What is the typical starting dose for a fentanyl (synthetic opioid) perfusion?

Fentanyl Infusion Dosing

For opioid-naïve patients requiring continuous IV fentanyl infusion, start with an initial bolus of 1-2 mcg/kg administered slowly over several minutes, followed by a continuous infusion individualized to response, with additional bolus doses of 25-50 mcg available every 5 minutes as needed. 1

Initial Bolus Dosing for Opioid-Naïve Patients

• Administer 1-2 mcg/kg IV fentanyl as the initial bolus, given slowly over several minutes to avoid glottic and chest wall rigidity, which can occur with doses as low as 1 mcg/kg when administered rapidly 1
• For brain-injured patients requiring intubation, higher bolus doses of 3-5 mcg/kg may be used, but reduce doses in hemodynamically unstable patients 1
• Allow 2-3 minutes for fentanyl to take effect before administering additional medications 1

Starting Continuous Infusion

• After achieving initial pain control with boluses, initiate the continuous infusion 1
• The infusion rate should be individualized based on the patient's response to the initial boluses 1
• If the patient requires two bolus doses within one hour, double the infusion rate 1

Breakthrough Dosing Protocol

• Order IV fentanyl bolus doses of 25-50 mcg every 5 minutes as required for breakthrough pain 2, 1
• If a patient is already receiving a fentanyl infusion and develops pain or respiratory distress, give a bolus dose equal to two times the hourly infusion dose 2
• After 2-3 days at steady state, reassess and adjust the basal infusion rate based on average daily breakthrough medication requirements 1

Conversion from Other Opioids to Fentanyl Infusion

From IV Morphine:

• Use a fentanyl:morphine potency ratio of 60:1 1
• Calculate the 24-hour morphine dose, multiply by 1/60 to get the fentanyl dose, then divide by 4 to correct for morphine's longer half-life 1

From IV Hydromorphone:

• The equivalent dose of IV hydromorphone for 50 mcg of IV fentanyl is approximately 0.8-1 mg 3
• Use an IV fentanyl to IV morphine ratio of approximately 100:1 and an IV morphine to IV hydromorphone ratio of approximately 5:1 3
• Reduce the calculated equianalgesic dose by 25-50% when converting between different opioids to account for incomplete cross-tolerance 1, 3

Critical Safety Monitoring

• Monitor patients for at least 24 hours after dose initiation or increase due to fentanyl's mean half-life of approximately 17 hours 1, 4
• Be prepared to administer naloxone (0.1 mg/kg IV or 0.2-0.4 mg for adults) and provide respiratory support at all times 2, 1
• Monitor oxygen saturation continuously 1
• There is significantly increased risk of apnea when fentanyl is combined with benzodiazepines or other sedatives—exercise extreme caution with co-administration 1
• Have vasoconstrictors (ephedrine or metaraminol) immediately available to treat hypotension 1

Common Pitfalls to Avoid

• Never administer fentanyl rapidly—chest wall rigidity can occur with doses as low as 1 mcg/kg when given too quickly 1
• Do not use fentanyl infusions in non-opioid tolerant patients without appropriate monitoring, as this may lead to fatal respiratory depression 4
• Starting with too high a conversion dose from other opioids can lead to respiratory depression; always reduce by 25-50% for incomplete cross-tolerance 1, 3
• Respiratory depression may last longer than the analgesic effect of fentanyl, requiring extended monitoring 2
• With repeated dosing or continuous infusion, fentanyl accumulates in skeletal muscle and fat, prolonging its duration of effect 2

Dose Adjustments for Special Populations

• Reduce doses by 50% or more in elderly patients 2
• Adjust doses based on considerations of size, age, and organ dysfunction 2
• Avoid morphine in patients with renal failure due to accumulation of renally cleared metabolites; fentanyl may be preferred in this population 3