Neuroanesthesia · 8 min
Neuroanesthesia & ICP — last-night quick guide
ICP control, autoregulation, neuroprotection, awake craniotomy, spine surgery.
Rule
Cerebral perfusion pressure
CPP = MAP − ICP (or CVP, whichever higher). Target CPP >60-70 in TBI; preserve in any neuro patient. CBF autoregulated MAP 50-150 in normals; CHRONIC HTN right-shifts the curve (need higher MAP). Pediatric autoregulation lower bound ~40-50.
ICP-friendly anesthesia rules
| Goal | How |
|---|---|
| Avoid hypoxia + hypotension | MAP ≥65-70, SpO2 >95%; even one episode worsens TBI outcome |
| Normocapnia | PaCO2 35-40; brief hyperventilation 28-32 ONLY for impending herniation (effect adapts in 6-12h) |
| Normoglycemia | BG 100-180; hyperglycemia worsens neurologic outcome |
| Normothermia | Avoid hyperthermia; mild hypothermia ↓ CMRO2 (used in some TBI) |
| Head-up 30° | Improves cerebral venous drainage |
| Avoid >1 MAC volatile | All volatiles uncouple CBF from CMRO2 → ↑ CBF + ICP at >1 MAC |
| Use TIVA propofol | ↓ CBF + CMRO2 + preserves autoregulation = neurosurgery default |
Rule
Osmotherapy for ↑ ICP
3% SALINE 3-5 mL/kg bolus (preferred modern — sodium target 145-155, no rebound, expands volume) > MANNITOL 0.5-1 g/kg IV (faster osmolar effect, but rebound + diuresis + hypovolemia + electrolyte derangement). Repeat 3% saline q6h to maintain Na 145-155.
Watch out
Awake craniotomy
Asleep-awake-asleep technique: GA for craniotomy + dural opening → wake during cortical mapping → re-sedate for closure. SCALP BLOCK (auriculotemporal + zygomaticotemporal + supraorbital + supratrochlear + greater/lesser occipital) bilateral with bupivacaine + epi. Sedation: dex (best — preserves spontaneous ventilation + cooperation). Communication critical; treat seizure with cold saline irrigation + propofol bolus + benzo.
Rule
Spine surgery + evoked potentials
MEP/SSEP monitoring requires partial-MAC volatile (≤0.5 MAC) + propofol TIVA + opioid; AVOID full-dose volatile (suppresses MEP); minimize NMB after intubation (TOF interferes with MEP). Position: prone — pad thoroughly (eyes, breasts, genitals); reverse Trendelenburg modestly to ↓ orbital pressure. Blood loss + transfusion targets.
Watch out
Posterior fossa + sitting position
Venous air embolism risk highest with sitting craniotomy. Monitor with TEE or precordial Doppler; large-bore CVC for aspiration; HEAD-UP not over 30°. PFO screen pre-op (echo) — increases paradoxical embolism risk.
Mnemonic — 5H + 5T
5 H's and 5 T's — PEA arrest reversibles
PEA arrest reversibles
- H1Hypovolemia — give fluid; look for bleeding
- H2Hypoxia — secure airway, 100% FiO2
- H3Hydrogen ion (acidosis) — ventilate, consider bicarb
- H4Hyper/Hypokalemia — calcium, insulin/glucose, bicarb if hyperK
- H5Hypothermia — active rewarming, especially before terminating
- T1Tension pneumothorax — needle decompress 2nd ICS midclav (or 4th-5th anterior axillary)
- T2Tamponade (cardiac) — pericardiocentesis
- T3Toxins — narcan (opioids), bicarb (TCA), lipid emulsion (LAST)
- T4Thrombosis (pulmonary) — PE → tPA if confirmed
- T5Thrombosis (coronary) — STEMI → cath lab post-ROSC
ACLS expects you to address all 10 cyclically during pulseless arrest. Bedside ultrasound speeds detection of tamponade, tension pneumo, RV strain.