075 UNATTENDED HOME TITRATION OF ADAPTIVE PRESSURE SUPPORT SERVO-VENTILATION

Abstracts of 3rd International Congress of the Association of Sleep Medicine (WASM) / Sleep Medicine 10, Suppl. 2 (2009) S1–S83

patient groups and OSAS SEM latencies were significantly shorter than normal MSLT patient SEM latencies (0.000≤p≤0.003). In the last study the mean SEM latency performed comparably to the standard sleep onset evidenced in both the MSLT (p=0.25) and the MWT (p=0.45) settings and significantly correlated with the sleep latency on both tests (p<0.05). Conclusion: Our algorithm is a reliable tool for automatic SEM detection. SEMs can be easily detected automatically and represent an effective marker of sleepiness in those conditions usually characterized by sleep onset with NREM sleep. Furthermore, automatic SEM detection was comparable to the standard polysomnographic assessment of sleep onset, thus providing a simplified technical requirement for the MSLT and the MWT. Further studies are warranted to evaluate SEM detection in other sleep disorders.

075

UNATTENDED HOME TITRATION OF ADAPTIVE PRESSURE SUPPORT SERVO-VENTILATION

M. González, L. Serra, F. Descalzi, N. Araya, A. Peña, A. de Marinis. Clínica Alemana de Santiago, Chile Non-invasive positive pressure ventilation is the gold standard for treating most sleep-related breathing disorders in adults, mainly with CPAP (Continuous Positive Airway Pressure). Nevertheless, patients other than typical obstructive sleep apnea (OSA) sufferers tend to respond poorly to this therapy. Recently, a modified type of ventilatory therapy called adaptive pressure support servo-ventilation (ASV) that is more adequate for patients with Idiopathic Central Sleep Apnea -ICSA-, Periodic Breathing (i.e., CheyneStokes Breathing -CSB-) and Complex Sleep Apnea Syndrome (CompSA) was developed. Unattended home titration using auto-CPAP devices is an accepted alternative for selected patients with OSA. Since ASV is capable of selfadjusting to the patient’s ventilatory requirements in predefined conditions, we performed a domiciliary titration protocol in patients with indications of ASV. Four consecutive males were recruited, 2 with ICSA and two with compSA, one with additional CSB. All patients were previously diagnosed by a sleep physician using polysomnography; mask fitting and ASV training was carried out by a specialized nurse, and patients took the device home for use during at least three consecutive nights. In addition to parameters registered by the Resmed AutoSet CS2® equipment, pulse oximetry recording was included in two cases. Outcomes measured were polysomnographic parameters compared to patients’ basal and/or CPAP titration studies. Patients were 61.7 (±17.6) years old, with BMI of 29.82 kg/m2 (±6.27). Basal AHI index was 61.7 events/h (±30.4), with 77-89% of central apneas in ICSA cases, rising from 20-25% to 75% in the CompSA cases. End Espiratory Pressure increase was required in all patients in order to control obstructive events (6 to 8 cms. of H2O). With ASV, AHI decreased to 12.7 events/h (±6.9), increasing minimum oxygen saturation and reducing arousals and time spent with oxygen saturation below 90% to a mean of 2.6 (±2.8) compared to baseline 44.7 (±39.2) and CPAP titration studies 60.3 (±36.9). Only one patient underwent polysomnography with ASV, which confirmed the adequacy of home settings. The device was well tolerated and patients were symptomatically relieved. This preliminary work shows that it is feasible to perform unattended ASV domiciliary titration on well-trained selected patients, though larger numbers and polygraphic confirmatory follow up are necessary before ASV can be routinely performed.

076

OPEN AND PARAMETRIC SLEEP STAGER BASED UPON CLASSICAL CRITERIA

1 ˙ , A. Wakarow 2 , U. Malinowska 1 , H. Klekowicz 1 , J. Zygierewicz S. Niemcewicz 2 , P.J. Durka 1 . 1 DBP IEP UW; 2 DP MUW

Introduction: Sleep staging relies on the division of polysomnographic recordings into those stages that conform to the criteria summarized by Rechtschaffen and Kales. Even to the present moment, these criteria, which were originally proposed in 1968, have been employed as the “golden standard” despite their drawbacks and the subsequent criticisms. Regardless of their numerous limitations, these classical criteria have continuously provided a good starting point for “creating a common language for clinicians and scientists to communicate about sleep” and facilitated the comparison of results between different laboratories. Objectives: The aims of this study were to provide the following: (1) an open and parametric method for determining the sleep stage, which is compati-

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ble with the classical criteria, that could improve and simplify the process of evaluating polysomnographic recordings, and (2) a high-resolution description of sleep microstructure as a continuous process, which would allow the data generated by all-night sleep EEGs to be monitored and examined in detail. Methods: The proposed technique involved the adaptive time-frequency approximations of signals, which is implemented via a matching pursuit algorithm (MP). This technique has been adopted and modified for the detection and evaluation of events that are related to sleep scoring. MP can describe signal structures in terms of frequency, amplitude, duration and exact time position. This parametric description simplifies the selection of relevant waveforms that are based directly upon the classical definition of these structures. In this way, the delta waves, sleep spindles, occurrence of K-complexes, alpha waves and theta waves that occur during sleep could be evaluated throughout the entire night of sleep. Results: A successful parameterization of those waveforms that have been identified and defined over the course of decades of visual analysis of sleep EEG recordings and of the automatic detection of sleep stages, which is based directly upon the classical R&K criteria, with concordance on the level of inter-expert agreement. Because of the fact that this method corresponds well with the visual analysis, the adaptation of the algorithm to the new AASM criteria can be achieved within the same framework. A complete system for automatic sleep staging with the source code is available at http://eeg.pl/stager. Conclusions: This proposed approach is directly compatible with many of the practices that have been previously employed in visual EEG analysis, which allows most of the standard criteria for sleep scoring to be explicitly implemented within the new method. This feature will serve as a valuable aid in sleep evaluation, which will remain directly based on the classical criteria. On the other hand, the proposed approach will enable the construction of new descriptors for the features and observations during an overnight sleep EEG, which can be based upon a continuous description of the detailed features of polysomnograms.

077

QUANTITATIVE ANALYSIS OF SLEEP EEG MICROSTRUCTURE BASED ON MATCHING PURSUIT PARAMETERIZATION

1 1 ˙ ´ , P. Suffczynski , T. Piotrowski 2 , P.J. Durka 1 . U. Malinowska 1 , J. Zygierewicz DBP UW; 2 DP MUW

1

Introduction: A number of patterns, transients and oscillations characterize the microstructure of sleep EEG. Visual analysis, which still constitutes the golden standard and point of reference, has severe limitations in terms of resolution and repeatability. Other approaches offer at best partial assessment via descriptors that are seldom compatible with the well-established notions derived from the tradition of visual analysis. Therefore standard analysis of human sleep is usually limited to conventional low-resolution stage classification. Objectives: To develop a parametric and repeatable method for analysis of sleep EEG that is compatible with the visual approach, allows for the description of all-night sleep recordings and related microstructures in a continuous way and enables the detailed study of the relationship between different EEG components. Methods: Adaptive time-frequency approximation, implemented via matching pursuit algorithm, was used for the detection and parameterization of events related to sleep scoring. This method allowed for the characterization of the structures present in the EEG in terms of their frequency, amplitude and their exact time position and duration. In this way, sleep spindles, K-complexes, vertex slow waves, alpha, delta and theta waves can be described. Results: The approach allowed us to trace the dynamic interplay of phasic events, which constitutes the microstructural web of sleep EEG. The methodology was successfully applied for the evaluation of appearances, content, percentage of time occupied by the waveforms, and classification of delta, alpha and theta waves. For sleep spindles, K-complexes and vertex slow waves, we analyzed the quantity and frequency of occurrence. The results derived with this methodology confirm well-known facts, such as the gradual changes in delta waves and sleep spindles that correlate inversely with the delta waves. However, this methodology allows deeper insight, such as the quantitative evaluation of the decreased frequencies of sleep spindles and delta waves with increased sleep depth, as well as the finding that increased delta power or spindle power in particular sleep periods was related