Evaluation of analgesic efficacy of intrathecal neostigmine added to bupivacaine in Patients undergoing lower limb orthopedic surgery

Objective : To evaluate the analgesic efficacy of neostigmine as an additive to intrathecal bupivacaine. Methods: Following Ethics Committee approval and informed patients consent, Sixty patients 18-80 yr old ASA physical status I or II, scheduled for lower limb surgery under spinal anesthesia, were studied in a prospective, double-blinded, randomized way. The patients were randomly allocated to one of two groups of 30 each. The neostigmine group (group N) received bupivacaine 20 mg combined with 25microgram 0.5ml neostigmine and the placebo group (group P) received bupivacaine 20 mg combined with 0.5ml distilled water intrathecally . Time to first requirement of analgesic supplement , postoperative analgesic requirements duration of sensory and motor blockade, hemodynamics variables, and Adverse events such as hypoxia (oxygen (SpO2)<90], bradycardia hypotension, 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, pethidine 25 mg intravenously , was to be given for post-operative pain relief as needed .