The Effect of Adding Dexmedetomidine or Dexamethasone to Bupivacaine-Fentanyl Mixture in Spinal Anesthesia for Cesarean Section

Spinal anesthesia is widely used in cesarean section, but it is associated with high incidence of side effects. To reduce the occurrence of side effects, intrathecal adjuvant was recommended to use in spinal anesthesia, with the aim in reducing the dose of intrathecal local anesthetic, which can subsequently decrease the incidence of spinal-induced side effects and prolong postoperative analgesia.Many augmentation strategies for intrathecal analgesia have been proposed. A meta-analysis by Popping et al. concluded that the concomitant use of an opioid such as fentanyl intrathecally allows the reduction in the dose of local anesthetic, while augmenting its analgesic potency thereby decreasing its adverse effects.

Dexamethasone relieves pain through reducing inflammation and blocking of nociceptive C- fibers transmission and by suppressing neural ectopic discharge. Post-operative analgesic effectiveness and duration was prolonged when dexamethasone was used as an adjunct for peripheral nerve blocks. Recent studies reported no complications associated with intrathecal dexamethasone.

Dexmedetomidine (DEX) is a potent, selective α2 adrenergic agonist and when given intrathecally, it exerts its analgesic effect via stimulating spinal α2 receptors. Wu et al., in their meta-analysis showed that addition of intrathecal DEX significantly increased the duration of postoperative analgesia and reduced analgesic consumption. The increase in duration of postoperative analgesia is dose dependent but with increase in the incidence of bradycardia.