Management of Raised Intracranial Pressure (Raised ICP)

Normal ICP is <15 mmHg; sustained levels >20-22 mmHg are considered pathological and require treatment. The management follows a stepwise, tiered approach.

1. Monitoring

Indications for ICP monitoring (per AANS guidelines):

GCS 3-8 with abnormal CT scan, OR
GCS 3-8 with normal CT but any two of: age >40, posturing, systolic BP <90 mmHg

Device types:

Ventricular catheter (EVD) - gold standard; directly measures CSF pressure and allows therapeutic CSF drainage
Fiberoptic / intraparenchymal strain gauge - less accurate over time but lower infection risk

Target: ICP <20 mmHg, CPP (cerebral perfusion pressure) >60 mmHg

CPP = MAP - ICP

2. General (First-Tier) Measures

These are initiated immediately for all patients at risk:

Intervention	Target / Detail
Head position	30° head-of-bed elevation; neutral neck position to avoid jugular vein compression
Analgesia/sedation	Fentanyl 25-50 mcg IV PRN; propofol preferred (reduces CBF + CMRO₂, rapidly clears for neuro exam)
Normothermia	Fever markedly raises ICP; aggressively treat hyperthermia
Normocapnia	Target PaCO₂ 35-40 mmHg; avoid hypercarbia (causes cerebral vasodilation)
Normooxia	Correct hypoxia; target SpO₂ >95%
Fluid management	Use isotonic saline (NS); avoid hypotonic fluids (D5W, 0.45% NaCl, lactated Ringer used cautiously); avoid albumin resuscitation (SAFE study showed harm in TBI)
Glucose	Maintain euglycemia
Seizure prophylaxis	Especially in TBI - seizures raise ICP dramatically (increase brain metabolism by 300-400%)

Adams and Victor's Principles of Neurology, 12th Ed., p. 913

3. Osmotherapy (Second-Tier)

Both agents work by creating an osmotic gradient across an intact blood-brain barrier, drawing water out of brain tissue and reducing volume. The very rapid onset is also facilitated by reduced blood viscosity and cerebral blood volume.

Mannitol (20%)

Dose: 0.25-1 g/kg IV every 3-6 hours
Limit: serum osmolality <320 mOsm/kg (renal failure risk >200 g/day)
Maintains serum Na >142 mEq/L, osmolality 290-315 mOsm/L
Preferred when: fluid overload is present (potent osmotic diuretic)
Caution: dehydration, hypotension

Hypertonic Saline (HTS)

Concentration	Volume	Route
3%	30-50 mL/hr continuous OR 150 mL boluses	Peripheral (acceptable)
7.5%	75 mL boluses	Central line required
23.4%	30 mL boluses	Central line required

Limit: serum Na <160 mEq/L
Preferred when: hemodynamic instability, hypovolemia (expands intravascular volume unlike mannitol)
Caution: heart failure (volume expansion), phlebitis with peripheral IV

Key distinction: Mannitol causes diuresis and can worsen dehydration; hypertonic saline expands volume. Choose based on hemodynamic context. Recent meta-analysis (Cai & He, 2024, PMID 38853675) supports HTS efficacy in TBI.

Rosen's Emergency Medicine, p. 70

4. Hyperventilation

Reduces PaCO₂ → cerebral vasoconstriction → reduced CBV → lowers ICP rapidly
Prophylactic hyperventilation is harmful - chronic hypocapnia causes cerebral ischemia
Short-term / rescue only: PaCO₂ target 30-35 mmHg
Reserved for: impending herniation, acute ICP spikes while arranging definitive treatment
Prehospital: use only if signs of herniation present (Cushing's triad, fixed dilated pupils, posturing)
Sabiston Textbook of Surgery, p. 804

5. CSF Drainage

Via EVD (external ventricular drain) - first-line therapeutic drainage when catheter is in situ
Aim: intermittent or continuous CSF drainage to reduce ICP
Risk: infection (bacterial meningitis in <3%), catheter-related; typically safe for 3-5 days

6. Sedation and Neuromuscular Blockade

Propofol infusion - reduces CMRO₂, CBF, and ICP; allows rapid offset for neurological assessment
Dexmedetomidine - controls agitation; does not suppress respiratory drive (ventilator dyssynchrony possible)
Neuromuscular blockade - prevents Valsalva-type surges; for short-term use

7. Barbiturate Coma (Refractory ICP)

For refractory intracranial hypertension not responding to above measures:

Pentobarbital: loading dose 10 mg/kg IV over 30 min, then continuous infusion 1-4 mg/kg/hr
Titrate to EEG burst suppression
Reduces CBF and CMRO₂ substantially
Major side effect: hypotension requiring vasopressors to maintain CPP
Consideration of barbiturate therapy should simultaneously trigger consideration of decompressive craniectomy
Rosen's Emergency Medicine, p. 70

8. Corticosteroids

Only indicated for vasogenic edema from brain tumors or abscess (dexamethasone)
Contraindicated in TBI - worsen outcomes (increased infections, hyperglycemia, mortality)
Not useful in ischemic stroke

9. Surgical Options

CSF diversion

EVD insertion / VP shunt (especially for hydrocephalus-related raised ICP)

Evacuation of mass lesions

Epidural hematoma >30 mL with neurological deficit or midline shift: emergent craniotomy
Subdural hematoma ≥1 cm or with midline shift + clinical decline: evacuation

Decompressive Craniectomy

Removes a large portion of skull to allow brain to expand outward
Indicated for medically refractory raised ICP
Evidence from DECRA trial (bifrontal DC for diffuse TBI with ICP >20 mmHg): reduced ICP but more unfavorable functional outcomes
RESCUEicp trial: DC vs. medical management for refractory ICP (>25 mmHg) - improved survival but with increased severe disability rates
Best used selectively, weighing ICP burden against functional outcome goals

10. Stepwise Summary (Tier-Based Approach)

Tier 1 (All patients):
  • HOB 30°, head neutral, normothermia, normoxia, normocapnia
  • Isotonic fluids, analgesia, sedation (propofol/fentanyl)
  • Treat pain/agitation, prevent Valsalva

Tier 2 (ICP confirmed >20 mmHg):
  • CSF drainage via EVD
  • Osmotherapy: mannitol OR hypertonic saline
  • Short-term hyperventilation (acute spikes only)
  • Optimize CPP (vasopressors if MAP low)

Tier 3 (Refractory ICP >25-30 mmHg):
  • Barbiturate coma (pentobarbital)
  • Neuromuscular blockade
  • Consider decompressive craniectomy

Surgical:
  • Evacuate compressive hematomas
  • EVD / shunt for hydrocephalus

Key Numbers to Remember

Parameter	Target
ICP	<20 mmHg
CPP	>60 mmHg
PaCO₂ (routine)	35-40 mmHg
PaCO₂ (herniation rescue)	30-35 mmHg
Serum osmolality (mannitol)	<320 mOsm/kg
Serum Na (HTS)	<160 mEq/L

Sources: Adams and Victor's Principles of Neurology 12th Ed. | Rosen's Emergency Medicine | Sabiston Textbook of Surgery | Cai & He, Brain Inj 2024 (PMID 38853675) - meta-analysis supporting HTS in TBI

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