Comparative Study between Nitroglycerine, Magnesium Sulfate and Dexmedetomidine to Induce Hypotension During Functional Endoscopic Sinus Surgery (FESS)
Authors: Fahmy Adel Mekhael , Salam Ehab HamedAbdel , Aziz Mai MohsenAbdel , Taleb Egyphillines EmadeldinRizk 
Published: October 2021

Abstract

Background
Functional Endoscopic Sinus Surgery (FESS) has been employed as a surgical intervention to treat chronic rhinosinusitis in patients with no response to drug therapy, during which the surgical vision may be greatly reduced by a small amount of bleeding. There by, the intraoperative controlled hypotension can improve the visibility. While excessive bleeding intraoperative cause serious complications in the postoperative period, including eye socket infections, visual acuity damage, meningeal infections, and other.

Objective
Induced hypotension limits intra operative (IO) blood loss provides better visibility of the surgical field and diminishes the incidence of major complications during Functional Endoscopic Sinus Surgery (FESS). We aimed at comparing Nitroglycerine; Magnesium Sulfate and Dexmedetomidine for inducing controlled hypotension and evaluate narcotic used, mac of inhalational anesthesia, and Ramsay Sedation Scale (RSS) in the recovery and pre-anesthetic time in patients undergoing Functional Endoscopic Sinus Surgery (FESS).

Patients and Methods
This study was conducted on 75 patients who underwent elective functional endoscopic sinus surgery (FESS) who matched the inclusion criteria and were randomly allocated into 3 groups each containing 25 patients. The first group received loading dose of dexmedetomidine 1μg/kg infused over 10 min before induction of anesthesia then 0.7 μg/kg/h via syringe pump, second group received nitroglycerine infusion at a dose of 2μg/kg/min according to the response started after induction, intubation, positioning and sterilization of the patient and third group received a loading dose of magnesium sulfate 40 mg/kg over 10 minutes followed by an infusion 15mg/kg/h via syringe pump.

Results
The result of our study showed that dexmedetomidine, magnesium sulfate, or nitroglycerine successfully induced deliberate hypotension and were effective in providing good surgical field during FESS, but dexmedetomidine showed superior hemodynamic profile. Compared with nitroglycerine, both dexmedetomidine and magnesium sulfate offered the advantage of inherent analgesic and sedative effect.

Conclusion
Dexmedetomidine, magnesium sulfate, or nitroglycerine successfully induced deliberate hypotension and were effective in providing good surgical field during FESS, but dexmedetomidine showed superior hemodynamic profile. Compared with nitroglycerine, both dexmedetomidine and magnesium sulfate offered the advantage of inherent analgesic and sedative effect. Dexmedetomidine also showed shorter duration of surgery with less blood loss and favorable frommer score with more surgeon satisfaction. Dexmedetomidine showed longest time to 1st analgesic rescue in PACU comparing with magnesium sulfate and nitroglycerine. So, it’s advised to use dexmedetomidine to induce hypotension than magnesium sulfate and nitroglycerine. However, dexmedetomidine should be used with caution as it caused hypotension and bradycardia, t had sedative effect with low aldert score comparing with nitroglycerine and magnesium sulfate.