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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
120
Patients in this group will receive the standard spinal anesthetic consisting of hyperbaric bupivacaine 0.5% (15 mg) combined with an equivalent volume of normal saline (0.9% NaCl), containing no active dexmedetomidine. The total intrathecal injection volume will be standardized to 3.5 mL across all groups by adjusting the volume of saline added. This group serves as the control to establish the baseline incidence and characteristics of post-spinal shivering and block dynamics without the intervention of the α2-adrenergic agonist.
Patients in this group will receive the standard spinal anesthetic (15 mg hyperbaric bupivacaine 0.5%) supplemented with a low dose of 2.5 µg of dexmedetomidine. Normal saline will be added to achieve the standardized total intrathecal volume of 3.5 mL.
Patients in this group will receive the standard spinal anesthetic combined with a moderate dose of 5 µg of dexmedetomidine. The total volume will be adjusted to 3.5 mL with normal saline.
Patients in this group will receive the standard spinal anesthetic supplemented with a higher dose of 10 µg of dexmedetomidine, with normal saline used to standardize the total volume to 3.5 mL.
Al-Azhar University
Cairo, Egypt, Egypt
Incidence of clinically significant shivering
Incidence of clinically significant shivering within 60 minutes after spinal injection, defined as Crossley and Mahajan shivering scale grade ≥2 (scale 0-4)The highest intensity of shivering experienced by the patient, scored on the 0-4 scale. The Crossley and Mahajan shivering scale is a clinically validated, four-grade ordinal scale (0-4) used to objectively quantify the severity of post-anesthetic shivering. It is defined as follows: Grade 0 signifies no shivering; Grade 1 indicates mild, intermittent fasciculations of the face, neck, or chest; Grade 2 represents visible, intermittent shivering involving more than one muscle group; Grade 3 denotes generalized, continuous shivering of the whole body; and Grade 4 describes gross, bed-shaking tremors that interfere with monitoring or procedure. Grade ≥2 is typically considered clinically significant and often triggers therapeutic intervention. The scale is assessed through direct visual observation of the patient by trained personnel.
Time frame: Throughout the intraoperative period until 60 minutes post-spinal.
Time to first shivering episode
The duration from the completion of the spinal injection to the onset of the first observable shivering (any grade).
Time frame: Intraoperative period, up to 60 minutes post-spinal.
Requirement of rescue anti-shivering drug
the number of patients required pharmacologic intervention (meperidine or tramadol) to treat severe shivering.
Time frame: Intraoperative period, as needed.
Dose of rescue anti-shivering drug
The total amount of pharmacologic intervention (meperidine or tramadol) to treat severe shivering.
Time frame: Intraoperative period, as needed.
Sedation level
The Ramsey Sedation Scale (RSS) is a simple, widely used six-level clinical tool (scores 1-6) for assessing a patient's level of sedation and responsiveness. It is scored as follows: 1 - Patient is anxious, agitated, or restless; 2 - Patient is cooperative, oriented, and tranquil; 3 - Patient responds only to commands; 4 - Patient exhibits a brisk response to a light glabellar tap or loud auditory stimulus; 5 - Patient exhibits a sluggish response to such a stimulus; and 6 - Patient exhibits no response to stimulus.
Time frame: Postoperative 24 hour
Patient satisfaction
The patient's overall satisfaction with the anesthesia experience.Using a Likert scale (e.g., 1-5 or 1-10) or a standardized satisfaction questionnaire.
Time frame: Postoperatively (e.g., prior to discharge from PACU).
Time to first analgesic request
The duration from the end of surgery until the patient first requires supplemental pain medication.
Time frame: 24 hours Postoperatively.
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