Ketamine anaesthesia in patients with intracranial pathology

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. Recently we reported an intracranial pressure (ICP) increase to 75 mm Hg secondary to ketamine injec-tion in a patient with high ICP due to cerebro-spinal fluid (c.s.f.) obstruction (Wyte et aL, 1972) and other investigators have noted ICP in-creases to 62 mm Hg in neurosurgical patients (list et al., 1972). Fitch and McDowall (1971) hav