Patient Specific Computational Modelling of Human Upper Airway Collapse

The upper human airway related problems have been recently recognised as a problem affecting a significant portion of the human population all over the world. One of the major human airway diseases is 'sleep apnoea', a sleep related disorder. A patient with a severe sleep apnoea can develop hypertension and severe heart disease including pulmonary hypertension, in addition to sleepless nights, traffic accidents, failure to work in the environment and marital disharmony. Though some treatment methods have been developed, they are not always user friendly and enforcing these treatment methods is difficult. Thus, no wonder that development of alternative treatment methods and improved diagnosis methods have been undertaken by many clinicians. Though many clinical trials have been conducted on human airway related problems, the understanding of the human airway diseases is far from satisfactory. The proposed 'patient specific' computational modelling, however, is expected to develop an excellent understanding of the human airway collapse, one of the major reasons for human airway diseases. The patient specific scans and some experimental flow, displacement and pressure measurements will be provided by the collaborating clinicians, who are dealing with human airway problems on a daily basis. The scans will be transformed into human airway geometries with the help of clinicians and relevant software. The collaborating clinicians will help the engineering scientists to differentiate the human airway walls and muscle from the air space. The skeleton of the geometry will be constructed using curves and surfaces. Once the geometries are extracted, a linear tetrahedron finite element mesh will be generated using the in house mesh generator. The mesh will be then used in the fluid and solid dynamic calculations. With the coupled analysis of the air and solid movement, it is expected that the model will be able to pinpoint the location/locations of human airway collapse. The majority of the software required for the analysis will be developed within the applicant's institution and some of them have already been developed. For geometry extraction standard software referred to as 3D-DOCTOR will be used in addition to the in house software. Fluid and solid dynamic calculations will be carried out using the finite element based in house turbulent flow and viscoelastic solid codes. The development of these tools for the human airway and coupling of the proposed software are expected to be completed by the fellow within the first three years of the proposed research. The last two years of the project period will be spent to generate more patient specific data to create a data base for airway collapse analysis. Towards the end of the project a correlation between various human airway parameters such as flow rate, pressure distribution, characteristic dimensions of nasal passages, tongue, uvula and neck, airway muscle tone (muscle properties), position of sleep (gravity) and obesity factor of patients and human airway collapse will be developed. This correlation will be put together in a spread sheet form so that practicing clinicians will be able to use the software to assess human airway related diseases. All human airway problems of interest such as sleep apnoea and new treatment methods, throat cancer and speech therapies, air way corrective surgeries etc. are within the remit of the proposed project.The outcome of the proposed project will benefit enormously the clinicians dealing with human airways, patients with airway problems, computational mechanics researchers and academics all over the world.