A Randomized, Double-Blinded Trial of Subarachnoid Bupivacaine and Fentanyl, With or Without Clonidine, for Combined Spinal/Epidural Analgesia During Labor

Subarachnoid clonidine may increase the duration of spinal opioid and local anesthetic analgesia during labor, but it may also increase hypotension and sedation, and the therapeutic range is unclear. We studied 110 term parturients of mixed parity having combined spinal/epidural analgesia during labor in this randomized, double-blinded trial. All received subarachnoid fentanyl 20 mug and bupivacaine 2.5 mg, plus either saline or clonidine (15, 30, or 45 mug). Of 101 per-protocol parturients (n = 25,24, 26, and 26 in Groups C0, C15, C30, and C45, respectively), 22 delivered before the cessation of spinal analgesia. Group demographics and pain scores from Time 0 to 120 min were similar. There was no significant difference among groups in the duration of spinal analgesia (P = 0.09) or in the duration of clonidine groups combined compared with control (median, 120 min [interquartile range, 96-139 min] versus 98 min [80-120 min]; P = 0.07). Systolic blood pressure was significantly lower in all clonidine groups between 40 and 90 min (P = 0.001). Hypotension (P = 0.05) and the requirement for ephedrine (P = 0.02) were dose dependent, but groups had a similar incidence of hypotension. The addition of clonidine 15-45 mug to subarachnoid fentanyl and bupivacaine reduced blood pressure and did not significantly increase the duration of spinal analgesia.