Opioid Free VS Opioid Anesthesia for Craniotomies

"Patients will receive over the 10 minutes prior to induction:~* Acetaminophen 1 gm i.v. infusion in 100ml over 10 minutes.~* Ketorolac 30 mg i.v. infusion in100 ml over 10 minutes.~* Mg SO4 loading dose 30 mg/kg i.v. infusion in 100 ml over 10 minutes.~* Dexmedetomidine loading dose 1 μg/kg i.v. infusion.~* Lidocaine loading dose 1.5 mg/kg i.v. infusion.~* Ketamine loading dose 0.25 mg/kg i.v. infusion.~The weight based doses of dexmedetomidine, lidocaine, ketamine will be prepared on 20 ml syringe and infused over 10 minutes prior to induction. In a dose of 0.1 ml/kg~Then after induction maintenance analgesic infusion will start in a rate that ranges from 0.025 to 0.05 ml/kg/h which is equivalent to:~* Dexmedetomidine 0.25-0.5 μg/kg/h~* Lidocaine 0.375-0.75 mg/kg/h~* Ketamine 0.0625- 0.125 mg/kg/h"

Placebo equivalent to acetaminophen, ketorolac, magnesium sulphate will be infused as 100 ml normal saline each over 10 minutes ,patients will receive fentanyl 2 μg/kg loading dose which will be prepared over 20 ml syringe and infused over 10 minutes prior to induction, Then after induction maintenance of analgesic infusion by fentanyl 0.5-1 μg/kg/h.