What is the recommended ratio of dexamethasone (Decadron) to lidocaine for injection?

Recommended Ratio of Dexamethasone to Lidocaine for Injection

For local anesthetic injections, the recommended ratio is 8 mg of dexamethasone to be added to lidocaine solution, with lidocaine dosed at 1-2 mg/kg. 1

Evidence-Based Rationale

The combination of dexamethasone with lidocaine provides several clinical benefits:

1. Prolonged Analgesia: Adding dexamethasone to lidocaine significantly extends the duration of both sensory and motor blockade 2

2. Pain Reduction: Dexamethasone at 8 mg is recommended for adults to reduce postoperative pain when used with local anesthetics 1

3. Dosing Guidelines:

   • Lidocaine: 1-2 mg/kg for initial loading dose, followed by 1-2 mg/kg/h for infusion 1
   • Dexamethasone: 8 mg for adults (or 0.15 mg/kg for children) 1

Clinical Application Algorithm

Step 1: Patient Assessment

• Confirm patient weight (avoid in patients <40 kg) 1
• Calculate ideal body weight for lidocaine dosing:
  • Men: height (cm) - 100
  • Women: height (cm) - 105 1

Step 2: Preparation

• For standard mixture:
  • Lidocaine 1-2 mg/kg (not exceeding 120 mg/h) 1
  • Add dexamethasone 8 mg 1

Step 3: Administration Technique

• Administer through a separate, dedicated cannula when using intravenous route 1
• For nerve blocks or local infiltration, mix directly in the same syringe
• Allow at least 10 minutes before surgical incision for optimal effect 1

Important Considerations and Precautions

• Maximum Doses:

  • Lidocaine with epinephrine: 7 mg/kg for adults, 3-4.5 mg/kg for children
  • Lidocaine without epinephrine: 4.5 mg/kg for adults, 1.5-2 mg/kg for children 1

• Timing Considerations:

  • Do not start lidocaine within 4 hours of any nerve block or fascial plane block
  • No nerve blocks should be performed until 4 hours after completion of IV lidocaine infusion 1

• Monitoring Requirements:

  • Continuous ECG and pulse oximetry
  • Regular blood pressure monitoring (every 5 minutes during initial infusion) 1

Special Situations

For specific procedures:

• Major Surgery (abdominal, pelvic, spinal): Consider IV lidocaine infusion (bolus 1-2 mg/kg followed by 1-2 mg/kg/h) with dexamethasone 8 mg 1

• Ambulatory Hand Surgery: Adding both dexamethasone and ketorolac to lidocaine IVRA provides superior perioperative analgesia compared to lidocaine alone 3

• Pediatric Patients: Use dexamethasone 0.15-0.25 mg/kg (max 0.5 mg/kg) with appropriately weight-adjusted lidocaine dosing 1

This combination approach provides effective pain control while minimizing the risks associated with higher doses of either medication alone.