What is the recommended propofol (propofol) infusion rate for a 47 kg patient undergoing neurosurgery?

Propofol Infusion for Neurosurgery in a 47 kg Patient

For a 47 kg patient undergoing neurosurgery, administer propofol as a continuous infusion at 50-100 mcg/kg/min (2.35-4.7 mg/kg/h for this patient), combined with short-acting opioids for analgesia during painful portions of surgery. 1

Induction Dosing

• Use slower induction with boluses of 20 mg every 10 seconds rather than rapid bolus administration in neurosurgical patients 2
• This slower technique results in reduced total induction requirements of 1-2 mg/kg (47-94 mg total for this patient) 2
• Rapid bolus doses should be avoided as they increase cardiorespiratory effects including hypotension, apnea, airway obstruction, and oxygen desaturation 2

Maintenance Infusion Rates

Initial Phase (First 10-15 minutes):

• Start with higher infusion rates of 150-200 mcg/kg/min (7.05-9.4 mg/kg/h for this patient) immediately following induction 2
• This higher initial rate is necessary to maintain adequate anesthesia during the early maintenance phase 2

Subsequent Maintenance:

• Decrease infusion rates by 30-50% after the first half-hour 2
• Target maintenance rates of 50-100 mcg/kg/min (2.35-4.7 mg/kg/h for this patient) to optimize recovery times 1, 2
• Research in neurosurgical patients demonstrates that intraoperative dosing is typically low (50-100 mcg/kg/min) because intracerebral surgery is not particularly painful 3

Critical Adjunctive Agents

Opioid Co-Administration:

• Combine propofol with short-acting opioids (fentanyl, alfentanil, sufentanil, or remifentanil) for analgesia during painful portions of surgery 1
• When propofol is used as the primary agent in neurosurgery, maintenance infusion rates should not be less than 100 mcg/kg/min and should be supplemented with analgesic levels of continuous opioid administration 2
• Opioid co-administration produces opioid-sparing effects and allows for lower propofol requirements 4

Hemodynamic Management

Cardiovascular Monitoring:

• Propofol decreases cardiac output, systemic vascular resistance, and arterial pressure in a dose-dependent manner 5, 1, 6
• Continuous monitoring of heart rate, blood pressure, and pulse oximetry is essential 5, 1, 6
• Have vasopressors immediately available (ephedrine or metaraminol) to treat hypotension 1

Specific Considerations for Neurosurgery:

• Mean arterial pressure is only moderately decreased if propofol is given as a mini-infusion rather than on a mg/kg bolus basis 3
• Propofol decreases cerebral blood flow, cerebral metabolic rate for oxygen, and intracranial pressure 3

Monitoring and Safety

Depth of Sedation:

• Use processed EEG monitoring (BIS 40-60) to prevent awareness and avoid excessive depth 1
• This monitoring is particularly important in neurosurgical cases where maintaining appropriate cerebral perfusion is critical 3

Respiratory Monitoring:

• Approximately 5-7% of patients may experience transient desaturation below 90% with propofol administration 7, 6
• Higher propofol infusion rates (50-75 mcg/kg/min) are associated with more episodes of transient hemoglobin oxygen desaturation 4

Propofol Infusion Syndrome (PRIS):

• Monitor for PRIS, especially with doses >70 mcg/kg/min or prolonged infusions 7, 6
• Signs include metabolic acidosis, hypertriglyceridemia, hypotension requiring increasing vasopressor support, arrhythmias, acute kidney injury, hyperkalemia, and rhabdomyolysis 7
• The recommended maintenance range of 50-100 mcg/kg/min for neurosurgery is below the high-risk threshold 1, 2

Recovery Considerations

Timing:

• Propofol has rapid onset (1-2 minutes) and short elimination half-life (3-12 hours) allowing for better control of sedation level 7
• This facilitates early neurological assessment, which is critical in neurosurgical patients 7
• Research demonstrates that propofol Ce at recovery is approximately 50% of the induction value 8

Early Awakening:

• Maintaining rates of 50-100 mcg/kg/min during maintenance optimizes recovery times 2
• Propofol provides shorter recovery time compared to benzodiazepines like midazolam 7

Common Pitfalls to Avoid

• Never use rapid bolus induction in neurosurgical patients; always use slow boluses of 20 mg every 10 seconds 2
• Avoid maintenance rates <100 mcg/kg/min when propofol is used as the primary agent without adequate opioid supplementation 2
• Do not fail to have vasopressors immediately available given propofol's predictable hypotensive effects 1
• Avoid using propofol in patients with egg, soy, or sulfite allergies 5, 6
• Do not forget that propofol has no analgesic properties; always consider adding analgesics for painful procedures 6