Is fentanyl safe for total intravenous anesthesia (TIVA) in an otherwise healthy adult undergoing a moderate‑duration surgery, and what dosing regimen should be used?

Fentanyl for Total Intravenous Anesthesia (TIVA)

Fentanyl is safe and effective for TIVA in healthy adults undergoing moderate-duration surgery, with an induction dose of 1-2 micrograms/kg administered 3-5 minutes before other agents, followed by maintenance boluses of 0.5-1.0 micrograms/kg every 15-30 minutes titrated to hemodynamic response. 1, 2

Induction Phase Dosing

• Administer fentanyl 1-2 micrograms/kg intravenously 3-5 minutes before propofol or other induction agents to allow peak effect-site concentration during laryngoscopy and intubation, the most nociceptive stimuli. 1, 2

• This timing strategy prevents inadequate analgesia during laryngoscopy and reduces hemodynamic instability. 1

• Administer neuromuscular blocking agents immediately after loss of consciousness to prevent fentanyl-induced chest wall and glottic rigidity, which can occur even at doses as low as 1 microgram/kg. 3, 2

Maintenance Phase Dosing

• Administer maintenance boluses of 0.5-1.0 micrograms/kg every 15-30 minutes, titrated to hemodynamic response and surgical stimulation intensity. 1

• For breakthrough pain during surgery, give 0.5-1.0 micrograms/kg and reassess within 5 minutes. 1

• The intermittent bolus technique is preferred over continuous infusion for standard TIVA cases, as fentanyl is primarily used as bolus doses rather than continuous infusions in standard protocols. 3

Opioid-Sparing Adjuvant Strategies

Consider adding adjuvants to reduce total fentanyl requirements by 25-30% and minimize side effects:

• Ketamine 0.5 mg/kg as an intraoperative adjunct reduces fentanyl dose requirements by 25-30%. 1, 3

• Dexmedetomidine with a loading dose of 1-3 micrograms/kg followed by 0.2-0.7 micrograms/kg/hour infusion reduces fentanyl requirements and provides additional sedation. 1, 3

• Acetaminophen 15-20 mg/kg IV loading dose, then 10-15 mg/kg every 6-8 hours, or NSAIDs (if not contraindicated) reduce total opioid consumption. 1, 3

Critical Monitoring Requirements

• Continuously monitor oxygen saturation, blood pressure, heart rate, and respiratory rate throughout fentanyl administration. 1, 3, 2

• Approximately 10% of patients receiving higher doses (>1.5 micrograms/kg total) may develop respiratory depression that persists postoperatively. 1, 3, 2

• Maintain vigilant postoperative monitoring for at least 2 hours, as respiratory depression may last longer than the analgesic effect. 1, 3

• Naloxone 0.2-0.4 mg (0.5-1.0 micrograms/kg) must be immediately available to reverse opioid effects, though it does not reverse benzodiazepines or propofol. 1, 3

Dosing Adjustments for Special Populations

• No dose reduction is needed for weight alone in otherwise healthy adults within normal weight parameters. 1

• For elderly patients (>60 years), reduce the initial bolus by 20-50% to account for altered pharmacokinetics. 1

• Fentanyl is safer than morphine in renal dysfunction and does not require dose adjustment for single-dose or short-term use, as it lacks renally cleared active metabolites. 1

Common Pitfalls to Avoid

• Inadequate pre-intubation dosing results in poor analgesia during laryngoscopy and increased hemodynamic instability. 1

• Rapid administration can cause chest wall and glottic rigidity; administer slowly over several minutes when treating pain outside the induction sequence. 3

• Failure to have naloxone immediately available delays treatment of respiratory depression. 1, 3

• Underestimating the duration of respiratory depression, which may outlast analgesic effects, leading to inadequate postoperative monitoring. 1, 3