I.V. infusion of magnesium sulphate during spinal anaesthesia improves postoperative analgesia

• Published in: British journal of anaesthesia : BJA Vol. 104; no. 1; pp. 89 - 93
• Main Authors: Hwang, J.-Y., Na, H.-S., Jeon, Y.-T., Ro, Y.-J., Kim, C.-S., Do, S.-H.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2010; Oxford University Press
• Subjects: Adult; Aged; anaesthetic techniques; anaesthetic techniques, subarachnoid; analgesia; analgesia, patient controlled; Analgesia, Patient-Controlled - methods; analgesia, postoperative; Analgesics, Non-Narcotic - administration & dosage; Analgesics, Non-Narcotic - blood; Analgesics, Opioid - administration & dosage; Anesthesia; Anesthesia, Spinal - methods; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anti-Inflammatory Agents, Non-Steroidal - administration & dosage; Arthroplasty, Replacement, Hip; Biological and medical sciences; Blood Pressure - drug effects; Drug Administration Schedule; Female; Heart Rate - drug effects; Humans; Infusions, Intravenous; ions; ions, magnesium; Ketorolac - administration & dosage; magnesium; Magnesium Sulfate - administration & dosage; Magnesium Sulfate - blood; Male; Medical sciences; Middle Aged; Morphine - administration & dosage; pain; Pain Measurement - methods; pain, postoperative; Pain, Postoperative - blood; Pain, Postoperative - prevention & control; patient controlled; postoperative; subarachnoid; ions, magnesium; anaesthetic techniques, subarachnoid; analgesia, patient controlled; analgesia, postoperative; pain, postoperative; Human; Postoperative; Analgesia; patient controlled; Pain; Subarachnoid; Anesthesia; Ions; Magnesium; anaesthetic techniques; Inorganic element
• ISSN: 0007-0912; 1471-6771
• DOI: 10.1093/bja/aep334

In a randomized, double-blind, prospective study, we have evaluated the effect of i.v. infusion of magnesium sulphate during spinal anaesthesia on postoperative analgesia and postoperative analgesic requirements. Forty patients undergoing total hip replacement arthroplasty under spinal anaesthesia were included. After the induction of spinal anaesthesia, the magnesium group (Group M) received magnesium sulphate 50 mg kg−1 for 15 min and then 15 mg kg−1 h−1 by continuous i.v. infusion until the end of surgery. The saline group (Group S) received the same volume of isotonic saline over the same period. After surgery, a patient-controlled analgesia (PCA) device containing morphine and ketorolac was provided for the patients. Postoperative pain scores, PCA consumption, and the incidences of shivering, postoperative nausea, and vomiting were evaluated immediately after surgery, and at 30 min, 4, 24, and 48 h after surgery. Serum magnesium concentrations were checked before the induction of anaesthesia, immediately after surgery, and at 1 and 24 h after surgery. Postoperative pain scores were significantly lower in Group M at 4, 24, and 48 h after surgery (P<0.05). Cumulative postoperative PCA consumptions were also significantly lower in Group M at 4, 24, and 48 h after surgery (P<0.05). Postoperative magnesium concentrations were higher in Group M (P<0.05 at 4, 24, and 48 h after surgery), but no side-effects associated with hypermagnesemia were observed. Haemodynamic variables and the incidences of shivering, nausea, and vomiting were similar in the two groups. I.V. magnesium sulphate administration during spinal anaesthesia improves postoperative analgesia.