Previous article Table of Contents  Next article

Year : 2016  |  Volume : 10  |  Issue : 2  |  Page : 187-191

Adding magnesium sulfate to bupivacaine in transversus abdominis plane block for laparoscopic cholecystectomy: A single blinded randomized controlled trial

Department of Anesthesia and Surgical Intensive Care, Mansoura University, Mansoura, Egypt

Correspondence Address:
K Al-Refaey
Department of Anesthesia and Surgical Intensive Care, Mansoura University, Mansoura
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1658-354X.168821

Rights and Permissions
Date of Web Publication02-Nov-2015


Introduction and Aim: Use of transversus abdominis plane block (TAP) in the management of postoperative pain after the laparoscopic cholecystectomy (LC) has been a common anesthetic practice. This study evaluates the effect of adding magnesium sulfate to bupivacaine in TAP block in LC regarding postoperative analgesia and analgesic consumption.
Patients and Methods: Ninety patients of American Society of Anesthesiologists I and II was divided into three groups: Control group (C group, n = 30), bupivacaine group (B group, n = 30), bupivacaine magnesium group (M group, n = 30).
Results: M group showed better analgesic profile in the 1 st postoperative day in the form of lower mean visual analog scale score (2.8 ± 0.6 for C group, 2.1 ± 0.5 for B group, 2.2 ± 0.5 for M group, P < 0.001), longer duration of analgesia (7 ± 2.8 h for C group , 16 ± 2.5 h for B group, 19 ± 2.2 h for M group, P < 0.006), lower morphine consumption (2 ± 0.1 mg for C group, 0.9 ± 0.1 mg for B group, 0.5 ± 0.1 mg for M group, P < 0.011). There was a significant lower incidence of postoperative nausea and vomiting (PONV) (32% for C group, 6% B group, 7% M group, P < 0.004).
Conclusion: Adding MgSo4 as an adjuvant to bupivacaine in TAP block; during anesthesia for LC; improved postoperative analgesia in the form of increased duration, decreased analgesic requirements and PONV.

Keywords: Anesthesia, laparoscopic cholecystectomy, regional, transversus abdominis plane

How to cite this article:
Al-Refaey K, Usama E M, Al-Hefnawey E. Adding magnesium sulfate to bupivacaine in transversus abdominis plane block for laparoscopic cholecystectomy: A single blinded randomized controlled trial. Saudi J Anaesth 2016;10:187-91

How to cite this URL:
Al-Refaey K, Usama E M, Al-Hefnawey E. Adding magnesium sulfate to bupivacaine in transversus abdominis plane block for laparoscopic cholecystectomy: A single blinded randomized controlled trial. Saudi J Anaesth [serial online] 2016 [cited 2021 Jun 23];10:187-91. Available from:

  Introduction Top

Laparoscopic cholecystectomy (LC) is one of the commonly performed surgical procedures that is associated with a moderate degree of postoperative pain especially on the 1 st postoperative day. [1],[2] Adequate postoperative analgesia allows early patient ambulation, decreases analgesic requirements, and hospital length of stay. [1],[2] Transversus abdominis plane (TAP) block is a recent analgesic technique that has proved its efficacy in perioperative pain therapy for LC. [1],[2],[3]

The aim of this study was to investigate the effect of adding magnesium sulfate to bupivacaine on postoperative pain scores (primary outcome), opioid consumption, and postoperative nausea and vomiting (PONV) (secondary outcomes) in the patients undergoing LC.

  Patients and Methods Top

After the approval of Local Ethical Committee, the consent was obtained from 90 patients scheduled for LC in Gastroenterology Surgical Center, Mansoura University, Egypt. Patients were of either American Society of Anesthesiologists I and II, with age ranging from 18 to 40 years, and body mass index <35. The patients were randomized into three groups (using closed envelope technique in blocks of 18); controlled group (C group), bupivacaine group (B group), and bupivacaine magnesium group (M group).

Anesthesia induction was the same in the three groups (propofol 1-1.5 mglkg, fentanyl 1 m/kg, and atracurium 0.5 mg/kg), then sevoflorane inhalational anesthesia for maintenance in 0.4 oxygen/air mixture.

In both M group and B group, the preemptive ultrasound guided subcostal TAP block (Toshiba Xario, Japan) was performed on both sides using 20 ml volume (0.25 bupivacaine in B group or 0.25 bupivacaine plus 0.5 g of MgSo 4 in M group). Surgical sterilization started 5 min after the block and surgery started 5 min later. Hemodynamic data (heart rate [HR], mean arterial pressure [MAP]) was collected immediately after induction, at the start of surgery, and each 10 min later.

At the end of surgery, and after the closure of surgical ports, anesthesia was terminated, and extubation was done when patients fulfilled the required criteria. Postoperative hemodynamic data (HR, MAP), visual analogue scale (VAS) score, and PONV were recorded at 0, 1, 2, 6, 12, and 24 h after surgery, Ramsay sedation was recorded at 0, 1, 2, and 6 h postoperatively. Boluses of morphine (0.02 mg/kg) were given whenever postoperative VAS score ≥4 for any patient in the three studied groups.

Statistical analysis

For sample size calculation, G*Power version was used. Mean postoperative VAS score was adopted as a primary variable and power of 80 was achieved accepting an effective size of 35%, if the total sample size of 84 was included in the study. Six cases were added to compensate for dropouts leading to a total sample size of 90 patients, 30 in each group.

Data were collected, tabulated, and statistically analyzed using SPSS program, version 16 (IBM-International Business Machines Corporation, Armonk, New York, United States). Continuous data were tested for normality and expressed in mean ± standard deviation if normally distributed, median (interquartile range) if not. Categorical data were presented as proportions. ANOVA test was used to detect the statistical significance between the studied groups considering a P < 0.05 as significant.

  Results Top

No statistical difference was found between the three studied groups as regards age, weight, height, HR, MAP, anesthetic, or surgery duration [Table 1]. Intra-operative HR measurements, MAP showed no significant difference among the three groups, this is shown in [Table 2].
Table 1: Patient characteristic and operative time among the 3 studied groups, data are presented as mean ± SD

Click here to view
Table 2: Intra-operative parameters between studied groups. Data is presented as mean±SD

Click here to view

Mean VAS score was statically lower in M group (2.8 ± 0.6 for C group, 2.1 ± 0.5 for B group, and 2.2 ± 0.5 for M group, P < 0.001). Also total morphine consumption (2 ± 0.1 for C group, 0.9 ± 0.1 for B group, and 0.5 ± 0.1 for M group, P < 0.011) was lower in M group. Duration of analgesia was longer in MAG group (7 ± 2.8 for C group, 16 ± 2.5 for B group, and 19 ± 2.2 for M group, P < 0.006). There was a significant lower incidence of PONV (32% for C group, 6% B group, and 7% M group, P < 0.004) shown in [Figure 1] and [Figure 2].
Figure 1: Postoperative analgesic profile and postoperative nausea and vomiting in the three studied groups

Click here to view
Figure 2: Visual analog scale score in the first 24 h in the three studied groups

Click here to view

  Discussion Top

Our study showed that using MgSo 4 as an adjuvant in TAP block in cases of LC resulted in a better analgesic profile, lower VAS score, lower analgesic consumption, and longer duration of analgesia with no recorded complications.

The use of TAP block has succeeded as an analgesic technique after LC in the last decade. [4],[5],[6],[7],[8] Also, adding MgSo 4 as an adjuvant to local anesthetics in regional procedures has proofed its efficacy in many clinical trials. [1],[2],[9],[10] In our study; MgSo 4 augmented the postoperative analgesic effect of TAP block. This result coincides with multiple previous studies that used intravenous (IV) MgSo 4 either IV bolus or infusion in thoracic, spine, gynecologic, neurosurgery, and abdominal surgeries. [3],[4],[5],[11],[12],[13],[14] Other studies used MgSo 4 as an adjuvant to various regional techniques such as brachial, intra-articular, epidural, or even intrathecal blocks where MgSo 4 had a beneficial effect on postoperative analgesia and analgesic requirements. [6],[15],[16]

N-methyl D-aspartate (NMDA) receptor is the major affecting site for the effects of magnesium. Magnesium is an antagonist of the NMDA receptor, acting as a noncompetitive antagonist, blocking ion channels in a voltage dependent fashion. This receptor is found in many parts of the body, including the nerve endings, and plays a well-defined role in modulating pain and a number of inflammatory responses. [4],[12],[17] NMDA receptor antagonists could prevent central sensitization that occurs due to the peripheral nociceptive stimulation. [14]

The mechanism of action by which TAP MgSo 4 potentiates the analgesic effect of local anesthetics still is not clear and may be related to systemic and or local actions. The analgesic effects of Magnesium are primarily based on antagonism of calcium influx into nerve fiber, and NMDA receptor blocking activity [5],[6],[7],[8],[11],[17] thus interfering with the release of neurotransmitter substances at synaptic junctions or may potentiate the action of local anesthetics. [16] Also, magnesium ions are known to elevate the firing threshold in both myelinated and unmyelinated axons. Divalent cations have been suggested to reduce the fixed negative surface charge on the outside of nerve membranes and thereby increase the trans-membranes potential (i.e., cause a hyper polarization). [16],[18]

Another suggested mechanism is systemic absorption. Serum magnesium levels are strongly associated with reduced postsynaptic activity of slow conducting unmyelinated C-fibers which are chiefly afferent fibers conveying the input signals from the periphery to central nervous system. Magnesium prevents the activation of NMDA receptors which causes calcium and sodium influx into the cell with an efflux of potassium and initiation of central sensitization and wind-up leading to the propagation of peripheral nociceptive stimulation. This antagonist prevents and abolish the hypersensitization, once it is established by blocking dorsal horn NMDA receptor activation induced by excitatory amino acid transmitters such as glutamate and aspartate. [7],[17],[18],[19]

The safety of perineural use of MgSo 4 has been an issue of debate among the multiple human and animal studies and also in many reports of inadvertent use. [20],[21],[22],[23],[24],[25],[26] Most neurological damage in the form of vaculation or demyelination was related to high dose and concentration of the drug, more than 15% in most reports. [27],[28] In our study, we used MgSo 4 of 2.5%, which is too much far from the postulated harmful concentration.

The lower incidence of PONV in both B and M groups is related to lower pain scores, and lower opioid consumption. [29],[ 30]

An area of limitation in this study was that serum Mg level had not been measured to be correlated to the efficacy of TAP block or another group receiving MgSo 4 should have been added to detect if the potentiation effect is related to a systemic or local action of MgSo 4 .

  Conclusion Top

Adding MgSo 4 as an adjuvant to bupivacaine in TAP block; during anesthesia for LC; resulted in improved postoperative analgesia in the form of increased duration and decreased analgesic requirements and was associated with less incidence of PONV.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Ra YS, Kim CH, Lee GY, Han JI. The analgesic effect of the ultrasound-guided transverse abdominis plane block after laparoscopic cholecystectomy. Korean J Anesthesiol 2010;58:362-8.  Back to cited text no. 1
Petersen PL, Stjernholm P, Kristiansen VB, Torup H, Hansen EG, Mitchell AU, et al. The beneficial effect of transversus abdominis plane block after laparoscopic cholecystectomy in day-case surgery: A randomized clinical trial. Anesth Analg 2012;115:527-33.  Back to cited text no. 2
Chen CK, Phui VE. The efficacy of ultrasound-guided oblique subcostal transversus abdominis plane block in patients undergoing open cholecystectomy. South Afr J Anaesth Analg 2011;17:308-10.  Back to cited text no. 3
Barbosa FT, Barbosa LT, Jucá MJ, Cunha RM. Applications of magnesium sulfate in obstetrics and anesthesia. Rev Bras Anestesiol 2010;60:104-10.  Back to cited text no. 4
Dean C, Douglas J. Magnesium and the obstetric anaesthetist. Int J Obstet Anesth 2013;22:52-63.  Back to cited text no. 5
Sirvinskas E, Laurinaitis R. Use of magnesium sulfate in anesthesiology. Medicina (Kaunas) 2002;38:695-8.  Back to cited text no. 6
Herroeder S, Schönherr ME, De Hert SG, Hollmann MW. Magnesium - essentials for anesthesiologists. Anesthesiology 2011;114:971-93.  Back to cited text no. 7
Shabbir PM. Miracle of magnesium sulfate. Indian J Allergy Asthma Immunol 2012;26:14-5.  Back to cited text no. 8
  Medknow Journal  
Chen CK, Tan PC, Phui VE, Teo SC. A comparison of analgesic efficacy between oblique subcostal transversus abdominis plane block and intravenous morphine for laparascopic cholecystectomy. A prospective randomized controlled trial. Korean J Anesthesiol 2013;64:511-6.  Back to cited text no. 9
El-Dawlatly AA, Turkistani A, Kettner SC, Machata AM, Delvi MB, Thallaj A, et al. Ultrasound-guided transversus abdominis plane block: Description of a new technique and comparison with conventional systemic analgesia during laparoscopic cholecystectomy. Br J Anaesth 2009;102:763-7.  Back to cited text no. 10
Albrecht E, Kirkham KR, Liu SS, Brull R. Peri-operative intravenous administration of magnesium sulphate and postoperative pain: A meta-analysis. Anesthesia 2013;68:79-90.  Back to cited text no. 11
Bottiger BA, Esper SA, Stafford-Smith M. Pain management strategies for thoracotomy and thoracic pain syndromes. Semin Cardiothorac Vasc Anesth 2014;18:45-56.  Back to cited text no. 12
Cizmeci P, Ozkose Z. Magnesium sulphate as an adjuvant to total intravenous anesthesia in septorhinoplasty: A randomized controlled study. Aesthetic Plast Surg 2007;31:167-73.  Back to cited text no. 13
Dabbagh A, Elyasi H, Razavi SS, Fathi M, Rajaei S. Intravenous magnesium sulfate for post-operative pain in patients undergoing lower limb orthopedic surgery. Acta Anaesthesiol Scand 2009;53:1088-91.  Back to cited text no. 14
Ghatak T, Chandra G, Malik A, Singh D, Bhatia VK. Evaluation of the effect of magnesium sulphate vs. clonidine as adjunct to epidural bupivacaine. Indian J Anaesth 2010;54:308-13.  Back to cited text no. 15
[PUBMED]  Medknow Journal  
Goyal P, Jaiswal R, Hooda S, Goyal R, Lal J. Role of magnesium sulphate for brachial plexus analgesia. Internet J Anesthesiol 2008;21:1-5. Available from: [Last cited on 2015 Apr 09].  Back to cited text no. 16
Buvanendran A, Kroin JS. Useful adjuvants for postoperative pain management. Best Pract Res Clin Anaesthesiol 2007;21:31-49.  Back to cited text no. 17
Akutagawa T, Kitahata LM, Saito H, Collins JG, Katz JD. Magnesium enhances local anesthetic nerve block of frog sciatic nerve. Anesth Analg 1984;63:111-6.  Back to cited text no. 18
Choi IG, Choi YS, Kim YH, Min JH, Chae YK, Lee YK, et al. The effects of postoperative brachial plexus block using MgSO(4) on the postoperative pain after upper extremity surgery. Korean J Pain 2011;24:158-63.  Back to cited text no. 19
Sun J, Wu X, Xu X, Jin L, Han N, Zhou R. A comparison of epidural magnesium and/or morphine with bupivacaine for postoperative analgesia after cesarean section. Int J Obstet Anesth 2012;21:310-6.  Back to cited text no. 20
Rouse DJ. Magnesium sulfate for the prevention of cerebral palsy. Am J Obstet Gynecol 2009;200:610-2.  Back to cited text no. 21
Hasanein R, El-Sayed W, Khalil M. The value of epidural magnesium sulfate as an adjuvant to bupivacaine and fentanyl for labor analgesia. Egypt J Anaesth 2013;29:219-24.  Back to cited text no. 22
Farouk S. Pre-incisional epidural magnesium provides pre-emptive and preventive analgesia in patients undergoing abdominal hysterectomy. Br J Anaesth 2008;101:694-9.  Back to cited text no. 23
Bilir A, Gulec S, Erkan A, Ozcelik A. Epidural magnesium reduces postoperative analgesic requirement. Br J Anaesth 2007;98:519-23.  Back to cited text no. 24
Dehghani SN, Bigham AS. Comparison of caudal epidural anesthesia by use of lidocaine versus a lidocaine-magnesium sulfate combination in cattle. Am J Vet Res 2009;70:194-7.  Back to cited text no. 25
Goodman EJ, Haas AJ, Kantor GS. Inadvertent administration of magnesium sulfate through the epidural catheter: Report and analysis of a drug error. Int J Obstet Anesth 2006;15:63-7.  Back to cited text no. 26
Ozdogan L, Sastim H, Ornek D, Postaci A, Ayerden T, Dikmen B. Neurotoxic effects of intrathecal magnesium sulphate. Braz J Anesthesiol 2013;63:139-43.  Back to cited text no. 27
Lee AR, Yi HW, Chung IS, Ko JS, Ahn HJ, Gwak MS, et al. Magnesium added to bupivacaine prolongs the duration of analgesia after interscalene nerve block. Can J Anaesth 2012;59:21-7.  Back to cited text no. 28
Gan TJ, Diemunsch P, Habib AS, Kovac A, Kranke P, Meyer TA, et al. Consensus guidelines for the management of postoperative nausea and vomiting. Anesth Analg 2014;118:85-113.  Back to cited text no. 29
Aubrun F, Mazoit JX, Riou B. Postoperative intravenous morphine titration. Br J Anaesth 2012;108:193-201.  Back to cited text no. 30


  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


Previous article    Next article
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

  IN THIS Article
  Patients and Methods
   Article Figures
   Article Tables

 Article Access Statistics
    PDF Downloaded336    
    Comments [Add]    

Recommend this journal