الفهرس 
ANATOMYOnly 14 pages are availabe for public view
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Abstract
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.
Dexmedetomidine is a highly selective α2 adrenergic receptor agonist. The sympatholytic effect of this α2 agonist made it attractive to be used as a hypotensive drug during the surgery. It results in a decrease in heart rate (HR) and cardiac output. This drug also has sedative, amnesic, anxiolytic, hypnotic and analgesic effects with minimal changes in respiratory variables. Furthermore, it reduces postoperative nausea, vomiting and shivering. Magnesium Sulfate is studied as a hypotensive agent for several years in different surgical procedures, it decreases anesthetic, analgesic, and muscle relaxant requirements as well as the incidence of nausea, vomiting and shivering. It affects the regulation of sympathetic tone and BP through blocking N-type and partially L-type calcium channels, and as a result inhibits norepinephrine release. As it also acts as an N-methyl- D-aspartate (NMDA) receptor antagonist therefore, it reduces analgesic and anesthetic requirements. Nitroglycerine is a directly acting vasodilator and it is frequently used to produce controlled hypotension because it is easily titratable and having very rapid onset. However the disadvantages of nitroglycerine are reflex tachycardia and venous congestion leading to increased blood loss.
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.
Patients were evaluated regarding their hemodynamics; preoperatively (baseline), pre and post induction, during the hypotensive period (at 10, 20, 30, 40,50 and 60 min of onset of hypotensive effect of the studying drug), before extubation and lastly 5 and 10 minutes after extubation.
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.