When a fluid-structure interaction keeps you awake: a physical approach to Obstructive Sleep Apnea

The Sleep Apnea Syndrome is known to be related with a partial (hypopnea) or to-tal (apnea) collapse of the upper airway. The patency of the upper airway is dictated by a combination of passive mechanical properties and active neural mechanisms. From a physical point of view, neglecting active neural control mechanisms, the airway col-lapse can be explained by the interaction of the airow during respiration (uid) with the surrounding tissues (structure). The characteristic recurrent collapse causes about 3 % of the adult population to suffer from Obstructive Sleep Apnea (OSA). A system-atic review of published studies on OSA insists on the necessity of a better understand-ing of the factors determining the airway obstruction in order to improve modelling, simulation and eventually prediction of the uid-structure interaction at the origin of OSA. Prediction of OSA is in particular important to foresee the outcome of surgical procedures and to estimate its long-term effectiveness. In order to be of practical use a surgical prediction tool demands reliable and accurate simulation results available within a reasonable time delay and exploiting relevant and `in-vivo ' accessible physi-ological data. In order to contribute to the understanding of OSA a physical approach is presented consisting mainly of three stages. At rst, relevant physical quantities are formulated based on physiological `in-vivo ' observations in order to dene the problem. Secondly, a simplied theoretical model is proposed based on assumptions derived of the order of magnitudes derived during the rst stage. Thirdly, an experi-mental validation of the assumptions and of the accuracy of the theoretical model is performed in a suitable experimental setup allowing to control model input parameter