What is the recommended starting dose of fentanyl (synthetic opioid analgesic) for a 33 kg child?

Fentanyl Dosing for a 33 kg Child

For a 33 kg child, the recommended starting dose of fentanyl is 1-2 micrograms/kg intravenously for intraoperative use (33-66 micrograms total) or 0.5-1.0 micrograms/kg (16.5-33 micrograms total) for breakthrough pain in the post-anesthesia care unit. 1

Dosing Guidelines Based on Clinical Context

Intraoperative Use

• Initial dose: 1-2 micrograms/kg IV (33-66 micrograms total) 1
• Administer slowly to avoid transient excessive blood concentrations
• Titrate to clinical effect

Breakthrough Pain in PACU

• Initial dose: 0.5-1.0 micrograms/kg IV (16.5-33 micrograms total), titrated to effect 1
• Can be repeated as needed based on clinical response

Outpatient Facial Trauma

• 2-3 micrograms/kg IV (66-99 micrograms total) for sedation and analgesia during facial trauma repair 2

Administration Considerations

Route of Administration

• Intravenous route is preferred for rapid onset
• Intraosseous (IO) administration is an acceptable alternative when IV access cannot be obtained
• Onset of action for IV administration: 1-2 minutes 3
• Peak effect: 3-4 minutes 3
• Duration of action: 30-60 minutes for a single dose 3

Safety Precautions

1. Monitoring Requirements:

   • Continuous monitoring of heart rate, blood pressure, oxygen saturation, and respiratory rate 3
   • Monitor for signs of opioid-induced sedation, which typically precedes respiratory depression

2. Potential Adverse Effects:

   • Respiratory depression (most serious)
   • Hypotension, particularly with rapid administration
   • Chest wall rigidity with rapid administration of high doses
   • Histamine release (less common than with morphine)

3. Reversal Agent Availability:

   • Have naloxone readily available: 0.1 mg/kg IV/IM/IO for children <5 years or <20 kg 1
   • For reversal of respiratory depression with therapeutic opioid use, use lower doses (1-15 μg/kg) 1

Special Considerations

Pharmacokinetics in Children

• Fentanyl is highly lipophilic, allowing rapid penetration of the blood-brain barrier 3
• Duration of action is redistribution-limited after single doses 4
• Terminal half-life can range from 1.5 to 6 hours in adults, but may be different in children 4

Risk Factors for Adverse Events

• Rapid IV administration increases risk of chest wall rigidity
• Combined use with other sedatives (particularly benzodiazepines) increases risk of respiratory depression 1
• Patients with increased intra-abdominal pressure may have prolonged elimination half-life 5

Important Cautions

• Always have resuscitation equipment immediately available
• Extravascular administration can result in severe skin injury
• Careful dose calculation is essential to avoid medication errors
• The duration of monitoring should extend beyond the expected duration of action due to potential for delayed respiratory depression
• Fentanyl is approximately 7.5 times more potent than oral morphine for intravenous administration 3

Remember that fentanyl dosing should be adjusted based on the specific clinical scenario, patient's prior opioid exposure, and concomitant medications. Start with the lower end of the dosing range when uncertainty exists.