J Korean Pain Soc.  2000 Jun;13(1):31-37.

Effects of Preincisional Administration of Magnesium Sulfate on Postoperative Pain and Recovery of Pulmonary Function in Patients Undergoing Gastrectomy

• Ko SH
• Jang YI
• Lee JR
• Han YJ
• Choe H

Abstract

BACKGROUND: Recent studies suggested that a preoperative block of N-methyl-D-aspartate (NMDA) receptors with NMDA antagonists may reduce postoperative pain. In this double-blind study, magnesium sulfate, a natural NMDA receptor antagonist, was administered preoperatively to investigate the effects of magnesium sulfate on postoperative pain and pulmonary function.
METHODS
Seventy patients who were to undergo gastrectomy under general anesthesia were randomly assigned to one of three groups. Groups 2 and 3 received intravenous magnesium, preoperatively (Group 2: 50 mg/kg bolus, 7.5 mg/kg/hr for 20 hr, Group 3: 50 mg/kg bolus, 15 mg/kg/hr for 20 hr). Group 1 received normal saline as the control group. Visual analog scale (VAS) for postoperative pain and mood, cumulative analgesic consumption, recovery of pulmonary function and side effects were evaluated at 6, 24, 48 and 72 hours after the operation.
RESULTS
In Groups 2 and 3, plasma concentration of magnesium were significantly higher than in Group I at 6 and 20 hours after infusion (P < 0.05). There were no significant differences in the analgesic consumption, and recovery of pulmonary function and the incidence of side effects at 6, 24, 48 and 72 hours after the operation among the three groups. In Group 3, pain scores at rest measured 24 and 48 hours after operation were lower than the control group, and pain scores when deep breathing were significantly lower than the control group at postoperative 6, 24, 48, and 72 hours.
CONCLUSIONS
We conclude that intravenous infusion of greater amount of magnesium has little effectiveness in reducing postoperative pain. However, further studies are needed to characterize the clinical significance of these effects on postoperative pain.

Keyword

Analgesia, postoperative; Ions, magnesium; Lung, pulmonary function; Receptors, NMDA

MeSH Terms

Anesthesia, General
Double-Blind Method
Gastrectomy*
Humans
Incidence
Infusions, Intravenous
Magnesium Sulfate*
Magnesium*
N-Methylaspartate
Pain, Postoperative*
Plasma
Receptors, N-Methyl-D-Aspartate
Respiration
Visual Analog Scale
Magnesium
Magnesium Sulfate
N-Methylaspartate
Receptors, N-Methyl-D-Aspartate