The effect of magnesium sulphate on postoperative analgesia requirements in gynecological surgeries

Intravenous Magnesium for the Management of Chronic Pain:An Updated Review of the Literature

Background

Available therapeutic options are currently limited by their modest efficacy. As a result, novel pharmacotherapeutic treatments with different mechanisms have recently attracted empirical attention. Magnesium, a divalent cation, is postulated to provide analgesic and anti-nociceptive effect through its action at the N-methyl-D-aspartate (NMDA) receptor.

Objective

Considering the evidence surrounding magnesium's potential as a therapeutic modality for chronic pain, we conducted a narrative review on the evidence of magnesium's therapeutic effects in chronic pain.

Methods

A review of the PubMed, and Google scholar databases was undertaken in May 2022 to identify completed studies that investigated the effectiveness of magnesium in the treatment of chronic pain from database inception to May 2022.

Results

A total of 33 studies were included in the narrative review, out of which 26 were randomized controlled trials. Findings on available studies suggest that intravenous infusion of magnesium is an emerging and promising option that may alleviate pain in some clinical populations. Our narrative synthesis showed that evidence for intravenous magnesium is currently equivocal for a variety of chronic pain syndrome. Findings indicate that evidence for efficacy is poor or equivocal for: CRPS, neuropathic pain, chronic low back pain, and migraine prophylaxis. However, there is good evidence supporting the efficacy of intravenous magnesium for treating renal colic pain and pelvic pain related to endometriosis.

Conclusion

Magnesium may be a promising pharmacologic solution for chronic pain. Future investigation is warranted on elucidating the neurobiological mechanisms of magnesium in attenuating pain signaling pathways.

Efficacy of memantine premedication in alleviating postoperative pain- A systematic review and meta-analysis

Many premedication agents with opioid-sparing properties have been used in patients undergoing various elective surgeries. Memantine is an N-methyl-D-aspartate (NMDA) receptor antagonist that has been used by many researchers as an opioid-sparing strategy. Various databases like PubMed, Scopus, Cochrane Library, and clinicaltrials.gov were searched after registering the review protocol in PROSPERO for randomized-controlled trials (RCTs) that investigated the efficacy and safety of memantine premedication in adult patients undergoing various elective surgeries. The risk of bias (RoB-2) scale was used to assess the quality of evidence. From the 225 articles that were identified after a database search, 3 studies were included for a qualitative systematic review and a quantitative meta-analysis. The pooled analysis revealed that the use of memantine provided better pain scores at 2nd (mean difference: -0.82, 95% CI: -1.60, -0.05, P = 0.04) with significant heterogeneity (P = 0.06; I² =71%), and 6 hours postoperatively (mean difference: -1.80, 95% CI: -2.23, -1.37, P < 0.00001), but not at 1 hour. The sedation scores at 1 hour were higher in the memantine group but comparable in the 2nd hour. The number of doses of rescue analgesia and nausea/vomiting in the postoperative period was comparable in both groups. The results of this review suggest that memantine premedication could provide better pain scores in the immediate postoperative period with acceptable adverse effects. However, the current evidence is insufficient to suggest the routine use of memantine as a premedication before elective surgeries.

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.

Management of pain using magnesium sulphate: A narrative review

Pain is one of the most complex and unpleasant sensory and emotional human experiences. Pain relief continues to be a major medical challenge. The application of systemic opioid and regional analgesia techniques has facilitated a decrease in the occurrence and gravity of pain. Magnesium has an evolving role in pain management. Magnesium sulphate (MgSO4), the pharmacological form of magnesium, is a physiological voltage-dependent blocker of N-methyl-D-aspartate (NMDA)-coupled channels. In terms of its antinociceptive role, magnesium blocks calcium influx, which inhibits central sensitization and decreases preexisting pain hypersensitivity. These properties have encouraged the research of magnesium as an adjuvant agent for intra- and post-operative analgesia. Moreover, the mentioned magnesium impacts are also detected in patients with neuropathic pain. Intravenous magnesium sulphate, followed by a balanced analgesia, decreases opioid consumption. This review has focused on the existing evidence concerning the role of magnesium sulphate in pain management in situations including neuropathic pain, postherpetic neuralgia, trigeminal neuralgia, migraine, and post-operative pain. Additional studies are required to improve the use of magnesium sulphate for pain to increase the quality of life of patients.

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.

Intravenous magnesium sulfate for postoperative analgesia after abdominal hysterectomy under spinal anesthesia: a randomized, double-blind trial

Background and objectives

Abdominal Hysterectomy (AH) is associated with significant inflammatory response and can result in moderate to severe postoperative pain. This study aimed to evaluate the efficacy of magnesium infusion in reducing postoperative pain and analgesic consumption after AH under spinal anesthesia with Intrathecal Morphine (ITM).

Method

Eighty-six patients were included in this clinical, controlled, randomized, double-blind study. Patients received in Group Mg, MgSO₄ 50 mg kg⁻¹ for 15 minutes followed by 15 mg kg⁻¹ h⁻¹ until the end of the surgery; and in Group C, (control) the same volume of isotonic saline. Both groups received 100 μg of ITM. All patients received dipyrone + ketoprofen intraoperatively and postoperatively, and dexamethasone intraoperatively only. We evaluated the intensity of pain, tramadol consumption, and adverse events 24 hours postoperatively.

Results

Serum magnesium concentrations were higher in Group Mg at the end, and one hour after the operation (p = 0.000). Postoperative pain scores were reduced in Group Mg at 6 hours at rest and on movement (p < 0.05). Tramadol consumption did not show a statistically significant difference between Group Mg and Group C (15.5 ± 36.6 mg and 29.2 ± 67.8 mg respectively, p = 0.53). Hemodynamic variables, the incidence of pruritus, nausea, and vomiting were similar in the two groups.

Conclusion

Infusion of MgSO₄ during AH undergoing spinal anesthesia with ITM reduced at 6 hours at rest and on movement. More studies should be performed to evaluate the potential antinociceptive effect of MgSO₄ in scenarios where a multimodal analgesia approach was employed.

Utilization of Magnesium for the Treatment of Chronic Pain

CONTEXT

The International Association for the Study of Pain (IASP) defines chronic pain as pain that persists or recurs for longer than 3 months. Chronic pain has a significant global disease burden with profound effects on health, quality of life, and socioeconomic costs.

EVIDENCE ACQUISITION

Narrative review.

RESULTS

There are several treatment options, including pharmacological therapy, physical rehabilitation, psychological therapies, and surgical interventions, for chronic pain management. Magnesium has been FDA-approved for several indications including hypomagnesemia, arrhythmia, prevention of seizures in eclampsia/preeclampsia, and constipation. Magnesium has been used for numerous off-label uses, notably for acute and chronic pain management. The mechanism of magnesium in pain management is primarily through its action as a voltage-gated antagonist of NMDA receptors, which are involved in pain transduction.

CONCLUSIONS

This narrative review will focus on the current evidence and data surrounding the utilization of magnesium as a treatment option for chronic pain.

Evidence review conducted for the AHRQ Safety Program for Improving Surgical Care and Recovery: focus on anesthesiology for gynecologic surgery

Enhanced recovery after surgery (ERAS) protocols for gynecologic (GYN) surgery are increasingly being reported and may be associated with superior outcomes, reduced length of hospital stay, and cost savings. The Agency for Healthcare Research and Quality, in partnership with the American College of Surgeons and the Johns Hopkins Medicine Armstrong Institute for Patient Safety and Quality, has developed the Safety Program for Improving Surgical Care and Recovery, which is a nationwide initiative to disseminate best practices in perioperative care to more than 750 hospitals across five major surgical service lines in a 5-year period. The program is designed to identify evidence-based process measures shown to prevent healthcare-associated conditions and hasten recovery after surgery, integrate those into a comprehensive service line-based pathway, and assist hospitals in program implementation. In conjunction with this effort, we have conducted an evidence review of the various anesthesia components which may influence outcomes and facilitate recovery after GYN surgery. A literature search was performed for each intervention, and the highest levels of available evidence were considered. Anesthesiology-related interventions for preoperative (carbohydrate loading/fasting, multimodal preanesthetic medications), intraoperative (standardized intraoperative pathway, regional anesthesia, protective ventilation strategies, fluid minimization) and postoperative (multimodal analgesia) phases of care are included. We have summarized the best available evidence to recommend the anesthetic components of care for ERAS for GYN surgery.