Effects of intra-operative magnesium sulfate infusion on orthognathic surgery: A prospective and randomized controlled trial

PurposeTo comprehensively understand the effects of intra-operative infusion of magnesium sulfate on patients who underwent orthognathic surgery, including remifentanil consumption, postoperative pain, postoperative nausea and vomiting (PONV), inflammatory response, and serum magnesium levels.MethodsSeventy-five adult patients undergoing orthognathic surgery under general balanced anesthesia were randomly divided into two groups. One group (Group M) received 50 mg/kg of magnesium sulfate in 20mL 0.9% saline after intubation, followed by a continuous infusion at a rate of 15mg/kg/h until 30 min before the anticipated end of surgery. The other group (Group C) received an equal volume of isotonic saline as a placebo. (Clinical trial registration number: chiCTR2100045981)ResultsThe primary outcome was remifentanil consumption. The secondary outcomes included the pain score assessed using the verbal numerical rating scale (VNRS) and PONV assessed using a Likert scale. Remifentanil comsumption in Group M was lower than Group C (mean ± SD: 0.146±0.04 μg/kg/min vs. 0.173±0.04 μg/kg/min, P=0.003). At 2h after surgery, patients in Group C suffered more severe PONV than those in Group M (median [interquartile range, IQR]: 1[[3]Sousa A.M. Rosado G.M. Neto Jde S. Guimaraes G.M. Ashmawi H.A. Magnesium sulfate improves postoperative analgesia in laparoscopic gynecologic surgeries: a double-blind randomized controlled trial.J Clin Anesth. 2016; 34: 379-384https://doi.org/10.1016/j.jclinane.2016.05.006Crossref PubMed Scopus (27) Google Scholar] vs. 1[0], mean rank: 31.45 vs. 42.71, P=0.040). At post-anesthesia care unit (PACU), postoperative pain in Group C was severe than Group M (3[[1]Fawcett W.J. Haxby E.J. Male D.A. Magnesium: physiology and pharmacology.Br J Anaesth. 1999; 83: 302-320https://doi.org/10.1093/bja/83.2.302Abstract Full Text PDF PubMed Scopus (534) Google Scholar] vs. 3[0], mean rank: 31.45 vs. 42.71, P=0.013). Changes in haemodynamics and surgical field scores did not differ between the groups (all P>0.05). The levels of cytokines (IL-4, IL-6, IL-8, IL-10, TNF-a, and MIP-1β) were not significantly different between the groups after surgery (all P>0.05). Postoperative serum magnesium levels in Group C were lower than those in Group M (0.74±0.07 mmol/L vs. 0.91±0.08 mmol/L, P=0.000) and the preoperative level (0.74±0.07 mmol/L vs. 0.83±0.06 mmol/L, P=0.219).ConclusionsIn orthognathic surgery, magnesium sulphate administration can reduce remifentanil requirement and relieve PONV and postoperative pain in the early postoperative phase.