Peri-operative Outcomes of Dexmedetomidine as an Additive to Subtenon Block Compared with Intravenous Dexmedetomidine for Patients Undergoing Vitreoretinal Surgery under General Anesthesia

Abstract

Background: Several medications such as dexmedetomidine can be used as adjuvants with anesthesia to reduce the stress response during surgery resulting in good post-operative outcomes and safe recovery times. Aims: To compare the peri-operative outcomes of subtenon block with or without dexmedetomidine versus dexmedetomidine infusion as adjuvants to general anesthesia in subjects undertaking retinal operations. Design: A prospective randomized double-blind controlled clinical trial Patients and methods: Through the use of sealed opaque envelopes, 120 participants were randomly divided into three groups. Group SB received subtenon bupivacaine and lidocaine and IV infusion of normal saline. Group SD received subtenon bupivacaine, lidocaine, and dexmedetomidine and IV infusion of normal saline, whereas Group DI received subtenon saline and IV infusion of dexmedetomidine. Peri-operative hemodynamics and intra-ocular pressure were measured and recorded. Intra-operative bleeding, recovery times, post-operative sedation and pain scores, first analgesic times, total analgesic requirements, and the incidence of PONV and OCR were also assessed and documented. Statistical analysis: A prospective analysis of the collected data was performed using the SPSS program for Windows (version 22). Results: The results showed that IV dexmedetomidine has decreased cardiovascular responses to surgery as signified by decreased HR and MAP with a significant drop in IOP measurements before induction and after intubation, in comparison to other groups. Administering dexmedetomidine either or IV in the subtenon block led to a significant reduction in pain scores of the first post-operative six hours, the total pethidine consumption, and the surgical bleeding. Conclusion: When used as a supplement to general anesthesia during retinal surgery, dexmedetomidine is effective at reducing the airway response to tracheal intubation and extubation and maintaining peri-operative hemodynamic stability. Dexmedetomidine is also an efficient method for lowering intraocular pressure, surgical bleeding, and postoperative analgesic consumption with a better recovery profile. It can be administered either through IV infusion or combined with local anesthetics in subtenon block.