This group will receive a bolus dose of Ketamine [Ketamine HCL - Sterop, Belgium] (0.3 mg/kg) by the ideal body weight diluted with 0.9% Normal Saline over 10 minutes by 20 ml syringe infused before induction. After which Ketamine infusion (500 mg vial diluted over 50 cc infusion syringe, concentration 10 mg/ml) will start with rate of 0.3 mg/kg/hr till 10 Minutes before the end of the surgery

This group will receive a bolus dose of Dexmedetomidine [Precedex® -Hospira, USA] (0.5 µcg/kg) by the ideal body weight diluted with 0.9% Normal Saline over 10 minutes by 20 ml syringe infused before induction. After which, the Dexmedetomidine infusion (200 µcg vial diluted over 50 cc infusion syringe, concentration 4 µcg/ml) will start with rate of 0.5 µcg/kg/hr till 10 Minutes before the end of the surgery

This group will receive a bolus dose of NS 0.9% over 10 minutes by 20 ml syringe infused before induction. After which, NS 0.9% (50 ml over 50 cc syringe) will be infused.

compare the use of ketamine versus dexmedetomidine when used as perioperative infusion in obese patients undergoing laparoscopic bariatric surgery regarding their analgesic efficacy as well as any side effects or drawbacks (PONV and effects on consciousness) that might associate with their use.

They will be assessed for sedation score with Modified Observer's assessment of alertness/sedation scale [MOAS/S] . The score will be repeated at 10, 30 and 60 minutes.

Agitated 6 Responds readily to name spoken in normal tone (alert) 5 Lethargic response to name spoken in normal tone 4 Responds only after name is called loudly and/or repeatedly 3 Responds only after mild prodding or shaking 2 Does not respond to mild prodding or shaking 1 Does not respond to deep stimulus 0

The patient will be assessed for pain by using the Numerical Rating Scale [NRS] with score is 0 for no pain and 10 for excruciating pain. The NRS score will be recorded 30 and 60 mins and 2, 6, 12, and 24 h after the surgery.

All patients will receive paracetamol (Perfilgan ®) 1 gm IV every 6 hours for 24 hours postoperatively. A rescue dose of morphine 4 mg per needed with minimum 6 hours interval between doses if the NRS Score is ≥ 4. total doses of morphine will be calculated.

All Patients will be assessed for PONV by using PONV Intensity Scale . The score will be done 6 hours and 24 hours after the surgery. Ondansetron (Zofran®) 4 mg will be given if the patient developed intense sensation of nausea and to be repeated after 30 Minutes

All the vital data will be recorded at 10 minutes, 30 minutes, 1 hour, 2 hours, 6 hours, 12 hours and 24 hours from discharge of operating room.

Postoperative complication (such as; airway obstruction, development of hypoxia, serious nausea and vomiting …, etc.) will be recorded.