Monitoring peripheral perfusion during hemodynamic challenges in human subjects with a low-cost optical wearable device

A compact, low-cost (<$150), wearable device that continuously monitors peripheral perfusion via laser speckle flow index (LSFI) was used to measure changes in blood flow in human subjects during a set of physiological challenges. One group (A) of subjects underwent arm occlusion followed by exercise (n=3) and a second group (B) of subjects underwent arm occlusion, cold stimulation, and exercise (n=4). Cold stimulation alone did not cause significant changes from baseline LSFI. The rate of increase of the LSFI signal over the 5-minute exercise period was 3 times larger in group A compared to group B. Although cold stimulation alone did not appear to cause vasoconstriction in the wrist, it did impact the rate at which perfusion increases during exercise. The low-cost device consistently monitored changes in hemodynamics in all subjects, including both increases and decreases in blood flow caused by occlusion and sympathetic nervous system stimulation.