Endothelial dysfunction assessment by finger photoplethysmogram

摘要

Cardiovascular diseases are still the number one cause of death globally. These diseases are associated with changes in the structure and function of the arteries. Endothelial cell dysfunction can cause fat accumulation in the arteries so that the arteries lose their elasticity and with increasing time can cause artery blockage or commonly called arteriosclerosis. Standardized assessment of endothelial cell function was performed by FMD (flow mediated dilation) procedure that requires arterial occlusion for 5 minutes and usually causes an uncomfortable numbness. This study aimed to find alternative method of endothelial cell dysfunction measurement that is more comfort to the subject. The proposed method requires the subject only to change the position of the arm vertically upwards. Standard photoplethysmogram (PPG) sensor was placed on the index finger to measure the variation of the blood volume that related to the function of endothelial cells. A ratio comparing the PPG amplitude of lifted arm to its normal position was used as an indicator of blood flow. Results showed a significant increase in blood volume ratios in group of high and moderate physical activity compared to group with low physical activity that is related to the cardiovascular diseases risk. Further study involving larger number of subjects and grouping by different cardiovascular disease risk is needed to validate the new proposed procedure.