The effect of upper airway surgery on obstructive sleep apnoea

Obstructive sleep apnoea (OSA) affects 1.5 million Australians and results in significant morbidity and mortality. However, half of patients cannot tolerate the leading treatment, continuous positive airways pressure (CPAP). For those intolerant of CPAP, a common treatment alternative involves upper airway surgery (UAS). Unfortunately, a significant number of patients referred for this treatment do not respond and suffer from residual OSA with its inherent cardiovascular and neurocognitive consequences. Furthermore, current clinical predictive tools are poor at identifying responders to UAS and there are no proven additional therapies to offer those patients failing UAS treatment. The key to providing better predictors of OSA resolution with UAS is to understand how these interventions affect the physiology responsible for OSA. It is clear that UAS improves upper airway anatomy/collapsibility. However, poor upper airway anatomy is not the only factor contributing to OSA. Recent evidence suggests that several additional, non­anatomical, physiological traits contribute to the pathogenesis of OSA including: 1) an oversensitive ventilatory control system (i.e. high loop gain), 2) a low respiratory arousal threshold, and 3) poor pharyngeal dilator muscle effectiveness characterised by an inability of the pharyngeal muscles to hold open or stiffen the airway during sleep. However, it is not known how UAS alter these non­anatomical traits and whether abnormalities in these traits are the reason for the variability in the success of UAS treatments. Furthermore, it is also not known if targeting non­ anatomical traits with additional treatments (i.e. combination therapy) will improve outcomes for those patients who have had only a partial response to UAS. Our goal is to be able to accurately identify which OSA patients are good candidates for UAS therapy by identifying robust predictors of OSA resolution with these interventions. Furthermore, we aim to offer additional treatments to ‘salvage’ those patients who have failed to respond completely to UAS.