Comparison of Labetalol and Dexmedetomidine Infusions for Hypotensive Anaesthesia in Middle Ear Surgery: A Randomised Controlled Trial

Abstract

Introduction: Hypotensive anaesthesia has become an inevitable choice for patients undergoing microscopic middle ear surgeries under general anaesthesia, especially to decrease the intraoperative bleeding leading to improved visibility and reduced complications. Out of several agents, Dexmedetomidine and Labetalol have both been established as effective agents to cause controlled hypotension. Aim: To compare the efficacy and safety of Dexmedetomidine and Labetalol for producing controlled hypotension in microscopic middle ear surgeries under general anaesthesia. Materials and Methods: This parallel group randomised controlled trial was conducted at the Department of Anaesthesiology, Tertiary Medical College, Institute of Post Graduate Medical Education and Research, in Kolkata, West Bengal, India over a period of 15 months from April 2018 to June 2019. A total of 78 patients, aged 18 – 60 years, posted for microscopic middle ear surgeries under general anaesthesia, were randomly divided into two groups. Group D received Dexmedetomidine infusion with a loading dose of 1 µg/kg followed by a maintenance infusion of 0.4 µg/kg/h, whereas Group L received Labetalol 20 mg bolus followed by infusion at a rate of 0.5 mg/min. Intraoperative blood loss assessed by the Bleeding Score (BS) and Final Opinion on Bleeding Score (FOBS), haemodynamic parameters and awakening time were measured at designated time frames. Data were summarised and analysed by Student’s Independent-samples t-test for numerical variables between groups, by Mann – Whitney U test when skewed and by Chi-square test or Fisher’s exact test for categorical variables between groups. Results: The groups were comparable demographically (p-values for age, body weight and duration of surgery were 0.679, 0.104, 0.893 respectively). BS and FOBS (2/2-3 for group D and 4/3-4 for group L) were both significantly lower in group D. Haemodynamically, both groups were equally stable, with better attenuation of intubation and extubation surge in group D. Awakening time was also less in group D in comparison to group L. Conclusion: Dexmedetomidine is a better alternative than Labetalol in producing controlled hypotension in patients undergoing microscopic middle ear surgeries under general anaesthesia. The Dexmedetomidine group showed less bleeding and improved haemodynamics than the Labetalol group. Awakening was also found to be faster in the dexmedetomidine group.