CONTINUOUS MONITORING OF JUGULAR BULB OXYGEN-SATURATION AND THE EFFECT OF DRUGS ACTING ON CEREBRAL METABOLISM

The laser absorption spectrophotometric technique was used to continuo usly monitor jugular bulb oxygen saturation (SjO2), and thus to calcul ate arteriovenous oxygen differences (AVDO2), in three subgroups of in tensively monitored, severely head injured patients. We have used this data to address two questions: 1. How do cerebral and systemic haemod ynamic changes affect SjO2 and AVDO2; and 2. Can ADVO2 Measurements be used to detect therapeutic changes in brain metabolism, in response t o drugs. The major haemodynamic factor affecting SjO2 and AVDO2 was in tracranial pressure (ICP). Increases in ICP were associated with conco mitant increases in SjO2, and decreases in AVDO2, suggesting cerebral hyperaemia in response to ICP waves. Systemic changes were less freque nt, but potent influences on SjO2. The short acting anaesthetic agent propofol produced a marked increase in SjO2 (decrease in AVDO2 to belo w the normal range) which became less marked with time. A new high aff inity glutamate antagonist produced no change in SjO2. With rigorous a ttention to technical factors, and exclusion of ''tra and intracranial haemodynamic effects, SjO2 monitoring may be a useful ''surrogate end point'' for the effect of drugs acting on brain metabolism.