Anesthesiology APPLIED Exam › Neuroanesthesia and neuromuscular

Raised intracranial pressure: evaluation and reduction

Neuroanesthesia and neuromuscular·~5 min read· Physician-reviewed✓ Sourced · 3

Stem

A 61-year-old man, 88 kg, is scheduled for craniotomy and resection of a large left frontal tumor. For a week he has had morning headaches and vomiting, and today he is drowsy but obeys commands. MRI shows surrounding edema, 7 mm of midline shift and effaced ventricles. Blood pressure is 168/94 and heart rate 58. He takes dexamethasone and levetiracetam.

Question

How do you assess his intracranial pressure, and how will you control it through the anesthetic?

Ideal answer

HeadlineRaised intracranial pressure with compliance exhausted: shift and effaced ventricles. My goal is perfusion pressure, MAP stays up while ICP comes down.

Look for symptoms and signs, to judge how near herniation he is: headache, vomiting, decreasing consciousness, papilledema, a dilated pupil, and Cushing's triad of hypertension, bradycardia and irregular breathing.
Propofol or etomidate, which lower flow and metabolism together; fentanyl, esmolol or lidocaine blunt laryngoscopy, because a surge transmits straight into a brain that has lost autoregulation.
Head up 30 degrees, neck neutral, PaCO2 30–35 mmHg, PaO2 well above 60 mmHg; mannitol 0.25–1 g/kg¹ or hypertonic saline if the brain is tight.
Total intravenous propofol if the surgeon reports swelling; no hypotension, hypoxia, hypercarbia, hyperthermia or hyperglycemia. His steroid continues for tumor edema; I ask about ventricular drainage.
A seizure treated immediately, because it doubles cerebral metabolism.

Breaking down the answer

Perfusion pressure, not just ICP — the fixed box makes every ventilator, pressure and drug choice a cerebral choice. CPP 60–70 mmHg:¹ with an ICP of 20, a mean of at least 80–90, by phenylephrine or norepinephrine, transduced at the external auditory meatus.
Relaxant choice — succinylcholine raises ICP a few mmHg for a few minutes: acceptable for a full stomach or a predicted difficult airway, attenuated by a defasciculating dose; after subarachnoid hemorrhage or a long-standing deficit, I weigh hyperkalemia.²
Rocuronium and ketamine — rocuronium 1.2 mg/kg is my default when the airway looks easy; ketamine stays out unless the patient is hypotensive and ventilated, when the older prohibition no longer holds.
Hyperventilation to 30–35, not lower — it works within minutes; below 30 I trade swelling for ischemia. Trauma: prolonged prophylactic hyperventilation to 25 mmHg or less is not recommended, and I avoid it in the first 24 hours, when flow is often critically low.¹
Mannitol versus hypertonic saline — mannitol works in 15–30 minutes, needs an intact blood-brain barrier and an osmolality below 320 mOsm/kg, and causes diuresis, which I replace, and transient hypervolemia. 3% saline when hypovolemic or hyponatremic, targeting sodium 145–155 mEq/L.
Volatile or TIVA — up to 0.5–1 MAC of sevoflurane is acceptable with hyperventilation, because metabolic suppression offsets vasodilation. Propofol lowers flow and metabolism in parallel; nitrous oxide raises both.
Steroids for tumors only — dexamethasone 10 mg reduces vasogenic edema around tumors and abscesses within hours; in trauma steroids are not recommended, and high-dose methylprednisolone increased mortality.¹

Follow-up question

The dura is open and the surgeon says the brain is swelling out through the craniotomy. What do you do?

Follow-up answer

HeadlineBrain swelling at the open dura; I announce it and check the simple causes first.

Airway and ventilation first, because kinked tubing and a high airway pressure are the most common cause; then head position and venous drainage: no neck flexion, no tie on the jugulars, no Trendelenburg. PaCO2 to 30 mmHg, more mannitol or 250 mL of 3% saline, propofol with the volatile and nitrous off, a deeper anesthetic, full paralysis confirmed, and cerebrospinal fluid drained if a ventricle is accessible. Hypertension is treated only once perfusion pressure is secure. If nothing works, high-dose barbiturates with the hemodynamics supported,¹ and the bone flap left off. If he later fails to wake, immediate CT.³

Pitfalls that cost points

Reciting the Monro-Kellie doctrine instead of stating a management plan.
Treating the blood pressure down because it reads 180 systolic, forgetting that Cushing's response is protective.

Rapid-fire

Q: Why does hyperventilation stop working within hours? A: The effect fades over 6–12 hours: cerebrospinal fluid bicarbonate falls to match the new PaCO2, the pH normalizes and vessels return to baseline caliber; abrupt normocarbia then causes rebound swelling.

Q: Why does PEEP matter? A: It raises intrathoracic pressure and impedes jugular drainage; up to 10 cmH2O is tolerated in most patients if the head is elevated and the mean pressure is held.

Q: Why does mannitol lose effect with repeated doses? A: It leaks across a damaged barrier, accumulates in injured tissue and reverses the gradient; osmolality above 320 mOsm/kg also causes renal injury.

Q: What does a unilateral dilated pupil mean? A: Uncal herniation compressing the third nerve; it needs immediate osmotherapy, hyperventilation and the surgeon.

Numbers to know

Item	Value
Normal ICP	5–15 mmHg; treat above 22 mmHg¹
CPP target	60–70 mmHg¹
PaCO2 for acute control	30–35 mmHg, temporary bridge to osmotherapy and decompression; flow changes ~3% per mmHg
Mannitol	0.25–1 g/kg IV over 15–20 min;¹ osmolality ceiling 320 mOsm/kg
Hypertonic saline	3% in 250 mL boluses or 23.4% 30 mL; sodium target 145–155 mEq/L
Head elevation	30 degrees, neck neutral

Sources

1.Guidelines for the Management of Severe Traumatic Brain Injury, 4th Edition (Executive Summary) · Brain Trauma Foundation, 2016 · braintrauma.orgTrauma-specific; ICP, CPP, hyperventilation, mannitol, steroid and barbiturate recommendations.
2.QUELICIN (succinylcholine chloride) injection prescribing information · FDA / DailyMed · dailymed.nlm.nih.govSection 5.4: increased risk of severe hyperkalemia with subarachnoid hemorrhage and degenerative CNS conditions.
3.Delayed Emergence · OpenAnesthesia (IARS) · openanesthesia.orgCited for the neurosurgical patient who does not wake: immediate CT before neurology consult.

Facts on this page were checked against these sources on Oct 14, 2026. Guidelines change; confirm doses against current institutional protocols.