An Investigation Of Peripheral Blood Volume And Oxygen Saturation Change In Obstructive Sleep Apnea
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Obstructive sleep apnea (OSA) is a type of sleep disordered breathing in which the airway collapse partially or fully and causes arousal to resume breathing. In a 2009 National sleep foundation poll of 1000 people, 63% of men and 50% of the females showed signs of sleep apnea. It also showed that subjects with sleep apnea have high risk of high blood pressure, stroke and mental disorders such as depression especially in female. Also by another group of researcher it has been shown that the prevalence of OSA is 4% in male and 2% in female. It has been also shown that 1 out of 20 adults are undiagnosed of OSA and this leads to cardiovascular morbidity. This investigation employed pulse oximetry to see the changes in the peripheral blood flow and the percentage oxygen saturation during simulated OSA. The effect of gravity (posture) on the peripheral blood flow and oxygen saturation was also studied. Features such as peak, nadir, peak to peak time, area under the curve, the amplitude of the photoplethysmography waveform and the rate of drop of oxygen saturation were analyzed. In addition, data were also collected from sleep apnea patients during sleep. The results shows that there is a difference in the area under the curve and the peak to peak time between the simulated apnea and normal breathing. For Sitting protocol A the average and the standard deviation for baseline is 0.4±0.098 (A.U.) and for the simulated apnea it is 0.57±0.087 (A.U.). The increase in the area under the curve is observed for rest of the protocol/positions. Similarly the peak to peak increase in breath hold as compared to baseline. For sitting protocol A, the average and the standard deviation are 0.41±0.084 (s) for baseline and 0.56±0.078 (s) for breath hold. But for the actual sleep apnea study these trends were not observed which might be due to less number of subjects. The drop in the oxygen saturation was quite different for simulated and the actual sleep apnea. The average and the standard deviation for the normal breathing was found to be -0.0015±0.002 and for apnea it was -0.2669±.044. Also these features were significantly different. Also there was no gravity effect and the effect of frequency of apnea observed. Hence we may say that the heart rate decreases (peak to peak time increases), the peripheral volume increases (area under the curve increases) and there is a drop in the oxygen saturation during apnea.