Can the blood content of the tissues be determined optically during pulse oximetry without knowledge of the oxygen saturation? -an in-vitro investigation

Current pulse oximeters become unreliable at low oxygen saturations because the influence of physiological artifacts that are not measured independently such as the blood content of the tissues increases considerably. The authors demonstrate that the blood content of simulated tissues in an in-vitro model may be determined and monitored continuously during pulse oximetry by considering the absolute absorption of red and infrared light.