Effect of continuous magnesium sulfate infusion on spinal block characteristics: A prospective study

Abstract

Background:Spinal anesthesia is an established mode of anesthesia for lower limb orthopedic surgeries. The limitations of the technique are short duration of action and limited post-operative analgesia. Concomitant use of intravenous infusion of magnesium sulfate may have an effect on the block characteristics and duration of action of intrathecal bupivacaine.Methods:A total of 80 American Society of Anesthesiologists I and II patients, either sex, 20-60 years of age scheduled for elective orthopedic fixation of fracture of long bones of lower limbs under spinal anesthesia were included. Spinal anesthesia administered with 2.5 ml heavy bupivacaine mixed with 10 mcg fentanyl. The groups were then divided to receive an infusion of injection magnesium sulfate 50 mg/kg/h over 15 min followed by 15 mg/kg/h until the end of the surgery (Group M) and 15 ml of Normal Saline over 15 min followed by 100 ml/h until the end of surgery (Group S). Onset, duration of sensory and motor block and amount of post-operative analgesic were noted.Results:A total of 6 patients (Group M) and seven patients (Group S) had inadequate block and excluded from the study. Mean block height was T6. Time required to achieve block height was 8.82 min versus 7.42 min in Groups M and S respectively (P = 0.04). Mean duration of motor block was longer in group M (160.63 ± 17.76 min) compared with Group S (130.12 ± 20.70 min) (P = 0.000). Time for regression of sensory block to T12/L1was 206.88 ± 20.96 min (Group M) and 163.88 ± 15.46 min (Group S) (P = 0.000). Hemodynamic parameters were similar and statistically not significant. Need for first analgesic requirement was after 262.88 ± 21.11 min in group M and 193.25 ± 17.74 min in the group S (P = 0.000). Mean dosage of tramadol needed in first 24 h was less in group M (190 ± 30.38 mg vs. 265 ± 48.30 mg, P = 0.000).Conclusion:Use of intravenous magnesium with spinal anesthesia reduces post-operative pain and analgesic consumption.

Effect of intravenous infusion of magnesium sulphate on postoperative analgesia in patients undergoing arthroscopic knee surgeries under spinal anaesthesia

“…Similar results were found in the studies of Hwang et al, Agarwal et al, and Kahraman F, Eroglu A. 4,6,7 Need for first analgesic requirement per time to first pain (min) is presented in Table 3. The time to first analgesic request was significantly longer in the magnesium sulphate infusion group in the study by Agarwal et al where need for first analgesic requirement was at 262.88±21.11 min in Mg group and 193.25±17.74 min in Non Mg (P=0.04).…”

“…6 Mean duration of motor block was longer in Mg group (160.63 ±17.76 min) compared with Non Mg Group (130.12 ± 20.70 min) (P = 0.000). Kahraman F and Eroglu A also found that in Group Mg, sensorial block regression was longer than that in Group Non Mg (175±39 versus 136±32 min) (P <0.01).…”

“…The time to first analgesic request was significantly longer in the magnesium sulphate infusion group in the study by Agarwal et al where need for first analgesic requirement was at 262.88±21.11 min in Mg group and 193.25±17.74 min in Non Mg (P=0.04). 6 Kumar et al also demonstrated that the duration of analgesia and the requirement of first rescue analgesia was longer in Mg group (333.91±202.41) min versus (232.68±140.62) min in the control group with P value of <0.05. 9 Postoperative pain scores assessed by visual analogue scale and the results are depicted in Table 4.…”

“…4 Agarwal and associates found that in Mg group, mean dosage of Tramadol needed in first 24 hrs was less compared with Non Mg group (190±30.38 mg versus 265±48.30 mg, P=0.000). 6 The results of rescue analgesia required in patients are tabulated in Table 6. The results showed that one patient in Mg group and 4 patients in Non Mg group required rescue analgesia, morphine 4.5 mg intramuscularly.…”

Efficacy of Magnesium Sulfate as Adjuvant to Ropivacaine 0.4% for Supraclavicular Brachial Plexus Block in Patients undergoing Upper Limb Surgery: A Randomized Controlled Trial

“…4 Magnesium exerts antinociceptive effects by regulation of calcium influx into the cell and antagonism of the N-methyl-D-aspartate receptors. 5 Many clinical investigations have demonstrated that magnesium administration during general anesthesia has reduced anesthetic requirement and postoperative analgesic consumption. 6,7 Magnesium has long been used for its antihypertensive, anesthetic sparing effects and its property to enhance the effects of analgesics.…”