ACCURACY OF CONTINUOUS JUGULAR BULB VENOUS OXIMETRY DURING CARDIOPULMONARY BYPASS

We evaluated the accuracy of fiberoptic catheter oximetry in the jugul ar bulb during conditions of normothermia, hemodilution, and hypotherm ia in 11 patients who underwent cardiac surgery with cardiopulmonary b ypass (CPB). An oximetry catheter was inserted into the right jugular bulb under general anesthesia, calibrated by the in vitro (n = 7) or i n vivo (n = 4) mode. Jugular bulb oxygen saturation (SjO2) with the ca theter oximeter was compared with a concurrent laboratory CO-oximeter value from a blood sample during surgery. Nasopharyngeal temperature ( NPT) and hemoglobin concentration (Hb) were also measured. The oximetr ic catheter SjO2 correlated closely with the CO-oximeter determination s in both calibration modes (in vitro, r2 = 0.88; in vivo; r2 = 0.96). Data in the in vitro calibrated group were grouped into three conditi ons; 1) normothermia and no hemodilution, 2) normothermia and hemodilu tion, and 3) hypothermia and hemodilution, and showed good correlation s between SjO2 values measured by the two methods (r2 = 0.90, r2 = 0.8 1, r2 = 0.79, respectively). The difference in SjO2 values by the two methods was not significantly affected by changes in NPT and Hb during CPB. In conclusion, the continuous SjO2 monitoring with catheter oxim etry during CPB would be accurate and reliable under either calibratio n mode. Moderate hypothermia and hemodilution during CPB did not signi ficantly influence the accuracy.