Continuous mixed venous oxygen saturation monitoring during general anesthesia

Clinical evaluation of continuous SvO2 monitoring during general anesthesia was made in 21 surgical patients utilizing a fiberoptic reflectometry system combined with a pulmonary artery flow-directed balloon catheter. On-line in vivo values for SvO2 by the system were closely related to those obtained in vitro from a Radiometer ABL-300. There was a good correlation between changes of in vivo SvO2 and corresponding changes in cardiac index. We also observed that there were significant correlations between SvO2 and oxygen extraction ratio, and SvO2 and oxygen delivery. These data indicate that continuous monitoring of SvO2 during general anesthesia can provide on-line information not only about hemodynamic state but also on oxygen transport, which will be especially helpful in managing hemodynamically unstable patients during anesthesia.