Supratentorial Craniotomy (tumor resection)
Patient phenotype
Usually 40–70, brain tumor (glioma, meningioma, mets). May have raised ICP, seizures, focal neuro deficit. Often on dexamethasone + AEDs (levetiracetam).
Procedure
Supine or lateral position, head pinned in Mayfield. Scalp incision, craniotomy bone flap, dural opening, microscopic tumor resection. Pin placement is the most stimulating moment.
Anesthetic plan
GETA with TIVA (propofol + remifentanil) preferred for fast wake-up + neurophysiologic monitoring. Avoid N₂O (pneumocephalus). Mannitol or hypertonic saline for brain relaxation.
Setup
- ·Standard ASA + temp + UOP
- ·5-lead ECG
- ·A-line — for tight BP control + ABG sampling
- ·Two large-bore PIVs
- ·CVC if hemodynamic instability or vasopressors expected
- ·Reverse Trendelenburg ramp pad
- ·Bispectral index for TIVA depth + wake-up
- ·Mannitol + hypertonic saline drawn
Biggest concerns by phase
Raised ICP — recognize + mitigate
Look for: HA worse in AM, papilledema, projectile vomiting, focal deficits, midline shift on imaging. Cushing triad (HTN + bradycardia + irregular respirations) is late + emergent. Avoid drugs that raise ICP (ketamine controversial in TBI now), keep PaCO₂ 30–35.
Hemodynamic stability + blunt the pin response
Mayfield pin placement = HUGE stimulus, BP can spike 40+ mmHg. Pre-pin: bolus opioid (fentanyl 2 mcg/kg or remifentanil 0.5 mcg/kg), local infiltration by surgeon, deepen propofol. Avoid sustained hypertension — risk of hemorrhage. Avoid hypotension — risk of ischemia.
Brain relaxation — multiple techniques
Mannitol 0.5–1 g/kg over 15 min OR hypertonic saline 3% 250 mL OR 23.4% 30 mL. Hyperventilate to PaCO₂ 30–35 (transient — too low → ischemia). Head-up 15–30°. CSF drain via ventriculostomy if available. Furosemide 0.25–0.5 mg/kg as adjunct.
Air embolism (especially sitting / semi-sitting)
Cross sinus opening + open vessels above heart = air entrainment. Watch for sudden ↓ETCO₂, mill-wheel murmur, ↓BP. TEE most sensitive. Treatment: stop entry (flood field with saline, pack bone wax), head-down + left lateral, aspirate from CVC tip in atrium, vasopressor.
Smooth, neuro-exam-ready emergence
Goal: extubate awake, calm, doing neuro exam within minutes. TIVA + dexmedetomidine 0.4–0.7 mcg/kg/hr facilitates this. Avoid coughing/bucking on tube (raises ICP, risks bleeding). Lidocaine 1.5 mg/kg pre-extubation, deep extubation if airway favorable.
Postop: bleeding, swelling, seizure, DVT
Watch for: declining mental status (rebleed, hematoma, swelling), focal deficits, seizure (continue AEDs), HTN (treat aggressively, < 140/90 typical target), DVT prophylaxis (mechanical first 24–48 h, then chemical per neurosurgeon).
Mock-defense scenarios
Practice answering these out loud. The probes show what an examiner is listening for.
Your craniotomy patient is in pins, dura is open. The surgeon says the brain looks tight and they can't get their working space. ETCO₂ is 36, MAP 75. What's your plan?
What an examiner probes for
- ▹Brain relaxation maneuvers in order: head-up, hyperventilate to 30–32, mannitol 0.5–1 g/kg, hypertonic saline alternative
- ▹Recognizes mannitol takes 15 min, plan ahead
- ▹Considers TIVA depth + drains if available
- ▹Communication: tell surgeon what you're doing, set expectation on timing
Mid-tumor resection, ETCO₂ suddenly drops from 32 to 18 with hypotension. Surgeon hasn't reported anything unusual. What's happening and what do you do?
What an examiner probes for
- ▹Recognizes air embolism (esp. if semi-sitting / head elevated)
- ▹First moves: tell surgeon to flood the field, head-down + left lateral, 100% O₂
- ▹Aspirate from CVC if in place, fluid bolus, vasopressor
- ▹Anticipates: TEE confirmation, possible cardiac arrest, postop CT
Sources
- Miller's Ch 57 (neuroanesthesia)
- Cottrell Neuroanesthesia 6e
- SNACC guidelines
Anatomy reference
Sourced reference images. 4 matches for "brain cortex cerebrum".
