The goal of this clinical trial is to assess the effect of IV pethidine and intrathecal pethidine on the incidence, onset, duration, and intensity of shivering in females undergoing caesarean section. The main question it aims to answer is: which route is more efficacious in preventing shivering.

Researchers will compare IV pethidine and intrathecal pethidine to see their effects on post spinal shivering, their effects on hemodynamic stability, nausea, vomiting, and sedation.

This study will be a single blinded, randomized, prospective controlled study. After obtaining written informed consents, 86 patients of American Society of Anesthesiologists physical status II, aged 20-40 years old, undergoing spinal anesthesia for elective cesarean section will be investigated at El-Shatby University Hospital.

The patients will be randomized into two groups of n=43 each using a computer-generated sequence. Allocation concealment will be done using sealed envelope technique. Depending on the group allocation either to receive IV Pethidine 0.5mg/kg (Group A n=43 patients) as premedication mixed into 10 ml isotonic saline slowly IV or intrathecal Pethidine 0.2 mg/kg and 2.5 ml Bupivacaine 0.5% (Group B n=43 patients). SA will be given at either L3-L4 or L4-L5 in the sitting position by the anesthetist using 22-25-gauge Quincke spinal needles. Patients will be covered with drapes but not actively warmed. 10mg ephedrine will be given if the patient becomes hypotensive (hypotension is defined as a decrease in MAP of >20% from the baseline). 0.5 mg atropine IV will be given if HR less than 50 beats/min. Rescue 4 mg ondansetron IV will be given for vomiting episodes. Room temperature will be maintained about 21 - 24ºC during the perioperative period in the OR and in the PACU, using temperature control system. The presence of shivering will be observed and graded after spinal injection by using Tsai and Chu Scale.

The following parameters will be measured:

1. Vital signs (heart rate, and blood pressure) will be measured at baseline and every 5 minutes after administration of the drug for 30 minutes, then every 15 minutes till the end of surgery and every 30 minutes in the first two hours postoperatively
2. Body temperature (in degrees Celsius), will be measured, using axillary thermometer before drug administration then every 15 minutes till the end of surgery. After surgery, axillary temperature will be measured every 30 minutes for 2 hours.
3. Using Tsai and Chu Scale for shivering assessment, the incidence, duration, time interval from onset of spinal block to shivering occurrence, and intensity of shivering will be recorded every 15 minutes during the surgery and every 30 minutes for 2 hours postoperatively in the recovery room.
4. Complications of the drugs, such as nausea, vomiting and sedation will be recorded.

The primary aim of this study will be to assess the effect of IV pethidine and intrathecal pethidine on the incidence, onset, duration, and intensity of shivering. The secondary aims will be to assess the effect of different routes of administration of the drug on hemodynamic stability, nausea, vomiting, and sedation.

Inclusion Criteria:

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Exclusion Criteria:

1. contraindications to spinal
2. uncontrolled hypertension, diabetes mellitus, hepatic, pulmonary diseases, and thyroid disease
3. obesity (BMI >35)
4. drug allergy
5. temperature below 36 degrees celcius or above 37.5 degrees celcius

Pregnant females undergoing caesarean section