Comparative evaluation of nitroglycerin, esmolol and dexemedetomidine on surgical field condition in patients undergoing functional endoscopic sinus surgery with controlled hypotension under general anaesthesia: An open label and randomized study

Chronic rhinosinusitis and nasal polyposis are commonly detected diseases that affect a large number of people. This is commonly treated surgically with functional endoscopic sinus surgery(FESS). Earlierit was also done under local anaesthesia which has gradually been replaced by general anaesthesia over years as general anaesthesia provides number of advantages over local anaesthesia such as immobile surgical field, adequate analgesia, effective protection of respiratory tract, controlled ventilation and reduced inconvenience and anxiety to the patient. Major disadvantage of FESS under general anaesthesia is the risk of surgical bleeding. Surgical bleeding decreases the visibility of surgical field and can lead to dangerous complications, increased duration and reduced quality of intervention and is therefore known to be a most serious problem associated with FESS. Controlled hypotension can be used as a specific measure to reduce surgical bleeding. It is defined as pharmacologically induced reduction in mean arterial blood pressure (MAP) by 20-30 percent of baseline or maintaining it between 60-70 mmHg reversibly throughout the surgery.

This will be an open label, randomized, comparative study among the three drugs namely dexemedetomidine, nitroglycerin, esmolol. We will enroll a total of 120 patients undergoing FESS under general anaesthesia with 40 patients in each group. Participants will be randomly assigned to one of the 3 groups.

Group D (dexemedetomidine)- Loading dose of dexemedetomidine 1mcg/kg will be given over 10 minutes followed by a maintainence infusion of 0.3-0.7 mcg/kg/hour

Group N (nitroglycerin)- No loading dose, continuous infusion of nitroglycerin will be given at dose 0.5-2 mcg/kg/min

Group E (esmolol)- Loading dose of esmolol 1mg/kg to be infused over 1 minute, followed by continuous infusion of 0.5-1 mg/kg/min

All the infusions will be titrated to keep MAP between 60-70 mmHg.

In this study we aim to compare the patients achieving satisfactory surgical field with use of any of these 3 drugs. In addition we will compare the amount of intraoperative blood loss, hemodynamic parameters and incidence of hypotension, bradycardia and post operative sedation and post operative nausea and vomiting in patients undergoing FESS under general anaesthesia.

In this study we hypothesize that owing to different mechanism of action of the 3 hypotensive agents i.e. dexemedetomidine, nitroglycerin and esmolol, after achieving a target MAP of 60-70 mmHg a difference in surgical field condition will be seen. Null hypothesis in this studt would state that there is no significant difference among the 3 hypotensive agents mentioned above, with regards to surgical field condition