The effect of nitrous oxide and halothane upon the intracranial pressure in hypocapnic patients with intracranial disorders.

In nine patients with severe intracranial disease causing increased intracranial pressure (ICP), the effects on ICP and cerebral perfusion pressure (CPP) of the following manoeuvres were studied: (1) endotracheal intubation, (2) addition of 50% nitrous oxide to the inspired gas after hyperventilation with oxygen and thereafter (3) addition of halothane to the nitrous oxide/oxygen mixture. The mean "peak" increase in ICP during endotracheal intubation was 16.6 mm Hg. Critically small CPP values were prevented by an increase in arterial pressure. Nitrous oxide caused only a minor increase in ICP. Halothane caused a mean increase in ICP of 7.6 mm Hg and critically small CPP values in three patients.