Contents
The Monro-Kellie Doctrine
- The skull is a fixed box containing 3 things: brain tissue, blood, and CSF
- If one component increases, another must decrease or ICP rises
- Initial compensation: displace CSF and venous blood
- Once compensation is exhausted, small volume changes cause large ICP spikes
Normal ICP and CPP
- Normal ICP: 5–15 mmHg; sustained >20–22 mmHg is treated
- CPP = MAP − ICP; target generally 60–70 mmHg
- CPP is the pressure actually perfusing the brain — protect it
- As ICP rises, CPP falls unless MAP rises to compensate → ischemia risk
Causes of Increased ICP
- Traumatic brain injury, intracranial hemorrhage, large ischemic stroke
- Brain tumors, abscess, or hydrocephalus (CSF obstruction)
- Cerebral edema (after injury, hypoxia, or hepatic failure)
- Anything that adds volume or blocks CSF/venous outflow
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Start Free Practice →Early Signs of Increased ICP
- Change in level of consciousness is the EARLIEST and most sensitive sign
- Restlessness, confusion, lethargy
- Headache, nausea/vomiting
- Pupillary changes and subtle motor weakness may begin
Late Signs — Cushing's Triad
- Hypertension with WIDENING pulse pressure
- Bradycardia
- Irregular respirations (e.g., Cheyne-Stokes)
- Cushing's triad is a LATE, ominous sign of impending herniation — act immediately
- Fixed/dilated pupil(s) and posturing also signal severe, late deterioration
Herniation Syndromes
- Uncal herniation: ipsilateral blown (fixed/dilated) pupil, contralateral weakness
- Central herniation: progressive LOC decline, then brainstem signs
- Cushing's triad and posturing reflect brainstem compression
- Herniation is a neurosurgical emergency
ICP Monitoring
- External ventricular drain (EVD): measures ICP AND drains CSF therapeutically
- Level the transducer to the tragus / foramen of Monro
- Watch the ICP waveform; sustained elevated P2 suggests poor compliance
- Maintain a closed, sterile system; monitor for infection and over/under-drainage
Management: Positioning & Ventilation
- Head of bed elevated ~30° with head midline (promotes venous drainage)
- Avoid neck flexion/rotation and tight ET tube ties that impede jugular outflow
- Maintain normocapnia (PaCO₂ ~35–40); hyperventilation only as a brief rescue
- Avoid hypoxia and hypotension — both worsen secondary brain injury
Management: Osmotherapy & Sedation
- Mannitol: osmotic diuresis pulls fluid from brain; monitor osmolality, volume, and BP
- Hypertonic saline (3%): osmotic agent; monitor sodium closely
- Sedation/analgesia to reduce metabolic demand and ICP spikes; treat fever and seizures
- Maintain CPP with fluids/vasopressors as needed to keep target ≥60 mmHg
Nursing Priorities & What to Avoid
- Cluster care to minimize stimulation; keep environment calm
- Pre-oxygenate and limit suctioning to <10–15 sec (suctioning spikes ICP)
- Avoid hip flexion, Valsalva, and activities that raise intrathoracic pressure
- Trend neuro exam (GCS, pupils), ICP, CPP; report deterioration immediately
Can you answer these 3 CCRN questions?
Here are 3 questions in the style of our premium bank. The full rationale explains exactly why the right answer is right — and why the distractors trap most test-takers.
Premium Practice Question
A head-injured patient develops BP 188/72, HR 48, and irregular respirations. These findings indicate:
- Early increased ICP
- Cushing's triad — a late sign of impending herniation
- Neurogenic shock
- Adequate cerebral perfusion
Rationale: Hypertension with a widening pulse pressure, bradycardia, and irregular respirations is Cushing's triad, a late and ominous sign of impending herniation requiring immediate intervention....
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Premium Practice Question
The MAP is 90 mmHg and the ICP is 25 mmHg. What is the CPP, and is it adequate?
- CPP 115, adequate
- CPP 65, adequate
- CPP 65, inadequate
- CPP 25, inadequate
Rationale: CPP = MAP − ICP = 90 − 25 = 65 mmHg, which is within the general target of 60–70 mmHg for cerebral perfusion....
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Premium Practice Question
Which nursing action best helps lower ICP?
- Keep the head turned sharply to one side
- Elevate the head of bed 30° with the head midline
- Perform prolonged endotracheal suctioning
- Cluster painful procedures together rapidly
Rationale: Elevating the head of bed to about 30° with the head midline promotes cerebral venous drainage and helps reduce ICP, while neck rotation and prolonged suctioning raise it....
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Frequently Asked Questions
What is the earliest sign of increased intracranial pressure?
A change in level of consciousness is the earliest and most sensitive sign of rising ICP, often appearing as restlessness, confusion, or lethargy before pupillary or vital-sign changes.
What is Cushing's triad?
Cushing's triad is hypertension with a widening pulse pressure, bradycardia, and irregular respirations. It is a late, ominous sign of severely elevated ICP and impending brain herniation that requires immediate intervention.
How is cerebral perfusion pressure (CPP) calculated?
CPP equals mean arterial pressure minus intracranial pressure (CPP = MAP − ICP). The general target is 60–70 mmHg; as ICP rises, CPP falls unless MAP increases, risking cerebral ischemia.
How is increased ICP managed?
Elevate the head of bed to about 30° with the head midline, maintain normocapnia and avoid hypoxia and hypotension, use osmotherapy (mannitol or hypertonic saline), provide sedation and treat fever and seizures, drain CSF via an EVD if present, and maintain CPP at target.
Why is suctioning limited in patients with high ICP?
Endotracheal suctioning stimulates coughing and raises intrathoracic and intracranial pressure, causing ICP spikes. It should be brief (under 10–15 seconds), preceded by pre-oxygenation, and not performed routinely.
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