Continuous mixed venous oxygen saturation monitoring during general anesthesia

Clinical evaluation of continuous\(S\bar v_{O_2 } \) 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\(S\bar v_{O_2 } \) 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\(S\bar v_{O_2 } \) and corresponding changes in cardiac index. We also observed that there were significant correlations between\(S\bar v_{O_2 } \) and oxygen extraction ratio, and\(S\bar v_{O_2 } \) and oxygen delivery. These data indicate that continuous monitoring of\(S\bar v_{O_2 } \) 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 hemodynamicaly unstable patients during anesthesia.