Local Anesthetics in Pediatrics
Key Points
- Local anesthetics block sodium channels in nerve membranes, preventing nerve impulse transmission
- Dose calculations must be weight-based and never exceed maximum safe doses
- Children are more sensitive to systemic toxicity than adults
- Regular monitoring of vital signs is essential during administration
Common Applications
- Minor surgical procedures
- Dental procedures
- Pain management
- Regional nerve blocks
- Topical anesthesia for procedures
Amide Local Anesthetics
Lidocaine (Xylocaine)
- Concentration: 0.5-2%
- Onset: 2-5 minutes
- Duration: 1-2 hours
- Maximum dose: 4.5mg/kg without epinephrine, 7mg/kg with epinephrine
- Available forms: Injectable solution, topical preparations
Bupivacaine (Marcaine)
- Concentration: 0.25-0.5%
- Onset: 5-10 minutes
- Duration: 4-8 hours
- Maximum dose: 2.5mg/kg without epinephrine, 3mg/kg with epinephrine
- Avoid in infants under 12 weeks due to prolonged clearance
Ropivacaine (Naropin)
- Concentration: 0.2-0.75%
- Onset: 5-10 minutes
- Duration: 3-6 hours
- Maximum dose: 3mg/kg
- Better safety profile than bupivacaine
Ester Local Anesthetics
Procaine (Novocaine)
- Concentration: 1-2%
- Onset: 2-5 minutes
- Duration: 30-60 minutes
- Maximum dose: 7mg/kg
- Higher risk of allergic reactions
Tetracaine
- Used primarily in topical preparations
- Duration: 2-3 hours
- Common component of TAC (tetracaine-adrenaline-cocaine) and LET (lidocaine-epinephrine-tetracaine) preparations
Topical Preparations
EMLA Cream (2.5% lidocaine + 2.5% prilocaine)
- Application time: 60 minutes minimum
- Maximum application area by age:
- 0-3 months: 1g over 10cm²
- 3-12 months: 2g over 20cm²
- 1-6 years: 10g over 100cm²
- 7-12 years: 20g over 200cm²
- Avoid in infants under 3 months on methemoglobin-inducing drugs
LET Gel (4% lidocaine, 0.1% epinephrine, 0.5% tetracaine)
- Used for lacerations
- Application time: 20-30 minutes
- Maximum dose: 3ml for children > 3 years
Clinical Applications
Regional Nerve Blocks
- Digital nerve blocks
- Penile nerve blocks for circumcision
- Ilioinguinal nerve blocks for hernia repair
- Caudal blocks for lower body procedures
Infiltration Techniques
- Linear: Along incision lines
- Field block: Surrounding area of procedure
- Ring block: Circumferential injection
Common Procedures
- Suturing
- IV placement
- Lumbar puncture
- Chest tube insertion
- Minor surgical procedures
Safety Guidelines
Pre-procedure Assessment
- Review allergies and past reactions
- Calculate maximum doses based on weight
- Check for contraindications
- Ensure resuscitation equipment availability
Monitoring Requirements
- Continuous pulse oximetry
- Blood pressure monitoring
- ECG for high-risk procedures
- Regular assessment of consciousness level
Signs of Toxicity
- Early signs:
- Perioral numbness
- Metallic taste
- Lightheadedness
- Tinnitus
- Late signs:
- Seizures
- Cardiovascular depression
- Respiratory arrest
Further Reading
