Group-I: Pre-induction dexmedetomidine + intraoperative dexmedetomidine plus anesthesia with propofol delivered by CLADS (induction + maintenance) [Dexmedetomidine group] Group-II: Pre-induction 0.9% saline solution + intraoperative 0.9% saline solution infusion + anesthesia with propofol delivered by CLADS (induction + maintenance) [Non Dexmedetomidine group]