Effects of Magnesium Sulfate on Pain, Nausea/Vomiting, and Anesthetic Consumption after Corneal Transplantation and Vitrectomy

Pain and postoperative nausea/vomiting (PONV) are of the most frequent complications after major ophthalmologic surgeries, and there is no general agreement on the effective method of controlling them. We compared the effects of magnesium sulfate on pain, nausea/vomiting, and anesthetic and analgesic requirement after corneal transplantation and vitrectomy surgeries.
110 patients undergoing corneal transplantation and vitrectomy under the same manner of general anesthesia were distributed into two equal groups. In the first group, magnesium sulfate (50 mg/kg) was administered during 10 minutes just before induction of anesthesia, and then during the surgery (15 mg/kg/hour). In the placebo group, normal saline was prescribed in the same way. Information concerning the pain (visual analog scale or VAS) and nausea/vomiting, total anesthetic and additional opioid consumption, and patient's hemodynamic status was collected and compared.
Findings: The mean intensity of pain and nausea were significantly lower in magnesium sulfate group compared to placebo group in the all periods during the study (pain: 1.8 and 2.8, respectively, P = 0.020; nausea: 0.35 and 1.1, respectively, P = 0.020). But, there were no significant difference in the incidence of vomiting (P = 0.500) and total doses of ondansetrone and pethidine consumption among the two groups (P > 0.050).
Magnesium sulfate administration is more effective than placebo to reduce anesthetic consumption, pain, and nausea/vomiting after corneal transplantation and vitrectomy.