What is the recommended anesthetic management for traumatic brain injury?

Anesthetic Management of Traumatic Brain Injury

The optimal anesthetic management for traumatic brain injury (TBI) requires total intravenous anesthesia with propofol, strict control of physiological parameters, and airway management based on clear intubation criteria to minimize secondary brain injury and improve mortality outcomes. 1, 2

Airway Management and Intubation Criteria

Early airway control is essential for patients with TBI. Indications for tracheal intubation include:

• GCS ≤ 8
• Significantly deteriorating conscious level (fall in GCS ≥ 2 points or motor score ≥ 1 point)
• Loss of protective laryngeal reflexes
• Failure to achieve PaO₂ ≥ 13 kPa
• Hypercarbia (PaCO₂ > 6 kPa)
• Spontaneous hyperventilation (PaCO₂ < 4.0 kPa)
• Bilateral fractured mandible
• Copious bleeding into the mouth
• Seizures 1

Induction Technique

A rapid sequence induction with manual in-line stabilization of the cervical spine is recommended:

1. Pre-induction monitoring: Apply neuromuscular monitoring before induction; establish arterial line when possible (with transducer at tragus level) or use NIBP at 1-minute intervals 1

2. Recommended induction regimen:

   • High-dose opioid: Fentanyl (3-5 μg/kg), alfentanil (10-20 μg/kg), or remifentanil TCI (≥ 3 ng/ml)
   • Induction agent: Propofol is preferred as it decreases cerebrospinal fluid pressure by 46% ± 14% while maintaining relatively stable arterial pressure 1, 3
   • For hemodynamically unstable patients, ketamine 1-2 mg/kg may be beneficial 1, 4
   • Neuromuscular blockade: Rocuronium 1 mg/kg or suxamethonium 1.5 mg/kg 1

3. Have vasopressors ready: Ephedrine or metaraminol should be immediately available to treat hypotension 1

Maintenance of Anesthesia

Total intravenous anesthesia (TIVA) with propofol is superior to inhalational techniques for TBI patients:

• Propofol provides better brain relaxation and lower ICP compared to inhalational agents 2
• Typical maintenance dose: 100-150 μg/kg/min (adjust based on hemodynamic response) 2
• For ICU sedation, the mean maintenance rate is approximately 27 ± 21 μg/kg/min (lower in patients >55 years at ~20 μg/kg/min) 3

Physiological Targets

Strict control of physiological parameters is crucial:

1. Blood pressure targets:

   • Systolic BP > 110 mmHg (MAP > 90 mmHg)
   • Systolic BP < 150 mmHg if within 6 hours of symptom onset and immediate surgery not planned 1

2. Ventilation targets:

   • PaCO₂: 4.5-5.0 kPa (33.8-37.5 mmHg)
   • Brief period of PaCO₂ 4.0-4.5 kPa may be used if impending uncal herniation 1

3. Oxygenation target:

   • PaO₂ ≥ 13 kPa (97.5 mmHg)
   • Avoid hyperoxia 1

Pharmacological Management

Essential medications to have available:

• Hypnotics: Propofol or midazolam
• Neuromuscular blocking agents: Suxamethonium, atracurium, or rocuronium
• Opioid analgesics: Alfentanil, fentanyl, or remifentanil infusion
• Anticonvulsants: Benzodiazepines, thiopentone, levetiracetam
• Osmotherapy: Mannitol 20% or hypertonic saline
• Vasoactive drugs: Ephedrine, metaraminol, noradrenaline, labetalol
• Intravenous fluids: 0.9% saline (preferred)
• Cross-matched blood for trauma patients 1

Special Considerations

1. Ketofol (ketamine-propofol combination):

   • May provide better hemodynamic stability than propofol alone
   • Associated with lower vasopressor requirements while maintaining similar brain relaxation 4

2. Monitoring:

   • Direct arterial pressure monitoring is preferred
   • Place transducer at level of tragus for accurate cerebral perfusion pressure assessment 1

3. Common pitfalls to avoid:

   • Hypotension: Even brief episodes can worsen outcomes
   • Hyperventilation: Aggressive hyperventilation can reduce cerebral blood flow
   • Hyperoxia: May increase oxidative stress
   • Venous outflow obstruction: Avoid tight securing of endotracheal tube with ties (use tape instead) 1

4. Hemodynamic stability:

   • TIVA with propofol provides better hemodynamic control than inhalational agents
   • Consider ketamine addition in hemodynamically unstable patients 2, 4

By following these guidelines, anesthetic management can help minimize secondary brain injury and potentially improve outcomes in TBI patients.