Background Bariatric surgery depends on the development of novel anesthetic techniques to reduce the incidence of complications and improve postoperative outcomes. Ketamine and dexmedetomidine have been used for perioperative analgesia and we hypothesized that they would decrease postoperative morphine requirements. The objective of this trial is to study whether choice of ketamine or dexmedetomidine infusion would affect postoperative total morphine consumption. Methods Ninety patients were equally randomized into three groups. The ketamine group received a bolus dose (0.3 mg/kg) of ketamine over 10 min, followed by an infusion of the same drug (0.3 mg/kg/h). The dexmedetomidine group received a bolus dose (0.5 mcg/kg) of dexmedetomidine over 10 min, followed by an infusion of this drug (0.5 mg/kg/h). The control group received a saline infusion. All infusions were given till 10 min before the end of surgeries. Intraoperative fentanyl was given when patient developed hypertension and tachycardia despite adequate anesthesia and muscle relaxation. Postoperative pain was managed by a rescue dose of 4 mg of IV morphine, with a minimum interval of 6 h between morphine doses if the numerical rating scale (NRS) score was ≥ 4. The primary outcome was the total morphine dose, and the secondary outcomes were intraoperative fentanyl requirement, time to extubation, postoperative nausea and vomiting (PONV), NRS scores, and modified observer’s agitation/sedation scale (MOASS) scores. Results Compared with ketamine, dexmedetomidine decreased the need for fentanyl intraoperatively (160 ± 42 µg), shortened the time to extubation (3 ± 1 min), and improved MOASS and PONV scores. In turn, ketamine decreased postoperative NRS scores and the need for morphine (3 ± 3 mg). Conclusions Dexmedetomidine treatment was associated with lower fentanyl doses, a shorter time to extubation, and better MOASS and PONV scores. Ketamine treatment was associated with significantly lower NRS scores and morphine doses. These results indicated that dexmedetomidine effectively decreased intraoperative fentanyl requirement and the time to extubation, while ketamine decreased the need for morphine. Trial registration This trail was registered on the clinicaltrials.gov registry (NCT04576975) on October 6, 2020.

Background: The development of different techniques in bariatric surgeries has required the development of novel anesthetic techniques to reduce the incidence of complications and improve post-operative patient outcomes. Ketamine and dexmedetomidine have been used for their peri-operative analgesic profiles in different studies. Methods: Ninety patients were studied and randomized equally into three groups. The Ketamine group received a bolus dose (0.3 mg/kg) of ketamine over 10 min followed by an infusion (0.3 mg/kg/h). The Dexmedetomidine group received a bolus dose (0.5 mcg/kg) of dexmedetomidine over 10 min followed by an infusion (0.5 mcg/kg/h). The control group received normal saline infusion. The total morphine dose was the primary outcome ,and intra-operative fentanyl requirements, time to extubation, post-operative nausea and vomiting (PONV), Numerical Rating Scale (NRS) scores, and Modified Observer’s Agitation/Sedation Scale (MOASS) scores were secondary outcomes of the study. Results: The Dexmedetomidine group showed decreased intra-operative fentanyl requirements (160.000 ± 42.345 µcg), less time to extubation (3.700 ± 0.925 min), and better scores on MOASS than the other groups. Post-operative NRS scores and the morphine requirement in the Ketamine group (1.867 ± 2.921 mg) were lower than in the other groups. The Dexmedetomidine group showed the lowest scores for PONV. Conclusions: The Dexmedetomidine group showed lower total fentanyl doses, a significantly shorter time to extubation, better MOASS scores, and lower PONV. The Ketamine group showed significantly lower NRS scores and morphine doses than the other two groups. Dexmedetomidine was effective on the reduction of intraoperative fentanyl requirement with early extubation, and ketamine was effective on the reduction of postoperative pain. Trial Registration: this trail has been registered on clinicaltrials.gov registry (NCT04576975) since 06/10/2020