To compare the duration of sensory and motor blockade produced by two different intrathecal doses of dexmedetomidine (5 µg and 10 µg) when added to hyperbaric bupivacaine in patients undergoing elective cesarean section

Cesarean section remains one of the most commonly performed surgical procedures worldwide, serving as a critical intervention to reduce maternal and neonatal morbidity when vaginal delivery poses increased risks. Global cesarean delivery rates have risen steadily, from approximately 7% in 1990 to around 21% in recent years, with projections indicating that by 2030, nearly one in three births may occur via cesarean section .This trend is particularly pronounced in regions like Latin America and the Caribbean (over 40%) and varies significantly by socioeconomic factors, healthcare access, and clinical indications . In Pakistan and similar settings, rates continue to increase, underscoring the need for optimized anesthetic techniques that prioritize maternal safety, fetal well-being, rapid recovery, and effective postoperative pain control.

Regional anesthesia, specifically spinal anesthesia, is the preferred method for elective cesarean sections due to its rapid onset, avoidance of airway complications associated with general anesthesia, minimal placental transfer of drugs, and enhanced maternal satisfaction. Hyperbaric bupivacaine is the most widely used local anesthetic for this purpose, providing reliable sensory and motor blockade. However, when used alone, bupivacaine offers relatively short-duration postoperative analgesia, which can delay ambulation, hinder early mother-infant bonding, and increase the need for systemic analgesics6. To address these limitations, various intrathecal adjuvants have been investigated to enhance block quality, prolong analgesia, and improve overall outcomes.

Dexmedetomidine, a highly selective α2-adrenergic agonist, exhibits sedative, anxiolytic, and analgesic properties without significant respiratory depression. When administered intrathecally, it inhibits nociceptive transmission through presynaptic C-fibers and postsynaptic dorsal horn neurons, resulting in prolonged sensory and motor blockade compared to bupivacaine alone8,9 . Multiple recent studies and meta-analyses have confirmed its efficacy as an adjuvant in obstetric spinal anesthesia, demonstrating extended analgesia duration, reduced shivering, and fewer side effects (e.g., pruritus, nausea) than opioids like fentanyl . However, the optimal intrathecal dose remains controversial: lower doses (e.g., 3-5 µg) may offer a favorable benefit-risk profile with minimal hemodynamic impact, while higher doses (e.g., 10 µg) provide greater prolongation but raise concerns about potential bradycardia or hypotension in parturient.

This prospective, double-blind, randomized clinical trial compares the effects of two commonly used doses of intrathecal dexmedetomidine-5 µg and 10 µg-when added to a standard dose of hyperbaric bupivacaine (12.5 mg) for elective cesarean section. The primary aim is to determine which dose yields superior prolongation of sensory and motor blockade while maintaining maternal hemodynamic stability and safety.

Inclusion Criteria:

• Parturients aged 20-40 years
• ASA physical status II
• Scheduled for elective cesarean section
• Ability to provide informed written consent

Exclusion Criteria:

• ASA physical status III or higher
• Emergency cesarean section
• Previous labor analgesia
• History of cardiovascular, neurological, or systemic disease
• Contraindications to spinal anesthesia
• Surgery duration exceeding 60 minutes