What is a safe dose of bupivacaine (local anesthetic) 0.25% in milliliters (mL)?

Safe Dosing of Bupivacaine 0.25%

The maximum safe dose of bupivacaine 0.25% is 1 mL/kg (equivalent to 2.5 mg/kg) for most regional anesthesia techniques, with specific volume adjustments based on the anatomical site and procedure type. 1, 2

Weight-Based Maximum Dose Calculation

• For a 70 kg adult: Maximum volume = 70 mL of 0.25% bupivacaine (175 mg total dose) 1, 2
• For a 10 kg child: Maximum volume = 10 mL of 0.25% bupivacaine (25 mg total dose) 2
• This 2.5 mg/kg limit applies to all peripheral nerve blocks, wound infiltration, and most regional techniques 1, 2

Procedure-Specific Volume Guidelines

High-Volume Blocks (Up to Maximum 1 mL/kg)

• Caudal block: 1.0 mL/kg of 0.25% bupivacaine 1
• Wound infiltration and peripheral nerve blocks: Maximum 1 mL/kg 1, 2

Moderate-Volume Blocks (0.5 mL/kg)

• Lumbar epidural: 0.5 mL/kg (maximum 15 mL initially) 1

Lower-Volume Blocks (0.2-0.5 mL/kg)

• Paravertebral block: 0.2-0.5 mL/kg 1
• Femoral nerve and fascia iliaca blocks: 0.2-0.5 mL/kg 1, 2
• Rectus sheath and TAP blocks: 0.2-0.5 mL/kg per side 1
• Quadratus lumborum block: 0.2-0.5 mL/kg 1

Minimal-Volume Blocks

• Thoracic epidural: 0.2-0.3 mL/kg (maximum 10 mL initially) 1
• Maxillary and external nasal nerve blocks: 0.15 mL/kg 1
• Intercostal block: 0.1 mL/kg 1

Critical Safety Considerations

Absolute Toxicity Threshold

• Never exceed 2.5 mg/kg total dose regardless of technique to avoid systemic toxicity including cardiovascular collapse 1, 2, 3
• Cardiotoxic effects (dysrhythmias, hypotension, cardiac arrest) have been reported at doses as low as 1.1 mg/kg in adults, well below the traditional maximum 3

When Maximum Volume Is Insufficient

• Consider ropivacaine 0.2% instead: Allows up to 1.5 mL/kg (3 mg/kg), providing 50% more volume with potentially improved cardiac safety profile 1, 2
• Consider levobupivacaine 0.25%: Same 2.5 mg/kg maximum but with reduced cardiac toxicity risk compared to racemic bupivacaine 2

Adjuvants to Extend Duration

• Add preservative-free clonidine 1-2 mcg/kg to prolong block duration without increasing local anesthetic dose 1, 2
• Add epinephrine 1:200,000 to decrease systemic absorption and extend duration 2, 4

Continuous Infusion Dosing

• Epidural infusion rate: 0.1-0.3 mL/kg/hour of 0.25% bupivacaine with appropriate monitoring 1
• Serum concentrations accumulate over days but are generally well-tolerated with gradual increases 5

Common Pitfalls to Avoid

• Bilateral blocks require halving the per-side dose: For rectus sheath or TAP blocks done bilaterally, use 0.2-0.5 mL/kg per side, ensuring total dose stays under 1 mL/kg 1
• Do not use preservative-containing formulations for neuraxial or continuous techniques: Only single-use ampules and single-dose vials are appropriate for epidural/spinal use 4
• Incremental dosing is mandatory for epidural techniques: Give 3-5 mL increments with sufficient time between doses to detect intravascular injection 4
• Test dose with epinephrine (3 mL of 0.5% with 1:200,000 epinephrine) should precede epidural boluses when not contraindicated 4