What is the recommended anesthesia plan for a 16kg male undergoing circumcision?

Anesthesia Plan for Pediatric Circumcision in a 16kg Male

For a 16kg male undergoing circumcision, general anesthesia with mask induction using sevoflurane is appropriate, combined with a multimodal approach including midazolam premedication, atropine for antisialagogue effect, ketamine and fentanyl for analgesia, followed by sevoflurane maintenance—but critically, this must be supplemented with a dorsal penile nerve block using local anesthetic to optimize pain control and minimize opioid requirements.

Recommended Anesthetic Technique

Premedication and Induction

• Midazolam (0.5 mg/kg PO or 0.1 mg/kg IV) provides anxiolysis and facilitates smooth induction 1
• Atropine (0.01-0.02 mg/kg IV) reduces secretions and prevents bradycardia, particularly important with ketamine use
• Mask induction with sevoflurane is appropriate for this age/weight, as it provides rapid, smooth induction with minimal airway irritation 2
• Ketamine (1-2 mg/kg IV) and fentanyl (1-2 mcg/kg IV) provide excellent analgesia for the procedure 1

Critical Addition: Regional Anesthesia

You must add a dorsal penile nerve block (DPNB) to your plan. The evidence strongly supports combining general anesthesia with local anesthetic techniques:

• Ultrasound-guided DPNB is superior to landmark-based techniques, requiring lower local anesthetic volumes (approximately 0.1-0.2 mL/kg of 0.25-0.5% bupivacaine or ropivacaine), reducing narcotic requirements, and decreasing complications 3
• Use lean body weight for local anesthetic dosing calculations to avoid toxicity 2
• Maximum lidocaine dose: 5 mg/kg; maximum bupivacaine dose: 2.5 mg/kg 2
• Epinephrine can be safely added to penile blocks—historical concerns about penile necrosis have been refuted by evidence 2

Maintenance

• Sevoflurane provides appropriate maintenance with rapid emergence 2
• The combination of ketamine, fentanyl, and regional block creates an opioid-sparing multimodal approach that reduces postoperative pain and complications 1, 3

Evidence-Based Rationale

Why Add Regional Anesthesia?

Recent high-quality evidence demonstrates that sedation-only or general anesthesia combined with local techniques provides superior outcomes 1:

• A 2025 study showed that systemic analgesia (midazolam, propofol, fentanyl, ketamine) provided equivalent pain control to combined techniques
• However, local infiltration increased complications (ecchymosis, edema) compared to systemic analgesia alone 1
• Nerve blocks (not infiltration) avoid these complications while providing superior analgesia 3

Ultrasound Guidance Advantages

• 1.8 times less likely to require rescue analgesia 3
• 2 times lower complication rate 3
• Lower local anesthetic volume requirements 3
• Longer duration until rescue analgesic needed 3
• Lower incidence of postoperative vomiting 3

Dosing Calculations for 16kg Patient

Systemic Medications

• Midazolam: 1.6 mg IV (0.1 mg/kg)
• Atropine: 0.16-0.32 mg IV (0.01-0.02 mg/kg)
• Ketamine: 16-32 mg IV (1-2 mg/kg)
• Fentanyl: 16-32 mcg IV (1-2 mg/kg)

Local Anesthetic (for DPNB)

• Use lean body weight for calculation 2
• 0.25% bupivacaine: maximum 40 mg (16 mL), but typically need only 3-5 mL total for bilateral DPNB 3
• Alternatively, 0.5% lidocaine: maximum 80 mg (16 mL) 2

Critical Safety Considerations

Airway Management

• Maintain spontaneous ventilation or use gentle positive pressure ventilation
• Have appropriately sized airway equipment available
• Position patient supine with slight head elevation 2

Monitoring

• Standard ASA monitors (ECG, pulse oximetry, NIBP, capnography)
• Temperature monitoring to maintain normothermia 2

Common Pitfalls to Avoid

1. Do not use local infiltration around the surgical site—this increases edema and ecchymosis without improving analgesia compared to nerve blocks 1
2. Do not exceed maximum local anesthetic doses—calculate based on lean body weight 2
3. Do not perform nerve block and IV lidocaine simultaneously—wait at least 4 hours between techniques 2
4. Do not omit the regional block—systemic analgesia alone, while effective, misses the opportunity for superior pain control with lower opioid requirements 3

Postoperative Care

• Simple analgesics (acetaminophen 15 mg/kg PO/PR) for breakthrough pain 4
• Minimal opioid requirements expected with proper regional technique 3
• Monitor for urinary retention (rare but possible)
• Discharge when fully awake, tolerating fluids, and pain controlled