ABSTRACT
BACKGROUND: Epidural "top-up" has been known to enhance spinal anesthesia in combined spinal-epidural anesthesia. Saline and local anesthetics were reported to have a volume effect when infused as epidural "top-up". In cesarean deliveries where high sensory block has been achieved using a combined spinal-epidural technique, we evaluated the effects of epidural "top-up" on the underlying spinal block. METHODS: Sixty-six parturients were allocated randomly into group C (control, n = 21), S (saline, n = 21), or B (bupivacaine, n = 24). Ten minutes after they received 8 mg of 0.5% hyperbaric bupivacaine intrathecally, nothing, 10 ml saline, or 10 ml of 0.25% bupivacaine were infused, respectively. The sensory level at 10 min, the maximal level and the time to reach it, and degrees of motor block and muscle relaxation were compared. We also investigated intraoperative side effects and postoperative findings in the PACU. RESULTS: There were significant changes in sensory level after epidural top-ups in the group S and B, but no differences in maximal height of sensory block and degree of muscle relaxation among the groups. Intraoperative pain was complained in fewer patients in the group B. Times to sensory and motor recovery were longer in patients of the group B. CONCLUSIONS: Eight milligrams of hyperbaric bupivacaine using a combined spinal-epidural technique was not sufficient for cesarean section. Epidural saline top-up showed volume effect, which didn't improve the spinal block. Epidural "top-up" of 0.25% 10 ml bupivacaine enhanced the spinal block and sustained the block postoperatively.