Comparative Dose-Response of Intrathecal Dexmedetomidine for Post-Spinal Shivering

Comparative Efficacy and Dose-Response of Intrathecal Dexmedetomidine in Attenuating Post-Spinal Shivering: Double-Blinded Randomized Controlled Trial

Dexmedetomidine, a highly selective α2-adrenergic agonist, when used intrathecally as an adjuvant to local anesthetics, prolongs sensory/motor block and may blunt thermoregulatory shivering mechanisms. Several randomized controlled trials and meta-analyses have demonstrated decreased shivering incidence with intrathecal dexmedetomidine, but reported doses vary (commonly 2.5, 5, and 10 µg, and in some trials up to 15-20 µg), and the balance between efficacy and adverse effects (sedation, bradycardia, and hypotension) is not fully established. Hence, a head-to-head randomized comparison of several low-to-moderate intrathecal doses is warranted.

Objective: to compare the safety and efficacy of three intrathecal dexmedetomidine doses (2.5 µg, 5 µg, 10 µg) versus placebo for the prevention of post-spinal shivering.

Inclusion Criteria:

• Adult patients (age 18-75 years)
• Scheduled for ureteric stone removal surgery
• ASA(American Society of Anesthesiologists) physical status I, II, or III
• Able to provide informed consent

Exclusion Criteria:

• Known allergy to dexmedetomidine, bupivacaine, or other study medications
• Preexisting bradycardia (heart rate <50 beats per minute)
• Second- or third-degree atrioventricular (AV) block without a pacemaker
• Severe hepatic dysfunction
• Uncontrolled hypotension
• Pregnancy
• Chronic use of α₂-agonists or antagonists (e.g., clonidine, tizanidine)
• Infection at the planned spinal puncture site
• Coagulopathy or bleeding disorder
• Inability to rate or communicate shivering (e.g., language barrier, cognitive impairment)