Effect of Oxygen Concentration Reduction on Photoplethysmographic Morphological Characteristics

Yang Li1, Jianqing Li1, Zhengtao Cao2, Chengyu Liu1
1Southeast University, 2Air Force Medical Center, PLA


Abstract

This paper aims to find out the difference of human photoplehysmography (PPG) morphological parameter K between in normal oxygen concentration regions and in low oxygen level environments. We implemented an experiment with a normobaric hypoxic chamber which generalized low oxygen level environment of 12.7% (equivalent to the altitude of 4000 m). The experiment contained two sections—10 minutes short exposure and a night of sleep. Fingertip PPG signal was recorded in the whole process. We carried out a comparative analysis for each subject in normal and hypoxic conditions. Result showed that the average K values in normoxic environment and hypoxic conditions for short exposure were 0.3456 and 0.3861 respectively, and for sleep were 0.3081 and 0.3419 respectively. Significance level p were both less than 0.05. Variations of PPG waveform parameter K reflect the changed peripheral vascular resistance. In hypoxic environment, the raised K value tallied with the physiological mechanism that hypoxic exposure increases peripheral vascular resistance. And this phenomenon happened since the beginning of hypoxia and could last for at least a night.