[Monitoring of cerebral oxygenation with SvjO(2) or PtiO(2)]

Jugular venous oxygen saturation (SvjO(2)) monitoring has been developed in order to detect cerebral ischaemia. The interpretation of SvjO(2) values remains nevertheless complex, and should be associated with cerebral haemodynamic multimonitoring with ICP and transcranial Doppler. With the hypothesis of a constant cerebral oxygen consummation, and also with a constant haematocrit, SvjO(2) variations correlates with cerebral blood flow variations. After a brain trauma, an SvjO(2)<50% or>75% is associated with a bad prognosis. To maintain SvjO(2)>50% constitutes a reasonable therapeutic objective, but the benefice associated with such a strategy has not been validated. Oxygen partial pressure (PtiO(2)) in the brain parenchyma may be monitored in the non-lesioned area (usually frontal) in order to detect a global cerebral ischaemia, or in the penumbra of a cerebral lesion in order to detect a local ischaemia. The values associated with an ischemic risk are not fully defined and may be under 10-15 mmHg. A concomitant metabolic monitoring by cerebral microdialysis is of importance to fully address the real cerebral local ischaemic burden. Scientific studies are mainly focused on patients with a brain traumatism. Nor SvjO(2), nor PtiO(2) monitoring have at present been demonstrated to be associated with a clinical benefit, and their use should be restricted to scientific research.