Dexmedetomidine infusion during middle ear surgery under general anaesthesia to provide oligaemic surgical field: A prospective study

BACKGROUND AND AIMS: Middle ear surgery requires bloodless surgical field for better operating conditions, deep level of anaesthesia and rapid emergence. Recent studies suggest that α2 agonists could provide desired surgical field, sedation and analgesia. The present study was aimed to evaluate the clinical effects of dexmedetomidine infusion as anaesthetic adjuvant during middle ear surgery using operating microscope. METHODS: Sixty four adult patients aged 18-58 years, American Society of Anaesthesiologists Grades I and II, of both gender were randomised into two comparable equal groups of 32 patients each for middle ear surgery under general anaesthesia with standard anaesthetic technique. After induction of general anaesthesia, patients of Group I were given dexmedetomidine infusion of 0.5 μg/kg/h and patients of Group II were given placebo infusion of normal saline. Isoflurane concentration was titrated to achieve a systolic blood pressure 30% below the baseline value. All patients were assessed intra-operatively for bleeding at surgical field, haemodynamic changes, awakening time and post-operative recovery. RESULTS: Statistically significant reduction was observed in the required percentage of isoflurane (0.8 ± 0.6%) to maintain the systolic blood pressure 30% below the baseline values in patients receiving dexmedetomidine infusion when compared to those receiving placebo infusion (1.6 ± 0.7%). Patients receiving dexmedetomidine infusion had statistically significant lesser bleeding at surgical field (P < 0.05). The mean awakening time and recovery from anaesthesia did not show any significant difference between the groups. CONCLUSION: Dexmedetomidine infusion can be safely used to provide oligaemic surgical field for better visualization using operating microscope for middle ear surgery.