Effect of Intravenous Magnesium on Post-spinal Fentanyl Induced Pruritus Incidence

Introduction: Adding opioids to local anesthetic solutions leads to enhanced anesthesia and provide postoperative analgesia. Intrathecaly injected opioids have some side effects, though. One of them is pruritus. Objective: We designed a randomized, double-blinded, placebo-controlled study to evaluate prophylactic impact of continuous IV Magnesium 10mg/kg over 30 minutes on intrathecal fentanyl-induced pruritus start at the end of the operation. Methods: ASA I-II Patient's candidate for orthopedic operations under spinal anesthesia (10-15mg hyperbaric bupivacaine and 25 µg fentanyl intrathecal) and will be divided randomly into two groups: Control group (Placebo group): bolus 100 ml nacl 0.9% at end of surgery Study group (Mg ++ group): (continuous IV Magnesium 10mg/kg in 100 ml Nacl0.9% over 30 minutes at end of surgery). Study outcome: 1. Hemodynamics: Systolic blood pressure, Mean arterial blood pressure, pulse rate, O2 saturation will be recorded in 5 min,10 min,30 min,60 min and every one hour till 6 hours after the operation. 2. Pruritus Patients were asked about existence (present=1,no=0), severity (mild=1, modret=2, sever =3) and site of pruritus (Face(trigeminal) =1, neuroaxial(dermatome)=2), 1,2,4, and 6 hours after operation. Incidence of pruritus total group incidence %. 3. The incidence of PONV.