randomized crossover study compared with manual titration over 2 nights where the sequence of the titration mode was changed. Therapy outcome was controlled after 6 weeks. Methods: 21 sleep apnea patients were treated using manual CPAP versus automatic APAP titration. The mode used during the 2nd night was continued for 6 weeks. Cardiorespiratory polysomnography, Epworth Sleepiness Scale (ESS), SF-36 score and compliance were assessed. Results: Apnea-hypopnea index reduction was equally effective at similar effective pressure independent of the titration mode. If APAP was applied during the 1st night, total sleep time was longer (384 vs. 331 min, p < 0.01) and sleep efficacy was higher (91 vs. 81%, p < 0.01) than after starting with manual titration with CPAP. Compliance was comparable in both groups (4.6 ± 1.9 h). The ESS improved in both groups (from 12.9 to 6.5). SF-36 scores and therapeutic pressure did not much change. Conclusions: Taking the sequence of titration into account, we found equal effectiveness of CPAP and APAP. Sleep quality was better with initial application of APAP – which favors attended automatic titration if only 1 titration night is possible. Both modes are comparable after 6 weeks regarding therapeutic pressure, efficacy, compliance and quality of life. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

To date, the only standard for the classification of sleep-EEG recordings that has found worldwide acceptance are the rules published in 1968 by Rechtschaffen and Kales. Even though several attempts have been made to automate the classification process, so far no method has been published that has proven its validity in a study including a sufficiently large number of controls and patients of all adult age ranges. The present paper describes the development and optimization of an automatic classification system that is based on one central EEG channel, two EOG channels and one chin EMG channel. It adheres to the decision rules for visual scoring as closely as possible and includes a structured quality control procedure by a human expert. The final system (Somnolyzer 24 × 7™) consists of a raw data quality check, a feature extraction algorithm (density and intensity of sleep/wake-related patterns such as sleep spindles, delta waves, SEMs and REMs), a feature matrix plausibility check, a classifier designed as an expert system, a rule-based smoothing procedure for the start and the end of stages REM, and finally a statistical comparison to age- and sex-matched normal healthy controls (Siesta Spot Report™). The expert system considers different prior probabilities of stage changes depending on the preceding sleep stage, the occurrence of a movement arousal and the position of the epoch within the NREM/REM sleep cycles. Moreover, results obtained with and without using the chin EMG signal are combined. The Siesta polysomnographic database (590 recordings in both normal healthy subjects aged 20–95 years and patients suffering from organic or nonorganic sleep disorders) was split into two halves, which were randomly assigned to a training and a validation set, respectively. The final validation revealed an overall epoch-by-epoch agreement of 80% (Cohen’s kappa: 0.72) between the Somnolyzer 24 × 7 and the human expert scoring, as compared with an inter-rater reliability of 77% (Cohen’s kappa: 0.68) between two human experts scoring the same dataset. Two Somnolyzer 24 × 7 analyses (including a structured quality control by two human experts) revealed an inter-rater reliability close to 1 (Cohen’s kappa: 0.991), which confirmed that the variability induced by the quality control procedure, whereby approximately 1% of the epochs (in 9.5% of the recordings) are changed, can definitely be neglected. Thus, the validation study proved the high reliability and validity of the Somnolyzer 24 × 7 and demonstrated its applicability in clinical routine and sleep studies. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]