Is it feasible to use magnesium sulphate as a hypotensive agent in oral and maxillofacial surgery?
We report the results of a feasibility study using intravenous magnesium sulphate for deliberate hypotension in 16 ASA 1 patients undergoing major oral and maxillofacial surgery. All the patients received a standard nitrous oxide, oxygen, isoflurane, opioid and muscle relaxant anaesthetic. Magnesium sulphate was infused at 40 g/h until the mean arterial pressure reached 55 +/- 5 mmHg, followed by a maintenance dose of 5 g/h until 30 minutes prior to the end of surgery. The mean arterial pressure was significantly (P < 0.01) reduced by the magnesium sulphate when compared to baseline values. Control of the mean arterial pressure was satisfactory. No patient had reflex tachycardia, cardiac arrhythmia or rebound hypertension. In 14 patients the surgeons thought that the blood loss was less than when using other hypotensive anaesthetic techniques. In 2 patients the surgeons thought the blood loss was excessive. In another 2 patients, the surgeons thought that there was excessive facial swe
