Controlled hypotension for functional endoscopic sinus surgery: a Comparative study between magnesium sulfate and nitroglycerin

Background Intraoperative bleeding during functional endoscopic sinus surgery (FESS) leads to poor visibility of the surgical field, and is of major concern. Controlled hypotension, using a variety of pharmacological agents, during general anesthesia reduces blood loss and helps clear visibility of the surgical field during FESS. The aim of this study was to compare the surgical conditions for FESS during controlled hypotension provided by nitroglycerin (NTG) versus magnesium sulfate (MGS) under general anesthesia. Patients and methods Fifty adult patients of both sexes requiring FESS under general anesthesia were randomly divided to receive either NTG infusion of 3–5 µg/kg/min (group NTG, n=25) or MGS (group MGS, n=25) 30 mg/kg, administered as a slow intravenous bolus and 10 mg/kg/h by continuous infusion during the operation, to provide controlled hypotension. In both the groups, the mean arterial blood pressure was reduced until the targeted mean arterial blood pressure (55–65 mmHg) was achieved. Results Both drugs produced the desired hypotension, in the magnesium group there were better operative conditions, reduction in the duration of surgery (85.3±13.1 vs. 92.9±10.3 min) and reduced anesthetic requirements [average end-tidal sevoflurane concentration (vol %) and fentanyl consumption (μg); P<0.0001]. However, there was longer extubation time (10.0±2.9 vs. 5.5±2.3 min) and recovery time (16.7±4.4 vs. 9.8±2.3 min) in comparison with the NTG group. Heart rate values were significantly higher in the NTG group compared with the magnesium group (P<0.0004). Conclusion Both NTG and MGS can be used safely to provide controlled hypotension during FESS. However, MGS was better as it provided optimum surgical condition and less tachycardia. In addition, it led to decreased anesthetic requirements.