Combined intrathecal and epidural magnesium sulfate supplementation of spinal anesthesia to reduce post-operative analgesic requirements: a prospective, randomized, double-blind, controlled trial in patients undergoing major orthopedic surgery.
BACKGROUND
New ways of decreasing post-operative analgesic drug requirements are of special interest after major surgery. Magnesium sulfate (MgSO(4)) alters pain processing and reduces the induction and maintenance of central sensitization by blocking the N-methyl-D-aspartate (NMDA) receptor in the spinal cord. We investigated whether supplementation of spinal anesthesia with combined intrathecally and epidurally infused MgSO(4) reduced patients' post-operative analgesia requirements.


METHODS
In a randomized, prospective, double-blind, placebo-controlled trial, we enrolled 120 consecutive patients undergoing orthopedic surgery during spinal anesthesia (levobupivacaine and sufentanil). Patients were randomly assigned to receive intrathecal MgSO(4) (94.5 mg, 6.3%), epidural MgSO(4) (2%, 100 mg/h), intrathecal and epidural MgSO(4) combined or spinal anesthesia alone (controls). Post-operative morphine consumption was assessed in all groups by patient-controlled analgesia (PCA).


RESULTS
Of the 120 patients enrolled, 103 (86%) completed the study. Morphine consumption at 36 h after surgery was 38% lower in patients receiving spinal anesthesia plus epidural MgSO(4) [- 14.963 mg; 95% confidence interval (CI), - 1.44 to - 28.49 mg], 49% lower in those receiving spinal anesthesia plus intrathecal MgSO(4) (- 18.963 mg; 95% CI, - 5.27 to - 32.65 mg) and 69% lower in the intrathecal-epidural combined group (- 26.963 mg; 95% CI, - 13.73 to - 40.19 mg) relative to control patients receiving spinal anesthesia alone. No complications developed during the post-operative course or at 1 month after surgery.


CONCLUSIONS
In patients undergoing orthopedic surgery, supplementation of spinal anesthesia with combined intrathecal and epidural MgSO(4) significantly reduces patients' post-operative analgesic requirements.
Arcioni
R
R
Department of Anesthesia and Intensive Care Medicine, La Sapienza University of Rome, II Faculty of Medicine, S. Andrea Hospital, Rome, Italy.
Palmisani
S
S
Tigano
S
S
Santorsola
C
C
Sauli
V
V
Romanò
S
S
Mercieri
M
M
Masciangelo
R
R
De Blasi
R A
RA
Pinto
G
G
D016058:Analgesia, Patient-Controlled / Q000379:methods; D000700:Analgesics / Q000008:administration & dosage / Q000627:therapeutic use*; D000701:Analgesics, Opioid / Q000008:administration & dosage; D000767:Anesthesia, Epidural / Q000379:methods*; D000775:Anesthesia, Spinal / Q000379:methods*; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D000779:Anesthetics, Local / Q000008:administration & dosage; D002045:Bupivacaine / Q000008:administration & dosage / Q000031:analogs & derivatives; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007278:Injections, Spinal / Q000379:methods; D000077554:Levobupivacaine; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage; D019637:Orthopedic Procedures / Q000379:methods*; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000517:prevention & control*; D011446:Prospective Studies; D013997:Time Factors
D000700:Analgesics; D000701:Analgesics, Opioid; D018686:Anesthetics, Intravenous; D000779:Anesthetics, Local; D008278:Magnesium Sulfate; D009020:Morphine; D000077554:Levobupivacaine; D002045:Bupivacaine