Increased Intracranial Pressure

Raised intracranial pressure (ICP) is a time-sensitive threat to cerebral perfusion, not simply an abnormal monitor value. The skull is a fixed-volume vault containing brain tissue, blood, and cerebrospinal fluid (CSF). For a time, a rise in one component can be buffered by displacement of CSF or venous blood. Once that reserve is exhausted, a small additional volume—such as expanding blood, oedema, or obstructed CSF—can produce a sharp ICP increase. Cerebral perfusion pressure (CPP) is calculated as CPP = MAP − ICP. An elevated ICP therefore lowers perfusion even when MAP has not changed; hypotension makes the fall worse. The nurse’s priority is to recognize a changing neurological pattern, protect oxygenation and systemic perfusion, correct reversible insults, and trigger stepwise treatment before herniation occurs. A patient with a head injury who becomes newly drowsy, develops repeated vomiting, or has one pupil larger than the other needs urgent reassessment and escalation. Do not wait for the next scheduled observation or for the ICP number to cross a threshold. Elevated ICP and acute herniation can occur independently, and clinical deterioration can be...