Carmen Garcia

Modulations of Heart Rate, ECG, and Cardio-Respiratory Coupling Observed in Polysomnography

The cardiac component of cardio-respiratory polysomnography is covered by ECG and heart rate recordings. However, their evaluation is often underrepresented in summarizing reports. As complements to EEG, EOG, and EMG, these signals provide diagnostic information for autonomic nervous activity during sleep. This review presents major methodological developments in sleep research regarding heart rate, ECG, and cardio-respiratory couplings in a chronological (historical) sequence. It presents physiological and pathophysiological insights related to sleep medicine obtained by new technical developments. Recorded nocturnal ECG facilitates conventional heart rate variability (HRV) analysis, studies of cyclical variations of heart rate, and analysis of ECG waveform. In healthy adults, the autonomous nervous system is regulated in totally different ways during wakefulness, slow-wave sleep, and REM sleep. Analysis of beat-to-beat heart-rate variations with statistical methods enables us to estimate sleep stages based on the differences in autonomic nervous system regulation. Furthermore, up to some degree, it is possible to track transitions from wakefulness to sleep by analysis of heart-rate variations. ECG and heart rate analysis allow assessment of selected sleep disorders as well. Sleep disordered breathing can be detected reliably by studying cyclical variation of heart rate combined with respiration-modulated changes in ECG morphology (amplitude of R wave and T wave).

Portable monitoring in sleep apnea

Portable sleep apnea monitoring or home testing for sleep-disordered breathing focuses on recent developments of these powerful diagnostic tools. Evidence-based reviews and innovative single studies with specific systems are considered. Systems become less intrusive and self applicable. Electrocardiogram-derived respiration, photoplethysmogram analysis, midsagittal jaw movements, and respiratory sound analysis are reviewed. Categories of systems with 4 to 6 channels and 1 to 3 channels are introduced and presented. The importance of a high pretest probability is elucidated. Open research questions regarding these systems are mentioned. Technological issues are not most important in this debate. The health economic aspects in using portable sleep apnea monitoring have to be considered as well. Portable monitoring of sleep apnea is probably less expensive than cardiorespiratory polysomnography and can help to overcome the limited availability of sleep lab-based diagnostic places. But by increasing the quantity of investigations it may cause additional costs too.

Diagnostik schlafbezogener Atmungsstörungen mittels portabler Verfahren

Portable monitoring of sleep disordered breathing is the first diagnostic method not only in Germany but today in other countries as well. The conditions under which portable monitoring can be done with reliable results are now well defined. The limitations for the use of portable monitoring are specified as well. The devices used for portable monitoring are classified in four categories according to the number and the kind of signals recorded. New technical developments in the field of portable monitoring (polygraphy) use an indirect assessment of sleep disordered breathing based on signals not directly recording respiration. The recording of ECG and deriving respiration, the analysis of the plethysmographically recorded pulse wave, the recording of jaw movements using magnets, and advanced analysis of respiratory sounds are recent approaches. These new methods are presented with few studies until now. More and larger clinical studies are needed in order to show which of these systems is useful in the diagnosis of sleep disordered breathing and which are the specific strengths and weaknesses.

Herzfrequenz und EKG in der Polysomnographie

ZusammenfassungDie Aufzeichnung des Elektrokardiogramms (EKG) und der Herzfrequenz sind integrale Bestandteile der kardiorespiratorischen Polysomnographie. In Ergänzung zu den neurophysiologischen Parametern erlauben diese Signale eine Bewertung der autonomen Regulation während des Schlafs. Eine Auswertung des nächtlichen EKG in Bezug auf zyklische Schwankungen der Herzfrequenz kombiniert mit atmungsabhängigen Veränderungen der EKG-Morphologie (Amplitude der R-Zacke, T-Welle) erlaubt ein zuverlässiges Erkennen von schlafbezogenen Atmungsstörungen. Eine Auswertung der Schlag-zu-Schlag-Regulation der Herzfrequenz erlaubt eine Abschätzung der Schlafstadien aufgrund der grundsätzlich verschiedenen Regulation des autonomen Nervensystems im Tiefschlaf und im REM-Schlaf. Auch Übergänge vom Wachen in den Schlaf sind aus dem Verlauf der Herzfrequenz ablesbar.In diesem Beitrag wird die technische Entwicklung der Analyse im historischen Ablauf von 1980 bis 2015 dargestellt sowie der sich aus der technischen Entwicklung ergebende physiologische und pathophysiologische Erkenntnisgewinn gezeigt.AbstractThe recording of ECG and heart rate are indispensable parameters of cardiorespiratory polysomnography. Complementing neurophysiological signals this allows an assessment of the autonomous nervous regulation during sleep. An evaluation of the nocturnal ECG is possible in terms of cyclical variations of heart rate and in terms of respiration modulated changes of ECG morphology (amplitude of R wave and T wave). This provides a reliable estimation of sleep disordered breathing. The autonomous nervous system is regulated in a totally different way during slow wave sleep and during REM sleep. An assessment of beat-to-beat variability of heart rate allows deriving sleep stages based on the difference in autonomous nervous system regulation. In addition the transitions from wakefulness to sleep can be tracked to some degree by an analysis of heart rate variability.This paper presents the technical development of the analysis in a historical sequence from 1980 to 2015. Linked to this the increase in physiological and pathophysiological knowledge derived from the technical developments is presented.

Sleep Detection Using a Depth Camera

The work at hand presents a method to assess the quality of human sleep within a non-laboratory environment. The monitoring of patients is performed by means of a Kinect device. This results in a non-invasive method which is independent of immediate physical contact to subjects. The results of a study which was carried out as proof of concept are discussed and compared with the polysomnography-based gold standard of sleep analysis.

The SIESTA database and the SIESTA sleep analyzer

Sleep research and sleep medicine require the recording of biosignals during sleep and their subsequent analysis. The sleep recording is called cardiorespiratory polysomnography. Currently the analysis of the recorded signals is performed by experienced and certified sleep technicians. In addition to visual sleep scoring many attempts had been made to develop computer assisted sleep analysis. In order to develop a computer assisted sleep analysis a systematic database with sleep recording from 200 healthy subjects and of 100 subjects with selected sleep disorders of high prevalence had been compiled as part of a European Commission funded research project. This database was the start for a normative polysomnography database and for the development of a computer based sleep analysis. The computer based sleep analysis is available as an internet service and is now used by many sleep centers for sleep research questions and clinical sleep evaluation in patients with sleep disorders.

P14.2 Influence of slow oscillating transcranial direct current stimulation (so-tDCS) on electroencephalogram (EEG) in general and sleep related parameters in healthy subjects

Introduction: Recent fMRI studies (Owen et al, Science, 2006; Monti et al, NEJM 2010) showed the possibility to use the voluntary modulation of mental states for detecting the residual level of awareness in patients with Disorders of Consciousness (DOC) and for implementing tools for binary communication. Objectives: In order to transfer the paradigms used in fMRI to the more portable EEG technique, this study aims at investigating the possibility to retrieve distinguishable activation patterns during different imagery tasks, by using advanced high resolution EEG methodology in the time and frequency domains. Methods: 61-channels EEG was recorded from 15 healthy volunteers during the execution of three imagery tasks, Playing Tennis (T), Prolonged Grasping (G) and Spatial Navigation in a domestic environment (N), and during Relax (R). EEG traces were projected on a cortical model by solving the electromagnetic linear inverse problem. Power Spectrum Density was computed on cortical waveforms and averaged in four frequency bands (Theta, Alpha, Beta and Gamma). T-tests for a significance level of 5%, corrected with False Discovery Rate, were performed for T-R, N-R and G-R comparisons and mapped on a cortical model. Results: Statistical maps showed a partial spatial overlapping between cortical areas involved in the execution of the three imagery tasks (T, G, N). However, the specific contribution in different frequency bands (Alpha for the two motor tasks and Beta for the navigation task) allows to separate the imaginative tasks. Conclusions: Results suggest that the high resolution EEG spectral mapping can be an effective way to address the analysis of imaginative functions, allowing to discriminate different mental states without the limitations of the use of an fMRI scanner, with important implications for DOC oriented Brain Computer Interface applications. Acknowledgements: This work was supported by the European ICT Program FP7-ICT-2009 4 Grant Agreement 247919 DECODER.

Improved follow-up by peripheral arterial tonometry in CPAP-treated patients with obstructive sleep apnea and persistent excessive daytime sleepiness

BackgroundOSA-patients with persistent excessive daytime sleepiness (EDS) despite CPAP treatment are challenging in daily clinical life. To rule out residual sleep-disordered breathing (SDB), CPAP device-derived data are used in outpatient setting. In case of no pathological finding, a more intensive work-up with is necessary. 6-channel portable monitoring (6Ch-PM) is frequently used to exclude residual SDB. Peripheral arterial tonometry (PAT), as embodied in the WatchPAT device, represents an alternative technique for detecting SDB based on changes in autonomic tone. We wanted to investigate whether PAT might be a useful tool to improve diagnostic work-up in this specific patient group by better identifying residual SDB due to insufficient CPAP-adjustment.MethodsForty-nine OSA patients (39 male, 10 female) with sufficient CPAP treatment according to device-derived data were consecutively recruited. EDS was assessed by Epworth Sleepiness Scale (ESS). All patients underwent home-based CPAP therapy control by 6Ch-PM and portable monitoring using PAT technology on two consecutive nights. A sequence of both types of monitoring was randomized to prevent possible first night effect bias.ResultsTwelve out of 49 patients showed persistent EDS according to ESS (ESS > 10 points). 6Ch-PM showed a residually increased AHI under CPAP-treatment in 2 of those 12 subjects (positive predictive value, PPV = 16.7%). PAT-PM revealed 5 patients of those 12 with residual SDB (PPV = 41.7%).ConclusionPAT could detect significantly more residual SDB under CPAP treatment than 6Ch-PM. Diagnostic work-up of CPAP-treated OSA patients with persistent EDS might be optimized, as insufficient pressure level adjustments could be recognized more precisely in time, possibly preventing more resource-consuming procedures, and potentially increased morbidity.Clinical trial registrationDRKS00007705

The effect of cranial electrotherapy stimulation on sleep in healthy women

OBJECTIVE Cranial electrotherapy stimulation (CES) is considered to be a potential treatment for insomnia. Women are more likely to suffer from insomnia than men. Therefore we studied the effect of CES on sleep efficiency in young healthy women. METHODS A randomized, controlled clinical study was conducted on 40 women (age 18-35 years) without sleep disorders. Each subject underwent two nights of polysomnography in a sleep center. During the second night, we applied CES with a commercial device (Alpha-Stim 100) using either active or sham stimulation (double-blinded). Sleep was evaluated with respect to differences between the active and sham modes. Sleep electroencephalogram (EEG) analysis was applied to determine frequency changes. RESULTS In our study we found no evidence of any direct influence of the Alpha-Stim 100 on sleep. After application of CES, we determined no significant differences between the active group and the control group (sham). Using EEG spectral analysis there was evidence of a frequency-lowering influence on the low-α frequency band (8-10 Hz). CONCLUSIONS At most we may assume a reproducible effect on the α frequency measured in the EEG for application of CES with current levels  >100 µA and presumably also with frequencies  >0.5 Hz, with application directly at the cranium. We found no influence on sleep parameters. The effect on the low-α band evidenced in quantitative EEG analysis would require further investigation in a study with sufficient effect size. SIGNIFICANCE This is the first study to investigate the effects of CES with polysomnography during and after therapy. Our study contributes to the few controlled trials that have been conducted to study CES and its effects on the EEG α band. Highlights • This is the first study to investigate the effects of the Alpha-Stim in polysomnography during and subsequent to therapy. • In a quantitative electroencephalogram analysis we studied the data obtained for systematic changes. • To minimize placebo effects in patients with sleep disorders, we conducted the tests on subjects without such disorders.

Prevalence and association analysis of obstructive sleep apnea with gender and age differences - Results of SHIP-Trend

Identification of obstructive sleep apnea and risk factors is important for reduction in symptoms and cardiovascular risk, and for improvement of quality of life. The population‐based Study of Health in Pomerania investigated risk factors and clinical diseases in a general population of northeast Germany. Additional polysomnography was applied to measure sleep and respiration with the objective of assessing prevalence and risk factors of obstructive sleep apnea in a German cohort. One‐thousand, two‐hundred and eight people between 20 and 81 years old (54% men, median age 54 years) underwent overnight polysomnography. The estimated obstructive sleep apnea prevalence was 46% (59% men, 33% women) for an apnea–hypopnea index ≥5%, and 21% (30% men, 13% women) for an apnea–hypopnea index ≥ 15. The estimated obstructive sleep apnea syndrome prevalence (apnea–hypopnea index ≥5; Epworth Sleepiness Scale >10) was 6%. The prevalence of obstructive sleep apnea continuously increased with age for men and women with, however, later onset for women. Gender, age, body mass index, waist‐to‐hip ratio, snoring, alcohol consumption (for women only) and self‐reported cardiovascular diseases were significantly positively associated with obstructive sleep apnea, whereas daytime sleepiness was not. Diabetes, hypertension and metabolic syndrome were positively associated with severe obstructive sleep apnea. The associations became non‐significant after adjustment for body mass. Women exhibited stronger associations than men. The prevalence of obstructive sleep apnea was high, with almost half the population presenting some kind of obstructive sleep apnea. The continuous increase of obstructive sleep apnea with age challenges the current theory that mortality due to obstructive sleep apnea and cardiovascular co‐morbidities affect obstructive sleep apnea prevalence at an advanced age. Also, gender differences regarding obstructive sleep apnea and associations are significant for recognizing obstructive sleep apnea mechanisms and therapy responsiveness.