Anesthesia for Supratentorial Craniotomy

Anesthesia for Supratentorial Craniotomy

Anesthesia for Supratentorial Craniotomy

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Preoperative Assessment & Goals - Brainy Prep Work

  • Neurological Status: Baseline GCS, focal deficits, seizure history/control.
  • ICP Assessment: Signs of ↑ICP (headache, N/V, papilledema). Cushing's triad (late).
  • Airway: Standard assessment; consider difficult airway with ↑ICP or cervical spine issues.
  • Systemic Review: CV (HTN, IHD), Respiratory (pulmonary edema risk), Renal function.
  • Medications: Continue anticonvulsants. Steroids (e.g., dexamethasone). Manage anticoagulants/antiplatelets.
  • Investigations: Recent MRI/CT. Baseline bloods (FBC, U&E, Coags).
  • Anesthetic Goals:
    • Maintain CPP ($CPP = MAP - ICP$; use CVP if higher). Target >60-70 mmHg.
    • Control ICP (target <20 mmHg).
    • Smooth induction & emergence.
    • Rapid recovery for neuro assessment. Brain MRI: Tumor Before and After Craniotomy

⭐ Patients on long-term phenytoin may exhibit resistance to non-depolarizing muscle relaxants due to enzyme induction.

Induction & Neuromonitoring - Setting the Stage

  • Primary Goals:
    • Maintain hemodynamic stability (MAP within 20% of baseline).
    • Control ICP (target < 20 mmHg).
    • Ensure adequate CPP (target 60-70 mmHg; $CPP = MAP - ICP$).
  • Induction Protocol:
  • Airway & Positioning: Head up 15-30° (promotes venous drainage), neutral neck.
  • Essential Monitoring:
    • Standard ASA (ECG, NIBP, SpO2, EtCO2, Temp).
    • Invasive Arterial BP (A-line): For continuous MAP & ABGs.
    • Neuromuscular monitoring (TOF).
    • Consider: CVP, EEG/BIS, SSEP/MEP if eloquent areas involved.

    ⭐ Rapid Sequence Intubation (RSI) is generally avoided due to risk of ICP spike with succinylcholine; a modified rapid sequence with rocuronium is preferred if aspiration risk is high. Craniotomy patient care pathway overview

Intraoperative Anesthetic Management - Skull Session Secrets

  • Brain Relaxation:
    • Head elevation: 15-30°.
    • Hyperventilation: PaCO₂ 30-35 mmHg.
    • Osmotic diuretics: Mannitol (0.25-1 g/kg) or Hypertonic Saline (HTS).
    • Loop diuretics: Furosemide (0.5-1 mg/kg).
    • CSF drainage (if available).
  • Anesthetic Choice:
    • TIVA (Propofol + Remifentanil) favored: ↓ICP, rapid emergence.
    • Volatiles: Maintain <1 MAC if used.
  • Hemodynamic Goals:
    • Maintain Mean Arterial Pressure (MAP) within 20% of baseline.
    • Cerebral Perfusion Pressure (CPP) >60-70 mmHg.
  • Fluid Management:
    • Isotonic crystalloids (Normal Saline preferred). Avoid hypotonic & glucose solutions.
  • ⚠️ Key Complications & Management:
    • Venous Air Embolism (VAE): Sudden ↓ETCO₂, ↓SpO₂, hypotension. Mgmt: Notify surgeon, flood field with saline, 100% O₂, aspirate from CVC, left lateral decubitus (Durant's maneuver).
    • Intraoperative Seizures: Propofol, thiopental, levetiracetam.

TIVA agents and cerebral physiology

⭐ During craniotomy, a sudden decrease in End-Tidal CO₂ (ETCO₂) accompanied by hypotension should immediately raise suspicion for Venous Air Embolism (VAE).

Emergence & Postoperative Care - Waking Up Well

  • Goal: Smooth emergence, stable hemodynamics, early neuro-assessment.
  • Smooth Emergence Strategies:
    • Lidocaine IV (1-1.5 mg/kg) or LTA.
    • Short-acting opioids (e.g., remifentanil, fentanyl).
    • Dexmedetomidine infusion.
    • Avoid $N_2O$ at closure (prevents pneumocephalus expansion).
  • Extubation Criteria: Awake, follows commands, adequate ventilation (TOF > 0.9).
  • Immediate Postoperative Care (PACU/Neuro-ICU):
    • Frequent neurological checks (GCS, pupils, motor function).
    • Strict BP control (e.g., SBP < 140-160 mmHg, avoid hypotension).
    • Multimodal analgesia (paracetamol, opioids; NSAIDs with caution).
    • Antiemetics (e.g., ondansetron).
    • Maintain normothermia, normocapnia, normoglycemia.
  • Key Complications to Monitor: Hematoma, seizures, ↑ICP, PONV, delayed awakening.

⭐ Delayed emergence or neurological deterioration post-craniotomy mandates urgent CT scan to exclude intracranial hematoma or acute hydrocephalus.

High‑Yield Points - ⚡ Biggest Takeaways

  • ICP management is crucial: target PaCO2 30-35 mmHg, mannitol, and consider CSF drainage.
  • Maintain Cerebral Perfusion Pressure (CPP) at 60-70 mmHg by optimizing MAP and ICP.
  • Anesthetic choices: TIVA or volatile agents (<1 MAC); strictly avoid Nitrous Oxide.
  • Ensure smooth emergence to prevent coughing, straining, and subsequent ICP elevation.
  • Key complications: Venous Air Embolism (VAE), seizures, and intracranial hematoma.
  • Preoperative: assess neurological deficits, ICP signs, and steroid/anticonvulsant use.

Practice Questions: Anesthesia for Supratentorial Craniotomy

Test your understanding with these related questions

A case of trauma comes to the emergency. On examination there is evidence of head injury, BP is 90/60 mmHg, and pulse is 150/min. Which of the following anesthetic agent should be used for induction?

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Flashcards: Anesthesia for Supratentorial Craniotomy

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_____ is safe to use in head trauma as it is not associated with rise in ICP

TAP TO REVEAL ANSWER

_____ is safe to use in head trauma as it is not associated with rise in ICP

Etomidate::Anaesthetic

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