Jugular bulb monitoring of cerebral oxygen metabolism in severe head injury: accuracy of unilateral measurements.

To investigate the accuracy of unilateral jugularvenous monitoring, we performed bilateral jugularvenous monitoring in 22 comatose head injured patients. Fiberoptic catheters were placed upstream in both internal jugular veins and advanced into the jugular bulbs. Arterial and bilateral jugularvenous blood samples were obtained simultaneously for in vitro determination of jugularvenous oxygen saturation (SJO2), arterial minus jugularvenous lactate content difference (AJDL) and modified lactate-oxygen-index (mLOI). Ischemia was assumed, if one of the following pathologies occurred at least unilaterally: SJO2 < 55%, AJDL < -0.37 mmol/L, mLOI > 0.08. The mean and maximum bilateral SJO2 differences varied between 1.4% to 21.0%, and 8.1% to 44.3% respectively. The bias and limits of agreement (mean differences +/- 2SD) between paired samples were -0.4% +/- 12.8%. Regarding AJDL bias and limits of agreement were -0.01 mmol/L +/- 0.18 mmol/L. At best 87% of defined ischemic events could be evaluated by monitoring at the side of predominant lesion or, in diffuse injuries, at the side of the larger jugular foramen in CT scan (CT approach). We conclude, due to the wide limits of agreement in bilateral SJO2 and AJDL the reliability of unilateral jugularvenous monitoring in patients with intracranial pathology is questionable. For diagnosing ischemia the CT approach has the highest sensitivity and is therefore recommended.