What is the recommended epidural bupivacaine dosing protocol (including test dose and continuous infusion) for an adult patient?

Epidural Bupivacaine Dosing Protocol for Adults

For adult epidural anesthesia, use 0.125% bupivacaine with fentanyl 2 mcg/ml as the standard concentration for continuous infusion, with initial bolus dosing of 0.2-0.3 ml/kg (max 10 ml) for thoracic epidurals or 0.5 ml/kg (max 15 ml) for lumbar epidurals using 0.25% bupivacaine. 1, 2

Test Dose Protocol

• Administer a test dose of 3 ml of the epidural solution before initiating full dosing to rule out intravascular or intrathecal placement (standard practice, though specific test dose protocols vary by institution)
• Monitor for signs of local anesthetic toxicity (tinnitus, metallic taste, perioral numbness) or spinal block (rapid onset motor/sensory block) for 3-5 minutes after test dose

Initial Bolus Dosing

For Lumbar Epidural

• Use 0.25% bupivacaine at 0.5 ml/kg (maximum 15 ml) as the initial bolus 1, 2
• In obese patients, calculate dose based on ideal body weight (height in cm - 100 for men, height in cm - 105 for women) 3

For Thoracic Epidural

• Use 0.25% bupivacaine at 0.2-0.3 ml/kg (maximum 10 ml) as the initial bolus 1, 2
• The lower volume for thoracic placement reflects the smaller epidural space and reduced spread requirements 4

Continuous Infusion Protocol

The optimal maintenance regimen is 0.125% bupivacaine with 2 mcg/ml fentanyl at 4-6 ml/hr background infusion. 5, 6, 7

Concentration Selection

• 0.125% bupivacaine is superior to 0.0625% for postoperative analgesia, requiring significantly less rescue analgesia (29 mg vs 110 mg ketorolac, p<0.001) 6
• 0.125% bupivacaine is preferable to 0.25% as it provides equivalent analgesia with lower incidence of urinary retention 6
• The 0.125% concentration provides excellent pain control without motor blockade 6

Infusion Rate

• Start with 4-6 ml/hr as background infusion 5, 8
• This rate with 0.125% bupivacaine/2 mcg/ml fentanyl provides VAS scores of 2-3 at rest and 3-4 with activity 5

Patient-Controlled Epidural Analgesia (PCEA) Settings

When using PCEA, program the pump with: bolus dose 3-4 ml, lockout interval 10-20 minutes, background infusion 4-6 ml/hr. 5, 7

• Bolus dose: 3-4 ml 5, 7
• Lockout interval: 10-20 minutes 5, 7
• Background infusion: 4-6 ml/hr 5, 7
• Solution: 0.0625-0.125% bupivacaine with 2 mcg/ml fentanyl 7, 8

PCEA Advantages

• PCEA with 0.0625% bupivacaine/fentanyl uses 40% less bupivacaine than continuous infusion while achieving comparable analgesia 7
• Lower cephalad spread with PCEA reduces unnecessary sensory blockade 7

Alternative Local Anesthetic: Ropivacaine

If using ropivacaine instead of bupivacaine, use 0.2% ropivacaine with 2 mcg/ml fentanyl at the same infusion rates. 9, 8

• Ropivacaine 0.2% with fentanyl provides equivalent analgesia to bupivacaine 0.125% with fentanyl 9, 8
• Ropivacaine may require slightly less volume (208 ml vs 236 ml over 48 hours, p=0.05) 8
• Do not use ropivacaine 0.1% - doubling concentration to 0.2% does not improve analgesia but increases drug consumption 9

Adjuvant Opioid Selection

Fentanyl 2 mcg/ml is the standard opioid adjuvant for epidural bupivacaine infusions. 5, 6, 7, 8

• Alternative: Hydromorphone 10 mcg/ml with 0.06% bupivacaine provides effective analgesia with VAS scores of 2-3 at rest 5
• Hydromorphone combination shows low rates of respiratory depression (0%) and sedation (0.08%) but 30% incidence of nausea 5

Common Pitfalls and Monitoring

Dose Calculation Errors

• Always use ideal body weight for obese patients - using actual body weight risks local anesthetic toxicity 1, 3
• For patients <40 kg, calculate doses carefully based on weight-based formulas 1, 2

Side Effect Management

• Expect 30% incidence of nausea with opioid-containing solutions 5
• Pruritus occurs in 15% of patients 5
• Hypotension occurs in 10% of patients - ensure adequate IV access and fluid resuscitation 5
• Urinary retention is more common with 0.25% bupivacaine - use 0.125% concentration to minimize this 6

Motor Block Assessment

• 0.125% bupivacaine should not produce motor blockade - if present, consider catheter migration or excessive dosing 6, 7
• Check motor strength regularly during the first 24 hours 5

Inadequate Analgesia

• If breakthrough pain occurs with 0.125% infusion, administer 3 ml boluses of 0.25% bupivacaine every 5 minutes up to 3 doses 7
• Consider increasing background infusion rate before increasing concentration 5