Increased Intracranial Pressure Overview

Overview

This lecture reviews increased intracranial pressure (ICP), including its causes, clinical signs, pathophysiology, monitoring, and nursing interventions, with a focus on key concepts for exams.

Definition and Pathophysiology

• Increased intracranial pressure (ICP) is a rise in pressure within the skull, requiring emergency treatment.
• Normal ICP is 5–15 mmHg; >20 mmHg needs immediate intervention.
• ICP is determined by three components: brain tissue, blood, and cerebrospinal fluid (CSF).
• The Monro-Kellie hypothesis states that if one component increases, others must decrease to maintain normal pressure.
• When compensatory mechanisms fail, brain herniation and death may occur.

Factors Affecting ICP

• Body temperature (hyperthermia increases ICP).
• Oxygenation status: hypoxia and increased CO₂ (hypercapnia) cause vasodilation, raising ICP.
• Body position: neck flexion/hip flexion, or improper bed angle can increase ICP.
• Increased intra-abdominal/thoracic pressure from vomiting, coughing, or Valsalva maneuver.

Cerebral Perfusion Pressure (CPP)

• CPP is the pressure driving blood flow to the brain, calculated as MAP minus ICP (CPP = MAP – ICP).
• Normal CPP: 60–100 mmHg; <50 mmHg risks brain ischemia.
• When MAP nears ICP, CPP drops, reducing brain perfusion.

Causes of Increased ICP

• Head trauma, traumatic brain injury.
• Increased CSF (hydrocephalus), hemorrhage, hematoma.
• Brain tumors.
• Central nervous system infections (meningitis, encephalitis).

Signs and Symptoms (MIND CRUSH Mnemonic)

• M: Mental status changes (earliest sign: restlessness, confusion).
• I: Irregular breathing (Cheyne-Stokes breathing).
• N: Nerve changes—cranial nerve/pupil changes, possible papilledema, abnormal Dolls’ eyes.
• D: Decerebrate/decorticate posturing, flaccidity.
• C: Cushing’s triad (late signs): increased systolic BP, widening pulse pressure, decreased HR, abnormal respirations.
• R: Reflexes—positive Babinski.
• U: Unconsciousness (late).
• S: Seizures.
• H: Headache, emesis (often projectile), motor deterioration (hemiplegia).

Nursing Interventions (PRESSURE Mnemonic)

• P: Position head 30–35°, keep head midline, avoid neck/hip flexion.
• R: Respiratory support—prevent hypoxia/hypercapnia, monitor ABGs, limit suction.
• E: Elevated temperature—prevent hyperthermia with antipyretics/cooling.
• S: Systems monitoring—neuro checks, Glasgow Coma Scale, monitor ICP (>20 mmHg report), EVD/ventriculostomy care.
• S: Straining avoidance—prevent vomiting, sneezing, Valsalva; calm environment.
• U: Unconscious care—prevent complications (skin, nutrition, DVT, infection), treat as conscious.
• R: Rx/Prescriptions—barbiturates (decrease metabolism), antihypertensives, vasopressors, anticonvulsants, mannitol (osmotic diuretic), loop diuretics, corticosteroids.
• E: Edema management—monitor for fluid overload/depletion, renal function, and electrolyte balance.

Key Terms & Definitions

• ICP (Intracranial Pressure) — Pressure within the skull (normal: 5–15 mmHg).
• Monro-Kellie Hypothesis — Concept that brain tissue, blood, and CSF volumes regulate ICP.
• CPP (Cerebral Perfusion Pressure) — Pressure ensuring blood flow to the brain; CPP = MAP – ICP.
• MAP (Mean Arterial Pressure) — Average arterial pressure; calculated from BP.
• Cushing’s Triad — Late signs of increased ICP: high systolic BP, bradycardia, irregular breathing.
• Ventriculostomy/EVD — Device to monitor and drain CSF, reducing ICP.
• Mannitol — Osmotic diuretic used to reduce cerebral edema.

Action Items / Next Steps

• Remember normal values for ICP (5–15 mmHg) and CPP (60–100 mmHg).
• Study the MIND CRUSH and PRESSURE mnemonics for signs, symptoms, and interventions.
• Take the free quiz on increased ICP.
• Review the Glasgow Coma Scale and practice calculating MAP and CPP.