Kucukakin (2010) reported that administration of up to 60 mg of intravenous melatonin during major vascular surgery was safe and without a significant impact on intra? or postoperative hemodynamic parameters.
Additionally, Bekker et al. (2013) conducted a prospective randomized double-blinded study on 54 patients undergoing multilevel spinal fusion under general anesthesia, and assessed the effect of intraoperative infusion of dexmedetomidine on quality of recovery after surgery, they reported that All patients remained hemodynamically stable perioperatively. In the same year, Kang et al. (2013) examined the effects of intraoperative infusion of dexmedetomidine on hemodynamic parameters in patients undergoing laparoscopic cholecystectomy in comparison with saline treated group. They reported that both HR and MAP at the end of surgery were lower in dexmedetomidine group than in placebo group. And this was thought to be caused by central sympatholytic effects due to ?2 adrenoceptor stimulation.