Effect of Addition of Magnesium Sulphate and Fentanyl to Ropivacaine Continuous Femoral Nerve Block in Patients Undergoing Elective Total Knee Replacement

摘要

This prospective double blinded study was designed to compare the effect of magnesium or fentanyl addition to ropivacaine in continuous femoral nerve block in patients undergoing elective total knee replacement under general anesthesia. Sixty patients undergoing elective TKR under general anesthesia, were randomly allocated into three equal groups, Group (R): given 30 mL Ropivacaine 0.2%. Group (R+F): given 30 mL Ropivacaine 0.2% and 4 μg mL^-1 fentanyl. Group (R+M): given 30 mL Ropivacaine 0.2% and 50 mg mL^-1 of magnesium sulphate, through femoral catheter. The following parameters were evaluated: (1) demographic data of the patients and duration of the surgery, (2) intraoperative and postoperative hemodynamics, (3) intraoperative fentanyl requirements, (4) the severity of postoperative pain for 24 h, (5) time to first request of analgesia and (6) amount of postoperative morphine consumed in 0-6, 6-12, 12-18, 18-24 and 0-24 h, postoperatively. There were no difference among the three groups as regards the demographic data, the duration of the surgery, the pre and postoperative hemodynamics, the total intraoperative fentanyl consumption and the VAS during the 1st postoperative hour. The postoperative pain showed significant lower values in groups (R+F) and (R+M) compared to group (R) when measured at 6, 12, 18 and 24 postoperative hours . The time for the first postoperative request for analgesia was statistically longer in the (R+M) group and (R+F) group compared with group (R). The postoperative morphine consumption was statistically lower in groups (R+F) and (R+M) compared to group (R) but insignificant between groups (R+F) and (R+M). The admixture of magnesium sulphate or fentanyl to ropivacaine for continuous femoral nerve block provided a significant prolongation of postoperative analgesia than ropivacaine alone.