Cerebral venous oxygen saturation monitoring: is dominant jugular bulb cannulation good enough?

Venous oxygen saturation at the clinically dominant jugular bulb (SjO2) and that at the confluence of the cerebral sinuses (SccsO2) were compared by direct simultaneous blood sampling of 13 severely head injured patients. The side of dominant jugular bulb (JB) was determined by neck compression test. The right side was chosen if the test was equivocal. In effect, the right side was cannulated in all cases. Subsequent angiography showed that two of the 13 cases were left side dominant. In all, 176 pairs of blood samples were analysed. Correspondence rates (the difference between each pair of blood samples being less than 4% of oxygen saturation) for individual case were good (80-100%) in nine cases including one case with left side dominance. Correspondence rates were moderate in two cases (50 and 56%); the differences were not clinically significant. In the remaining two cases, including one with left side dominance, the correspondence rates were poor (0 and 4%, respectively); SccsO2 was always lower than SjO2; median differences were 13.4 and 23.1%. Ischemia in the cerebral hemispheres would have been underestimated if management were based on SjO2. Monitoring at the dominant JB accurately reflected the global and hemispheric cerebral oxygenation in 11/13 of cases. Monitoring at the non-dominant JB is not recommended.