Christoph Schöbel

Effectively incorporating selected multimedia content into medical publications.

Until fairly recently, medical publications have been handicapped by being restricted to non-electronic formats, effectively preventing the dissemination of complex audiovisual and three-dimensional data. However, authors and readers could significantly profit from advances in electronic publishing that permit the inclusion of multimedia content directly into an article. For the first time, the de facto gold standard for scientific publishing, the portable document format (PDF), is used here as a platform to embed a video and an audio sequence of patient data into a publication. Fully interactive three-dimensional models of a face and a schematic representation of a human brain are also part of this publication. We discuss the potential of this approach and its impact on the communication of scientific medical data, particularly with regard to electronic and open access publications. Finally, we emphasise how medical teaching can benefit from this new tool and comment on the future of medical publishing.

Impact of SERVE-HF on management of sleep disordered breathing in heart failure: a call for further studies

Sleep disordered breathing (SDB) (obstructive sleep apnea, central sleep apnea/Cheyne–Stokes respiration or the combination of both) is highly prevalent in patients with a wide variety of cardiovascular diseases including hypertension, arrhythmia, coronary artery disease, myocardial infarction and stroke (reviewed previously in the September issue of this journal). Its close association with outcomes in chronic heart failure with reduced ejection fraction (HF-REF) suggests that it may be a potential treatment target. Herein, we provide an update on SDB and its treatment in HF-REF.

Effect of CPAP therapy on daytime cardiovascular regulations in patients with obstructive sleep apnea

Obstructive sleep apnea (OSA) is a sleep disorder with a high prevalence that causes pathological changes in cardiovascular regulation during the night and also during daytime. We investigated whether the treatment of OSA at night by means of continuous positive airway pressure (CPAP) improves the daytime consequences. Twenty-eight patients with OSA, 18 with arterial hypertension, 10 with normal blood pressure, were investigated at baseline and with three months of CPAP treatment. Ten age and sex matched healthy control subjects were investigated for comparisons. We recorded a resting period with 20min quiet breathing and an exercise stress test during daytime with ECG and blood pressure (Portapres). The bicycle ergometry showed a significant reduction of the diastolic blood pressure at a work load of 50W and 100W (p<0.05 and p<0.01, respectively) and a decrease of the heart rate recovery time after the stress test (p<0.05). These results indicate a reduction of vascular resistance and sympathetic activity during daytime. The coupling analysis of the resting periods by means of symbolic coupling traces approach indicated an effect of the CPAP therapy on the baroreflex reaction in hypertensive patients where influences of the systolic blood pressure on the heart rate changed from pathological patterns to adaptive mechanisms of the normotensive patients (p<0.05).

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.

Addendum zum Positionspapier „Schlafmedizin in der Kardiologie. Update 2014“

Somnologie 2017 · 21:51–52 DOI 10.1007/s11818-017-0104-x Online publiziert: 6. Februar 2017

Estimating sleep disordered breathing based on heart rate analysis

Heart rate variability and the analysis of the ECG with ECG derived respiration has been used to diagnose sleep disordered breathing. Recently it was possible to distinguish obstructive sleep apnea and central sleep apnea. This can be achieved by analyzing both, heart rate variability and the more mechanically induced ECG derived respiration in parallel. In addition the analysis of cardiopulmonary coupling facilitates to predict the personal risk factor for cardiovascular disorders. The analysis of heart rate, ECG and respiration goes beyond this analysis. Some studies indicate that it is possible to derive sleep stages from these signals. In order to derive sleep stages a more complex analysis of the signals is applied taking into account non-linear properties by using methods of statistical physics. To extract coupling information supports the distinction between sleep stages. Results are reported in this review.

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.

Characterization of Respiratory Events in Obstructive Sleep Apnea Using Suprasternal Pressure Monitoring

STUDY OBJECTIVES In obstructive sleep apnea (OSA) esophageal pressure (Pes) is the gold standard for measurement of respiratory effort, and respiratory inductance plethysmography (RIP) is considered an accepted measurement technique. However, the use of RIP could lead to limited accuracy in certain cases and therefore suprasternal pressure (SSP) monitoring might improve the reliability of OSA diagnosis. We aimed to use SSP for the visual characterization of respiratory events in adults and compared results to those obtained by RIP from polysomnography (PSG). METHODS In patients with OSA, a 1-night SSP recording using the PneaVoX sensor (Cidelec, Sainte-Gemmes-sur-Loire, France) was done. In parallel, PSG was performed according to American Academy of Sleep Medicine criteria. A subgroup of patients agreed to have Pes measurement in addition. Characterizations of apneas as obstructive, central, and mixed as well as hypopneas as central and obstructive were done by visual evaluation of SSP, RIP, and Pes in random order by two independent scores (S1 and S2). The sensitivity and specificity of characterization by SSP compared to RIP and to Pes were calculated. RESULTS Synchronous recordings of SSP and PSG were analyzed from n = 34 patients with OSA (AHI 34.1 ± 24.2 events/h); 9 of them had synchronized Pes monitoring as well. Interscorer agreement for apnea characterization as obstructive, central, and mixed based on SSP, RIP, and Pes were found, with R2 values from 0.91-0.99. The sensitivity of SSP in apnea characterization with reference to RIP (S1/S2) was 91.5%/92.3% for obstructive, 82.7%/76.2% for central, and 87.4%/79.9% for mixed. The sensitivity of SSP in apnea characterization with reference to Pes was (S1/S2) 93.1%/92.1% for obstructive, 80.8%/81.6% for central, and 91.7%/90.8% for mixed. Hypopnea was only classified for the nine patients with Pes. CONCLUSIONS This study demonstrated a good agreement in the detection of respiratory effort with the SSP signal using the PneaVoX sensor compared to the RIP belts signals as well as to the Pes signal. These findings were consistently found by two independent scorers. In summary, results suggest that SSP is a reliable signal for the classification of respiratory events and could be used as an additional tool for OSA characterization in clinical practice.

Revised recommendations for computer-based sleep recording and analysis

Sleep recording is the quantitative method used in sleep centers in order to assess sleep disorders and to quantify pathological events occurring during sleep. Cardiorespiratory polysomnography is the method used for sleep recording. Standards for sleep recording stem back to 1968 and were compiled by Rechtschaffen and Kales with specifications for recording and analysis of the sleep EEG. An update considering digital technology and possibly computer based analysis techniques was needed. As the result of a two year process with a large committee in 2007 a revised manual was published. The manual includes for the first specifications for digital signals acquisition and some descriptions for developing computer based sleep analysis. The new manual was prepared using the formal tools of evidence based medicine. The method for preparing the new manual are presented critically the results relevant for computer based sleep recording and analysis are presented in detail and perspectives for computer based sleep analysis are pointed out.