The relation between intracranial pressure,mean arterial pressure and cerebral blood flow in patients with severe head injury

In patients with severe head injuries ICP, MAP and CBF were measured continuously. In most patients there was a positive vasopressor response to increasing ICP, but the ICP/MAP ratio varied considerably in individual cases. CBF was diminished either by increasing ICP or by decreasing MAP. This effect was more marked with ICP above 40 mm Hg or MAP below 110 mm Hg. In terminal stages there was often a negative MAP/ICP ratio accompanied by massive cerebral hyperaemia. Key words: Severe head injury--intracranial pressure--mean arterial pressure--cerebral blood flow--cerebral perfusion pressure--critical limit of ICP and CBF. Abbreviations: ICP equals intracranial pressure (mm Hg); CBF, Flow equals cerebral blood flow (ml/min); MAP equals mean arterial pressure (mm Hg); CPP equals cerebral perfusion pressure (mm Hg) (difference between MAP and ICP); BP equals blood pressure.