Spinal Anaesthesia

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).

Neuraxial ultrasonography has been shown a safe and effective technique to enhance the overall success rate of lumbar puncture and reduce the number of injection attempts. However, the current blind palpation landmark technique is known to be highly inaccurate and may increase the risk of multiple insertion attempts, patient suffering and complication rates such as spinal cord injury. Various clinical studies have confirmed the effectiveness of ultrasound imaging compared with the traditional palpation method. However, none of the present system can achieve real-time guidance. The overall aim of this proposal is to develop an ultrasound guided automated spinal landmark identification with real-time neuraxial needle insertion system (uSINE) to improve patient safety and efficacy of neuraxial procedure needle insertion success. This will be achieved in 4 phases of technology development and clinical trial phases. The investigators will recruit 20 subjects in a prospective cohort study to investigate the spinal needle first attempt success rate as a clinically relevant outcome. The secondary aim is to develop an automated spinal landmark identification algorithm using image processing to identify spinal landmarks in 50 obese patients. Third phase objective will be to obtain clinical data, and evaluation and annotation of the clinical data of spinal ultrasonography in 65 obese patients (BMI \> 30kg/m2), whereas the fourth phase will measure the uSINE identification accuracy and first-attempt puncture success rate of uSINE in a clinical study of 65 obese patients (BMI \> 30kg/m2).

Neuraxial blockade is commonly performed using a manual palpation technique, but the procedure can be challenging, particularly in patients with high body mass index, pregnancy, or spinal deformities. Preprocedural ultrasound may improve identification of the optimal injection site, yet its use in clinical practice remains limited, partly due to a lack of structured training. This multicentre randomised controlled trial investigates whether anaesthesiologists performing ultrasound-assisted spinal anaesthesia achieve better clinical outcomes and higher patient satisfaction compared with the traditional manual palpation technique. Both novice anaesthesia residents and more experienced anaesthesiologists are included. Participants receive structured simulation-based training using either ultrasound-assisted or manual palpation techniques, following a mastery learning approach with predefined performance standards. After certification, participants perform spinal anaesthesia during elective lower limb surgery, with clinical performance assessed by senior anaesthesiologists. The primary outcome is first-attempt success of spinal block. Secondary outcomes include number of attempts, needle redirections, time spent, need for assistance, and overall block success. Patient satisfaction and complications are assessed as tertiary outcomes. This study aims to provide evidence on the clinical effects of structured training in ultrasound-assisted neuraxial access and to explore the role of prior clinical experience.