Optical sensor for hemoglobin content and oxygen saturation. Application to artificial heart research

A hybrid optical sensor that can measure both hemoglobin content ([ Hb]) and oxygen saturation (OS) of whole blood has been developed. The measurement errors in [Hb] and OS are 0.5 g% and 1.2%, respectively, over an hematocrit range of 25 to 45%. The oxygen content derived from the optical sensor yielded a standard error of 0.1 to 0.2 vol%. The sensors were mounted in the outflow ports of left and right artificial hearts that maintained the entire circulation and were used to chronically monitor arterial and mixed venous [Hb] and OS. In combination with pump output and pressure measurements, oxygen delivery and oxygen consumption of the animal was derived on-line using a microprocessor. In the experiment that lasted 40 days, both sensors functioned well, with stable measurements, and no thrombus formation around the sensor at the time of autopsy. The optical sensors are useful for monitoring cardiopulmonary function and metabolic status of patients without requiring blood samples. In addition, the pump output may be controlled through the level of mixed venous OS or in combination with the arterial OS.