Increased Intracranial Pressure (ICP)

A patient's blood pressure is climbing while their heart rate drops — most students think cardiac. But in a neuro patient, this triad means the brain is herniating.

Increased intracranial pressure (ICP) develops when the volume inside the rigid skull exceeds compensatory capacity (normally 5–15 mmHg in adults). Early signs are subtle: restlessness, confusion, headache (worse in the morning or with coughing/straining), and a decreasing level of consciousness — the earliest and most reliable indicator. As ICP rises, you see pupil changes: ipsilateral pupil dilation with sluggish or absent light response from CN III compression. Late signs form the Cushing's triad — widening pulse pressure (systolic climbs, diastolic drops), bradycardia, and irregular respirations. This is a brainstem compression response and signals impending herniation. Projectile vomiting without preceding nausea is another late finding. In infants, look for a bulging fontanel, high-pitched cry, and poor feeding. The progression follows a predictable path: mental status changes first, then pupil changes, then vital sign changes last. By the time Cushing's triad appears, the window for intervention is closing rapidly.

Key Distinctions

Don't confuse Cushing's triad (hypertension, bradycardia, irregular respirations from ICP) with Cushing's syndrome (cortisol excess — moon face, buffalo hump). Students frequently mistake late signs for early signs — vital sign changes like Cushing's triad are late and ominous, not early warnings. A unilaterally fixed, dilated pupil indicates ipsilateral herniation, not a bilateral finding — bilateral fixed pupils signal a more advanced, potentially irreversible stage.

Clinical Pearl

Early ICP = the mind goes first. Late ICP = the vitals go last. If you're catching it on the monitor, you're already behind — catch it at the bedside with mental status.

Monitoring & Interventions

Once increased ICP is identified, nursing interventions aim to reduce intracranial volume across three compartments: brain tissue, blood, and CSF. Position the head of bed at 30 degrees with the head in midline — turning the neck kinks the jugular veins and blocks venous outflow, spiking ICP further. Maintain a quiet, dim environment and space out care to avoid repeated stimulation. Avoid hip flexion, Valsalva maneuvers (straining, coughing), and suctioning beyond 10 seconds per pass — each triggers transient ICP spikes. Maintain normothermia — fever increases cerebral metabolic demand and worsens ICP; use antipyretics and cooling measures as needed. Hyperosmotic agents are the pharmacologic frontline: mannitol (0.25–1 g/kg IV) draws fluid from brain tissue into the vascular space. Monitor serum osmolality — hold mannitol if osmolality exceeds 320 mOsm/kg to prevent renal failure. Hypertonic saline (3% NaCl) is an alternative that expands plasma volume without the osmotic rebound risk. Monitor sodium closely; target varies by protocol but generally stays below 160 mEq/L. An external ventricular drain (EVD) both monitors ICP numerically (normal 5–15 mmHg) and therapeutically drains CSF. Keep the drainage system leveled at the tragus of the ear (the external landmark approximating the foramen of Monro). Before repositioning the patient: clamp the drain → reposition → relevel at the tragus → unclamp. Maintain cerebral perfusion pressure (CPP = MAP − ICP) above 60 mmHg — below this threshold, ischemia begins.

Key Distinctions

Don't confuse mannitol with hypertonic saline: mannitol is a diuretic osmotic agent (monitor osmolality), while 3% NaCl expands volume (monitor sodium). Students mix up the EVD leveling landmark — the tragus of the ear is the correct surface landmark because it approximates the foramen of Monro. Neither the shoulder nor the top of the head is appropriate. Elevating HOB reduces ICP via venous drainage; Trendelenburg is contraindicated and can be fatal.

Clinical Pearl

Head up, head straight, lights down, hands off. Think of managing ICP like keeping a full cup from overflowing — every small tilt or jolt matters.