Recommended Dosages for Epidural Spinal Anesthesia Using Bupivacaine and Lidocaine
For epidural anesthesia, bupivacaine should not exceed 10 mg for test dosing, while standard epidural dosing is 3-5 mL of 0.25-0.5% solution (7.5-25 mg) with maximum total dose not exceeding 175-225 mg in 24 hours; lidocaine dosing is typically 2-3 mL of 1.5% solution for test dosing and 15-20 mL of 1-2% solution for full epidural block. 1, 2, 3
Bupivacaine Dosing for Epidural Anesthesia
Test Dosing
- A test dose of 10 mg bupivacaine (or equivalent) is recommended to detect intrathecal catheter placement while minimizing risk of high or total spinal anesthesia 1
- This test dose should produce clinically evident sensory, motor, or autonomic effects if placed intrathecally
Standard Epidural Dosing
- For epidural anesthesia, administer in incremental doses of 3-5 mL with sufficient time between doses to detect toxic manifestations 2
- Concentration selection based on desired effect:
- 0.25% - Produces incomplete motor block; use for operations where muscle relaxation is not important
- 0.5% - Provides motor blockade but may be inadequate for operations requiring complete muscle relaxation
- 0.75% - Produces complete motor block; most useful for abdominal operations requiring complete muscle relaxation (contraindicated for obstetrical use)
Maximum Dosage
- Maximum single dose: 175 mg without epinephrine, 225 mg with epinephrine 1:200,000 2
- Total daily dose should not exceed 400 mg in 24 hours
- Reduce dosages for elderly, debilitated patients, and those with cardiac/liver disease
Lidocaine Dosing for Epidural Anesthesia
Test Dosing
- 2-3 mL of 1.5% lidocaine HCl (30-45 mg) is recommended as a test dose 3
- Should be administered at least 5 minutes prior to injecting the total volume required
Standard Epidural Dosing
- Dosage varies with number of dermatomes to be anesthetized (generally 2-3 mL per dermatome) 3
- Available in concentrations of 1% and 2% with or without epinephrine
Maximum Dosage
- With epinephrine: maximum 7 mg/kg not exceeding 500 mg total 3
- Without epinephrine: maximum 4.5 mg/kg not exceeding 300 mg total
- For continuous epidural anesthesia, maximum recommended dosage should not be administered at intervals less than 90 minutes
Administration Techniques and Safety Considerations
Fractional Dosing
- Rapid injection of large volumes should be avoided 1, 2, 3
- Use fractional (incremental) doses when feasible
- Allow sufficient time between doses to detect toxic manifestations
Monitoring for Intrathecal Placement
- Catheter aspiration should be performed to detect intrathecal placement 1
- Negative aspiration is reassuring but does not entirely preclude misplacement
- Multi-orifice catheters provide more reliable aspiration test results
Special Populations
- Obstetric patients: Only 0.25% and 0.5% bupivacaine should be used; incremental doses of 3-5 mL of 0.5% solution not exceeding 50-100 mg at any dosing interval 2
- Elderly patients: Dosage reduction required; cephalad spread is more extensive and duration of epidural blockade is shorter in elderly patients 4
- Pediatric patients: Bupivacaine not recommended for patients younger than 12 years 2
Clinical Pearls and Pitfalls
Common Pitfalls
- Failing to perform adequate test dosing before administering full dose
- Injecting too rapidly, which can lead to high block and hemodynamic instability
- Not recognizing intrathecal catheter placement, which can result in high or total spinal anesthesia
Practical Considerations
- When using combined spinal-epidural technique, low-dose spinal anesthesia (7.5 mg 0.5% bupivacaine) combined with epidural anesthesia (6 mL 2% lidocaine) can provide satisfactory anesthesia while minimizing hemodynamic effects 5
- For postoperative analgesia, continuous epidural infusion of 0.2% ropivacaine or 0.125% bupivacaine at 6 mL/hr provides adequate pain relief 6
- In epidural top-up situations, volumes of 5-10 mL produce similar increases in sensory blockade level 7
By following these dosing recommendations and safety precautions, optimal anesthesia can be achieved while minimizing the risk of complications associated with epidural spinal anesthesia using bupivacaine and lidocaine.