Continuous measurement of oxygen delivery and oxygen consumption in awake live animals

For continuous measurement of both SO2 and [Hb] of whole blood, a hybrid type optical sensor was developed, tested in vitro and applied to the continuous measurement of arterial and mixed venous SO2 and [Hb] of awake live animals whose circulation was entirely supported by a pair of artificial hearts. The purpose of using artificial hearts was to control the cardiac function precisely and to obtain independent responses of the peripheral circulatory system. Both sensors in the arterial and venous circuits functioned satisfactorily for a duration of 40 days; no blood clots were observed around the sensor and the mixed venous SO2 varied sensitively in response to changes in the respiratory status, pump output, [Hb], and oxygen consumption, thus showing that it could be used as an indicator to evaluate the adequacy of oxygen delivery to peripheral tissues.