|Year : 2017 | Volume
| Issue : 4 | Page : 239-246
Magnesium sulfate versus tramadol as adjuvants to local anesthetics in sciatic nerve block for lower extremities surgeries
Ibrahim A Youssef1, Ahmaed Q Mouhamed1, Haidy S Mansour MD 2, Nehal F Ramadan3
1 Department of Anesthesiology and Intensive Care, Faculty of Medicine, Minia University, Minya, Egypt
2 Department of Anesthesiology and Intensive Care, Faculty of Medicine, Minia University, Minya; Department of Anesthesia, Minia University Hospital, Minya, Egypt
3 Department of Anesthesiology and Intensive Care, Minia Insurance Hospital, Minya, Egypt
|Date of Submission||05-Nov-2016|
|Date of Acceptance||06-Apr-2017|
|Date of Web Publication||11-Oct-2017|
Haidy S Mansour
Department of Anesthesiology and Intensive Care, Faculty of Medicine, Minia University Hospital, Minia University, Minia
Source of Support: None, Conflict of Interest: None
The aim of this study was to compare the effect of addition of tramadol and magnesium sulfate as adjuvants to local anesthetics lidocaine 2% and bupivacaine 0.5% in sciatic nerve block classic posterior approach.
Patients and methods
A total of 90 ASA I or II patients, aged 17–50 years, scheduled for lower extremities surgeries under sciatic nerve block classic posterior approach were randomized into three equal groups. All groups received 20 ml of local anesthetics, which consisted of 10 ml bupivacaine 0.5% and 8 ml lidocaine 2% mixed with 2 ml saline in the control (C) group, 2 ml of 150 mg magnesium sulfate made in saline in the magnesium (M) group, and 2 ml of 100 mg tramadol in the tramadol (T) group. The onset and duration of both sensory and motor blocks, the intraoperative pain assessment by visual analogue scale, intraoperative analgesic requirements, postoperative pain by visual analogue scale, time to first analgesic request after surgery, postoperative diclofinac consumption, and adverse effects were assessed.
The onsets of sensory and motor blocks were rapid in the M group, then C group, and lastly, T group. Much more time was needed for group T until sensory and motor blocks faded away followed by group M and then group C. There was a significant delay in the time of first analgesic request in groups M and T when compared with group C. There was a significant decrease in the total dose of diclofinac consumption in groups T and M in comparison with group C, where the patients consumed more analgesia.
Magnesium sulfate and tramadol as adjuncts to local anesthetics increase the duration of sensory and motor sciatic nerve block. The time for first rescue analgesia was longer in groups M and T, and they both showed decreased postoperative analgesic consumption.
Keywords: magnesium, sciatic nerve block classic posterior approach, tramadol
|How to cite this article:|
Youssef IA, Mouhamed AQ, Mansour HS, Ramadan NF. Magnesium sulfate versus tramadol as adjuvants to local anesthetics in sciatic nerve block for lower extremities surgeries. Res Opin Anesth Intensive Care 2017;4:239-46
|How to cite this URL:|
Youssef IA, Mouhamed AQ, Mansour HS, Ramadan NF. Magnesium sulfate versus tramadol as adjuvants to local anesthetics in sciatic nerve block for lower extremities surgeries. Res Opin Anesth Intensive Care [serial online] 2017 [cited 2021 Jun 15];4:239-46. Available from: http://www.roaic.eg.net/text.asp?2017/4/4/239/216455
| Introduction|| |
Peripheral nerve blocks are ideally suited for lower extremity ambulatory surgeries because of the peripheral location of the surgical site and the potential to block pain pathways at multiple levels. In contrast to other anesthetic techniques, such as general or spinal anesthesia, properly conducted peripheral nerve blocks avoid hemodynamic instability and pulmonary complications and facilitate postoperative pain management and timely discharge . The sciatic nerve block is used alone or in association with other nerve blocks. It is particularly well-suited for surgeries on the knee, calf, Achilles tendon, ankle, and foot. It provides complete anesthesia of the leg below the knee with the exception of the medial strip of skin, which is innervated by the saphenous nerve . Several approaches to sciatic nerve block have been described. The most frequently performed are probably the Labat’s classical posterior approach and its modification .
The use of a nerve stimulator has the advantage of identifying peripheral nerves by producing a muscle twitch rather than eliciting uncomfortable paresthesia. It also offers the anesthesiologist a method of confirming nerve localization in uncooperative patients .
Adjuncts to local anesthetics for peripheral plexus blockade have been proposed to enhance the quality and duration of anesthesia and postoperative analgesia. Clonidine, epinephrine, and opioids are such examples . Tramadol is a synthetic 4-phenyl-piperidine analogue of codeine, and it displays central analgesic effects because of its monoaminergic and µ-receptor agonistic activity; it also has peripheral local anesthetic properties  and modifies the action of lidocaine for intravenous regional anesthesia . Magnesium sulfate used as an adjuvant to local anesthetics as the l-glutamate is perhaps the most important excitatory neurotransmitter in the central nervous system. Blocking the N-methyl-d-aspartic acid (NMDA) subtype of glutamate receptor offers an attractive method of reducing afferent stimulation of the spinal cord and therefore blocking pain transmission .
This study aimed at determining the effect of adding magnesium sulfate and tramadol as adjuvants to local anesthetics in sciatic nerve block classic posterior approach for lower extremity orthopedic surgeries.
| Patients and methods|| |
After obtaining approval from our Institutional Ethics Committee, a prospective double-blind, randomized controlled study was conducted in El-Minia University Hospital. A total of 90 patients of both sexes, with their age ranging from 17 to 60 years, having ASA physical status I or II, and undergoing foot surgery (e.g. amputation or hammer toe corrections) or ankle surgery (e.g. bone fusions or internal fixation), were included. This study was done from December 2010 to December 2011. All patients gave written informed consent.
The exclusion criteria were patient refusal, pregnancy, patients with neurologic or neuromuscular disease, diabetic patients, patients with coagulation disorders, patients taking anticoagulant drugs, and patients with skin infection at the site of needle insertion. We use visual analogue scale (VAS) as a tool for measuring perioperative pain, and we instructed the patients about it preoperatively.
Patients were randomized into three equal groups according to a computer-generated random number table. Group C (n=30) received 20 ml of local anesthetics made up of 10 ml bupivacaine 0.5%, 8 ml lidocaine 2%, and 2 ml saline. Group M (n=30) received 20 ml of local anesthetics made up of 10 ml bupivacaine 0.5%, 8 ml lidocaine 2%, and 2 ml of 150 mg magnesium sulfate made in saline. Group T (n=30) received 20 ml of local anesthetics made up of 10 ml bupivacaine 0.5%, 8 ml lidocaine 2%, and 2 ml of 100 mg tramadol. The drug solutions were prepared by an anesthesiologist not involved in the study.
After the patients’ arrival, an intravenous access was established, and continuous ECG, noninvasive systolic, diastolic and mean arterial blood pressure, heart rate, and pulse oximetry were monitored before and during the block performance and throughout the surgical procedure.
Patients were positioned in Sims’ position. A line was drawn from the posterior superior iliac spine to the midpoint of the greater trochanter. A perpendicular line was drawn bisecting this line, which extended 5 cm caudally. A second line was drawn from the greater trochanter to the sacral hiatus. The intersection of this line with the perpendicular line indicated the point of needle entry.
After sterilization of the site of needle insertion, a stimulating needle (12 cm, 20 G short-beveled), attached to a nerve stimulator and attached to the surface electrode, was inserted at an angle of 90° to the skin and advanced until either dorsiflexion or plantar flexion of the foot was obtained. First, we set the stimulating current between 1.5 and 2 mA; moreover, the frequency of stimulation was set at 2 Hz. The intensity of the current was gradually decreased as the needle approached the targeted nerve. The needle position was adjusted to maintain an adequate muscular response with a stimulating current less than 0.5 mA. The goal is palpable or visible twitches of the hamstrings, calf muscles, foot, or toes at 0.2–0.5 mA current. The solution was injected in the studied groups after reaching the goal.
Patients in our study needed a saphenous nerve block for the skin at the medial aspect of the leg. Saphenous nerve block was done by injecting 5–10 ml of 2% lidocaine as a ring deeply subcutaneously starting at the medial surface of the tibial condyle and ending at the dorsomedial aspect of the upper calf. Arterial blood pressure, heart rate, and pulse oximetry oxygen saturation were evaluated preoperatively and intraoperatively every 5 min after local anesthetic injection for 120 min by an independent blinded observer.
Sensory block-onset assessments by pinprick test were performed in the distributions of the common peroneal and tibial nerves. The extent of the sensory block of each nerve was classified as follows: 0=normal sensation in the respective nerve distribution (no block), 1=blunted sensation (analgesia), and 2=absence of sensation (anesthesia) . Motor block onset was assessed by asking the patient to plantar flex or dorsiflex the foot. It was classified as follows: 0=normal movement, 1=decreased movement, and 2=no movement . When the sensory block or motor block score was less than 2 at the end of the 40-min assessment period, the sciatic block was considered incomplete and excluded from our study. Moreover, the durations of the sensory nerve block and motor block were assessed.
Assessment of VAS was done every 15 min during surgery, with ‘no pain’=0 cm and the top ‘the highest pain you could ever have’=10 cm . If a VAS of more than 3 was reported by the patient, 1 µg/kg of supplemental intravenous fentanyl was given. Intraoperative analgesic requirements, numbers of patient needing fentanyl, and the total dose of fentanyl required during surgery were assessed.
Postoperative pain assessment by VAS for the first 24 h, at 2, 4, 6, 8, 12, and 24 h postoperatively, was done. If a VAS of more than 3 was reported by the patient, intramuscular diclofenac sodium (75 mg) was given. The time of first analgesic request, number of patients in need, and total dose of diclofenac sodium were assessed.
The level of sedation recorded before nerve block and assessment was repeated every 10 min for the first 30 min and then every 20 min until the end of surgery using a five-point sedation scale : 1, wide awake; 2, drowsy; 3, dozing intermittently; 4, mostly sleeping; and 5, awakens only when aroused. Sedation was defined as a patient receiving scale 3, 4, or 5.
Adverse effects were assessed as hypotension, bradycardia, pruritus, nausea and vomiting, sedation, inadvertent intravascular injection, vascular or lymphatic injury, numbness around the mouth, dyesthesia, and neuropraxia.
Statistical analysis and sample size
Sample size was estimated using pain scores as the primary variable. Assuming a SD of 1 cm, we calculated a group size of 30 patients which would be sufficient to detect a difference of 1 cm on the VAS at an α threshold of 0.007 with 90% power. Statistical analysis was performed with IBM SPSS version 20 software. Ordinal data were expressed as mean±SD. Categorical data were expressed as number and percentage. Independent t-test was used for quantitative data between the two groups. Paired t-test was used for quantitative data between two measures within each group. One-way analysis of variance test was used for quantitative data between three groups. χ2-Test was used for percentage data. Wilcoxon signed rank test was used for quantitative nonparametric data between two measures within each group. Mann–Whitney U-test was used for quantitative nonparametric data between two groups. Kruskal–Wallis H-test was used for quantitative nonparametric data between three groups. For all tests, a P-value of less than 0.05 was considered statistically significant.
| Results|| |
Patients’ characteristics were comparable in the three groups ([Table 1]).
The onset of sensory and motor block was more rapid in the M group than in the C or T group (P<0.0001) and was more rapid in group C when compared with group T (P<0.0001). The duration of sensory and motor block was prolonged in group T, followed by group M and then group C (P<0.0001; [Table 2]).
The severity of intraoperative pain measured by VAS showed a significant difference between the three groups at 75, 90, and 120 min and a nonsignificant difference between the three groups at 15, 30, 45, and 60 min. There was a nonsignificant difference between groups C and M and a significant difference between groups C and T at 45, 60, 75, 90, and 120 min. Moreover, there was a significant difference between groups M and T at 75, 90, and 120 min ([Table 3]). Intraoperative intravenous fentanyl (1 µg/kg) was needed in 10 patients in group C, six patients in group M, and four patients in group T, which was nonsignificant between the three groups, with nonsignificant differences in request for analgesia and total dose of intraoperative fentanyl consumption between the three groups.
There was an increase in VAS of more than 3 at 4 h in group C, at 12 h in group M, and at 24 h in group T. There was a nonsignificant difference between the three groups at 2 h postoperatively and significant difference between the three groups at 4, 6, 8, 12, and 24 h. There was a significant increase in VAS in group C than group M and then group T, and significant difference between groups M and T, but there was a nonsignificant difference between groups T and M at 24 h ([Table 4]). The time for the first postoperative analgesic request was significantly longer in T group and followed by M group when compared with C group. The postoperative diclofinac consumption was significantly lower in T and M groups compared with C group ([Table 5]).
When comparing heart rate, mean arterial blood pressure, and oxygen saturation in the three groups, there was insignificant difference in preoperative and intraoperative data in the same group or in between the three groups ([Figure 1],[Figure 2],[Figure 3]).
Regarding adverse effects, hypotension occurred in one patient in both groups C and M and in two patients in group T. Nausea and vomiting occurred in one patient in group C and one patient in group T. Sedation occurred in one patient in C group and in two patients in groups M and T. There was no significant difference on comparing the three groups.
| Discussion|| |
The present study was designed to examine the effects of magnesium and tramadol on the nerve block produced by local anesthetic. Tramadol was described to stimulate serotonin release intrathecally, while inhibiting norepinephrine reuptake centrally. It also is a weak μ-opioid and κ-opioid receptor agonist, and also blocks voltage-gated sodium channels in vitro ,. Tramadol has local anesthetic properties possibly by blocking K+ channels . Recently, some investigators demonstrated its efficacy in antagonizing glutamate NMDA receptors, which are known to be involved in the pathophysiology of chronic pain .
Magnesium is an NMDA antagonist that plays a role in moderating calcium influx into the neurons. Magnesium has been shown to decrease peripheral nerve excitability and to enhance the ability of lidocaine to raise the excitation threshold of A-β fibers .
Our results confirmed that the onset of sensory and motor block was significantly more rapid in the magnesium (M) group (7.9±2.8 and 10.8±3.2 min) than in the control (C) (11.7±5.03 and 16.2±5.2 min) and tramadol (T) groups (18.2±3.4 and 23.4±3.1 min), and the sensory and motor block was significantly delayed in group T when compared with group C and group M (P=0.0001). Moreover, the duration of the sensory and motor block was significantly prolonged in group T (6.2±0.7 and 6.9±0.8 h) and group M (4.6±0.4 and 5.1±0.5 h) than in group C (3.1±0.6 and 3.6±0.7 h) and was significantly prolonged in group T when compared with group M (P=0.0001).
Our results came in accordance with Kaabachi et al. , who reported that the benefit of block prolongation during axillary block which associated with the addition of 100 and 200 mg tramadol to lidocaine is limited by the slow onset of the block.
In a randomized, double-blinded study, Kapral et al.  observed that the addition of tramadol to 1% mepivacaine for axillary brachial plexus block resulted in a significant prolongation in the duration of the blockade without any adverse effects. They argued that tramadol may be an alternative to clonidine or epinephrine as an adjuvant to local anesthesia for an axillary block.
Regarding the results by Ashraf et al. , they compared the effect of addition of 50 mg magnesium sulfate to ropivacaine 0.2% (R+M), and the placebo group received 0.2% ropivacaine only (R) in femoral nerve block. They concluded that the admixture of magnesium sulfate to ropivacaine for continuous femoral nerve block provided a significant prolongation in the duration of motor and sensory block than ropivacaine alone. Moreover, previous works demonstrated that the admixture of 150 mg magnesium to prilocaine for axillary brachial plexus block provided a pronounced prolongation of sensory and motor block without adverse effects .
Our investigations demonstrated that intraoperative analgesic request of 1 µg/kg intravenous fentanyl was insignificant in between the three groups. Regarding the time for the first intraoperative request for analgesia, it was insignificant between the three groups. The total dose of fentanyl consumed was insignificant between the three groups. However, all patients required diclofinac sodium during the first 24 h postoperatively. The time for the first analgesic request was significantly early in group C (7.4±1.4 h) than in group M (13±1.7 h) and group T (15.4±3.4 h), was significant when comparing group M to group T (P=0.001), and was significant when comparing the three groups (P=0.001). So, tramadol and magnesium sulfate significantly increase postoperative analgesic duration compare with control group and significantly decrease the postoperative analgesic consumption during the first 24 h.
This is in accordance with a study by Nagpal et al.  who compared the effects of 100 mg tramadol administered as an adjunct to 0.5% bupivacaine in supraclavicular block to that of systemic administration. They agreed with our results that 100 mg tramadol as an adjunct to supraclavicular plexus blocks prolongs the duration of motor blockade and demands for rescue analgesia. It also improved the quality of anesthesia and extended the duration of postoperative analgesia.
Other colleagues agree with our results that the admixture of magnesium sulfate or fentanyl to ropivacaine for continuous femoral nerve block provided a significant prolongation of postoperative analgesia than ropivacaine alone .
In another study by Muthiah et al. , where 150 mg magnesium was added as an adjuvant to 30 ml of 0.25% bupivacaine in 3-in-1 block prolonged the mean duration of analgesia (788.5±435.9 min) significantly when compared with 30 ml of 0.25% bupivacaine with saline in the control group (465.5±290.3 min).
Other preliminary study is in agreement with Lee et al. ; in their study, interscalene nerve block was performed with 150 mg magnesium sulfate added to 0.5% bupivacaine (M group) or normal saline 2 ml (saline group). They suggested that a significant difference was found, as the duration of analgesia was longer in the magnesium group than in the saline group (664±188 vs. 553±155 min, respectively). Patients in the magnesium group had significantly decreased pain NRS scores at 12 h, but the fentanyl consumption was similar in both groups .
Moreover, Robaux et al.  concluded that the number of patients requesting analgesia in the postoperative period was significantly less in the three tramadol groups compared with the placebo group (P=0.02). Their study demonstrates that tramadol added to mepivacaine for brachial plexus anesthesia extended the duration and improved the quality of postoperative analgesia in a dose-dependent fashion.
Regarding the adverse effects, we found that the dose of 150 mg magnesium used in our study shows no significant difference. This dose has been safely used by Mukherjee et al. , who used 150 mg magnesium as an adjuvant in ropivacaine to induced supraclavicular brachial plexus block, and no significant adverse effects have been reported.
In addition, Lennart Christiansson  confirmed that tramadol added to 1.5% mepivacaine for brachial plexus block enhanced the block in a dose-dependent manner and the duration of analgesia, with acceptable adverse effects.
Therefore, from our study and other studies, we concluded that using 150 mg magnesium sulfate and 100 mg tramadol to lidocaine 2% and bupivacaine 0.5% as adjuvant increases the duration of sensory and motor sciatic nerve block. It delays the time for the first postoperative analgesic request and decreases postoperative analgesic consumption. Moreover, using tramadol as an adjunct to local anesthetics delays the onset of sensory and motor sciatic nerve block more than using magnesium sulfate.
One of the limitations of our study was that we did not use ultrasound-guided block owing to its nonavailability in our institution at the time of the study, because ultrasound guidance localization of sciatic nerve is easy, and the variability in different parameters caused owing to clinical blocks can be reduced.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]