Project Summary
OSA is defined by repetitive collapse of the upper airway, a process which leads to transient hypoxemia and
arousals from sleep, and is associated with various cardiovascular, metabolic, and neurocognitive
consequences. OSA is the most common respiratory disorder, affecting roughly 10% of middle aged men and
women in the USA and up to 1 billion globally. Although continuous positive airway pressure (PAP) is an
efficacious therapy, it is not always well tolerated and adherence is less than ideal. OSA is increasingly
recognized as a multifactorial disorder that can occur in different people for different reasons, not only due to
anatomical predisposition (collapsibility of the upper airway), but also related to low arousal threshold (wake up
too easily), dysfunction in upper airway dilator muscles and instability in ventilatory control. Through careful
measurement of these underlying factors and the symptoms experienced in OSA, this proposal seeks to
understand how different mechanisms underlying OSA – endotypes – lead to different symptoms or
consequences – phenotypes. These different phenotypes range from having no appreciable symptoms, to
falling asleep at the wheel, to experiencing cardiometabolic consequences. Additionally, addressing the
underlying cause might be useful to personalize therapy, to predict adherence to PAP, and to understand which
symptoms will or will not improve with long term PAP therapy. A major challenge in clinical practice is
understanding whether particular symptoms are due to OSA, and whether these symptoms will improve with
treatment. Moreover, we are currently struggling to find alternative therapies for OSA which will likely depend on
underlying mechanism. Similarly, we do not currently know which patients to put into clinical trials since it seems
unlikely that, e.g., all OSA patients will have cardiovascular benefits to PAP therapy since not all are at risk of
heart disease. Our goals are 1) To understand the contribution of the underlying cause, or endotype, of OSA to
the symptoms experienced by people with OSA, 2) To elucidate how the endotype predicts response to non
CPAP therapies, such as oxygen or sedative hypnotics, and 3) To define how underlying endotype (mechanism)
mediates changes in phenotype (clinical manifestations of disease) with treatment of OSA. Ultimately we hope
that our efforts will advance the OSA field and help to alleviate suffering or reduce/prevent disease burden.