This chapter discusses the importance of brain relaxation via management of intracranial pressure (ICP). Optimal respiratory management to control ICP is imperative, as respiratory dysfunction is common in patients with elevated ICP. Regardless of whether the progression is acute or insidious, elevated ICP will develop as compensatory mechanisms are exhausted. In situations of acute elevations of ICP, first oxygenate the patient appropriately and elevate the head of bed (HOB) up to 30°. During surgical operations, ICP may be affected by four variables: hyperventilation, diuretics, head position, and anesthetic drugs. The cranium and vertebral canal are relatively inelastic parts, so any increase in volume of brain, blood, or cerebrospinal fluid (CSF) will increase the ICP. Hypocapnia blunts the increase in cerebral blood flow (CBF) and ICP that usually occurs with volatile anesthetics. Elevated ICP is something all providers must be acutely aware of both inside and outside the operating room.