We aim to study  the effect  of intravenous dexmedetomidine and intravenous magnesium sulphate infusions on haemodynamic profile ,  sedation score  and duration of post operative analgesia in patients undergoing  laparoscopic cholecystectomy. 

Patients will be randomly allocated into 2 groups using sealed envelope technique based on a computer generated random number table  which will be as follows: Group D will receive dexmedetomidine infusion and group M will receive intravenous infusion of magnesium sulphate.

After securing a wide bore intravenous cannula and  initiating standard ASA monitoring ( electrocardiography, non invasive blood pressure monitoring, pulse oximetry)  the baseline data (T0) including systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP), and heart rate (HR) will be  monitored and recorded . Ringer Lactate will be started at the rate of 10ml/kg/hour. The  patients will be premedicated with midazolam 0.05 mg/kg, intravenous fentanyl 2 μg/kg, intravenous glycopyrrolate 0.01mg/kg and intravenous ondansetron 0.1 mg/kg . The study drugs will be given as follows:

Group D: Dexmedetomidine 1μg/kg  in 100 ml  normal saline over 10 minutes

 Group M: Magnesium sulphate  40 mg/kg  or a maximum dose of 2 g in 100 mL over 10 min.

Induction will be done using propofol 2 mg/kg followed by atracurium (0.5mg/kg) to facilitate tracheal intubation. Tracheal intubation will be done by an experienced  anaesthesia personnel . It will be performed after TOF is 0 with a 7.0  mm and  8.0 mm internal diameter (ID) endotracheal tube in female and male patients respectively.

Group D will receive  dexmedetomidine maintenance infusion at rate of 0.5 μg/kg/hr and  Group M will receive magnesium sulphate infusion at rate of 15 μg/kg/hr.

 The pneumoperitoneum will be performed using non-humidified and non-heated CO2, with the intra-abdominal pressure maintained around 10 -14 mmHg.

 Patients will be ventilated to maintain normocapnia.  All patients will receive fentanyl  1  μg/kg hourly and the muscle relaxant top up will be given when the TOF ratio is1/ 4 or more.The sevoflurane will be maintained at 4% with oxygen in air 1:1 . If the pulse rate or systolic blood pressure or mean arterial pressure increase to more than 20% baseline values then an additional dose of fentanyl 1 μg/kg will be administered. The total fentanyl and atracurium consumed will be recorded. The sevoflurane consumption rate  will be calculated as per the following formula :

Ml of liquid anaesthetic /hour = 3.3 X dial concentration ( V/V%) X fresh gas flow ( litres /min)

Port site local infiltration with 10 ml 0.25% bupivacaine will be given at the end of surgery.

Heart rate (HR), systolic blood pressure (SBP) and mean arterial blood pressure (MAP) will be recorded at baseline before loading dose; after anaesthetic induction, immediately post intubation, during and after 5 minutes of pneumoperitoneum insufflation and then at 15, 30, 60, 90, 120 min (every half hourly till surgery end); and postoperatively at end of surgery, post-extubation, and at 10 and 30 min after extubation.

The sevoflurane will be stopped just after the last suture. The time for extubation from stopping the sevoflurane to removal of the ETT will be recorded. 

The sedation score will be assessed according to the Ramsay Sedation Score immediately postoperatively and at 10 and 30 minutes in the PACU.

The pain score will be assessed as per the Visual Analogue Scale (VAS) on a scale of 0-10 till the VAS is 4 or more than 4. Intravenous paracetamol 1 gram and additional dose of fentanyl (if needed) will be given as rescue analgesics.

All intraoperative and postoperative complications will be recorded.

Categorical variables will be analyzed using chi-square  test. Continuous variables will be analyzed using unpaired Student’s t-test or univariate two-group repeated measures “mixed-design” analysis of variance (ANOVA) with post hoc Dunnett’s test as appropriate. Nominal and nonnormally distributed variables will be analyzed using Mann-Whitney U test.

A p value < 0.05 will be considered as significant. Statistical analyses will be performed by computerized statistical software (SPSS, version 21; SPSS, Chicago, Ill).