RBC aggregation assisted light transmission through blood and occlusion oximetry

Optical transmission of tissue in-vivo and model red blood cells (RBC) suspensions in-vivo have been measured in red and near infrared region targeting better understanding of the nature of in-vivo pulsatile signals. It is shown experimentally (both in vitro and in vivo) that the pulsatile signal may result not just from volumetric changes, but also from light scattering fluctuations. Theoretical predictions on time evolution of optical transmission for the case of very long over-systolic occlusion also have been proved experimentally for both in vivo measurements and in-vitro model sets. The interconnection of the shape of optical signal and geometry of RBC aggregates is confirmed.