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The measurement of arousals during sleep is useful to quantify sleep fragmentation. The criteria for electroencephalography (EEG) arousals de®ned by the American Sleep Disorders Association (ASDA) have recently been criticized because of lack of interobserver agreement. The authors have adopted a scoring method that associates the increase in chin electromyography (EMG) with the occurrence of an arhythm in all sleep stages (Universite  Catholique de Louvain (UCL) de®nition of arousals). The aim of the present study was to compare the two scoring de®nitions in terms of agreement and repeatability and the time taken for scoring in patients with obstructive sleep apnoea syndrome (OSAS) of varying severity.Two readers using both ASDA and UCL de®nitions scored twenty polysomnographies (PSGs) each on two occasions. The PSGs were chosen retrospectively to represent a wide range of arousal index (from 6±82) in OSAS patients.There was no difference in the arousal indices between readers and between scoring methods. The meanSD difference between the two de®nitions (the bias) was 1.13.76 (95% con®dence interval: -0.66±2.86). There was a strong linear relationship between the arousal index scored with the two de®nitions (r=0.981, p<0.001). MeanSD scoring duration was signi®cantly shorter for UCL than for ASDA de®nitions (18.55.4 versus 25.36.6 min, p<0.001).In conclusion, it has been found that in obstructive sleep apnoea syndrome patients, the American Sleep Disorders Association and Universite  Catholique de Louvain de®nitions were comparable in terms of agreement and repeatability.

Sleep quality is affected in patients with sleep apnea-hypopnea syndrome (SAHS) with nocturnal and diurnal consequences. Most of these patients who are treated with positive airway pressure (CPAP) return to normal sleep patterns. We could consider good sleepers those patients who present more sleep spindles in stage II, and slower wave sleep as a good sign of better sleep quality.The objective in this research study was to compare the microstructure of stage II using the number of spindles and the increase of slow wave sleep before and after CPAP night titration.We developed a wavelet filter using a spline cubic function from a wavelet mother, which was appropriate to be used over electroencephalographic signal. By means of this filter in a multi-resolution mode, the spindles were detected from the increase of the IV band power; the sampling rate of the device determined the filter characteristics. The staging of polysomnographic studies was made by an expert according AASM (American Academy of Sleep Medicine) and then processed by the filter to get the index of sleep spindles before-and-after CPAP during stage II as well as the relationship between fast and slow powers from the EEG signal. An increase in the power of the slow waves vs. fast activity was observed in all the cases as a feature of better sleep. The neuroprotective effect described in previous research works regarding the density of the sleep spindles seems to be detected in patients improving their sleep quality after the correction of the apnea-hypopnea syndrome using CPAP.Slow wave sleep; CPAP 5. Oronasal flow sensors. One of them, of a thermistor type, and a nasal cannula with a pressure transducer to detect flow limitation through nasal pressure measurement.

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