Curtin University researchers have used computer simulation to analyse the breathing airflow in the throat, potentially allowing the detection of obstructive sleep apnoea (OSA) even while the patients are awake and without the need for costly and time-consuming sleep studies.
In Australia, OSA is estimated to affect 24 per cent of men and 6 per cent of women over 55 and, when severe, increases the risk of heart failure by more than 50 per cent.
The diagnosis of OSA and the evaluation of its severity are usually made through an overnight polysomnography (sleep study), in which the patient is hooked up to bio-monitoring sensors that measure sleep disturbance.
But as part of a collaborative study, Dr Julien Cisonni from Curtin’s Department of Mechanical Engineering reconstructed three-dimensional models of the airways for a set of diagnosed OSA sufferers and “control” subjects without OSA.
“An optical probe was used to map the airway, from the oesophagus to the nasal cavity and, using this information, it was then possible to create a 3D model of the patient’s throat,” Dr Cisonni said.
“With these models, we were then able to virtually simulate the airflow in the pharynx and identify flow features that distinguished the subjects with OSA from the controls. “
“One of the observations was that the shape of the airway of the OSA sufferers generated lower pressure in the pharynx and therefore stronger ‘suction’ forces on the pharyngeal tissue, which made the airway more prone to collapse.”
Dr Cisonni said the research suggested there could be a quicker and more convenient way of detecting OSA and recommending treatment options for it.
“What our study suggests is that OSA could be identified, even when the individual concerned is awake and breathing normally,” Dr Cisonni said.
“It is likely that more than half of the people affected by OSA are not aware of it. The development of innovative tools based on airway scans and flow simulations would ease OSA diagnosis and facilitate early intervention.”
One of the challenges in the field of biomechanics applied to OSA is the characterisation, for a particular individual, of the passive movement of the soft tissue of the airway induced by the circulation of breathing airflow.
The better understanding of these mechanisms would allow predicting the outcome of surgical procedures, which are increasingly used as a cure for OSA.
The research was undertaken in conjunction with The University of Western Australia and Sir Charles Gairdner Hospital.
Dr Julien Cisonni, Research Fellow, Curtin University, Department of Mechanical Engineering
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