What is the induction dose of propofol (intravenous anesthetic agent)?

Propofol Induction Dose

For healthy adults under 55 years (ASA I-II), the induction dose is 2-2.5 mg/kg administered as incremental boluses of approximately 40 mg every 10 seconds until loss of consciousness occurs. 1

Standard Induction Dosing by Patient Population

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

• Dose: 2-2.5 mg/kg administered as approximately 40 mg every 10 seconds, titrated to clinical response 1
• This applies to unpremedicated patients or those premedicated with oral benzodiazepines or intramuscular opioids 1
• The corresponding effect site concentration at loss of verbal response is approximately 2.34 μg/mL 2

Elderly, Debilitated, or ASA III-IV Patients

• Dose: 1-1.5 mg/kg administered as approximately 20 mg every 10 seconds 1
• Critical pitfall: Rapid bolus administration must be avoided in this population, as it significantly increases the risk of hypotension, apnea, airway obstruction, and oxygen desaturation 1
• The reduced clearance and higher blood concentrations in these patients necessitate the lower dosing 1

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

• Dose: 2.5-3.5 mg/kg for unpremedicated or lightly premedicated children 1
• Younger pediatric patients within this age range require higher induction doses than older pediatric patients 1
• Lower dosages are recommended for ASA III-IV pediatric patients 1
• Pain on injection is a significant concern; consider pretreating small veins with lidocaine or using antecubital or larger veins 1

Neurosurgical Patients

• Dose: 1-2 mg/kg using slower boluses of 20 mg every 10 seconds 1
• Slower induction with careful titration to clinical responses results in reduced dosage requirements 1

Cardiac Anesthesia Patients

• Dose reduction required due to propofol's effects on preload (decreased ventricular filling) and afterload (decreased arterial resistance) 1
• The American Society of Anesthesiologists emphasizes careful titration in this population 1

Critical Administration Principles

Timing Between Doses

• Allow 3-5 minutes between dose adjustments to assess clinical effects and avoid excessive drug accumulation 1
• The onset of action is 30-45 seconds (equivalent to arm-brain circulation time) 3

Impact of Premedication

• Opioid and benzodiazepine premedication significantly reduces propofol requirements 1
• Morphine premedication (0.15 mg/kg) with nitrous oxide has been shown to decrease necessary propofol maintenance infusion rates compared to non-narcotic premedication 1
• When propofol is combined with small doses of opioids and benzodiazepines, subhypnotic doses of propofol can achieve adequate anesthesia while reducing hemodynamic instability 3

Common Pitfalls and Safety Considerations

Cardiovascular Depression

• Hypotension is the most common complication, occurring in a dose-dependent manner due to decreased cardiac output, systemic vascular resistance, and arterial pressure 3, 4
• Have vasopressors (ephedrine or metaraminol) immediately available 5
• Consider elevation of lower extremities when additional fluid therapy is contraindicated 5

Respiratory Depression

• Dose-dependent respiratory depression occurs, with potential for apnea, particularly with rapid bolus administration 3
• Continuous monitoring of heart rate, blood pressure, and pulse oximetry is mandatory 3

Contraindications

• Avoid in patients with egg, soy, or sulfite allergies, as propofol contains 10% soybean oil and 1.2% purified egg phosphatide 3
• Propofol is NOT contraindicated in sulfonamide allergy 3

Pain on Injection

• Occurs in up to 30% of patients receiving intravenous bolus 3
• This is particularly important in pediatric patients, where pretreatment with lidocaine or use of larger veins is recommended 1