Low-dose combined spinal-epidural anesthesia for cesarean delivery: a comparison of three plain local anesthetics

The new local anesthetics have been poorly studied for intrathecal use during Cesarean section surely in low doses and in combination with an opioid substance. The purpose of the present study was to compare bupivacaine and the newer local anesthetics in equipotent doses. During the induction of combined spinal-epidural anesthesia, 91 elective Cesarean section patients were randomly assigned to receive a spinal injection of either 10 mg ropivacaine or 6.6 mg bupivacaine or levobupivacaine both combined with sufentanil 3.3 microg. After securing the epidural catheter patients were turned to the supine position respecting a 15 degrees left lateral tilt. The three local anesthetics were compared with respect to sensory and motor block, the need for epidural supplementation, the severity of hypotension and neonatal outcome. More patients in bupivacaine had a Bromage-3 motor block at incision. The ropivacaine group required additional local anesthetics by the epidural route in 23% of the cases versus 10% in the bupivacaine group and 9% with levobupivacaine. This caused the interval between the spinal injection and the end of surgery to be longer in the ropivacaine group. Hemodynamic values were comparable between the three groups although a trend towards better systolic blood pressures and a lower incidence of severe hypotension were noticed in favor of levobupivacaine. Apgar scores and umbilical pH values did not differ. When performing a low-dose combined spinal-epidural technique for Cesarean section, the present study confirms that the new local anesthetics can be used successfully, induce less motor block but that ropivacaine requires at least a 50% larger dose than bupivacaine or levobupivacaine.