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

Abstract

A severe reduction in haemoglobin concentration can lead to a decrease in jugular venous bulb oxygen saturation (Sj(O(2))). However, recent evidences suggests that cerebral oxygen saturation (Sc(O(2))) measured by near infrared spectroscopy decreased during even mild haemodilution. We therefore tested the hypothesis that the changes in Sc(O(2)) may not be parallel to those in Sj(O(2)) during haemodilution. In addition, as cerebral oxygen balance during the operation can vary depending on the anaesthetics used, the changes in Sj(O(2)) and Sc(O(2)) during haemodilution were compared between patients under propofol and isoflurane/nitrous oxide anaesthesia. 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 Sj(O(2)). A cerebral oximeter, INVOS 4100S was used to monitor Sc(O(2)). 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. Mean (sd) control values of Sj(O(2)) 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 Sc(O(2)) 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, Sj(O(2)) values remained unchanged in both groups, whereas Sc(O(2)) values significantly decreased in both groups (from 57 to 51% in Group P and from 59 to 52% in Group S). The results indicated that, although the changes in Sj(O(2)) and Sc(O(2)) during a reduction in haemoglobin concentration were similar under propofol and sevoflurane/nitrous oxide anaesthesia, the changes in Sc(O(2)) were not parallel to those in Sj(O(2)). The discrepancy of the results in Sj(O(2)) and Sc(O(2)) may make the interpretation of their values difficult during haemodilution.