Intravenous ketamine anaesthesia induced abrupt increases in intracranial pressure levels ranging from 25 to 82 mm Hg on nine occasions in five patients with abnormal cerebrospinal fluid flow dynamics and/or other intracranial pathology. The mean gain in intracranial pressure in patients with cerebral abnormalities was 41.5 (SD 16.6) mm Hg. This is compared with a ketamine-induced mean pressure increase of 19.4 (SD 6.9) mm Hg found by other investigators in a group of neurologically normal patients. Intravenous injection of thiopentone may terminate intracranial pressure elevations caused by ketamine.
