AbstractsMedical & Health Science

Obstructive sleep apnoea syndrome (OSAS) is a frequently occurring disease with multiple co-morbidities. Left untreated, OSAS has important health and socioeconomic consequences but effective therapies are available. Consequently, its diagnosis is important. The usual pathway for a reliable diagnosis includes detailed sleep history, clinical examination followed by attended full polysomnography (PSG) which is the reference standard for the diagnosis of respiratory sleep disorders. This approach is a time and resource consuming process given its increasing demand. Therefore, several less elaborate sleep portable monitoring (PM) devices have been developed for the diagnosis of OSAS. Up to now however, no single device has been widely accepted as an alternative to PSG because of important limitations such as the lack of sleep/wake status assessment, the lack of detection of arousals during sleep (an important contribution in the calculation of the respiratory arousal index, an index of disease severity, and a criteria used for respiratory events - hypopnoea- scoring). This thesis focuses on the added value of mandible movement (MM) assessment in a new type of PM system, the Somnolter®, for the detection and diagnosis of sleep disordered breathing (SDB) in adults. Mouth opening is a common observation during sleep in patients suffering from sleep-disordered breathing and is different from mandible posture during sleep in healthy adults. We demonstrated that this approach allows for a better accuracy in the detection of SDB in an automated analysis, both in men and women. The first finding was a better detection of hypopnoea when compared to a PM without MM analysis, thanks to the associated salient mandible movement (SMM). SMM has been used as a surrogate for respiratory arousal. We also found that this method improved the accuracy of the apnoea hypopnoea index calculation (AHI), the most important index in SDB severity assessment. The calculation of this AHI depends on the total sleep time (TST) which is the denominator. Thus, the second important finding of this work was the sleep/wake state assessment which provided the TST. Thirdly, we were able to demonstrate that mandible behaviour under CPAP treatment was similar to the one found in healthy subjects. Typically, this translates into a mouth in a more closed position without repeated downward excursions. Indeed, mandible downward excursions and breathing effort are highly correlated. The fourth finding was that the MM analysis might be an interesting non-invasive marker of breathing effort during sleep and is less sleep disruptive than the invasive conventional method (oesophageal pressure). A fifth finding was the feasibility of successfully training scorers for the visual recognition of these patterns. Specific mandible patterns have been isolated, described and correctly identified in active wakefulness, in quiet sleep, in quiet wakefulness, during obstructive and central apnoea and hypopnoea, during mixed apnoea, during snoring and respiratory related arousals.…