What is the recommended propofol (propofol) infusion regimen for neurosurgery anesthesia?

Propofol Infusion for Neurosurgery Anesthesia

For neurosurgical procedures, maintain anesthesia with a continuous propofol infusion at 50-100 mcg/kg/min combined with short-acting opioids (fentanyl, alfentanil, sufentanil, or remifentanil), using slower induction with 20 mg boluses every 10 seconds and having vasopressors immediately available. 1, 2

Induction Protocol

Neurosurgical patients require slower induction compared to general surgery patients. 2

• Administer propofol as boluses of 20 mg every 10 seconds until loss of consciousness 2
• Expected induction dose: 1-2 mg/kg (lower than the 2-2.5 mg/kg used in general surgery) 2
• Avoid rapid bolus administration, as this increases risk of hypotension, apnea, airway obstruction, and oxygen desaturation 2
• In elderly, debilitated, or ASA-PS III/IV patients, use approximately 1-1.5 mg/kg (approximately 20 mg every 10 seconds) 2

Maintenance Infusion Regimen

The standard maintenance rate is 50-100 mcg/kg/min for neurosurgical procedures. 1, 2

• When propofol is the primary anesthetic agent, maintain infusion rates at minimum 100 mcg/kg/min and supplement with analgesic levels of continuous opioid administration 2
• When an opioid is the primary agent, propofol maintenance rates should not be less than 50 mcg/kg/min, with careful attention to ensure amnesia 2
• Higher initial infusion rates (150-200 mcg/kg/min) may be required during the first 10-15 minutes following induction 2
• Subsequently decrease infusion rates by 30-50% during the first half-hour of maintenance 2
• Titrate infusion rates downward in the absence of clinical signs of light anesthesia to avoid unnecessarily high administration rates 2

Opioid Combination Strategy

Propofol has minimal analgesic effect and must be combined with opioids for painful neurosurgical procedures. 3, 1

• Short-acting opioids are preferred: fentanyl, alfentanil, sufentanil, or remifentanil 1
• Morphine premedication (0.15 mg/kg) with nitrous oxide 67% in oxygen decreases necessary propofol maintenance infusion rates 2
• Higher propofol doses will reduce opioid requirements 2
• Co-administration of opioids and other CNS depressants potentiates propofol's sedative effect 3, 2

Critical Hemodynamic Management

Propofol causes dose-dependent decreases in cardiac output, systemic vascular resistance, and arterial pressure. 3, 1

• Have vasopressors immediately available (ephedrine or metaraminol) to treat hypotension 1
• Consider elevation of lower extremities or pressor agents when additional fluid therapy is contraindicated 1
• Monitor heart rate, blood pressure, and pulse oximetry continuously 3, 1
• Propofol reduces myocardial oxygen consumption 2
• Lower heart rates occur during maintenance, possibly due to reduced sympathetic activity and/or baroreceptor reflex resetting 2
• Administer anticholinergic agents when increases in vagal tone are anticipated 2

Neurophysiologic Effects

Propofol decreases cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and intracranial pressure (ICP). 4, 5

• These effects make propofol particularly suitable for neurosurgical procedures 4, 5
• Propofol minimally interferes with cerebral autoregulation and CO2 responsiveness 5
• Brain relaxation is encouraged through decreased CMRO2 and CBF 5
• The intraoperative dosage can be relatively low (50-100 mcg/kg/min) because intracerebral surgery is not inherently painful 4

Monitoring Requirements

Use processed EEG monitoring (BIS 40-60) to prevent awareness and avoid excessive anesthetic depth. 1

• Continuous vital signs monitoring including pulse oximetry, capnography, blood pressure, and heart rate is mandatory 1
• Establish invasive arterial blood pressure monitoring before induction when feasible 1

Recovery and Emergence

Propofol provides rapid and predictable recovery, allowing early neurological evaluation. 4, 6, 5

• Recovery can be rapid due to the low intraoperative dosage used in neurosurgery 4
• Ensure return of airway reflexes and adequate tidal volumes before extubation 1
• Early postoperative neurological assessment is facilitated by propofol's favorable recovery profile 6, 5

Important Safety Considerations

Avoid propofol in patients with egg, soy, or sulfite allergies (propofol contains 10% soybean oil and 1.2% purified egg phosphatide). 3, 1

• Propofol is NOT contraindicated in patients with sulfonamide allergy 3
• Pain on injection occurs in up to 30% of patients receiving intravenous bolus 3
• Propofol's pharmacokinetics are not significantly affected by cirrhosis or renal failure 3
• Onset of action is 30-45 seconds (one arm-brain circulation time) 3
• Duration of effect is 4-8 minutes 3

Common Pitfalls to Avoid

• Never use rapid bolus induction in neurosurgical patients - this dramatically increases risk of cardiovascular and respiratory depression 2
• Do not use propofol as monotherapy for painful procedures - it lacks analgesic properties and requires opioid supplementation 3, 1
• Avoid inadequate monitoring - continuous hemodynamic monitoring is essential given propofol's cardiovascular effects 3, 1
• Do not use propofol with high-dose opioid technique when propofol is the primary anesthetic, as this increases likelihood of hypotension 2