Is Asthma in Subjects With Obstructive Sleep Apnoea (OSA) Due to Dysanapsis

There is no evidence that the World Wide prevalence of asthma is declining. There is some evidence that this Western disease may give the appearance of declining prevalence due to improved healthcare. However evidence from the Office of National Statistics suggests that the mortality rate for asthma may be increasing year on since 2007 until 2017. The true burden of asthma in the United Kingdom is difficult to ascertain.

Obesity has effects on lung function which lead to low functional residual capacity and low end reserve volume. This leads to rapid shallow breaths near to the airway closing pressure and lung closing volume as illustrated in this review. This suggests that obesity itself may be a source of breathlessness.

High Body Mass Index (BMI) has been shown to be associated with asthma. It was also associated with wheeze that is not asthma. This finding suggests that obesity in itself may be linked to wheeze which is not asthma. It has been shown in children that sleep disordered breathing is associated with asthma as well as wheeze. Obese children are known to display dysanapsis (airway cross sectional area is small for the size of the lung) whether associated with or without asthma, however if associated with asthma, the severity of asthma can be worse.

AIM: To investigate if asthma is truly associated with Sleep disordered breathing in adult subjects. To investigate if there is an association of wheeze with dysanapsis in patients with sleep disordered breathing

NULL HYPOTHESIS: There is no difference between subjects who have sleep disordered breathing with asthma and those subjects who have sleep disordered breathing without asthma, with respect to lung function parameters.