Evaluation of a 7.5 French pulmonary catheter for continuous monitoring of cerebral venous oxygen saturation.

We studied a 7.5 French Opticat fiberoptic catheter/Oximetrix computer system as a tool for continuous monitoring of oxygen saturation of jugular venous blood. Eight healthy volunteers had a catheter placed with the tip in the bulb of the right internal jugular vein. During baseline condition, hyperventilation, and rebreathing, jugular venous oxygen saturations ranging from 35 to 85% were obtained. Simultaneous with drawing a blood sample, the value obtained with the fiberoptic catheter was recorded. The oxygen saturation of the blood sample was analyzed in vitro using a bench oximeter. A total of 150 paired values was obtained. In 15 of these cases, the computer indicated that the intensity of the reflected light was insufficient. A difference of > 12% oxygen saturation between the paired values was obtained for all of these pairs. The regression coefficient for the remaining 135 data pairs was 0.95, the mean difference was -0.54%, and the limits of agreement were -9.5 to 8.4%. We conclude that the 7.5 French Opticat catheter is useful if values obtained during improper light intensity are excluded.