CONTINUOUS MONITORING OF JUGULAR BULB OXYGEN-SATURATION IN COMATOSE PATIENTS - THERAPEUTIC IMPLICATIONS

Comatose patients run a high risk of developing cerebral ischaemia whi ch may considerably influence final outcome. It would therefore be ext remely useful if one could monitor cerebral blood flow in these patien ts. Since there is a close correlation between the arteriovenous diffe rence of oxygen and cerebral blood flow, it was a logical step to plac e a fiberoptic catheter in the jugular bulb for continuous measurement of cerebrovenous oxygen saturation. We have monitored cerebral oxygen ation in 54 patients, comatose because of severe head injury, intracer ebral haemorrhage or subarachnoid haemorrhage. Normal jugular venous o xygen saturation (SJVO(2)) ranges between 60 and 90%. A decline to bel ow 50% is considered indicative of cerebral ischaemia. Spontaneous epi sodes of desaturation (SJVO(2) < 50% for at least 15 min) were frequen t during the acute phase of these insults. Many of these desaturation episodes could be attributed to hyperventilation, even though consider ed moderate. Likewise, insufficient cerebral perfusion pressure and se vere vasospasm were found to be important causes of desaturation episo des. In many instances, tailoring of ventilation or induced hypervolae mia and hypertension were capable of reversing these low flow states. The new method of continuous cerebrovenous oximetry is expected to con tribute to a better outcome by enabling timely detection and treatment of insufficient cerebral perfusion.