Empfehlungen zur computergestützten Aufzeichnung und Auswertung von Polygraphien

Technology to Detect Driver Sleepiness

This article reports on sleepiness, drowsiness, tiredness, and fatigue. An assessment of sleepiness can be done with electroencephalograms, electrooculograms, and electromyograms in validated tests, such as the multiple sleep latency test and the maintenance of wakefulness test. These 2 tests serve as references for quantitative assessment of daytime sleepiness and drowsiness. Correlates for sleepiness, such as reaction time tests, can be used but are less reliable. Questionnaires are self-administered and popular measures for perceived sleepiness. Driver drowsiness assessment is an important part of sleep laboratory testing, because European Union regulations require assessments due to risk of accidents in patients with sleep disorders.

The Narcotrend monitor and the electroencephalogram in propofol-induced sedation

BACKGROUND

The Narcotrend (NCT) is a one-channel electroencephalogram (EEG) monitor of the level of sedation. It is based on a visual EEG scoring system, which was developed by Loomis and modified by Kugler, to yield a visual expert classification (VEC) scheme for differentiation of six levels of sedation (A-F), which are subdivided into 16 substages. We designed the present study to test whether results of the automated classification of one-channel NCT input reflect those from VEC of five-channel EEG.

METHODS

Twelve healthy male volunteers received propofol using two different infusion regimens in a randomized, crossover design with concomitant NCT monitoring and VEC. Scoring results of NCT were compared with those of VEC.

RESULTS

During the infusion period, score differences of more than three substages were observed in 14 of 24 (= 58%) propofol administrations (4%-7% of total data). Often, the NCT indicated lighter sedation than VEC, which revealed more delta activity from nonfrontal leads. During recovery, NCT reported deeper sedation than VEC in 6 of 24 (= 25%) propofol administrations. Discordant trends (periods of at least five subsequent epochs with monotonic, but opposite trends for both NCT and VEC) were noted in 9 of 24 propofol administrations (37%). Furthermore, NCT had several periods when no staging information was displayed, varying from a few seconds to 10 min.

CONCLUSIONS

As the algorithm of NCT is proprietary and not accessible to the public, reasons for the observed differences between NCT and VEC cannot be analyzed and explanations must remain speculative.

European guidelines for the accreditation of Sleep Medicine Centres

This document describes guidelines for accreditation of Sleep Medicine Centres in Europe. These guidelines are the result of a consensus procedure, in which representatives of the European Sleep Research Society (ESRS) and representatives of different European National Sleep Societies (ENSS) were involved. The information obtained during different rounds of consultation was gathered and processed by the members of the Steering Committee of the ESRS. The scope of the guidelines is to define the characteristics of multidisciplinary Sleep Medicine Centres (SMCs), in terms of requirements regarding staff, operational procedures and logistic facilities. Accreditation of SMCs is proposed to be the responsibility of the individual ENSS. The Accreditation Guidelines may thus be considered an instrument for the national societies to develop new or standardize existing accreditation questionnaires, as well as procedures for visiting the site, drafting the accreditation report, and finally, granting the accreditation. The Accreditation Guidelines are meant to be a line of action, that ideally should be followed as close as possible, but that may be subject to certain exceptions, depending on local customs or regulations.

Peripheral arterial tonometry, oximetry and actigraphy for ambulatory recording of sleep apnea

Autonomous nervous functions change with sleep stages and show characteristic changes associated with sleep disorders. Therefore, continuous monitoring of autonomous nervous functions during sleep can be used for diagnostic purposes. Recently, the peripheral arterial tonometry (PAT) has been introduced to determine peripheral arterial vascular tone on the finger being determined by sympathetic activity. We investigate a new ambulatory recording system which uses PAT, oximetry and actigraphy (Watch-PAT) in order to detect sleep apnea and arousal. The Watch-PAT is battery operated and attached to the wrist and has two finger sensors. Twenty-one patients with suspected sleep apnea were recorded with cardiorespiratory polysomnography and the new system in parallel. Seventeen recordings could be evaluated. The correlation for the apnea/hypopnea index derived from the sleep laboratory and the respiratory disturbance index derived from the Watch-PAT was r = 0.89 (p < 0.01) and between arousals and the respiratory disturbance index was r = 0.77 (p < 0.01). The correlation for the total sleep time compared between the two systems was r = 0.15 (n.s.). The Watch-PAT detects apneas and hypopneas with a reasonable reliability and it is very sensitive to arousals. The number of Watch-PAT events lies between the sum of apneas plus hypopneas and arousals. Arousals are not unique to apnea events and therefore the specifity of the Watch-PAT is limited. In conclusion, the Watch-PAT is well suited to perform therapy control studies in patients suffering from sleep apnea and being treated.

A method for automated temporal knowledge acquisition applied to sleep-related breathing disorders

This paper presents a method for the discovery of temporal patterns in multivariate time series and their conversion into a linguistic knowledge representation applied to sleep-related breathing disorders. The main idea lies in introducing several abstraction levels that allow a step-wise identification of temporal patterns. Self-organizing neural networks are used to discover elementary patterns in the time series. Machine learning (ML) algorithms use the results of the neural networks to automatically generate a rule-based description. At the next levels, temporal grammatical rules are inferred. This method covers one of the main "bottlenecks" in the design of knowledge-based systems, namely, the knowledge acquisition problem. An evaluation of the rules lead to an overall sensitivity of 0.762, and a specificity of 0.758.

Computer based sleep recording and analysis

Sleep analysis is based on polysomnography. Modern polysomnographic systems are computer based. Visual and automatic analysis of sleep and respiration is supported by most computer based systems. Four functions can be distinguished in computer based polysomnography: recording, documentation during the recording, automatic and visual analysis and report generation. This review compiles the minimal requirements for digital sleep recording, documentation, analysis and reporting. The basic principles of automatic sleep analysis are reported. The requirements and the basic principles for the analysis of non-electroencephalography (EEG) signals, such as respiration, snoring, oxygen saturation, electrocardiography (ECG) and options are reported. New developments in sleep EEG processing are discussed to enlighten how computer based sleep analysis can add quantative parameters to the rules for visual sleep staging established by Rechtschaffen and Kales 30 years ago. This helps to extend our understanding of sleep.