Monitoring peripheral blood flow change using transmission photoplethysmography sensor

Perfusion monitoring plays an important role in determining tissue oxygenation. This paper presents a non-invasive method to monitor peripheral blood flow changes, as an indicator for perfusion. A transmission mode finger sensor and a vascular Doppler ultrasound monitor were used to acquire photoplethysmograph (PPG) and blood velocity data. A series of vascular occlusion tests were conducted on 7 healthy human volunteers using a pressure cuff, to induce changes in peripheral blood flow conditions. The high frequency PPG signal (PPG
_AC
) pulse amplitude was determined as an estimate for volumetric blood flow. Results shows PPG
_AC
amplitude can detect changes in peripheral flow, with respect to the ultrasound Doppler. The two measurements showed good positive correlation (R
²
=0.705/ However, this correlation may degrade with significant dynamic change in vessel diameter and/or at high blood flow conditions.