Intravenous magnesium sulphate decreases postoperative tramadol requirement after radical prostatectomy*

Unravelling the analgesic effects of perioperative magnesium in general abdominal surgery: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Prior research has established the effectiveness of magnesium in relieving postoperative pain. This article aims to evaluate magnesium sulfate for perioperative analgesia in adults undergoing general abdominal surgery under general anesthesia.

OBJECTIVE

The primary aim was to assess pain scores at 6 and 24 hours postoperatively in patients receiving magnesium sulfate vs. the control group. Secondary outcomes were postoperative opioid consumption, perioperative complications, and time to rescue analgesia.

METHODS

A comprehensive database search identified studies comparing magnesium sulfate with control in adults undergoing general anesthesia for general abdominal surgery. Using random-effects models, data were presented as mean ± Standard Deviation (SD) or Odds Ratios (OR) with corresponding 95% Confidence Intervals (95% CI). A two-sided p-value < 0.05 was considered statistically significant.

RESULTS

In total, 31 studies involving 1762 participants met the inclusion criteria. The magnesium group showed significantly lower postoperative pain scores at both early (within six hours) and late (up to 24 hours) time points compared to the control group. The early mean score was 3.1 ± 1.4 vs. 4.2 ± 2.3, and the late mean score was 2.3 ± 1.1 vs. 2.7 ± 1.5, resulting in an overall Mean Difference (MD) of -0.72; 95% CI -0.99, -0.44; p < 0.00001. The magnesium group was associated with lower rates of postoperative opioid consumption and shivering and had a longer time to first analgesia administration compared to the saline control group.

CONCLUSION

Magnesium sulfate administration was linked to reduced postoperative pain and opioid consumption following general abdominal surgery.

Is intravenous magnesium sulphate a suitable adjuvant in postoperative pain management? - A critical and systematic review of methodology in randomized controlled trials

A growing worldwide focus on opioid-free anaesthesia entails multimodal analgesic strategies involving non-opioids such as magnesium sulphate (MgSO4). Several systematic reviews have concluded there is beneficial analgesic effect of MgSO4 administration but do not take considerable heterogeneity among the studies into consideration. Medical literature published until June 2021 was searched in PubMed/Medline, Embase, Central and Web of Science: The final search yielded a total of 5,672 articles. We included only randomised controlled trials assessing the effect of intravenous MgSO4 on opioid consumption and acute postoperative pain when compared to either placebo or standardized analgesic treatment. The primary aim was to compare the homogeneity of essential variables and confounders. A post-hoc meta-analysis demonstrated a reduction in both postoperative morphine consumption (-6.12 mg) and pain score (-12.32 VAS points) in favour of the MgSO4-groups. Data for meta-analysis was missing from 19 studies (45%) on morphine consumption and 29 studies (69%) for pain score, the majority of which reports no effect for either morphine consumption or pain score. The calculated heterogeneity among the included studies was considerable for both outcomes; I 2=91% for morphine consumption and I 2=96% for pain score. Although we found a per se reduction in opioid consumption and pain score, methodological heterogeneity and clinical shortcomings of pre-, intra-, and post anaesthetic data precludes conclusions on clinical importance of intraoperative intravenous MgSO4. In addition, the reduction is likely less than what can be gained from using standardized analgesic treatment.

Effect of Perioperative Intravenous Magnesium Sulfate on Postoperative Pain After Iliac Venous Stenting

BACKGROUND

The aim of the present study was to evaluate the effect of perioperative intravenous (IV) magnesium sulfate (MS) on low back pain (LBP) severity after iliac venous stent implantation.

METHODS

The present study was a single-center retrospective study. A total of 97 patients who had undergone iliac venous stenting for post-thrombotic syndrome between January 1, 2019 and January 11, 2021 were considered for inclusion in the present study. The patients were divided into two groups: those who had received perioperative MS infusions (group M) and those who had not (control group; group C). Group M was given an IV bolus of 20 mg/kg before anesthesia induction and an IV MS infusion of 20 mg/kg/h during the procedure. Postoperative LBP severity was evaluated using the numerical rating scale at 1, 6, 12, and 24 hours after the procedure. The total tramadol consumption within 24 hours was measured with the help of a patient-controlled analgesia device. Moreover, additional analgesic needs and complaints of nausea and vomiting were evaluated.

RESULTS

A total of 97 patients were considered for inclusion in the present study. Of the 97 patients, 29 were excluded because of a lack of follow-up data, leaving 68 patients for the final analysis (group M, n = 36; group C, n = 32). The demographic data, body mass index, sedation time, procedure time, and stented side data were similar between the two groups (P > .05). The rates of atropine and ephedrine use during the procedure were similar between the two groups (P > .05). The numerical rating scale scores were significantly lower for group M at all follow-up periods (P < .001). The total tramadol consumption at 24 hours postoperatively was 191.94 ± 68.194 mg for group M and 378.75 ± 31.367 mg for group C (P < .001). Additional analgesics were used by 8 patients (22.2%) in group M and 17 patients (53.1%) in group C. Additional analgesic needs were significantly lower for group M (P = .008). Nausea and vomiting were observed in six (19.4%) and four (11.1%) patients in group M and eight (32%) and five (15.6%) patients in group C, respectively (P > .05).

CONCLUSIONS

For patients undergoing iliac venous stenting, perioperative MS infusion was an effective and safe treatment option that reduced LBP severity, opioid consumption, and the need for additional analgesics in the acute postoperative period.

The effect of intravenous magnesium on postoperative morphine consumption in noncardiac surgery: A systematic review and meta-analysis with trial sequential analysis

BACKGROUND

Several studies suggest that systemic magnesium reduces postoperative opioid consumption and the intensity of pain, but others report conflicting results. The efficacy and safety profile of intravenous magnesium in noncardiac surgery remain uncertain.

OBJECTIVES

The aim of this review was to investigate the effect of intravenous magnesium on the consumption of postoperative morphine in the first 24 h in adults undergoing noncardiac surgery.

DESIGN

Systematic review and meta-analysis with trial sequential analysis.

DATA SOURCES

MEDLINE, EMBASE, CENTRAL from their inception until January 2019.

ELIGIBILITY CRITERIA

All randomised clinical trials comparing intravenous magnesium versus placebo in noncardiac surgery were systematically searched in the databases. Observational studies, case reports, case series and nonsystematic reviews were excluded.

RESULTS

Fifty-one trials (n=3311) were included for quantitative meta-analysis. In comparison with placebo, postoperative morphine consumption at 24-h was significantly reduced in the magnesium group, with a mean difference [95% confidence interval (CI)] of -5.6 mg (-7.54 to -3.66, P < 0.001, I = 92%, level of evidence low). The trial sequential analysis for the effect of magnesium on postoperative morphine consumption was conclusive. Patients who received magnesium had a longer time to the first analgesia request [143 (103 to 183) min, P < 0.001, I = 99%, level of evidence low] and a lower incidence of shivering [0.26 (0.15 to 0.44), P < 0.001, I = 35%, level of evidence very low]. However, no significance differences were demonstrated in postoperative pain scores in the first 24 h (mean difference, 95% CI) -0.30 (-0.69 to 0.09, P = 0.13, I = 91%, level of evidence low), bradycardia (odds ratio, 95% CI) 1.13 (0.43 to 2.98, P = 0.80, I = 35%, level of evidence very low) and postoperative nausea and vomiting (odds ratio, 95% CI) 0.90 (0.67 to 1.22, P = 0.49, I = 25%, level of evidence moderate).

CONCLUSION

The current meta-analysis demonstrates that the use of intravenous magnesium as part of multimodal analgesia may reduce morphine consumption in the first 24 h after surgery and delay the time to the first request for analgesia in patients undergoing noncardiac surgery. However, the included studies were of low-quality with substantial heterogeneity.

TRIAL REGISTRATION

CRD42018086846.

Magnesium for Pain Treatment in 2021? State of the Art

Background: Magnesium (Mg) is commonly used in clinical practice for acute and chronic pain and has been reported to reduce pain intensity and analgesics consumption in a number of studies. Results are, however, contested. Objectives: This review aims to investigate randomised clinical trials (RCTs) on the effectiveness of Mg treatment on pain and analgesics consumption in situations including post-operative pain, migraine, renal pain, chronic pain, neuropathic pain and fibromyalgia. Results: The literature search identified 81 RCTs (n = 5447 patients) on Mg treatment in pain (50 RCTs in post-operative pain, 18 RCTs in migraine, 5 RCTs in renal pain, 6 RCTs in chronic/neuropathic pain, 2 RCTs in fibromyalgia). Conclusion: The level of evidence for the efficacy of Mg in reducing pain and analgesics consumption is globally modest and studies are not very numerous in chronic pain. A number of gaps have been identified in the literature that need to be addressed especially in methodology, rheumatic disease, and cancer. Additional clinical trials are needed to achieve a sufficient level of evidence and to better optimize the use of Mg for pain and pain comorbidities in order to improve the quality of life of patients who are in pain.

The Influence of Two Different Doses of Magnesium Sulfate on Intraocular Pressure Variations after Injection of Succinylcholine and Endotracheal Intubation: A Prospective, Randomized, Parallel Three-Arm, Double-blind, Placebo-controlled Clinical Trial

Background:

The use of succinylcholine for rapid sequence induction in patients with open globe injuries may be detrimental to the eye.

Aim:

The aim of this study is to determine if the premedication with magnesium sulfate (MgSO₄) could attenuate the increase in intraocular pressure (IOP) associated with succinylcholine injection and intubation.

Setting:

Operation theaters in a tertiary care University Hospital between December 2014 and July 215.

Design:

This was a prospective, randomized, parallel three-arm, double-blind, placebo-controlled clinical trial.

Participants:

One hundred and thirteen patients’ physical status ASA Classes I and II underwent elective cataract surgery under general anesthesia.

Patients and Methods:

These patients allocated into three groups: Group C (control group) received 100 ml normal saline, Group M1 received 30 mg/kg MgSO₄ in 100 ml normal saline, and Group M2 received 50 mg/kg MgSO₄ in 100 ml normal saline. IOP, mean arterial pressure (MAP), and heart rate (HR) reported at 5-time points related to study drug administration. In addition, any adverse effects related to MgSO₄ were recorded. Intragroup and between-groups differences were examined by analysis of variance test.

Results:

We noticed a significant decrease in IOP in M1 (n = 38) and M2 (n = 37) groups as compared with C group (n = 38) after study drugs infusion, 2 and 5 min after intubation, P < 0.001. While the difference between M1 and M2 groups was insignificant, P = 0.296 and P = 0.647, respectively. There was a significant decrease in MAP and HR in M1 and M2 groups as compared with C group 2 and 5 min after intubation, P = 0.01. While the difference between M1 and M2 groups was insignificant, P = 1.

Conclusion:

MgSO₄ 30 mg/kg as well as 50 mg/kg effectively prevented the rise in IOP, MAP, and HR associated with rapid sequence induction by succinylcholine and endotracheal intubation.

The Effect of Systemic and Regional Use of Magnesium Sulfate on Postoperative Tramadol Consumption in Lumbar Disc Surgery

AIM

To investigate the effect of magnesium administered to the operative region muscle and administered systemically on postoperative analgesia consumption after lumbar disc surgery.

MATERIAL AND METHOD

The study included a total of 75 ASA I-II patients aged 18-65 years. The patients were randomly allocated into 1 of 3 groups of 25: the Intravenous (IV) Group, the Intramuscular (IM) Group, and the Control (C) Group. At the stage of suturing the surgical incision site, the IV Group received 50 mg/kg MgSO4 intravenously in 150 mL saline within 30 mins. In the IM Group, 50 mg/kg MgSO4 in 30 mL saline was injected intramuscularly into the paraspinal muscles. In Group C, 30 mL saline was injected intramuscularly into the paraspinal muscles. After operation patients in all 3 groups were given 100 mg tramadol and 10 mg metoclopramide and tramadol solution was started intravenously through a patient-controlled analgesia device. Hemodynamic changes, demographic data, duration of anesthesia and surgery, pain scores (NRS), the Ramsay sedation score (RSS), the amount of analgesia consumed, nausea- vomiting, and potential side effects were recorded.

RESULTS

No difference was observed between the groups. Nausea and vomiting side effects occurred at a rate of 36% in Group C, which was a significantly higher rate compared to the other groups (p < 0.05). Tramadol consumption in the IM Group was found to be significantly lower than in the other groups (p < 0.05).

CONCLUSION

Magnesium applied to the operative region was found to be more effective on postoperative analgesia than systemically administered magnesium.

Optimal pain management for radical prostatectomy surgery: what is the evidence?

BACKGROUND

Increase in the diagnosis of prostate cancer has increased the incidence of radical prostatectomy. However, the literature assessing pain therapy for this procedure has not been systematically evaluated. Thus, optimal pain therapy for patients undergoing radical prostatectomy remains controversial.

METHODS

Medline, Embase, and Cochrane Central Register of Controlled Trials were searched for studies assessing the effects of analgesic and anesthetic interventions on pain after radical prostatectomy. All searches were conducted in October 2012 and updated in June 2015.

RESULTS

Most treatments studied improved pain relief and/or reduced opioid requirements. However, there were significant differences in the study designs and the variables evaluated, precluding quantitative analysis and consensus recommendations.

CONCLUSIONS

This systematic review reveals that there is a lack of evidence to develop an optimal pain management protocol in patients undergoing radical prostatectomy. Most studies assessed unimodal analgesic approaches rather than a multimodal technique. There is a need for more procedure-specific studies comparing pain and analgesic requirements for open and minimally invasive surgical procedures. Finally, while we wait for appropriate procedure specific evidence from publication of adequate studies assessing optimal pain management after radical prostatectomy, we propose a basic analgesic guideline.

Perioperative Systemic Magnesium to Minimize Postoperative Pain

Background:

Systemic magnesium has been used to minimize postoperative pain with conflicting results by clinical studies. It remains unknown whether the administration of perioperative systemic magnesium can minimize postoperative pain. The objective of the current investigation was to evaluate the effect of systemic magnesium on postoperative pain outcomes.

Methods:

A wide search was performed to identify randomized controlled trials that evaluated the effects of systemic magnesium on postoperative pain outcomes in surgical procedures performed under general anesthesia. Meta-analysis was performed using a random-effect model. Publication bias was evaluated by examining the presence of asymmetric funnel plots using Egger regression.

Results:

Twenty randomized clinical trials with 1,257 subjects were included. The weighted mean difference (99% CI) of the combined effects favored magnesium over control for pain at rest (≤4 h, −0.74 [−1.08 to −0.48]; 24 h, −0.36 [−0.63 to −0.09]) and with movement at 24 h, −0.73 (−1.37 to −0.1). Opioid consumption was largely decreased in the systemic magnesium group compared with control, weighted mean difference (99% CI) of −10.52 (−13.50 to −7.54) mg morphine IV equivalents. Publication bias was not present in any of the analysis. Significant heterogeneity was present in some analysis, but it could be partially explained by the sole intraoperative administration of magnesium compared with the intraoperative and postoperative administration. None of the studies reported clinical toxicity related to toxic serum levels of magnesium.

Conclusion:

Systemic administration of perioperative magnesium reduces postoperative pain and opioid consumption. Magnesium administration should be considered as a strategy to mitigate postoperative pain in surgical patients.

Effect of magnesium sulfate with propofol induction of anesthesia on succinylcholine-induced fasciculations and myalgia

Background:

Magnesium sulfate and propofol have been found to be effective against succinylcholine-induced fasciculations and myalgia, respectively, in separate studies. A prospective randomized double blind controlled study was designed to assess the effect of a combination of magnesium sulfate with propofol for induction of anesthesia on succinylcholine-induced fasciculations and myalgia.

Materials and Methods:

Randomly selected 60 adult patients scheduled for elective surgery under general anesthesia were allocated to one of the two equal groups by draw of lots. The patients of MG Group were pretreated with magnesium sulfate 40 mg/kg body weight in 10 ml volume, while patients of NS group were given isotonic saline 0.9% in the same volume (10 ml) intravenously slowly over a period of 10 min. Anesthesia was induced with fentanyl 1.5 mcg/kg and propofol 2 mg/kg, followed by administration of succinylcholine 2 mg/kg intravenously. Muscle fasciculations were observed and graded as nil, mild, moderate, or severe. Postoperative myalgia was assessed after 24 h of surgery and graded as nil, mild, moderate, or severe. Observations were made in double blind manner.

Results:

Demographic data of both groups were comparable (P > 0.05). Muscle fasciculations occurred in 50% patients of MG group versus in 100% patients of NS group with a significant difference (P < 0.001). After 24 h of surgery, no patient of MG group and 30% patients of NS group had myalgia with a significant difference (P < 0.002).

Conclusion:

Magnesium sulfate 40 mg/kg intravenously may be used with propofol for induction of anesthesia to control succinylcholine-induced fasciculations and myalgia.

Evaluation of dose effects of magnesium sulfate on rocuronium injection pain and hemodynamic changes by laryngoscopy and endotracheal intubation

Background

Rocuronium produces injection pain in 50-80% of treated patients. Therefore, a variety of pretreatments have been attempted to reduce this issue. We evaluated the efficacy of 3 different doses of magnesium on the rocuronium injection pain and following hemodynamic changes by laryngoscopy and tracheal intubation (LTI).

Methods

Two hundreds patients, ASA I and II, undergoing general anesthesia for elective surgery were randomly divided to 4 groups: group 1, 2, 3, 4 received saline 5 ml, magnesium 5, 10 and 20 mg/kg prior to 0.6 mg/kg of rocuronium, respectively. Then, group 1 only was treated with esmolol (20 mg) before LTI. Pain intensity with rocuronium injection was assessed using a four-point scale according to patient's movement. Cardiovascular responses at baseline, after induction, 1 minutes after LTI were determined.

Results

Compared to saline, 10 and 20 mg/kg of magnesium significantly reduced the incidence of overall movement after rocuronium injection (34% and 36% in group 3 and 4, respectively vs. 76% in the group 1) (P < 0.0001). Generalized movement was seen in 4% of patients in groups 3 and 4, respectively. Compared to baseline values, diastolic blood pressure (DBP) immediately after LTI significantly increased within groups 1 and 2 (P < 0.001), but not within groups 3 and 4.

Conclusions

Magnesium (10 and 20 mg/kg) prior to rocuronium was effective in attenuating rocuronium associated injection pain and cardiovascular changes by LTI.

Effect of magnesium infusion on thoracic epidural analgesia

INTRODUCTION

Patients of lung volume reduction surgery (LVRS) having an ASA status III or more are likely to be further downgraded by surgery to critical levels of pulmonary function.

AIM

To compare the efficacy of thoracic epidural block with (0.125%) bupivacaine, fentanyl combination and (0.125%) bupivacaine, fentanyl combination with adjunctive intravenous magnesium infusion for the relief of postoperative pain in patients undergoing LVRS.

METHODS

Patients were operated under general anesthesia. Thirty minutes before the anticipated completion of skin closure in both groups, (Group A and Group B) 7 ml of (0.125%) bupivacaine calculated as 1.5 ml/thoracic segment space for achieving analgesia in dermatomes of T4, T5, T6, T7, and T8 segments, along with fentanyl 50 μg (0.5 ml), was administered through the catheter, activating the epidural block, and the time was noted. Thereafter, in patients of Group A, magnesium sulfate injection 30 mg/kg i.v. bolus was followed by infusion of magnesium sulfate at 10 mg/kg/hr and continued up to 24 hours. Group B was treated as control.

RESULTS AND ANALYSIS

A significant increase in the mean and maximum duration of analgesia in Group A in comparison with Group B (P<0.05) was observed. Total epidural dose of fentanyl and bupivacaine required in Group A was significantly lower in comparison with Group B in 24 hours.

DISCUSSION

Requirement of total doses of local anesthetics along with opioids could be minimized by magnesium infusion; therefore, the further downgradation of patients of LVRS may be prevented.

CONCLUSION

Intravenous magnesium can prolong opioid-induced analgesia while minimizing nausea, pruritus, and somnolence.

The challenge of pain management in patients with myasthenia gravis

Myasthenia gravis (MG) is an autoimmune disorder of the neuromuscular junction. The complexity of the disease and its treatments make MG patients particularly susceptible to adverse effects of drugs. MG is not a painful condition; however, as pain management armamentarium includes drugs from diverse pharmacological groups and with potential for drug-drug interactions, managing pain in patients with MG can be challenging. The underlying disease and the concomitant medications of each patient must be considered and the analgesic treatment individualized. This review presents an update on the various aspects of pain pharmacotherapy in patients with MG, focusing primarily on medications used to treat chronic pain. Drugs discussed are opioids, nonsteroidal anti-inflammatory drugs, antidepressants, anticonvulsants, muscle relaxants, benzodiazepines, intravenous magnesium, and local anesthetics. Drug interactions with agents used for MG treatment (acethylcholinesterase inhibitors, corticosteroids, immunosuppressants) and plasmapheresis are discussed. The clinical usefulness and limitations of each of the drug classes and agents are described.

Wound infiltration with magnesium sulphate and ropivacaine mixture reduces postoperative tramadol requirements after radical prostatectomy

PURPOSE

This prospective, randomized, double-dummy study was undertaken to compare the effects of magnesium sulphate (MgSO(4)) administered by the intravenous vs. the infiltration route on postoperative pain and analgesic requirements.

METHODS

Forty ASA I or II men scheduled for radical retropubic prostatectomy under general anaesthesia were randomized into two groups (n=20 each). Two medication sets A and B were prepared at the pharmacy. Each set contained a minibag of 50 ml solution for IV infusion and a syringe of 45 ml for wound infiltration. Group MgSO(4).IV patients received set A with 50 mg/kg MgSO(4) in the minibag and 190 mg of ropivacaine in the syringe. Group MgSO(4)/L received set B with isotonic saline in the minibag and 190 mg of ropivacaine +750 mg of MgSO(4) in the syringe. The IV infusion was performed over 30 min at induction of anaesthesia and the surgical wound infiltration was performed during closure. Pain was assessed every 4 h, using a 100-point visual analogue scale (VAS). Postoperative analgesia was standardized using IV paracetamol (1 g/6 h) and tramadol was administered via a patient-controlled analgesia system. The follow-up period was 24 h.

RESULTS

The total cumulative tramadol consumption was 221 +/- 64.1 mg in group MgSO4.IV and 134 +/- 74.9 mg in group MgSO(4).L (P<0.01). VAS pain scores were equivalent in the two groups throughout the study. No side-effects, due to systemic or local MgSO(4) administration, were observed.

CONCLUSION

Co-administration of MgSO(4) with ropivacaine for postoperative infiltration analgesia after radical retropubic prostatectomy produces a significant reduction in tramadol requirements.

Sublingual oxybutynin reduces postoperative pain related to indwelling bladder catheter after radical retropubic prostatectomy †

BACKGROUND

Bladder discomfort related to an indwelling catheter can exacerbate postoperative pain. It mimics overactive bladder syndrome that is resistant to conventional opioid therapy. Muscarinic receptor antagonists are effective for treatment of the overactive bladder. The aim of this study was to assess the efficacy of oxybutynin in the management of postoperative pain after radical prostatectomy.

METHOD

Forty-six ASA I or II men undergoing radical retropubic prostatectomy under general anaesthesia were randomly assigned to two groups, in a double-blind fashion: Group O and Group P (n = 23 each). Group O and Group P received, respectively, sublingual oxybutynin 5 mg or placebo every 8 h during the 24 h after surgery. A 16F Foley catheter was placed during the vesico-urethral anastomosis and the balloon inflated with 10 ml of saline. Pain was assessed in the recovery room starting 10 min after extubation using a 100-point visual analogue scale (VAS). The patients were asked to specify whether pain was related to the surgical incision or bladder pain. Standardized postoperative analgesia included acetaminophen and tramadol administered via a patient-controlled analgesia system.

RESULTS

The incidence of bladder catheter pain was 65% (15 of 23 patients) in Group P compared with 17% (4 of 23 patients) in Group O (P < 0.01). Overall VAS scores at rest were significantly lower in Group O. Cumulative tramadol consumption was 322.9(124.3) mg [mean(sd)] in Group P and 146(48) mg in Group O (P < 0.01). No oxybutynin-related side-effects were reported.

CONCLUSIONS

Sublingual oxybutynin is an effective treatment for postoperative pain after radical retropubic prostatectomy and produces a significant reduction in tramadol requirements.