A bispectral index guided study on the effect of dexmedetomidine on sevoflurane requirements during elective laparoscopic surgeries

Background: General inhalational anaesthesia associated with adjuvant intravenous agents provides better sedation, hypnosis and analgesia. Drugs with such effects already established in the literature include benzodiazepines and opioids. Aim: Aim of the study was to evaluate the effect of continuous infusion of Dexmedetomidine, on Sevoflurane requirement during general anesthesia with continuous monitoring of depth of anesthesia by BIS (Bispectral index) analysis in patients undergoing elective laparoscopic surgeries. Materials and methods: 60 patients with ASA grade I and II, aged between 35-55 years, submitted to elective laparoscopic cholecystectomies under General Anesthesia were randomly divided into two groups of 30 each, one group received a loading dose of Dexmedetomidine at 1 mcg/kg for 10 min (10 minutes before starting the surgery), followed by maintenance dose of 0.5 mcg/kg/hour, till the end of surgery. The other group received similar volume of IV Normal Saline. MAP, HR, SpO2, EtCO2 and BIS were evaluated. Results: There was no significant difference (p>0.05) between Dexmed and Saline groups with respect to mean age, weight, height, duration of anaesthesia and ASA grade. There was no significant difference (p>0.05) in the baseline heart rates and baseline mean arterial pressure between the two groups. There was a clinically and statistically significant reduction in HR and MAP in the Dexmed group throughout intraoperative period compared to Saline group (p <0.05). There was a statistically significant rise in HR and MAP in the Saline group during laryngoscopy and 15 minutes after the creation of pneumoperitoneum (p<0.05). Dexmed group had a stable hemodynamics during laryngoscopy and creation of pneumoperitoneum. No statistically significant difference was noted in the extubation time of both the groups. Mean RAMSAY Sedation score and Modified ALDRETE score was higher in Dexmed group. Usage of Sevoflurane (in ml) and usage of Sevoflurane /min was significantly low in Dexmed group. Conclusion: Dexmedetomidine as a preanesthetic medication and intraoperative infusion was effective in blunting stress response to laryngoscopy and creation of pneumoperitoneum. It also decreased intraoperative anaesthetic requirement and had significant anaesthetic sparing property during BIS guided general anaesthesia providing a lighter sedation without the prolongation of extubation time or without any significant adverse effects.