All participants will be given clear information about the study through the clinical trial information sheet. Written consent will be obtained from those who meet the eligibility criteria and agree to participate. Eligible patients will then be randomly assigned to one of three groups using (25 mg, 50 mg, 75 mg) Magnesium Sulfate. Patients in the intervention group will receive spinal anesthesia with 0.5% hyperbaric bupivacaine along with 25mg,50mg,75mg of intrathecal magnesium sulfate diluted in normal saline. Patients in the control group will receive only spinal anesthesia with 0.5% hyperbaric bupivacaine intrathecally. We will record how often shivering occurs during and after surgery and grade its severity using a standard shivering scale. All patients will be closely monitored for blood pressure, heart rate, and any side effects related to intrathecal magnesium sulfate during and after the procedure.
• The study drug will be prepared according to group allocation:
Group A: 25 mg Mg SO₄
Group B: 50 mg Mg SO₄
Group C: 75 mg Mg SO₄
• Spinal anesthesia will be administered at L3–L4 or L4–L5 using standard technique with 0.5% hyperbaric bupivacaine plus study drug.
• Patients will remain unaware of group allocation (single-blind). A trained independent observer, blinded to group allocation, will record all intraoperative observations.
• Standard monitoring (ECG, NIBP, SpO₂) will be applied. Parameters will be recorded at predefined intervals (0, 5, 10, 15, 30, 45, 60 minutes):
Heart rate
Blood pressure
Core temperature
Shivering score (Wrench scale)
• Primary outcome: Incidence and severity of shivering will be assessed using the Wrench shivering scale (0–4).
• Secondary Outcomes will be recorded:
Onset and duration of sensory block
Duration of motor block
Sedation level (Ramsay scale)
Adverse effects (hypotension, bradycardia, nausea, vomiting)
• Management of Adverse Events:
Hypotension will be treated with IV fluids and vasopressors
Bradycardia will be treated with atropine.
The antidote for magnesium sulfate is Calcium gluconate.
All adverse events will be recorded in the pro forma
• Data will be recorded on a structured questionnaire. Each patient will be assigned a unique ID number. Data will be entered into SPSS software for analysis, and confidentiality will be maintained throughout.