Aims to investigate why individuals with Quadriplegia have high rates of sleep apnoea.
The causes of the extremely high prevalence of sleep apnoea in people with quadriplegia are unknown. It is critical to determine the precise mechanisms of sleep apnoea in this population so as to guide the development of novel, effective therapeutic approaches which can be more readily used by individuals with quadriplegia. The overall aim of this research stream is the development of quadriplegia-specific sleep apnoea treatment strategies, based on an exploration of the causes for sleep apnea in this group.
Many factors contribute to Obstructive Sleep Apnea in able bodied individuals including the size of an individuals upper airway (throat), how effectively their tongue muscles work at holding the airway open and how much air is in their lungs (lung volume). Immediately after acute quadriplegia, traumatic tissue swelling and surgical fixation are likely to reduce the size of the upper airways. Later, increases in body fat and neck size contribute to reduced lung volume, increased blood flow, decreased airflow and increased airflow resistance in the nose and the pharynx. In addition, people with quadriplegia typically place a greater reliance on the diaphragm and accessory muscles of respiration in the neck for ventilation resulting in muscle hypertrophy. This may lead to further narrowing of the upper airway, which will provide a greater resistance to airflow and may make the upper airway more prone to collapse.
The SHiQ Mechanics project will investigate upper airway collapsibility in quadriplegia, using MR imaging and measurements made during sleep. The upper airway will be imaged, particularly the soft tissue and vascular structures. Anatomy will be examined through measurement of upper airway resistance and critical closing pressure (a measure of the collapsibility of the upper airway). Once these parameters are characterised, lung volume will be measured using helium dilution/magnetometers.