|Year : 2015 | Volume
| Issue : 4 | Page : 116-120
The addition of magnesium sulfate or dexamethasone to levobupivacaine for ultrasound-guided supraclavicular brachial plexus block for upper-limb surgery: a double-blinded comparative study
Adel A.N. Mahgoub
Department of Anesthesia and Surgical Intensive Care, Faculty of Medicine, University of Alexandria, Alexandria, Egypt
|Date of Submission||09-Sep-2015|
|Date of Acceptance||09-Dec-2015|
|Date of Web Publication||17-Mar-2016|
Adel A.N. Mahgoub
Assistant Professor of Anesthesia and Surgical Intensive Care, Faculty of Medicine, University of Alexandria, Alexandria, 88206
Source of Support: None, Conflict of Interest: None
Levobupivacaine (chirocaine) is a long-acting amide local anesthetic that can be used in different applications like epidural, spinal, peripheral nerve, ocular block, topical application, and local infiltration. Clinical effects are comparable to those of bupivacaine or ropivacaine. Studies are needed on different adjuvants with levobupivacaine, such as dexamethasone and magnesium sulfate.
Aim of this study
The aim of the study was to compare the effect of adding either magnesium sulfate or dexamethasone to levobupivacaine in supraclavicular brachial plexus block.
Materials and methods
Sixty adult patients presented for upper-limb surgery under supraclavicular brachial plexus block using ultrasound. The patients were randomly arranged into two equal groups: magnesium sulfate was added to levobupivacaine in one group and dexamethasone was added in the other group. Duration of postoperative analgesia was recorded.
There was no statistically significant difference in the duration of postoperative analgesia between the two groups.
There is no preferential difference in postoperative analgesia between dexamethasone and magnesium sulfate when added to levobupivacaine
Keywords: brachial plexus block, dexamethasone, levobupivacaine, magnesium sulfate
|How to cite this article:|
Mahgoub AA. The addition of magnesium sulfate or dexamethasone to levobupivacaine for ultrasound-guided supraclavicular brachial plexus block for upper-limb surgery: a double-blinded comparative study. Res Opin Anesth Intensive Care 2015;2:116-20
|How to cite this URL:|
Mahgoub AA. The addition of magnesium sulfate or dexamethasone to levobupivacaine for ultrasound-guided supraclavicular brachial plexus block for upper-limb surgery: a double-blinded comparative study. Res Opin Anesth Intensive Care [serial online] 2015 [cited 2017 Oct 17];2:116-20. Available from: http://www.roaic.eg.net/text.asp?2015/2/4/116/178904
| Introduction|| |
Patients undergoing surgery in the upper extremity often report postoperative pain that is intense and difficult to control. The pain itself is not only associated with patient suffering but can also lead to a number of complications that may lead to an unintended long-term stay in the hospital after surgery .
Upper-limb surgery can be performed under general or regional anesthesia. Regional anesthesia has several advantages, including decreased hemodynamic instability, avoidance of airway instrumentation, and intraoperative and postoperative analgesia. Brachial plexus blockade is a very reliable method of regional anesthesia for the upper limb, some authors calling it spinal anesthesia of the upper limb .
Ultrasonography has revolutionized the practice of regional anesthesia. By real-time visualizing of needle entry throughout the procedure, the relationship between the anatomical structures and the needle can reduce the incidence of complications. In addition, direct visualization of the spread of local anesthesia around the nerves provides instant feedback regarding the likely success of the block. The advantages that ultrasound guidance provides are only as good as the experience of the anesthesiologist performing the block. Supraclavicular brachial plexus block (BPB) has changed from an approach with the highest risk of pneumothorax to a block with minimal risks, making it the ideal choice for most upper-extremity surgeries .
Various approaches have thus been adopted to help alleviate postoperative pain, with the majority of them using high doses of opioids or nerve block. Opioids, however, have side effects such as severe nausea and vomiting .
Nerve blocks, mostly using local anesthetics, can control postoperative pain effectively while avoiding the side effects of using large doses of opioids. The BPB in particular is a widely used option in upper-extremity surgeries.
The ideal local anesthetic should provide effective analgesia for the duration of the surgical operation and provide postoperative analgesia for a considerable duration as well as have a good safety profile. Bupivacaine is a widely used long-acting local anesthetic in both surgery and obstetrics, with a good safety record, but its use has resulted in fatal cardiotoxicity, usually after accidental intravascular injection. Hence, for several years there has been a need for a long-acting local anesthetic, similar to bupivacaine, but with an improved cardiovascular safety profile .
Levobupivacaine is a single enantiomer of the long-acting local anesthetic bupivacaine. This change in the molecular structure has resulted in levobupivacaine being a lesser arrhythmogenic and lesser central nervous system (CNS) depressant than the same dose range of bupivacaine. The duration of the nerve block with levobupivacaine is much longer than with bupivacaine .
Various drugs are used in combination with local anesthetics to help reduce the anesthetics' time to onset of effect, to prolong the duration of action, and to increase the chance of successful blockade. Toward these ends, a number of studies have been conducted, with varying results ,,,,,,,,,.
Magnesium helps to regulate the amount of calcium inside the cells and is known to be able to control pain. For example, magnesium sulfate (MgSO 4 ), when injected intravenously, helps reduce the consumption of anesthetics during surgery; in addition, when administered through epidural injection, it helps to decrease the amount of opioids needed postoperatively . Despite its known benefits for pain control, magnesium has never been studied extensively for its effects as an adjuvant to aesthetics during BPBs.
Dexamethasone relieves pain by reducing inflammation and blocking the transmission of nociceptive C-fibers and suppressing ectopic neural discharge. It has been shown that the duration of postoperative analgesia is prolonged when dexamethasone is given as an adjunct for peripheral nerve blocks. Studies indicate that 8 mg dexamethasone added to perineural local anesthetic injections augments the duration of peripheral nerve block analgesia. The increase in the duration of analgesia is unclear .
| The aim of this study|| |
The aim of the study was to compare the duration of postoperative analgesia after adding either magnesium sulfate or dexamethasone to levobupivacaine for performing supraclavicular BPBs for upper-limb surgeries.
| Materials and methods|| |
After taking informed consent from the patients we enrolled 60 adult (age from 20 to 60 years) patients who presented for upper-limb surgery and who met the requirements of the American Society of Anesthesiologists (ASA) physical status classification system's class 1 or class 2. The exclusion criteria were morbid obesity (BMI > 40 kg/m 2), a history of chronic pain or psychiatric disorder, drug or alcohol abuse, and hypersensitivity to local anesthetics. The purpose and methods of the study were explained to the participating patients; their written consent was collected before the study.
The patients were randomly assigned to two equal groups: group M, which was given magnesium sulfate along with levobupivacaine, and group D, in which dexamethasone was added to levobupivacaine.
Patients were scheduled for upper-limb surgeries and asked to fast overnight for 6 h before surgery. Patients were received in the holding area in the operating room (OR) where their vital signs were checked and an intravenous cannula was inserted in the other upper limb and they received midazolam 2 mg intravenous for sedation.
In the operating room supraclavicular brachial plexus block was performed using an ultrsound machine (Ultrasound, HD 9; Philips, Bothel, Washington, USA) with linear probe 6-12 [Figure 1]. The supraclavicular area was explored with an ultrasound machine. The skin was prepared with DuraPrep solution (3 mol/l, DuraPrep) and draped with sterile drapes. The ultrasound probe was covered with a sterile cover 15 × 20 cm (3 mol/l, Tegaderm film) and a sterile ultrasound gel was used to facilitate viewing. The needle used was a 22-G 55-mm-long B beveled needle (SonoPlexStim cannula; Pajunk). Inplane approach was used during the block and 25 ml of levobupivacine 0.5% mixed with 200 mg of MgSO 4 (magnesium Daihan injection; Daihan Pharm. Co. Ltd) was administered to the M group or mixed with 8 mg dexamethasone was given to the D group to perform the block. We ensured that the local anesthetic mixture spread well around the brachial plexus in the suprascapular area [Figure 1], [Figure 2] and [Figure 3].
|Figure 1: The layout of the block field . Sterile drapes: the probe is covered with a sterile cover and the needle is inserted in plane .|
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|Figure 2: Ultrasound imaging of the suprascapular area. Brachial plexus, subclavian artery, first rib, and the pleura can be identified .|
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|Figure 3: Ultrasound image of the block needle in plane approach with start of spread of local anesthetic around the plexus .|
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For all patients ECG, blood pressure, and oxygen saturation level were monitored by means of an ECG machine, a noninvasive blood pressure monitor, and a pulse oximeter.
The success of the block was tested every 5 min for 20 min. Elbow flexion and finger flexion extension for motor block were assessed and a cold gel pad was used to test the sensory block. If after 20 min there were no signs of block the procedure was considered a failure and the patient was withdrawn from the study.
The duration of postoperative analgesia offered by the block was recorded.
Before the surgery, the patients were educated on how to rate pain on the visual analogue scale, which has a line along which patients can rate the severity of their perceived pain by marking a number (0-10) that best represents the pain. They were educated on how to use patient-controlled analgesia as well and how to press the button themselves when they feel pain of a score greater than 3 out of 10.
The patients were tested in the recovery unit for sensory and motor blocks using a cold gel pad and ordering the patient to flex and extend the fingers and elbow. The patients were tested in the ward every 3 h. The total time from the block until the patient started to show signs of recovery of the block or started to complain of pain was recorded.
Patient-controlled analgesia was adjusted so that it delivered 2 mg of morphine sulfate intravenously with a lockout interval and maximum of 20 mg every 4 h.
Statistical analysis of data was done using the χ2 -test or Student's t-test. Analytical results were considered statistically significant if the P value was less than 0.05.
| Results|| |
There were no significant differences in the patients' sex, age, height, weight, duration of surgery, or type of surgery between group D and group M [Table 1]. No significant differences were observed between the groups with respect to blood pressure and heart rate.
There was no significant difference in the total duration of analgesia between the two groups [Table 2].
|Table 2: Total time from the block until the patient started to feel pain|
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| Discussion|| |
Many adjuvants have been tested in combination with different local anesthetics ,,,,,,,,,. Levobupivacaine is a relatively new local anesthetic that has not been tested with other additives like magnesium sulfate or dexamethasone. In this study we tried to compare the effect of both additives head to head during supraclavicular BPB for upper-limb surgery.
The primary goal of the study was to measure the duration of the block, which was estimated from the start of the block until the patient started to complain of pain in the surgical site.
It was found that there was no statistical difference in the duration of the block between group M and group D (10 h:45 min ± 1 h:20 min and 11 h:10 min ± 1 h:05 min, respectively).
Magnesium, a cation existing inside the cell whose quantities are second only to potassium, plays a crucial role in activating enzymes in the cardiovascular system. In addition, magnesium acts as a physiological calcium antagonist. It is used to treat arrhythmia, myocardial or nerve ischemia, and gestational toxicosis, and to inhibit uterine contraction ,. More recently, magnesium's effects of N-methyl-d-aspartate receptor antagonism and sympathetic blocking have been noted, and magnesium is now used to help reduce the consumption of anesthetics and pain medications. Magnesium blocks the effects of excitatory amino acids (e.g. glutamate, aspartate) on N-methyl-d-aspartate receptors and contributes to central sensitization ,.
Studies on the pain control effects of magnesium have shown conflicting results. Lee et al.  reported that the preoperative intravenous injection of magnesium was effective in controlling postoperative pain. In contrast, Ko et al.  reported that the same approach was not effective.
There are only a small number of studies that have used MgSO 4 during BPBs. Gunduz et al.  used prilocaine, a local anesthetic, during a BPB and observed that the drug, when used in combination with magnesium, prolonged the duration of the sensory and motor nerve block without causing adverse events.
The difference in our study is that we used levobupivacaine, which has a long duration of action, and the block was facilitated by ultrasound imaging that confirms the spread of local anesthetic around the targeted nerves, which helps achieve better block.
Dexamethasone relieves pain by reducing inflammation and blocking the transmission of nociceptive C-fibers and suppressing ectopic neural discharge. It has been shown that the duration of postoperative analgesia is prolonged when dexamethasone is given as an adjunct for peripheral nerve blocks .
| Conclusion|| |
There is no preferential difference in postoperative analgesia between dexamethasone and magnesium sulfate when added to levobupivacaine. Another study is needed to compare them with a control group.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]