Mathematic analysis of arterial pulse oximetry time series during sleep in amyotrophic lateral sclerosis

Abstract

We aim to clarify the difference in the dynamics of oxyhemoglobin saturation (SpO2) between amyotrophic lateral sclerosis (ALS) and obstructive sleep apnea syndrome (OSAS) patients during sleep. We developed an algorithm to automatically detect and quantify the characteristics of the decrease and recovery phenomena of SpO2 during sleep. We compared the mean values of the characteristic indices between ALS (N=10) and OSAS (N=23) patients. The decreasing time in the case of ALS patients was significantly longer compared to that in the case of OSAS patients, whereas the decreasing area was significantly smaller. This implies that the decreasing process of SpO2 during the early phase of sleep is slower in ALS patients compared to that in OSAS patients. Moreover, a two-dimensional histogram analysis of decreasing amplitude and velocity showed that there are multiple decreasing patterns of SpO2 during sleep.