No abstract

We evaluated the accuracy of fiberoptic catheter oximetry in the jugular bulb during conditions of normothermia, hemodilution, and hypothermia in 11 patients who underwent cardiac surgery with cardiopulmonary bypass (CPB). An oximetry catheter was inserted into the right jugular bulb under general anesthesia, calibrated by the in vitro (n = 7) or in vivo (n = 4) mode. Jugular bulb oxygen saturation (SjO2) with the catheter 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 oximetric catheter SjO2 correlated closely with the CO-oximeter determinations 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 conditions; 1) normothermia and no hemodilution, 2) normothermia and hemodilution, and 3) hypothermia and hemodilution, and showed good correlations between SjO2 values measured by the two methods (r2 = 0.90, r2 = 0.81, 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 oximetry during CPB would be accurate and reliable under either calibration mode. Moderate hypothermia and hemodilution during CPB did not significantly influence the accuracy.

The effects of intravenous administration of fentanyl on carotid sinus baroreflex control of hemodynamics were investigated in chronically instrumented rabbits. Carotid sinus baroreflex was assessed by bilateral carotid occlusion (BCO), and the responses of mean arterial pressure (MAP), heart rate (HR), mean ascending aortic flow (MAF), and total peripheral resistance (TPR) were obtained. Hemodynamic responses to BCO were examined with cumulative doses of 5, 10, and 15 micrograms/kg of fentanyl. Fentanyl did not affect MAP and TPR but reduced HR and MAF dose dependently. Fentanyl did not attenuate the MAP response to BCO significantly. In contrast, fentanyl significantly attenuated the TPR response from 0.126 +/- 0.003 to 0.104 +/- 0.005 mmHg.min-1.ml-1 and augmented the HR response from 31 +/- 2 to 47 +/- 3 beats/min in the conscious state and at 15 micrograms/kg of fentanyl, respectively. The administration of atropine after the fentanyl attenuated MAP and HR responses to 79.9 and 27.7% of those of 10 micrograms/kg of fentanyl, respectively. We suggest that these dissociated hemodynamic responses reflect the vagotonic and sympatholytic effects of fentanyl on the baroreflex pathways.

SummaryTranscranial Doppler and continuous measurements of jugular venous oxygen saturation were used to monitor intra-operative cerebral haemodynamics in a patient with Takayasu's arteritis who underwent carotid revascularisation. These techniques were found to be of clinical value for detection of cerebral hypoperfusion and assessment of the effects of therapeutic intervention.

No abstract