Experimental validation of blood flow derived from pulse oximeter wave signals in beagles
Purpose Pulse oximeter wave reflects blood volume changes in tissue, suggesting the possibility of monitoring changes in tissue blood flow. Thus, our aim was to examine the correlation between tissue blood flow derived from pulse oximeter wave signals (Qpulse) at a toe and the arterial flow measured by a Doppler probe at the femoral artery (QDoppler). Methods Six beagles under general anesthesia were studied. A 24-G catheter was placed in the proximal femoral artery for drug infusion and an ultrasonic transit-time flow probe applied to the artery to measure QDoppler. The pulse oximeter signals from the right toe were processed with in-house－developed software to obtain Qpulse. Three saline solutions containing respectively the vasodilators isosorbide dinitrate (20μg/mL), adenosine (20μg/mL), and nicardipine (10μg/ mL) were infused at increasing rates of 0, 2.5, 5.0, 10, or 20 mL/h for 8 minutes into the femoral artery with a syringe pump. Results Both QDoppler and Qpulse increased fourfold with increasing rates of infusion of the three vasodilators. Plotting of QDoppler and Qpulse across the three vasodilators in each animal revealed linear correlations (R2 = 0.17－0.76). Overall regression analysis showed a less strong but still statistically significant linear relation (y=3.68x + 18.5, R2 = 0.25, P < 0.01). Conclusions We found a linear correlation between QDoppler and Qpulse in a wide range of femoral arterial blood flow measures induced by different vasodilators in each animal. Arterial flow wave derived from pulse oximetry was quantitatively validated. doi：10.11482/KMJ-E41（1）1 (Accepted on January 26, 2015)
