[Intracranial pressure irregularities in experimental subarachnoid hemorrhage]

The intracranial pressure (ICP) irregularities, i.e., pressure waves, were studied in dogs with experimental subarachnoid hemorrhage. Animals were lightly anesthetised, immobilised with panchronium bromide and respirated artificially. Subarachnoid infusion of hemolysed red blood cells was used to induce intracranial hypertension. Recordings of both systemic blood pressure (SBP) and ICP were undertaken continuously. After the infusion of hemolysed blood the ICP increased gradually and reached to 50 mmHg or more at the terminal stage. The pressure waves were classified into two types, i.e., the fast waves and the slow waves. The fast waves had a duration of 10-30 seconds, being accompanied by a marked increase of the SBP. The slow waves gradually increased their frequency and the duration, when the ICP increased more than 20 mmHg or more resembling plateau-like waves. Postmorten examination showed hemogenic meningitis at the base of the brain, especially the medulla oblongata. The results suggest that studies of the slow waves is of value for analyzing plateau waves.