The Study Of Corelation Between The Photoplethysmography (PPG)Waveform And The Blood Volume Change

ObjectiveThe purpose of this research is trying to investigate utilizing the photoplethysmography (PPG) waveform, as a non-invasive measurement, to estimate the blood volume during lower body negative pressure(LBNP) simulated human’s hypovolemia.MethodsWith Institutional Review Board(IRB) approved, we recruited9non-smoking healthy volunteers (7of them are men,2of them are women). The subjects underwent the low body negative pressure to simulate the hypovolemia.Both vital signs such as heart rate and beat to beat arterial blood pressure and PPG waveform were monitored. We utilized the peak analysis in LabChart (ADInstruments) to get the Height, Width and Peakarea and then analyzed them statistically.ResultsAmong all the7subjects, the maximum tolerated negative pressure was-110mmHg, the minimum tolerated negative pressure was-90mmHg, the mean tolerated negative pressure was-100±7.07mmHg. The heart rate(HR) pre decreased from67.9bpm to sympt101.2bpm(p=0.003). The systolic blood pressure before the negative pressure was given(pre) decreased from126mmHg to102mmHg(p=0.008) when the subjects informed us uncomfortable sign (sympt);the diastolic blood pre decreased from73mmHg to sympt72mmHg(p=NS);the pulse pressure pre decreased from54mmHg to sympt29mmHg(p<0.001). The HR increased and the blood pressure(BP) decreased with the negative pressure increased progressively.PPG width pre decreased from0.8292s to sympt0.4454s (p<0.001);peakarea pre decreased from0.0241V. s to sympt0.0062V.s (p=0.01); AC pre decreased from0.0285v to sympt0.0114v (p=0.01);height pre decreased from0.0437v to sympt0.0083v (p=0.007).PPG width, peakarea, AC and height are decreased progressively with the negative pressure decreased in this way and they all have the same trend with the change in the HR and BP during LBNP.ConelusionBy analyzing the heart rate, blood pressure and PPG waveform on different timing during LBNP simulated hypovolemia,we concluded as follow:1. Lower body negative pressure test can be used to simulate the human central hypovolemia environment2. PPG waveform has a same trend to reflect the change in blood volume with heart rate and blood pressure. It has a potential possibility to monitor the real-time blood volume change.3. PPG AC and PPG height are corelated with the arterial blood flow which can be used. It has a potential possibility to estimate the stroke volume(SV).