What is the recommended regimen for propofol (propofol) infusion in neurosurgical cases to avoid hypotension and ensure adequate cerebral perfusion?

Propofol Infusion in Neurosurgical Cases

For neurosurgical procedures, maintain propofol at 50-100 mcg/kg/min via continuous infusion, combined with short-acting opioids (fentanyl, alfentanil, sufentanil, or remifentanil) for analgesia, with vasopressors immediately available to treat hypotension and maintain cerebral perfusion pressure. 1

Maintenance Infusion Regimen

• Administer propofol as a continuous infusion at 50-100 mcg/kg/min rather than repeated boluses to minimize hemodynamic instability 1
• Avoid rapid or large boluses, as these cause significant hypotension and decreased cerebral perfusion pressure 2
• When induction is required, use an infusion or slow bolus of approximately 20 mg every 10 seconds instead of rapid administration 2
• Slower induction titrated to clinical response generally results in reduced dosage requirements (1-2 mg/kg) 2

Critical Hemodynamic Management

Have vasopressors immediately available (ephedrine or metaraminol) before starting propofol infusion 1. This is non-negotiable in neurosurgical cases where maintaining cerebral perfusion pressure is paramount.

• Propofol decreases cardiac output, systemic vascular resistance, and arterial pressure in a dose-dependent manner 3, 4
• In patients with increased intracranial pressure or impaired cerebral circulation, significant decreases in mean arterial pressure must be avoided to prevent decreased cerebral perfusion pressure 2
• When additional fluid therapy is contraindicated, consider elevation of lower extremities or pressor agents 1, 2
• Correct fluid deficits prior to propofol administration 2

Adjunctive Analgesic Agents

Combine propofol with short-acting opioids since propofol has minimal analgesic properties 1, 4:

• Fentanyl: 0.5-1 mcg/kg boluses as needed 5
• Alfentanil: 5 mcg/kg initial bolus, then 1-3 mcg/kg as required 5
• Sufentanil or remifentanil are also appropriate options 1
• Co-administration of opioids potentiates propofol's sedative effects and may result in more pronounced cardiovascular depression 2

Essential Monitoring Requirements

• Use processed EEG monitoring (BIS or Entropy) targeting BIS 40-60 to prevent awareness while avoiding excessive depth 1, 5
• Establish invasive arterial blood pressure monitoring before induction when feasible, with transducer at tragus level 5
• Monitor heart rate, blood pressure, and pulse oximetry continuously 3
• When increased ICP is suspected, hyperventilation and hypocarbia should accompany propofol administration 2

Neurosurgical-Specific Considerations

Propofol offers specific advantages in neurosurgery:

• Decreases cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and intracranial pressure (ICP) 6
• Maintains cerebral autoregulation and CO2 responsiveness better than volatile anesthetics 7
• Provides rapid and predictable recovery, allowing early neurological evaluation 8, 7
• The intraoperative dosage can be kept low (50-100 mcg/kg/min) since intracranial surgery is not inherently painful 6

Dosing Adjustments and Special Populations

• In elderly, debilitated, or ASA-PS III or IV patients, rapid bolus administration should not be used during sedation 2
• Reduce propofol dose by 20-80% when combined with sedative or analgesic agents 9
• In premedicated patients, geriatric patients, patients with recent fluid shifts, or hemodynamically unstable patients, use slower administration rates 2
• There is wide interpatient variability in propofol requirements, which may change over time 2

Common Pitfalls to Avoid

• Never use rapid bolus dosing during maintenance - this causes profound hypotension and decreased cerebral perfusion 2
• Do not rely on propofol alone for analgesia during painful portions of surgery - it has no analgesic effect 4
• Avoid doses exceeding 1.5 mcg/ml effect-site concentration when using target-controlled infusion, as this significantly increases risk of over-sedation and hypoventilation 5
• Do not abruptly discontinue propofol infusion, as rapid awakening may cause anxiety, agitation, and resistance to mechanical ventilation 2

Recovery and Emergence

• Propofol's rapid clearance allows for quick emergence when infusion is discontinued 8
• Recovery time is typically faster than with midazolam or traditional balanced techniques 8
• Ensure return of airway reflexes and adequate tidal volumes before extubation 5
• The rapid recovery profile makes propofol particularly advantageous when early neurological assessment is critical 7