Principles of intracranial pressure monitoring and treatment.

Intracranial pressure (ICP) is governed by volumes of intracranial blood, cerebrospinal fluid, and brain tissue. Expansion of any of these volumes will trigger compensatory changes in the other compartments, resulting in initially limited change in ICP. Due to the rigid skull, once compensatory mechanisms are exhausted, ICP rises very rapidly. Intracranial hypertension is associated with unfavorable outcome in brain-injured patients. This chapter discusses the pathophysiology of raised ICP, as well as typical waveforms, monitoring techniques, and clinical management. The dynamics of ICP are more important than the absolute value at any given time point, but mean ICP exceeding 20-25mmHg is usually treated aggressively. Algorithms based on data from patients with traumatic brain injury are applied also in other conditions. However, an understanding of the underlying pathophysiology allows adaptation of therapies to other pathologies. Typically, a three-staged approach is used, starting with restoration of systemic physiology, sedation, and analgesia. If these measures are insufficient, surgical options, such as drainage of cerebrospinal fluid or evacuation of mass lesions, are considered. In the absence of surgical options, stage 2 treatments are initiated, consisting of either mannitol or hypertonic saline. If these measures are insufficient, stage 3 therapies include hypothermia, metabolic suppression, or craniectomy.