Comparative study of dexmedetomidine versus midazolam for monitored anaesthesia care in middle ear surgeries

Background: Monitored anaesthesia care (MAC) involves administration of local anaesthesia in combination with intravenous sedatives, anxiolytic and/or analgesics, which is a common practice during ENT procedures that are superficial, less invasive and can be done under local anesthesia in well counseled patients. Midazolam has been in use for MAC because of a number of beneficial effects. Recent studies suggest that α2 agonists provide adequate sedation and analgesia and also improve surgical field visibility. Dexmedetomidine, a highly selective α2 agonist is emerging as a preferred choice for MAC. Aim: To compare the efficacy of Inj. Dexmedetomidine and Inj. Midazolam for Middle ear surgeries under Local Anaesthesia with Monitored Anaesthesia Care in terms of sedation, analgesia and hemodynamic stability in the perioperative period. Methods: 96 patients of either sex, aged between 18-60 years of ASA grade I & II undergoing Middle ear surgeries under local anaesthesia with Monitored Anaesthesia Care were divided into two groups of 48 patients each to receive either Inj. Dexmedetomidine (Group D) 1 µg/kg IV bolus over 10 minutes followed by continuous infusion at the rate of 0.5 µg/kg/hr. or Inj. Midazolam (Group M) 40 µg/kg IV bolus over 10 minutes followed by continuous infusion at the rate of 20 µ/kg/hr for sedation during surgery. Sedation as titrated to Ramsay sedation score of 3. Vital parameters like Heart rate, Blood pressure, SpO2, Respiratory rate were recorded every 5 minutes for up to 120 minutes in the intraoperative period and for 120 minutes in post operative period. The need for rescue sedation (Inj. Propofol), rescue analgesic (Inj. Fentanyl) and surgeon satisfaction scores were assessed. Results: Analgesic effect of Dexmedetomidine was better than Midazolam (p<0.001). Sedation was comparable in both groups (p>0.05). Fall in Heart Rate was significantly more in Group D compared to baseline value and compared to Group M. Blood Pressure was maintained within normal limits in both the groups but the fall in SBP, DBP and MAP from baseline value was significantly more in Group D than in Group M (p < 0.05). Surgeon satisfaction scores were significantly higher with Dexmedetomidine compared to Midazolam. Conclusion: Dexmedetomidine is a safe and attractive agent for sedation in patients undergoing middle ear surgeries under local anaesthesia with monitored anaesthesia care as it provides a calm patient, causes better analgesia and rapid recovery.