Fentanyl Dosing for Anesthesia Induction

Dosage Recommendations

The initial recommended dose of fentanilo for anesthesia induction is 50-100 μg intravenously, with supplemental doses of 25 μg every 2-5 minutes until adequate sedation is achieved, according to the American Gastroenterological Association 1, 2
For healthy adults under 60 years: 50-100 μg IV as initial dose 1
For patients over 60 years: reduction of dose by 50% or more (25-50 μg) 1
For patients with physical status ASA III or higher: consider dose reduction 2

Onset of action: 1-2 minutes 1
Duration of effect: 30-60 minutes 1
Primary adverse effect: respiratory depression (can last longer than analgesic effect) 1
At high doses, it can induce thoracic wall rigidity and generalized skeletal muscle hypertonia 1

When used with midazolam or other benzodiazepines, a synergistic interaction occurs that requires dose reduction 1
For induction with propofol: administer fentanilo first (100-150 μg), followed by propofol 3

Fentanilo in high doses: 3-5 μg/kg 4
Use lower doses in unstable patients (e.g., multiple trauma) 4
Combine with an induction agent (propofol or ketamine) and a neuromuscular blocker 4

Have naloxona available (0.2-0.4 mg IV every 2-3 minutes) to reverse opioid effects if necessary 1
Continuously monitor oxygen saturation, blood pressure, and heart rate 3
Respiratory depression is more likely in patients with underlying respiratory disease or in combination with benzodiazepines 1
Be prepared for airway management, as combination with other sedatives can cause significant respiratory depression 3