Combined spinal epidural analgesia for labour: a formula

1. Preload with 500 mL isotonic intravenous solution.
2. Insert epidural needle at L2-L3 or L3-L4 as with traditional technique.
3. Insert a long (41Ž2 in.; 11.8 cm) 25- or 27-gauge Whitacre or Quincke needle through the epidural needle into the cerebrospinal fluid (CSF). If you do not have the long spinal needles, you can do the spinal injection first. The track made by the spinal needle will not interfere with placement of the epidural needle.
4. Identify the CSF, and then inject 1.0 mL of 0.25% bupivacaine hydrochloride (for epidural use; no epinephrine) combined with 25 µg fentanyl citrate (0.5 mL) and dilute with 0.5 mL saline. The total volume is 2 mL. If you are unable to identify the CSF, the needle may simply be off to the side of the epidural space. Alternatively, some anesthetists use only fentanyl (37.5 µg) intrathecally with good effect.
5. Withdraw the spinal needle and thread the epidural catheter according to the usual technique.
6. After the spinal analgesia has been started and the epidural catheter placed, a low-dose continuous infusion of 0.05% bupivacaine is initiated. Remove 24 mL from a 100-mL saline bolus. Add 20 mL 0.5% bupivacaine (0.10% final concentration) and 4 mL fentanyl (200 µg; 0.0002%). Run the mixture of 0.10% bupivacaine/0.0002% fentanyl at 10 mL/hour with an infusion pump.
7. Monitor the mother's blood pressure and pulse, as well as the fetal heart rate every 5 minutes for 20 minutes. Then monitor blood pressure and pulse every 30 minutes and fetal heart rate every 15 minutes.
8. After 30 minutes, test the mother for hypotension. If absent and if she feels that she can walk, test for motor block by asking her to stand and to attempt, while attended, a partial knee bend. If she is successful, encourage her to walk and (or) sit in a chair for the duration of labour.
9. Some centres discontinue the intravenous infusion (or use a saline lock) if the patient successfully walks after 30 minutes.
10. Subsequent top-ups, if required, involve considerably smaller doses than expected with conventional epidural techniques. Dilute 5 mL of 0.25% bupivacaine with 15 mL saline in a 20-mL syringe. Give 10 mL by test dose plus slow bolus. Repeat in 20 minutes if analgesia is inadequate. Remember: a top-up should be provided promptly, because onset is very slow with such dilute concentrations.