Dexemedetomidine on Shivering Cesarean Section Under Spinal Anesthesia A Randomized Clinical Trial

Patients and Methods Setting and ethics and trial registration The present randomized clinical study is planned to be conducted at Gynecology and Obstetrics Department, Assiut University Hospitals in the time from February through March, 2023. The study protocol will be approved by the independent institutional review board and all participants with provide informed consent prior to enrollment. The study will be registered at clinicaltrials.gov before recruitment of the first patient. Sample size calculation To detect a 20 % of differences between shivering scores in the studies groups, the sample size was calculated using a study power of 95.0 % and two-sided significance level of 5.0 % with 1:1 ratio. The estimated sample size for each group was 164 patients. We added 10 % of patients as expected dropout rate. So, the final sample size will be 191 patients per group. Sample size was calculated using G Power 3.1.6.9 (Kiel University, Germany).

Patient recruitment The present study will include American Society of Anesthesiology (ASA) I-II women scheduled for elective CS under intrathecal anesthesia. Patients will be excluded if they had local infection, bleeding disorder or known allergy to any of the study medications.

Randomization, blinding and allocation Patients in each study category will be equally and randomly assigned to receive either DEXA or DEXM using computer generated random tables and sealed envelopes. Independent researchers who aren't aware of the scope of the study will be assigned to assess and report patient outcome. Used medications will be prepared in similar packages to secure adequate blinding.

Preoperative preparation, monitoring and anesthesia All patients will be instructed, prepared and monitored according the standard guidelines.

Preoperative medications will include IV granisetron 1gm and ranitidine 50mg. Spinal anesthesia will be accomplished using 10-12 mg of 0.5% hyperbaric bupivacaine. When adequate level of anesthesia is guaranteed, CS is started under appropriate hemodynamic monitoring. Once the baby is delivered, 10 IV units of oxytocin will be administered.

Study interventions Patients in the studied groups will receive either or intravenous DEXM 10 µg (Sween et al., 2021) or IV infusion of DEXA 8 mg (Esmat et al., 2021). Outcome assessment The primary outcome of the present study is the incidence of clinically significant postoperative shivering (Grade 2/3) assessed by 4-point scale (Badjatia et al., 2008) as follows:

1. None (Grade 0): no shivering noted on palpation of the masseter, neck, or chest wall
2. Mild (Grade 1): shivering localized to the neck and/ or thorax only
3. Moderate (Grade 2): shivering involved gross movement of the upper extremities (in addition to neck and thorax)
4. Severe (Grade 3): shivering involved gross movements of the trunk and upper and lower extremities Secondary outcome measures will be postoperative pain, hypotension, sedation grade, patient satisfaction, time to sensory and motor onset and time to use of first rescue analgesia.

Statistical analysis All reported data will be recorded and statistically analyzed using appropriate statistical tests.