Cerebral oximetry: a useful monitor during carotid artery surgery.

Cerebral oximetry was evaluated as a monitor of oxygenation during carotid endarterectomy in 22 patients. The oximeter was a reliable continuous monitor, identifying changes in cerebral oxygenation during episodes of hypotension and after arterial occlusion. Changes in oxygenation correlated well with the surgical assessment of backbleeding after arterial clamping, but less well with other methods which are used to make a decision on insertion of an arterial shunt. There was no correlation between internal carotid artery stump pressure and change in cerebral oxygenation after application of the arterial cross clamp. However, cerebral oxygenation correlated weakly with the change in middle cerebral artery velocity as measured by transcranial Doppler ultrasonography (r = 0.49, p < 0.02).