What are the recommended intrathecal doses of ropivacaine, bupivacaine, lidocaine, and opiates (such as fentanyl or sufentanil)?

Recommended Intrathecal Doses of Local Anesthetics and Opiates

For intrathecal anesthesia and analgesia, bupivacaine 1.25-2.5 mg, ropivacaine 2-5 mg, with fentanyl 12.5-25 μg or sufentanil 2-7 μg are the recommended doses for initiation, with maintenance achieved through continuous infusions or intermittent boluses. 1

Initial Dosing for Labor Analgesia

Local Anesthetics

• Bupivacaine: 1.25-2.5 mg (0.1-0.25% solution, 1-2.5 ml) 1
• Ropivacaine: 2-5 mg (0.1-0.2% solution, 2-5 ml) 1
  • Note: Ropivacaine is approximately 20-50% less potent than bupivacaine intrathecally 2, 3
• Levobupivacaine: Similar to bupivacaine, with potency ratio of 0.8 compared to bupivacaine 1
• Lidocaine: Not commonly recommended for intrathecal labor analgesia in current guidelines

Opioids

• Fentanyl: 12.5-25 μg (maximum 15 μg recommended to minimize adverse effects) 1
• Sufentanil: 2-7 μg (maximum 2.5 μg recommended to minimize adverse effects) 1
  • Potency ratio of sufentanil to fentanyl is 4.4:1 1

Maintenance Dosing

Continuous Infusion

• Bupivacaine: 0.0417-0.1% with fentanyl 2-2.5 μg/ml at 1-3 ml/h 1
• Ropivacaine: 0.1-0.2% with fentanyl 2-2.5 μg/ml at 1-3 ml/h 1
• With sufentanil: 0.75-1 μg/ml instead of fentanyl 1

Intermittent Boluses

• 1-2 ml of maintenance solution for breakthrough pain 1
• Patient-controlled option: 0.5-1 ml of maintenance solution every 20-30 minutes 1

Cesarean Section Anesthesia

• Titrate incremental doses of bupivacaine/ropivacaine to achieve T4 sensory level 1
• Add fentanyl/sufentanil and morphine/diamorphine for enhanced analgesia 1
• For hyperbaric bupivacaine, 8-12 mg is effective, with 8 mg sufficient when combined with 10 μg fentanyl 4

Potency Considerations

• Ropivacaine is 20% less potent than bupivacaine for cesarean delivery 2
• In some studies, ropivacaine is approximately half as potent as bupivacaine 3
• When combined with sufentanil, 2-4 mg ropivacaine provides similar analgesia to 2.5 mg bupivacaine 5

Safety Considerations and Monitoring

Monitoring Requirements

• Frequent non-invasive blood pressure measurements
• Continuous fetal heart rate monitoring for 30 minutes after initiation
• Respiratory monitoring
• Ambulation is not recommended during labor if medication is administered 1

Potential Complications

• High or total spinal anesthesia
• Hypotension
• Respiratory depression
• Pruritus from opioids

Important Caveats

1. Dosing should occur in an operating theater with basic monitoring and backup equipment available to manage potential high spinal complications 1
2. Hyperbaric solutions are rarely used for initiating intrathecal catheter analgesia 1
3. If intrathecal placement is recognized after administration of 10 mg bupivacaine, further incremental doses should only be given when sensory block recedes to T10 1
4. For accidental dural puncture cases where an intrathecal catheter is placed, careful labeling and precautions are essential to prevent accidental drug administration 1

These recommendations are based on the most recent guidelines from the Obstetric Anaesthetists' Association and provide a structured approach to intrathecal dosing for various clinical scenarios.