What is the recommended dosage and usage of Propofol (propofol) for inducing and maintaining anesthesia?

Propofol Dosing and Administration for Anesthesia

For induction of general anesthesia in healthy adults under 55 years (ASA I-II), administer 2-2.5 mg/kg IV titrated as approximately 40 mg every 10 seconds until loss of consciousness, followed by maintenance infusion at 50-100 mcg/kg/min, with mandatory dose reductions of approximately 50% in elderly, debilitated, or ASA III-IV patients (1-1.5 mg/kg for induction). 1

Induction Dosing by Patient Population

Healthy Adults (ASA I-II, <55 years)

• Standard dose: 2-2.5 mg/kg IV for unpremedicated or premedicated patients 1
• Administration technique: Titrate approximately 40 mg every 10 seconds against clinical response until onset of anesthesia 1
• Onset: 30-45 seconds (arm-brain circulation time) 2
• Premedication with opioids or benzodiazepines reduces required induction dose 1, 3

Elderly, Debilitated, or ASA III-IV Patients

• Reduced dose: 1-1.5 mg/kg (approximately 20 mg every 10 seconds) 1
• Critical warning: Rapid bolus must be avoided as it significantly increases risk of hypotension, apnea, airway obstruction, and oxygen desaturation 1
• Slower titration is mandatory due to reduced clearance and higher blood concentrations in this population 1

Pediatric Patients (3-16 years, ASA I-II)

• Standard dose: 2.5-3.5 mg/kg IV 1
• Younger children require higher doses than older pediatric patients within this range 1
• Lower dosage recommended for ASA III-IV pediatric patients 1
• Pretreat small veins with lidocaine or use antecubital/larger veins to minimize injection pain 1

Neurosurgical Patients

• Reduced dose: 1-2 mg/kg using slower boluses of 20 mg every 10 seconds 1
• Slower induction titrated to clinical response results in reduced dosage requirements 1
• Propofol decreases cerebral blood flow, cerebral metabolic rate, and intracranial pressure, making it suitable for neurosurgery 4

Maintenance Anesthesia Dosing

Standard Maintenance Regimen

• Infusion rate: 50-100 mcg/kg/min in adults to optimize recovery times 1, 2
• Duration of single bolus effect: 4-8 minutes 2
• Allow 3-5 minutes between dose adjustments to assess clinical effects 1
• Titrate downward in absence of light anesthesia signs to avoid unnecessarily high rates 1

Adjustments for Surgical Stimulation

• Administer 25-50 mg incremental boluses and/or increase infusion rate for stress response to surgical stimulation 1
• For minor procedures: Combine with 60-70% nitrous oxide 1
• For major/intra-abdominal procedures: Increase propofol rate and/or add opioids if nitrous oxide not used 1

Combination with Analgesics

• Propofol has no analgesic properties—must combine with short-acting opioids (fentanyl, alfentanil, sufentanil, remifentanil) for painful procedures 2, 4
• Morphine premedication (0.15 mg/kg) with 67% nitrous oxide decreases required maintenance infusion rate compared to benzodiazepine premedication 1
• Co-administration of opioids and CNS depressants potentiates propofol's sedative effect 2, 4

Critical Safety Considerations

Cardiovascular Monitoring and Management

• Propofol causes dose-dependent decreases in cardiac output, systemic vascular resistance, and blood pressure 2, 5, 4
• Continuous monitoring of heart rate, blood pressure, and pulse oximetry is mandatory 2, 5
• Have vasopressors immediately available (ephedrine or metaraminol) to treat hypotension 4
• Consider lower extremity elevation or pressors when additional fluid therapy is contraindicated 4

Respiratory Depression

• Propofol causes dose-dependent respiratory depression 2, 5
• Post-induction apnea occurs more frequently with propofol than other anesthetics 6
• Apnea is minimized by avoiding pre-induction hyperventilation 3

Propofol Infusion Syndrome (PRIS)

• PRIS typically occurs with doses >70 mcg/kg/min (>4-5 mg/kg/hr) for >48 hours, but has been reported at doses as low as 1.9-2.6 mg/kg/hr 2, 7
• Presents with metabolic acidosis, rhabdomyolysis, arrhythmias, myocardial failure, renal failure 2, 7
• Mortality rate up to 33% 2
• Immediately discontinue propofol if PRIS suspected (worsening metabolic acidosis, hypertriglyceridemia, hypotension with increasing vasopressor requirements, arrhythmias) 2

Special Population Warnings

Pulmonary Hypertension

• Use with extreme caution due to potential for significant hemodynamic instability 5
• Systemic vasodilation and decreased cardiac output can worsen right ventricular function 5
• If must be used: administer in small incremental doses by slow infusion, carefully titrating to endpoints 5
• Be prepared for rapid intervention including immediate discontinuation, IV fluids, and vasopressors 5

CYP2B6 Poor Metabolizers

• Reduce infusion dose by approximately 50% (to 25 mcg/kg/min instead of standard 50-100 mcg/kg/min) 2
• This prevents excessive drug exposure and prolonged sedation in confirmed poor metabolizers 2

Contraindications and Allergies

• Avoid in patients with egg, soy, or sulfite allergies 2, 4
• Formulation contains 10% soybean oil and 1.2% purified egg phosphatide 2
• Not contraindicated in sulfonamide allergy 2, 4

Administration Technique and Monitoring

• Use syringe or volumetric pumps for controlled infusion rates 1
• Shake well before use; do not use if excessive creaming, large droplets, or phase separation visible 1
• Blood concentrations are generally proportional to infusion rates at steady-state 1
• Use processed EEG monitoring (BIS 40-60) to prevent awareness and avoid excessive depth 4
• Pain on injection occurs in up to 30% of patients receiving IV bolus 2, 4

Pharmacokinetic Considerations

• Highly lipophilic with rapid blood-brain barrier passage 2
• Rapidly metabolized in liver by conjugation to glucuronide and sulfate 2
• Terminal half-life of 1-3 days after prolonged infusion 2
• Pharmacokinetics not significantly affected by cirrhosis or renal failure 2, 4
• Pharmacokinetic parameters altered by weight, sex, age, and concomitant diseases 2

Recovery Profile

• Rapid recovery even after prolonged use 6, 7
• Superior to methohexitone with less movement and rapid postoperative recovery 6
• Low incidence of postoperative nausea and vomiting 6, 3
• Particularly suitable for outpatient surgery 6