Adding Different Additives to Bupivacaine-fentanyl Mixture in Spinal Anesthesia for Cesarean Section

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.

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.

spinal anesthesia with 10 mg hyperbaric bupivacaine 5% (2 ml) + 25 μg fentanyl (0.5 ml) + normal saline (0.5 ml).

spinal anesthesia with 10 mg hyperbaric bupivacaine 5% (2 ml) + 25 μg fentanyl (0.5 ml) + 5 μg dexmedetomidine in a volume of (0.5 ml).

spinal anaesthesia with 10 mg hyperbaric bupivacaine 5% (2 ml) + 25 μg fentanyl (0.5 ml) + 2 mg dexamethasone in a volume of 0.5 ml).

spinal anaesthesia will be performed with the patient in sitting position at the L3-L4 or L4-L5 interspaces with a 25 or 27 G spinal tip needle with the study drug in the total volume of 3 ml.

Numerical Rating Scale (NRS) for pain that ranged from (0 = no pain) to (10 = intolerable pain). If score is >3 will need analgesia in the form of morphine 3 mg will be given till NRS decreases to ≤3. NRS will be assessed and recorded immediately postoperative, 2, 4, 8, 12, 18, 24 h after the operation, by an anesthesiologist, who is blinded to the study groups.

Maternal satisfaction will be evaluated on a 0-3 score (0 = poor, 1 = fair, 2 = good, and 3 = excellent).

Inclusion Criteria: 90 parturient the statue of American Society of Anesthesiologists' physical class II prepared for an elective cesarean section. Exclusion Criteria: BMI > 35kg/m2 gestational age < 28 weeks diabetes or gestational diabetes hypertension or pre-eclampsia contraindications to spinal anesthesia height less than 160 Cm history of psychiatric disease taking α-receptor antagonist drugs -a history of allergy to the study drugs- excessive hemorrhage needing transfusion.