Effects of tracheal intubation on intracranial pressure following induction of anaesthesia with thiopentone or althesin in patients undergoing neurosurgery.

Intracranial pressure (i.c.p.) and mean arterial pressure (m.a.p.) were studied in 20 patients during the induction of anaesthesia for craniotomy. Tubocurarine was administered as the muscle relaxant and either thiopentone or Althesin for the induction of anaesthesia. No significant differences were found in the i.c.p. changes with induction, intubation or pharyngeal packing, between the thiopentone and the Althesin groups. Except for two patients (one in each group) the increases in i.c.p. associated with intubation were small. In these two patients moderate increases from normal values to 28 and 37 mm Hg were recorded, but in one of these patients coughing and straining followed intubation. Marked decreases in m.a.p. were noted in both groups, but the recovery of m.a.p. was significantly more rapid in the Althesin group. Only two patients had i.c.p. values greater than 20 mm Hg before operation and in neither did i.c.p. increase above control values during induction and intubation. Packing the pharynx produced minimal changes in i.c.p. in all patients.