A Comparative Study between Nitroglycerin and Magnesium Sulfate during Shoulder Arthroscopic Surgery in the Beach Chair Position

Abstract
Background: This study was designed to compare the efficacy of intravenous infusion of nitroglycerin versus mag-nesium sulfate for controlled hypotensive anesthesia during arthroscopic shoulder surgery in Beach Chair Position (BCP).
Aim of Study: To compare the efficacy of nitroglycerin versus magnesium sulfate in inducing deliberate hypotension and satisfactory surgical field in patients undergoing arthro-scopic shoulder surgery.
Material and Methods: Fourty patients scheduled for arthroscopic shoulder surgery under general anesthesia in BCP, randomly assigned into two equal groups, nitroglycerin group (NTG group, n=20) received infusion of 0.5-5μg/kg/min and magnesium group (Mg group, n=20) received 40mg/kg, as slow bolus before induction in 100mL saline solution over 10min then 15mg/kg/h by infusion during the operation to achieve a mean arterial blood pressure (MAP) of about 50 to 65mmHg.
Results: Controlled hypotension was achieved in both groups. There was no significant difference in MAP between two groups in first 30mins after infusion then magniseum group produced significantly lower MAP values till stopping of infusion. Heart Rate (HR) was significantly lower in mg group compared with the NTG group. More patients required fentanyl consumption intraoperative (p<0.0001) and frequent administration of rocuronium (p=0.001) in NTG group. How-ever, there was longer extubation time and recovery time in Mg group compared with the NTG group. Bleeding score was insignificantly lower in Mg group and surgeon's satisfaction score was significantly better (p=0.035) in the Mg group.
Conclusions: Nitroglycerin and magnesium sulfate can effective in achieving hypotensive anesthesia during arthro-scopic shoulder surgery. However, MgSO4 provide a favorable surgical field condition and better surgeon's satisfaction.