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Abstract This study was done aiming at comparing the peri-operative effects of dexmedetomidine and fentanyl in patients scheduled for lumbar discectomy with TIVA. The hemodynamics, the rate difference of propofol consumption, the analgesic requirements and the postoperative recovery charachteristics were compared. Fifty patients undergoing single level posterior approach lumbar discectomy were allocated into two groups; D and F. Patients in Group D received dexmedetomidine 0.6 μg/kg IV over 10 minutes and patients in Group F received fentanyl 1 μg/kg IV as loading doses before induction. After pre-oxygenation, anesthesia was induced with 20 mg of propofol boluses given until the BIS became less than 60. After loss of consciousness and adequate manual ventilation, Cisatracurium at a dose of 0.15 mg/kg was used to facilitate tracheal intubation. After orotracheal intubation, the lungs were ventilated. All patients were placed in a prone position on a standard operating frame. Anesthesia was maintained with air/oxygen mixture (1:1), controlled ventilation and propofol infusion (50-150 μg/kg/min). The TOF was assessed every 10 minutes. Cisatracurium (0.03mg/kg) was administered when the TOF count becomes ≥2. Dexmedetomidine infusion was maintained at a dose of 0.2 μg/kg/h for group (D) and fentanyl infusion was maintained at a dosage of 0.5 μg/kg/h for group (F). Dexmedetomidine and fentanyl infusions were increased by 0.1 μg/kg/h according to the hemodynamics. The infusions of dexmedetomidine and fentnayl were adjusted to keep the mean arterial blood pressure not <20 % nor >10 % from the preoperative baseline value. End tidal CO2 of 35-40 mmHg was maintained. BIS range between 40 and 60 was considered adequate for hypnotic state. Absence of the 4th, 3rd and 2nd twitches of the TOF was the targeted degree of muscle relaxation. Summary 106 The Fentanyl infusion was terminated at the end of discectomy and the dexmedetomidine infusion was terminated at the beginning of skin closure. Paracetamol at a dose of 15 mg/kg IV was given at the start of skin closure for both groups. Propofol was discontinued towards the end of the case with the goal of achieving a quick recovery without allowing BIS values over 60 before the dressing is applied. Neostigmine (0.05 mg/kg) and atropine (0.02 mg/kg) were administered to antagonize residual neuromuscular block at the end of the procedure. The patient was extubated at a T4/T1 of 0.75 and BIS of 90-100. After the operation, the patient was transferred to the recovery room and the consciousness score was evaluated every 5 min using the modified Aldrete score (respiration, O2 saturation, motor activity, consciousness and blood pressure) until ready for discharge. The propofol induction and maintenance doses were significantly lower in group D than group F. Cisatracurium consumption was insignificantly lower in group D than group F. The MAP after induction was significantly lower in group D than group F. Both dexmedetomidine and fentanyl effectively abolished the stress response to laryngoscopy and intubation. The maintenance doses of dexmedetomidine and fentanyl were increased to 0.3 μg/kg/hr and 0.2 μg/kg/hr respectively to counteract the stress response to surgical skin incision. No rebound increase in MAP was noted after dexmedetomidine discontinuation. All over the perioperative period, the HR was lower in group D than group F. A single case in group D developed bradycardia after induction of anesthesia. The patient’s HR increased spontaneously to 63 beat/minute after intubation, so it didn’t necessitate any interference hence the stress of intubation was enough. At the end of anesthesia, extubation time was slightly longer in group F than in Summary 107 group D however to a statistically insignificant extent. PACU discharge time was slightly prolonged however to a statistically insignificant extent in group D than group F. Patients in group D required supplemental analgesia significantly earlier than those of group F. The incidence of nausea was significantly lower in group D than in group F. The incidence of vomiting was lower in group D than group F however to a statistically insignificant extent. The incidence of shivering and respiratory depression was lower in group D than group F however to a statistically insignificant extent. The incidence of bradycardia and dry mouth was higher in group D than group F however to a statistically insignificant extent. |