Critical care management of head injury

Cerebral injury from trauma can be due to primary or secondary mechanisms. Primary injury results from mechanical disruption of brain tissue occurring at the time of the initial trauma. Secondary insults occur in the period following the initial injury, and involve several pathophysiological processes, with a prominent role for ischaemia. This article outlines the pathophysiological changes in acute head injury. Management of head injury in the critical care unit aims to avoid, detect and treat such secondary injuries through manipulation of cerebrovascular and systemic physiology. The interventions employed for these purposes need to be used in a rational manner, with adherence to clear protocols, and require careful monitoring of systemic and intracranial physiology. Several expert bodies provide advice regarding the components of such protocols, and focus on the maintenance of cerebral perfusion pressure above 60 mm Hg, intracranial pressure below 20 mm Hg, adequate oxygenation, avoidance of severe or needless hypocapnia, and control of blood sugar and body temperature. All clinical trials of neuroprotective agents in head injury have failed, but there may be a future role for such drugs.