Effect of -methyl--aspartate (NMDA) receptor antagonist combination as adjuvant to general anesthesia in functional endoscopic sinus surgery

Background
This randomized, placebo-controlled, double-blind study was designed to assess controlled hypotension using -methyl--aspartate (NMDA) receptor antagonists in patients undergoing functional endoscopic sinus surgery under general anesthesia.
Methods
In this randomized, double blind, prospective study, 40 patients undergoing functional endoscopic sinus surgery under general anesthesia were divided into two groups of 20 patients each. Group 1: Patients received after the induction of anesthesia an intravenous (IV) ketamine (racemic) bolus 0.2 mg/kg followed by continuous infusion 0.15 mg/kg/h in addition to IV bolus of magnesium sulfate 50 mg/kg in 15 min, followed by a continuous infusion 8 mg/kg/h until extubation. Group 2: Patients received after the induction of anesthesia a bolus and a continuous infusion of normal saline (placebo) until extubation.
Results
Group 1 patients had significantly lower ( value < 0.001) infusion rates of nitroglycerin than the placebo group 2 patients at all measured intervals. Intraoperative bleeding measured by bleeding scale was significantly less in group 1 than in group 2. The MAP was significantly lower in group 1 after starting infusion, after extubation, and at postanesthesia care unit (PACU) admission. The HR was significantly higher in group 2 during hypotensive period, after extubation, and at PACU admission. Surgeon satisfaction by using the Likert scale showed that group 1 was significantly higher than scores in group 2. As regards the use of postoperative rescue analgesic drug if VAS ˃ 3, the number of patients who needed pethidine as a postoperative rescue analgesic was significantly less in group 1 compared with group 2. There is no statistically significant difference between the two groups as regards the Aldrete score.
Conclusion
Continuous infusion of NMDA receptor antagonists magnesium and ketamine had led to optimal surgical field and reduction in MAP, heart rate, blood loss, and nitroglycerin consumption.