Effects of epidural injection on spinal block during combined spinal and epidural anesthesia for cesarean delivery

Background and Objectives: Epidural injection has been known to enhance spi nal anesthesia in combined spinal and epidural (CSE) anesthesia. Saline and local anesthetics have been reported to have a volume effect, elevating se nsory level when supplementing a volume into the epidural space. We evaluat ed the effects of epidural injection when using the CSE technique for cesar ean delivery. Methods: Sixty-six parturients were allocated randomly into group C (contro l, n = 21), S (saline, n = 21), or B (bupivacaine, n = 24): epidural inject ions of 10 mt saline and 0.25% bupivacaine were given in groups S and B, re spectively, 10 minutes after they received 8 mg of 0.5% hyperbaric bupivaca ine intrathecally, and no injection was given in group C. The sensory level at 10 minutes, the maximal level and the time to reach it, and degree of m otor block and muscle relaxation were compared. We also investigated intrao perative side effects and postoperative findings in the postanesthesia care unit. Results: Epidural injection raised the sensory level significantly in group s S and B, but the maximal height of sensory block and degree of muscle rel axation did not differ among the groups. Fewer patients complained of intra operative pain in group B than in the other groups (P < .001). Conclusions: We could not achieve satisfactory surgical analgesia with 8 mg of hyperbaric bupivacaine injected into the subarachnoid space using the n eedle-through-needle technique in cesarean deliveries. An epidural saline i njection elevated the sensory level, which did not improve the spinal block , whereas an epidural injection of 10 mt of 0.25% bupivacaine enhanced the spinal block and sustained the block postoperatively.