• Neurocritical Care · Critical Care
Intracranial Pressure (ICP) Management
Monroe-Kellie Doctrine · CPP Targets · Stepwise ICP Protocol · Osmotherapy · EVD · Decompressive Craniectomy
📊 ICP Targets & Key Principles
<15 mmHg
Normal ICP
15–20 mmHg
Borderline — monitor closely
>20–25 mmHg
Treat — ICP Crisis
Monroe-Kellie Doctrine
The cranium is a rigid, fixed-volume box. Volume = Brain (80%) + Blood (10%) + CSF (10%). Increase in any component must be compensated by reduction in another — once compensatory mechanisms are exhausted, ICP rises exponentially.
Cerebral Perfusion Pressure (CPP)
CPP = MAP − ICP
Target CPP: 60–70 mmHg
CPP <50 mmHg → cerebral ischemia
CPP >70 mmHg → ARDS risk (vasopressors)
Autoregulation intact: CPP 50–150 mmHg
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⚠️ Cushing's Triad — Herniation Imminent
🔴 Hypertension (widened pulse pressure)
🫀 Bradycardia
🌬️ Irregular / slow respirations
Cushing's Triad = brainstem compression from tentorial herniation. Emergent intervention required: hyperventilate to PaCO₂ 30–35 mmHg, mannitol/HTS bolus, immediate neurosurgical consult. Pupillary asymmetry/blown pupil = uncal herniation.
📋 Stepwise ICP Management Protocol (Tier 0 → 3)
Tier 0 — Universal
Head of Bed + Basics
HOB 30°, head midline (no neck flexion)
Normothermia (avoid fever — 0.5 mmHg ICP rise/°C)
Euglycemia 140–180 mg/dL
Avoid hypoxia (SpO₂ >94%) & hypercapnia (PaCO₂ 35–45 mmHg)
Adequate analgesia/sedation; avoid Valsalva, coughing
Isotonic fluids only
Tier 1 — First Line
Osmotherapy
Mannitol 20%: 0.5–1 g/kg IV over 15–20 min
Hypertonic saline 3%: 250 mL IV bolus; or 23.4% via central line
CSF drainage via EVD (if placed)
Sedation/analgesia optimization: propofol + fentanyl
Neuromuscular blockade if refractory agitation
Tier 2 — Second Line
Deeper Interventions
Mild hyperventilation: target PaCO₂ 30–35 mmHg (short-term bridge only — causes vasoconstriction)
High-dose barbiturates: pentobarbital coma (EEG burst suppression)
Repeat osmotherapy boluses; serum Na target 145–155 mEq/L
Optimize CPP with vasopressors (norepinephrine)
Tier 3 — Salvage
Surgical Options
Decompressive craniectomy: removes bone flap to allow brain expansion — reduces ICP by 50–60%
EVD placement: continuous or intermittent CSF drainage (target ICP <20)
Indications: refractory to medical Rx, GCS deterioration, herniation signs
💊 Osmotherapy — Mannitol vs Hypertonic Saline
Mannitol 20%
Dose: 0.5–1 g/kg IV q4–6h PRN
Onset: 15–30 min; duration 2–6h
Hold if serum osm >320 mOsm/L
Risk: hypotension, hypovolemia, rebound ICP
Monitor: Osmol gap, BUN/Cr, UO
Hypertonic Saline
3% NaCl: 250 mL IV bolus (peripheral OK)
23.4% NaCl: 30 mL IV via central line only
Target serum Na: 145–155 mEq/L
Preferred if: hypotension, hypovolemia, renal failure
Monitor Na q4–6h; avoid rapid correction
🌡️ Temperature Control & Monitoring
Targeted Temperature Management (TTM): Normothermia (36–37°C) is first goal; prevent fever aggressively (each 1°C fever = ↑ICP)
Therapeutic hypothermia (32–35°C): may reduce ICP in refractory cases; risk of coagulopathy, infection, cardiac arrhythmias
ICP monitoring: Intraventricular catheter (gold standard) — allows both monitoring and CSF drainage
Intraparenchymal probe (Camino, Codman) — monitoring only; no drainage
DVT prophylaxis: Delay pharmacologic prophylaxis ≥24–48h post-hemorrhage; use sequential compression devices (SCDs) immediately
Seizure prophylaxis: levetiracetam or phenytoin for 7 days in traumatic brain injury
⚠️ Critical Reminders
●No hypotonic fluids (D5W, 0.45% NaCl) — lowers serum osmolality, drives water into brain, worsening cerebral edema and ICP
●Avoid hypoxia (SpO₂ <94%) and hypercapnia (PaCO₂ >45) — both cause cerebral vasodilation and acute ICP spikes
●Prolonged hyperventilation (PaCO₂ <30 mmHg) causes ischemia via excessive vasoconstriction — use as bridge only (<30 min)
●DVT prophylaxis timing: Mechanical (SCD) immediately; LMWH/heparin delay ≥24–48h post-haemorrhage; failure to initiate → high DVT/PE mortality
CCM Notes · FOAMed · Critical Care Clinical Reference
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Based on BTF TBI Guidelines 4th Ed / NCS ICP Guidelines
Educational use only