[The influence of some inhalation anaesthetics on the intracranial pressure with special reference to nitrous oxide (author's transl)].

The influence of inhalation anaesthetics on intracranial pressure (ICP), arterial blood pressure and cerebral perfusion pressure (CPP) was investigated on 12 unconscious patients with head injury having an initial ICP of about 20 mm Hg. Halothane, enflurane and nitrous oxide induced a considerable rise of ICP during a 15 to 25 minute period of observation. The moderate fall in blood pressure caused by halothane and enflurane enhanced the reduction of the calculated CPP. Besides, a regular fall in blood pressure of about 16% was observed under the influence of nitrous oxide, subsequently reducing the CPP in some cases under 40 mm Hg. Inhalation anaesthetics, including nitrous oxide, should therefore not be used in patients with decreased intracranial compliance before the increased ICP is treated.