Effect of Preoperative Intranasal Dexmedetomidine on Incidence of Intraoperative Shivering in Patients Undergoing Cesarean Section Under Spinal Anesthesia

Shivering is a common and distressing complication occurring in 40% to 60% of women undergoing cesarean section under spinal anesthesia. Beyond causing significant maternal discomfort, shivering markedly increases oxygen consumption and metabolic demand, elevates cardiopulmonary workload, and interferes with clinical monitoring. While intravenous meperidine remains a widely used pharmacological agent for shivering prophylaxis, it carries dose-dependent adverse effects such as nausea, vomiting, sedation, and potential neonatal depression. Intranasal dexmedetomidine provides an alternative needle-free method of administration that rapidly absorbs through the nasal mucosa and reduces shivering without suppressing respiratory drive. The primary purpose of this randomized controlled trial is to evaluate the efficacy of preoperative intranasal dexmedetomidine in reducing the incidence of intraoperative shivering compared with intravenous meperidine and placebo in women undergoing elective cesarean section under spinal anesthesia. A total of 99 parturients will be randomly allocated to one of three parallel groups (33 patients per group) using a double-dummy design: * Group D: Receives intranasal dexmedetomidine (1 mcg/kg) 30 minutes before spinal anesthesia, plus an intravenous saline placebo at spinal induction. * Group M: Receives intranasal saline placebo 30 minutes before spinal anesthesia, plus intravenous meperidine (0.5 mg/kg) at spinal induction. * Group C: Receives intranasal saline placebo 30 minutes before spinal anesthesia, plus intravenous saline placebo at spinal induction. Participants will be monitored throughout the surgical procedure to determine the occurrence of shivering, maternal hemodynamic parameters (heart rate, blood pressure, oxygen saturation), sedation levels using the Richmond Agitation-Sedation Scale (RASS), need for rescue anti-shivering medication, side effects, and neonatal outcomes (Apgar scores and birth weight).