CLINICAL AND ELECTROPHYSIOLOGICAL FINDING S UNDER CONTINUOUS-INFUSIONOF THIOPENTAL

Twenty comatous, recently brain damaged patients, seventeen suffering from head injury, three from spontaneous intracranial bleeding, mean a ge 28 years, 75 % male were treated against elevated intracranial pres sure with continuous infusion of thiopental during a mean time of four days. Serum thiopental level, brainstem reflexes, electroencephalogra m and evoked potentials (early auditory evoked potentials and early so matosensory potentials of the median nerve) were measured every day. L oss of EEG and brain stem reflexes occured correlating to the serum le vel of thipental. The different functions failed in the following sequ ence: 1. spontaneous eye movements (4-36 mumol/l), 2. oculocephalic re flex (37-75 mumol/l), corneal reflex (from 47 mumol/l on), pupillary l ight reflex (from 80 mumol/l on), coughing reflex (above 100 mumol/l), 4. EEG (above 200 mumol/l). Evoked potentials, however, remained unch ainged until maximum serum level (230 mumol/l). Evoked potentials can be used to survey reliably the progress of disease in patients with hi gh serum levels of thiopental. They are able to exclude brain death in patients with an isoelectric EEG and loss of brain stem reflexes. Bel ow a serum level of 20 mumol/l is no clinical relevant influence on br ain stem function.