Airflow-Oximetry Combined Signal Based Automatic Detection of Sleep Apnea in Adults

Publication Type:
Thesis
Issue Date:
2020
Full metadata record
Sleep apnea, a common sleep disorder, can significantly decrease the quality of life and is closely associated with major health risks such as cardiovascular disease, sudden death, depression, and hypertension. It also elicits brain and physiological changes that vary across the night. Conventional diagnosis of sleep apnea using polysomnography (PSG) is costly and time-consuming, requiring manual scoring of sleep stages and respiratory events. Current automatic diagnostic algorithms used to detect sleep apnea vary in approaches with the use of different physiological signals. An effective, reliable, and accurate automatic method for the diagnosis of sleep apnea will be time-efficient and economical. This thesis is a narration of the work that led to the development of a novel algorithm suitable for the automatic diagnosis of sleep apnea. A systematic literature review of the existing methods (approaches and algorithms) was performed before designing the algorithm. This review presented an overview of methods to diagnose sleep apnea using respiratory and oximetry signals. The review identified the research gaps with indicating the major concerns, challenges, benefits, and limitations of using respiratory and oximetry signals for the diagnosis of sleep apnea. This thesis examined the electroencephalogram (EEG) spectral powers resulting from apnea duration of varying length and reported the changes in the relative powers in EEG frequency bands before and at apnea termination. The study was carried out for the purpose of justifying the usability of EEG for the automatic diagnosis of sleep apnea. It investigated the spectral power changes in delta, theta, alpha, sigma, and beta frequency bands of EEG as a function of apnea duration from 375 events. The study revealed a significant reduction in EEG relative powers (the low frequency theta, alpha, and sigma powers) both before and at apnea termination. The findings from the EEG spectral analysis suggests that the application of EEG signal in sleep apnea diagnosis is not reliable due to the random variations in spectral powers as well as the major challenges associated with EEG acquisition and its processing. Due to the limitations associated with the EEG for an unattended home diagnosis of sleep apnea, the EEG signal was excluded from the automatic detection approach […]
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