Comparison of changes in jugular venous bulb oxygen saturation and cerebral oxygen saturation during variations of haemoglobin concentration under propofol and sevoflurane anaesthesia

Abstract

Background. A severe reduction in haemoglobin concentration can lead to a decrease in jugular venous bulb oxygen saturation (SjO2). However, recent evidences suggests that cerebral oxygen saturation (ScO2) measured by near infrared spectroscopy decreased during even mild haemodilution. We therefore tested the hypothesis that the changes in ScO2, may not be parallel to those in SjO2 during haemodilution. In addition, as cerebral oxygen balance during the operation can vary depending on the anaesthetics used, the changes in SjO2 and ScO2 during haemodilution were compared between patients under propofol and isoflurane/nitrous oxide anaesthesia. Methods. Forty-two patients with pre-donated autologous blood were randomly assigned to receive propofol (Group P) or sevoflurane/nitrous oxide (Group S) anaesthesia. A fibreoptic catheter was placed in the jugular bulb to measure SjO2. A cerebral oximeter, INVOS 4100S was used to monitor ScO2. Arterial and jugular bulb blood samples were drawn simultaneously at: (i) 10 min after the start of operation, (ii) after 400 ml of blood loss, (iii) after 800 ml of blood loss, (iv) just before the transfusion of pre-donated autologous blood, and (v) after 400 ml transfusion. Results. Mean (SD) control values of SjO2 in Group P were significantly lower than those in Group S (55 (8)% vs 71 (10)%, respectively; P<0.05), whereas there was no significant difference in control values of ScO2 between the two groups. During the operation, haemoglobin (Hb) concentrations significantly deceased in the both groups compared with control values (from 9.8 to 7.6 g dl-1 in Group P and from 9.9 to 8.0 g dl-1 in Group S). During a reduction in Hb concentration, SjO2 values remained unchanged in both groups, whereas ScO2 values significantly decreased in both groups (from 57 to 51% in Group P and from 59 to 52% in Group S). Conclusion. The results indicated that, although the changes in SjO2 and ScO2 during a reduction in haemoglobin concentration were similar under propofol and sevoflurane/nitrous oxide anaesthesia, the changes in ScO2 were not parallel to those in SjO2. The discrepancy of the results in SjO2 and ScO2 may make the interpretation of their values difficult during haemodilution. © The Board of Management and Trustees of the British Journal of Anaesthesia 2004. All rights reserved.