You’re a new CA-2 carrying the code pager for the first time. You are called to the neurosurgical intensive care unit (ICU) for an emergent intubation. On arrival, you find serious badness. Seems a middle-age man scheduled to undergo craniotomy for tumor the next day has become progressively more unresponsive, and in the last 5 minutes, his right pupil has dilated and become unresponsive to light. The ICU team wants to transport him for an emergent head CT but wisely called you first. What is your management plan?

In caring for the patient with intracranial hypertension, the role of the anesthesiologist is ultimately to maintain a favorable balance between the delivery of oxygen (and glucose) and the brain’s metabolic requirements. Under normal circumstances, flow and metabolism are elegantly controlled to maintain a physiological balance. Under pathological conditions, however, anesthesiologists have a unique role in affecting oxygen delivery and metabolism in order to try to improve oxygen delivery to potentially ischemic brain. For key terms and definitions, see Table 132.1.

When considering oxygen delivery to the brain, it is important to remember that the brain is contained within the indistensible skull. Under normal circumstances, the contents of the skull can be divided into three categories: Brain (80% of intracranial volume), cerebrospinal fluid (CSF) (15%), and blood (5%). Under pathological conditions, tumor or hematoma may gradually or acutely increase intracranial volume. Under chronic conditions, compensatory mechanisms to offset this increasing intracranial volume include increased reabsorption of CSF or diversion of CSF to the spinal canal. Once these compensatory mechanisms are exhausted, however, intracranial pressure (ICP) rapidly increases within the intracranial vault (Fig. 132.1) and cerebral perfusion pressure (CPP) is compromised:

CPP = MAP − ICP

where MAP is mean arterial pressure. Acute increases in intracranial volume, such as seen with head trauma or intracranial hemorrhage, are much more poorly tolerated, and ICP may rise precipitously.