Evaluation of the Analgesic Effect of Midazolam and Ketamine as an Additive to Intrathecal Bupivacaine in Patients Undergoing Cesarean Section

Objective :To compare the analgesic effect of intrathecal midazolam and ketamine as an additive to bupivacaine in patients undergoing cesarean section .

Methods:Following Ethics Committee approval and informed patients consent, Ninety patients 18-45 yr old ASA physical status I or II, scheduled for cesarean section under spinal anesthesia, were studied in a prospective, double-blinded, randomized way. The patients were randomly allocated to one of three groups of 30 each. The ketamine group (groupK) received bupivacaine 10mg combined with 0.1 mg/kg ketamine preservative free ,the midazolam group (group M) received bupivacaine 10mg combined with0.02 mg/ kg midazolam and the placebo group (group P) received bupivacaine 10mg combined with 0.5ml distilled water intrathecally . Time to first requirement of analgesic supplement, Sensory block onset time, maximum sensory level , onset of motor block, duration of blockade, hemodynamics variables, the incidence of hypotension, ephedrine requirements, bradycardia ,hypoxemia [Saturation of peripheral oxygen (SpO2)<90], postoperative analgesic requirements and Adverse events, such as sedation, dizziness , Pruritus and postoperative nausea and vomiting were recorded. Patients were instructed preoperatively in the use of the verbal rating scale (VRS) from 0 to 10 (0no pain, 10maximum imaginable pain) for pain assessment. If the VRS exceeded four and the patient requested a supplement analgesic, diclofenac Na supp 100 mg was to be given for post-operative pain relief as needed . For breakthrough pain(VRS >4) if time of administration of diclofenac Na less than 8h,Pethidine 25 mg IV was given.

The patients were randomly allocated to one of three groups of 30 each. The ketamine group (groupK) received bupivacaine 10mg combined with 0.1 mg/kg ketamine preservative free ,the midazolam group (group M) received bupivacaine 10mg combined with0.02 mg/ kg midazolam and the placebo group (group P) received bupivacaine 10mg combined with 0.5ml distilled water intrathecally .

Inclusion Criteria:

• patients with American Society of Anesthesiologists(ASA) physical status I and II, undergoing elective cesarean section

Exclusion Criteria:

• significant coexisting disease such as hepato-renal and cardiovascular disease
• any contraindication to regional anesthesia such as local infection or bleeding disorders
• allergy to ketamine or midazolam
• long-term opioid use or a history of chronic pain.