Efficacy of adding fixed dose dexmedetomidine to nitroglycerin for controlled hypotension in functional endoscopic sinus surgery

Abstract

Background Functional endoscopic sinus surgery (FESS) is a surgical procedure during which all possible measures to minimize bleeding should be considered, as even small amount of blood may obstruct vision. Controlled hypotension is one of these measures used to limit intraoperative blood loss to provide the best possible surgical field. The aim of this study was to compare the effect of a fixed dose of dexmedetomidine (DEX) and nitroglycerin (NTG) with NTG alone on hemodynamic parameters, NTG dose, surgeon satisfaction, and blood loss during controlled hypotensive anesthesia in FESS. Patients and methods Fifty patients of both sexes, classified as American Society of Anesthesia physical status I and II, aged between 20 and 50 years, and candidates for FESS were randomly allocated into two groups by using the sealed envelope method. Group I (n=25) received hypotensive anesthesia with NTG and group II (n=25) received hypotensive anesthesia with NTG and DEX. DEX 1 μg/kg over 10 min was given, and then infused by a syringe pump at a fixed rate of 0.5 μg/kg/h before induction of anesthesia in group II only. After induction and intubation NTG was infused in both groups and titrated to obtain a target mean arterial blood pressure (MAP) of 55–65 mmHg. The MAP and heart rate (HR) were measured at baseline, and then periodically. The following parameters were also recorded: duration of surgical interference (time from the beginning to the end of surgical intervention), blood loss volume, surgeon satisfaction, time to achievement of the target MAP, time to reversibility of MAP to baseline, and the highest dose of NTG needed to reach target MAP. Results There was no significant difference between two groups regarding demographic data, basal hemodynamics, duration of surgical intervention, American Society of Anesthesia physical status, surgeon satisfaction, and all measurements of MAP except time of intubation, which was significantly less in group II. On the other hand, there was a significant difference between both groups regarding HR, time to achievement and reversibility of MAP, blood loss volume, and the highest dose of NTG needed to reach the target MAP, as all of these measurements were significantly lower in group II. Conclusion DEX (1 μg/kg bolus, followed by 0.5 μg/kg/h infusion) and NTG is superior to NTG alone in rapid achievement of target MAP with lower HR and lower NTG doses and in reducing blood loss volume during FESS.