Critical care of the head-injury patient

Abstract

C RITICAL CARE of the head-injury patient will be examined in this article from the perspective of the management in the intensive care unit (ICU). Most head injuries result from automobile accidents in the context of acceleration-deceleration. At present, penetrating injuries because of high-velocity missiles fired from too easily accessible guns in the possession of children, gangs, and citizens are probably as prevalent. Athletics is another source of head injury. More than 2 million Americans annually suffer a head injury; 70,000 to 90,000 of these will be permanently disabled. At this time, the prognosis after major head injury is not much better than it was 20 years ago, although the pathophysiology is better understood thanks to a shift in the focus of interest from gross to submolecular and molecular biochemical mechanisms. Traditionally, the three anatomically distinct hematomas--epidural, subdural, and intracerebral-have been and are still managed by neurosurgeons and other head trauma caregivers (including anesthesiologists) as space-occupying lesions that are dangerous when of sufficient size to increase intracranial pressure (ICP) and decrease cerebral perfusion pressure (CPP). Recent molecular biological evidence confirms the suspicion that inflammatory and vasoactive factors released at the hematoma interface are inciting changes within the parenchyma independent of any direct pressure effect. The term autoregulation does not refer to vehicular regulation but to the homeostatic mechanism that results in little variation in cerebral blood flow (CBF) within the range of mean systemic blood pressure (BP) from 60 to 160 mm Hg (or 50 to 150 mm Hg CPP).