Photoplethysmographic Pulse Amplitude Response to Flow Mediated Dilation

In this paper, the photoplethysmographic (PPG) pulse amplitude response to flow-mediated dilation (FMD) is investigated. Vessel dilation is induced in the right-arm brachial artery (BA) in response to a shear force due to the sudden opening of the BA following supra-systolic blockage of blood supply for 4 minutes. The diameter of the BA is recorded through ultrasound imaging measurement before and after blockage. Concurrently, PPG of the left and right index fingers are recorded before blood occlusion (baseline) and after release. Results on ten human subjects (age 49.7 ± 10.4 years, range 34–64 years) show that the PPG pulse amplitude measured at the finger of the stimulated arm shows a very distinctive pattern associated to the FMD in the conducting artery. A potential application for the proposed technique is the evaluation of the vascular endothelial function, using a significantly lower-cost and less operator-dependent alternative to conventional ultrasound-FMD.