The analgesic efficacy and safety of neuraxial magnesium sulphate: a quantitative review

Magnesium Sulfate in Pediatric Abdominal Cancer Surgery: Safety and Efficacy in Ultrasound-Guided Transversus Abdominis Plane (US-TAP) Block in Conjugation with Levobupivacaine

Purpose

Magnesium sulfate (MgSO4) may enhance the effects of local anesthetics when used as an adjuvant in peripheral nerve blocks. Our objective was to evaluate efficiency and safety of utilizing MgSO4 alongside levobupivacaine in bilateral ultrasound-guided transversus abdominis plane (US-TAP) block for postoperative pain in pediatric cancer patients who underwent abdominal surgery.

Methodology

A randomized double-blinded controlled trial at South Egypt Cancer Institute, Assiut University, Assiut, Egypt, included that 40 pediatric patients with Wilms' tumor or neuroblastoma were randomly allocated to get bilateral (US-TAP) block and divided into two groups; M group: received US-TAP with 0.6 mL/kg levobupivacaine 0.25% + 2 mg/kg MgSO4 and C group: received with 0.6 mL/kg levobupivacaine 0.25% only. FLACC scores (Face, Leg, Activity, Cry, Consolability) were used to evaluate post-operative pain, first analgesic request, total analgesic consumption, adverse effects, as well as hemodynamics were monitored for 24 h and recorded at time points (2, 4, 6, 8, 12, 18, and 24h). Parent's satisfaction at discharge, also, was evaluated.

Results

FLACC score in M group was significantly lower than in C group from 4 h to 24 h with the first analgesic request being longer (15.95 ± 1.99 vs 7.70 ± 0.80 (h); p < 0.001) and lower total analgesic consumption (231.75 ± 36.57 vs 576.00 ± 170.71 (mg); p < 0.001) when comparing M group to C group, respectively. Both groups had insignificant differences regarding hemodynamics, parent satisfaction, postoperative agitation, and side effects except vomiting occurred in two patients in the C group and one patient in the M group.

Conclusion

We conclude that adding magnesium sulphate as an adjuvant to local anaesthetic in US-TAP block for pain management in pediatric abdominal cancer surgeries resulted in better and longer analgesia, with less consumption of rescue analgesics with no serious side effects.

The Antinociceptive Effect of Magnesium Sulphate Administered in the Epidural Space in Standing Horses

To study the antinociceptive properties of epidural magnesium sulphate (MgSO₄) in standing horses Experimental, placebo-controlled, masked, cross-over A group of six healthy horses Through an epidural catheter, 1 mg kg ^-1 MgSO₄ (treatment Mg) diluted to a volume of 15 mL or the same volume of saline (treatment S) was administered over 15 minutes. Electrical, thermal and mechanical nociceptive thresholds were determined on the pelvic limb before and 20, 40, 60, 80, 100, 120, 140, 160 and 180 minutes after the start of the injection. Heart rate (HR) and respiratory frequency (f_R) were recorded every 10 minutes. Blood samples were collected before treatment and every 30 minutes throughout the study period. Data were assessed for normality using a Shapiro-Wilk test. A linear mixed model with horse as random effect and time, treatment and their interaction as fixed effects was used. Treatments were compared at 20, 60, 120 and 180 minutes using the Wilcoxon rank sum test stratified for horse (global α = 0.05, with Bonferroni correction α = 0.0125). Epidural MgSO₄ caused a significant increase in the electrical threshold (mA) (P = .0001), but no significant differences in thermal and mechanical nociceptive thresholds. During the injection of MgSO_4, two horses collapsed. One stood up within 20 minutes and was able to continue the study, the second one was excluded. A significant difference was found for HR at T180 (Mg 44 ± 23 beats minute^-1; S 32 ± 9 beats minute^-1) (P = .0090). Epidural administration of MgSO₄ caused an increase in the electrical threshold of the pelvic limbs of horses. Caution is warranted however, as with the current dose, 2 horses collapsed.

Effect of intravenous magnesium on postoperative pain control for major abdominal surgery: a randomized double-blinded study

Background

This study aimed to evaluate the postoperative analgesic effect of magnesium sulfate during abdominal surgery.

Methods

This randomized double-blinded study involved 84 patients candidates for abdominal surgery into two same groups. In the magnesium group, at first 25 mg/kg/1 h magnesium sulfate; and then, 100 mg/kg/24 h was infused in the intensive care unit. The pain intensity (the primary outcome), was assessed using the numeric rating scale (NRS) every 3 h. If the NRS was > 3, morphine (as a secondary outcome) was used and evaluated. The results were analyzed using SPSS ver. 19 software, and statistical significance was set at P < 0.05

Results

Demographic parameters were similar between the groups. The pain intensity were similar at first and then at the third hour in both groups (P = 0.393 and P = 0.172, respectively), but thereafter between 6 and 24 h, the pain severity was significantly lower in the magnesium group (4.4 ± 1.3 in the control and 3.34 ± 1 in the magnesium group at 6th hour and P = 0.001). In addition, morphine intake in the first 24 h in the two groups had a significant difference, with 13.2 ± 5.7 mg in control group and 8 ± 3.5 mg in magnesium group (P = 0.001).

Conclusions

In this study, intravenous magnesium sulfate after abdominal surgeries for 24 h resolved the pain intensity after six hours and reduced morphine dosage.

The Options for Neuraxial Drug Administration

Neuraxial drug administration, i.e., the injection of drugs into the epidural or intrathecal space to produce anesthesia or analgesia, is a technique developed more than 120 years ago. Today, it still is widely used in daily practice in anesthesiology and in acute and chronic pain therapy. A multitude of different drugs have been introduced for neuraxial injection, only a part of which have obtained official approval for that indication. A broad understanding of the pharmacology of those agents is essential to the clinician to utilize them in a safe and efficient manner. In the present narrative review, we summarize current knowledge on neuraxial anatomy relevant to clinical practice, including pediatric anatomy. Then, we delineate the general pharmacology of neuraxial drug administration, with particular attention to specific aspects of epidural and intrathecal pharmacokinetics and pharmacodynamics. Furthermore, we describe the most common clinical indications for neuraxial drug administration, including the perioperative setting, obstetrics, and chronic pain. Then, we discuss possible neurotoxic effects of neuraxial drugs, and moreover, we detail the specific properties of the most commonly used neuraxial drugs that are relevant to clinicians who employ epidural or intrathecal drug administration, in order to ensure adequate treatment and patient safety in these techniques. Finally, we give a brief overview on new developments in neuraxial drug therapy.

Efficacy of magnesium sulfate as an adjuvant to rocuronium in general anaesthesia: a meta-analysis

Objective

Magnesium sulfate is considered to be an effective adjuvant to rocuronium in general anaesthesia. We conducted a meta-analysis to clarify its efficacy.

Methods

We searched the PubMed, Embase, Web of Science, Cochrane Library, WanFang, Chinese Biomedical Literature, and China National Knowledge Infrastructure databases for randomized controlled trials (RCTs) of magnesium sulfate as an adjuvant to rocuronium from the start of the database establishment until May 2020.

Results

Eleven RCTs were analysed. The pooled meta-analysis showed that using magnesium sulfate as an adjuvant significantly shortened the onset time and prolonged the clinical duration of neuromuscular blockade by rocuronium compared with the control group without magnesium sulfate. However, there was no significant difference in recovery index of neuromuscular block between the magnesium and control groups. Furthermore, magnesium sulfate significantly increased the rates of excellent and clinically acceptable intubation conditions.

Conclusion

Adding magnesium sulfate to rocuronium during general anaesthesia can alter the neuromuscular parameters, including shortening the anaesthesia-onset time and prolonging the clinical duration, without significantly increasing the recovery time. Pretreatment with magnesium sulfate may also improve intubation conditions during general anaesthesia.

Dexmedetomidine versus magnesium sulfate as an adjuvant to local anesthetics in spinal anesthesia: a meta-analysis of randomized controlled trials

Objective

To compare the efficacy of dexmedetomidine and magnesium sulfate as an adjuvant to local anesthetics in spinal anesthesia.

Methods

A search of PubMed, Medline, Embase, the Cochrane Library, and Google Scholar was performed. Randomized controlled trials comparing the efficacy of dexmedetomidine and magnesium sulfate as a local anesthetic adjuvant in spinal anesthesia were identified. The primary outcome was sensory block duration. The mean difference (MD) or odds ratio along with the 95% confidence interval (CI) was used to analyze the outcomes.

Results

Six studies involving 360 patients were included. Intrathecal dexmedetomidine was associated with a significantly longer sensory block duration (MD = −73.62; 95% CI = −101.09 to −46.15), faster onsets of sensory blockade and motor blockade, and a longer motor block duration than intrathecal magnesium sulfate. There was no significant difference between the regarding the rates of hypotension, bradycardia, shivering, and postoperative nausea and vomiting between the groups.

Conclusions

Dexmedetomidine is superior to magnesium sulfate as an adjuvant to local anesthetics in spinal anesthesia because of its more rapid onset and longer duration of spinal block without significant adverse effects.

Optimizing Perioperative Use of Opioids: A Multimodal Approach

Purpose of Review

The main purpose of this article is to review recent literature regarding multimodal analgesia medications, citing their recommended doses, efficacy, and side effects. The second part of this report will provide a description of drugs in different stages of development which have novel mechanisms with less side effects such as tolerance and addiction.

Recent Findings

Multimodal analgesia is a technique that facilitates perioperative pain management by employing two or more systemic analgesics along with regional anesthesia, when possible. Even though opioids and non-opioid analgesics remain the most common medication used for acute pain management after surgery, they have many undesirable side effects including the potential for misuse. Newer analgesics including peripheral acting opioids, nitric oxide inhibitors, calcitonin gene-related peptide receptor antagonists, interleukin-6 receptor antagonists and gene therapy are under intensive investigation.

Summary

A patient's first exposure to opioids is often in the perioperative setting, a vulnerable time when multimodal therapy can play a large role in decreasing opioid exposure. Additionally, the current shift towards faster recovery times, fewer post-operative complications and improved cost-effectiveness during the perioperative period has made multimodal analgesia a central pillar of Enhanced Recovery After Surgery (ERAS) protocols.

Placenta accreta spectrum disorders - Peri-operative management: The role of the anaesthetist

The incidence of placenta accreta spectrum (PAS) is increasing and will become more commonly encountered by obstetric anaesthetists in the elective and emergency settings. Significant maternal and neonatal morbidity is associated with these disorders, and hence it is important for anaesthetists to have early involvement in perioperative planning. Major haemorrhage should be anticipated and requires robust perioperative preparation including Patient Blood Management (PBM) and use of intraoperative strategies for haemorrhage management wherever possible. Several institutions have demonstrated good outcomes with regional anaesthesia alone, but the choice of anaesthetic technique requires individualised planning considering patient, anaesthetic and surgical factors. Optimisation of postoperative analgesia needs additional consideration; it is key to good recovery, minimising the impact on quality of life and reducing the risk of persistent post-surgical pain. Further research is required to ascertain the optimal multi-modal analgesic regime including the role of peripheral nerve blockade.

Effectiveness of Magnesium in Preventing Shivering in Surgical Patients: A Systematic Review and Meta-analysis

BACKGROUND

Clinical trials regarding the antishivering effect of perioperative magnesium have produced inconsistent results. We conducted a systematic review and meta-analysis with Trial Sequential Analysis to evaluate the effect of perioperative magnesium on prevention of shivering.

METHODS

We searched PubMed, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, and 2 registry sites for randomized clinical trials that compared the administration of magnesium to a placebo or no treatment in patients undergoing surgeries. The primary outcome of this meta-analysis was the incidence of shivering. The incidence of shivering was combined as a risk ratio with 95% CI using a random-effect model. The effect of the route of administration was evaluated in a subgroup analysis, and Trial Sequential Analysis with a risk of type 1 error of 5% and power of 90% was performed. The quality of each included trial was evaluated, and the quality of evidence was assessed using the Grading of Recommendation Assessment, Development, and Evaluation approach. We also assessed adverse events.

RESULTS

Sixty-four trials and 4303 patients (2300 and 2003 patients in magnesium and control groups, respectively) were included. The overall incidence of shivering was 9.9% in the magnesium group and 23.0% in the control group (risk ratio, 0.42; 95% CI, 0.33-0.52). Subgroup analysis revealed that the incidence of shivering was lower with IV (risk ratio, 0.29; 95% CI, 0.29-0.54; Grading of Recommendation Assessment, Development, and Evaluation, moderate), epidural (risk ratio, 0.24; 95% CI, 0.13-0.43; Grading of Recommendation Assessment, Development, and Evaluation, low), and intrathecal administration (risk ratio, 0.64; 95% CI, 0.43-0.96; Grading of Recommendation Assessment, Development, and Evaluation, moderate). Only trials with low risk of bias were included for Trial Sequential Analysis. The Z-cumulative curve for IV magnesium crossed the Trial Sequential Analysis monitoring boundary for benefit even though only 34.9% of the target sample size had been reached. The Z-cumulative curve for epidural or intrathecal administration did not cross the Trial Sequential Analysis monitoring boundary for benefit. No increase in adverse events was reported.

CONCLUSIONS

Perioperative IV administration of magnesium effectively reduced shivering and Trial Sequential Analysis suggested that no more trials are required to confirm that IV magnesium effectively reduces shivering.

Comparison of hemodynamic changes of magnesium sulfate and dexmedetomidine for an axillary brachial plexus block

Introduction:

Axillary brachial plexus block is used for anesthesia in hands and forearm surgery. The aim of this study was to compare the hemodynamic changes of magnesium sulfate and dexmedetomidine in axillary block.

Materials and Methods:

This randomized, double-blind clinical trial was conducted on 99 patients undergoing a forearm and hand surgery at the Vali-Asr Hospital. Patients were divided into three groups. Dexmedetomidine group consisted of lidocaine 1.5% plus 0.5 μg/kg dexmedetomidine, magnesium sulfate group included lidocaine 1.5% plus 100 mg magnesium sulfate, and the control group received lidocaine 1.5% with normal saline. The final volume was divided into 35 groups in three groups. Blood pressure, heart rate, and oxygen saturation were measured every 5 minutes during surgery, and data were analyzed by SPSS 23.

Results:

There was a statistically significant difference between the three groups in terms of the mean blood pressure during surgery (P < 0.05). At all times, blood pressure in the dexmedetomidine group was lower as compared to the other two groups. But in the 20^th and 25^th minutes, there was a relative increase in blood pressure. There was a significant difference between the three groups in terms of heart rate during surgery in minutes 20, 25, 65–100, and 110–120 (P < 0.05).

Conclusion:

The final result showed that the blood pressure and heart rate of the dexmedetomidine group patients at different times were less than the other two groups.

Analgesic effect of adding magnesium sulfate to epidural levobupivacaine in patients with pre-eclampsia undergoing elective cesarean section

Background and Aims:

Magnesium is a physiological antagonist of NMDA receptor and a calcium channel blocker. This study was designed to test the analgesic effect of magnesium sulfate (MgSO₄) when added to epidural anesthesia in mild pre-eclampsia.

Material and Methods:

Sixty parturients with mild pre-eclampsia were allocated randomly to two equal groups. The Placebo group received 20 ml levobupivacaine hydrochloride 0.5% plus 5 ml isotonic saline 0.9% using two separate syringes. The Magnesium group received the same amount of local anesthetic plus 5 ml of 10% MgSO₄(500 mg) using two separate syringes. The primary outcome was pain free period. While, the secondary outcomes were the onset of motor block and the time needed to achieve complete motor block. The analgesic profile was evaluated by visual analog scale (VAS) during rest or motion, the time to first request for analgesia, and the total analgesic consumption.

Results:

The pain-free period was significantly longer in the Magnesium group (311.3 ± 21.4) compared to placebo group (153.1 ± 22.18). The total postoperative consumption of fentanyl was significantly lower in the Magnesium group (42.4 ± 5.3) than that in the placebo group (94.4 ± 9.9), with a P value 0. 01. Both the onset time of motor block and the time needed to achieve complete motor block were significantly shorter among the Magnesium group (4.4 ± 1.4 and 8.2 ± 0.4, respectively), with a P value of 0. 01.

Conclusion:

The addition of 500 mg MgSO₄ to epidural anesthesia fastens both sensory and motor blockade and improves postoperative analgesic profile.

Effect of Adding Magnesium Sulphate to Epidural Bupivacaine and Morphine on Post-Thoracotomy Pain Management: A Randomized, Double-Blind, Clinical Trial

Post-thoracotomy pain is very severe and may cause pulmonary complications. Thoracic epidural analgesia can greatly decrease the pain experience and its consequences. However, finding new methods to decrease the amount of administered opioids is an important issue of research. We aimed to evaluate the effect of adding epidural magnesium sulphate to bupivacaine and morphine on pain control and the amount of opioid consumption after thoracotomy. Eighty patients undergoing thoracotomy at a tertiary cardiothoracic referral centre were enrolled in a randomized, double-blind trial. Patients were randomly allocated to two groups. Bupivacaine (12.5 mg) and morphine (2 mg) were administered epidurally to all patients at the end of operation. Patients in the magnesium (Mg) group received epidural magnesium sulphate (50 mg), and patients in the control (C) group received normal saline as an adjuvant. Visual analogue scale (VAS) score and the amount of morphine consumption were measured during 24 hr post-operation. Thirty-nine patients in the Mg group and 41 patients in the C group completed the study. Patients in the Mg group had significantly less VAS score at recovery time (p < 0.05), 2 hr (p < 0.01) and 4 hr (p < 0.05) after surgery. The patient-controlled analgesia pump was started earlier in the C group than in the Mg group (p < 0.05). The amount of morphine needed in the Mg group was significantly lower than in the C group (5.64 ± 1.69 mg/24 hr versus 8.44 ± 3.98 mg/24 hr; p < 0.001). Pruritus was seen in the C group (9.7%) and absent in the Mg group (p < 0.05). Co-administration of magnesium sulphate with bupivacaine and morphine for thoracic epidural analgesia after thoracotomy leads to a reduction in post-operative pain score and the need for opioid administration.

Adjunct medications for peripheral and neuraxial anesthesia

Regional and neuraxial anesthesia can provide a safer perioperative experience, greater satisfaction, reduced opioid consumption, and reduction of pain, while minimizing side effects. Ultrasound technology has aided clinicians in depositing local anesthetic medication in precise proximity to targeted peripheral nerves. There are a plethora of adjuvants that have been utilized to prolong local anesthetic actions and enhance effects in peripheral nerve blocks. This manuscript describes the current state of the use of adjuncts, e.g., dexmedetomidine, dexamethasone, clonidine, epinephrine, etc., in regional anesthesia. Additionally, evidence behind dosing and block prolongation is summarized along with patient outcomes, adverse effects, and future directions.

Effect of magnesium added to local anesthetics for caudal anesthesia on postoperative pain in pediatric surgical patients: A systematic review and meta-analysis with Trial Sequential Analysis

BACKGROUND

Magnesium has been investigated as an adjuvant for neuraxial anesthesia, but the effect of caudal magnesium on postoperative pain is inconsistent. The aim of this systematic review and meta-analysis was to evaluate the analgesic effect of caudal magnesium.

METHODS

We searched six databases, including trial registration sites. Randomized clinical trials reporting the effect of caudal magnesium on postoperative pain after general anesthesia were eligible. The risk ratio for use of rescue analgesics after surgery was combined using a random-effects model. We also assessed adverse events. The I2 statistic was used to assess heterogeneity. We assessed risk of bias with Cochrane domains. We controlled type I and II errors due to sparse data and repetitive testing with Trial Sequential Analysis. We assessed the quality of evidence with GRADE.

RESULTS

Four randomized controlled trials (247 patients) evaluated the need for rescue analgesics. In all four trials, 50 mg of magnesium was administered with caudal ropivacaine. The results suggested that the need for rescue analgesia was reduced significantly by caudal magnesium administration (risk ratio 0.45; 95% confidence interval 0.24-0.86). There was considerable heterogeneity as indicated by an I2 value of 62.5%. The Trial Sequential Analysis-adjusted confidence interval was 0.04-5.55, indicating that further trials are required. The quality of evidence was very low. The rate of adverse events was comparable between treatment groups.

CONCLUSION

Caudal magnesium may reduce the need for rescue analgesia after surgery, but further randomized clinical trials with a low risk of bias and a low risk of random errors are necessary to assess the effect of caudal magnesium on postoperative pain and adverse events.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry UMIN000025344.

Intrathecal magnesium sulfate does not reduce the ED50 of intrathecal hyperbaric bupivacaine for cesarean delivery in healthy parturients: a prospective, double blinded, randomized dose-response trial using the sequential allocation method

Background

Addition of intrathecal magnesium sulfate to local anesthetics has been reported to potentiate spinal anesthesia and prolong analgesia in parturients. The current study was to determine whether intrathecal magnesium sulfate would reduce the dose of hyperbaric bupivacaine in spinal anesthesia with bupivacaine and sufentanil for cesarean delivery.

Methods

Sixty healthy parturients undergoing scheduled cesarean delivery were randomly assigned to receive spinal anesthesia with 0.5% hyperbaric bupivacaine and 5 μg sufentanil with either 0.9% sodium chloride (Control group) or 50% magnesium sulfate (50 mg) (Magnesium group). Effective anesthesia was defined as a bilateral T₅ sensory block level achieved within 10 min of intrathecal drug administration and no additional epidural anesthetic was required during surgery. Characteristic of spinal anesthesia and the incidence of side effects were observed. The ED₅₀ for both groups was calculated using the Dixon and Massey formula.

Results

There was no significant difference in the ED₅₀ of bupivacaine between the Magnesium group and the Control group (4.9 mg vs 4.7 mg) (P = 0.53). The duration of spinal anesthesia (183 min vs 148 min, P < 0.001) was longer, the consumption of fentanyl during the first 24 h postoperatively (343 μg vs 550 μg, P < 0.001) was lower in the Magnesium group than that in the Control group.

Conclusions

Intrathecal magnesium sulfate (50 mg) did not reduce the dose requirement of intrathecal bupivacaine, but can extend the duration of spinal anesthesia with no obvious additional side effects.

Trial registration

This study was registered with Chinese Clinical Trial Registry (ChiCTR) on 15 Jul. 2014 and was given a trial ID number ChiCTR-TRC-14004954.

Magnesium in obstetric anesthesia and intensive care

Magnesium, one of the essential elements in the human body, has numerous favorable effects that offer a variety of possibilities for its use in obstetric anesthesia and intensive care. Administered as a single intravenous bolus dose or a bolus followed by continuous infusion during surgery, magnesium attenuates stress response to endotracheal intubation, and reduces intraoperative anesthetic and postoperative analgesic requirements, while at the same time preserving favorable hemodynamics. Applied as part of an intrathecal or epidural anesthetic mixture, magnesium prolongs the duration of anesthesia and diminishes total postoperative analgesic consumption with no adverse maternal or neonatal effects. In obstetric intensive care, magnesium represents a first-choice medication in the treatment and prevention of eclamptic seizures. If used in recommended doses with close monitoring, magnesium is a safe and effective medication.

Regional anaesthesia in neonates, infants and children: an educational review

Prophylactic analgesia with local anaesthesia is widely used in children and has a good safety record. Performing regional blocks in anaesthetised children is a safe and generally accepted practice. When compared with adults, lower concentrations of local anaesthetics are sufficient in children; the onset of a block occurs more rapidly but the duration is usually shorter. Local anaesthetics have a greater volume of distribution, a lower clearance and a higher free (non-protein-bound) fraction. The recommended maximum dose has to be calculated for every individual. Peripheral blocks provide analgesia restricted to the site of surgery, and some of them have a very long duration of action. Abdominal wall blocks, such as transverse abdominis plane or ilio-inguinal nerve block, should be performed with the aid of ultrasound. Caudal anaesthesia is the single most important technique. Ropivacaine 0.2% or levobupivacaine 0.125 to 0.175% at roughly 1 ml  kg⁻¹ is adequate for most indications. Clonidine and morphine can be used to prolong the duration of analgesia. Ultrasound is not essential for performing caudal blocks, but it may be helpful in case of anomalies suspected at palpation and for teaching purposes. The use of paediatric epidural catheters will probably decline in the future because of the potential complications.

Local Anesthetic Peripheral Nerve Block Adjuvants for Prolongation of Analgesia: A Systematic Qualitative Review

Background

The use of peripheral nerve blocks for anesthesia and postoperative analgesia has increased significantly in recent years. Adjuvants are frequently added to local anesthetics to prolong analgesia following peripheral nerve blockade. Numerous randomized controlled trials and meta-analyses have examined the pros and cons of the use of various individual adjuvants.

Objectives

To systematically review adjuvant-related randomized controlled trials and meta-analyses and provide clinical recommendations for the use of adjuvants in peripheral nerve blocks.

Methods

Randomized controlled trials and meta-analyses that were published between 1990 and 2014 were included in the initial bibliographic search, which was conducted using Medline/PubMed, Cochrane Central Register of Controlled Trials, and EMBASE. Only studies that were published in English and listed block analgesic duration as an outcome were included. Trials that had already been published in the identified meta-analyses and included adjuvants not in widespread use and published without an Investigational New Drug application or equivalent status were excluded.

Results

Sixty one novel clinical trials and meta-analyses were identified and included in this review. The clinical trials reported analgesic duration data for the following adjuvants: buprenorphine (6), morphine (6), fentanyl (10), epinephrine (3), clonidine (7), dexmedetomidine (7), dexamethasone (7), tramadol (8), and magnesium (4). Studies of perineural buprenorphine, clonidine, dexamethasone, dexmedetomidine, and magnesium most consistently demonstrated prolongation of peripheral nerve blocks.

Conclusions

Buprenorphine, clonidine, dexamethasone, magnesium, and dexmedetomidine are promising agents for use in prolongation of local anesthetic peripheral nerve blocks, and further studies of safety and efficacy are merited. However, caution is recommended with use of any perineural adjuvant, as none have Food and Drug Administration approval, and concerns for side effects and potential toxicity persist.

Spinal anesthesia revisited: toxicity of new and old drugs and compounds

PURPOSE OF REVIEW

Neural toxicity of substances injected into the intrathecal space has been a matter of debate since the introduction of spinal anesthesia in clinical practice. In recent years, new local anesthetics and adjuvants have been proposed for intrathecal use, and new techniques such as the use of ultrasound have been propagated. The present review summarizes recent clinical and experimental data on the neurotoxic effects of drugs and substances used for or in conjunction with spinal anesthesia.

RECENT FINDINGS

Chloroprocaine has been demonstrated to be associated with a lower risk of transient neurologic symptoms compared with lidocaine. However, despite extensive research, the issue of chloroprocaine or bisulfite neurotoxicity has not yet been resolved.Recent experimental data have identified a smaller neurotoxic potential for ropivacaine compared to levobupivacaine, procaine and bupivacaine. The addition of epinephrine has not been shown to increase lidocaine neurotoxicity. In-vivo experimental data suggest that lidocaine and bupivacaine neurotoxicity is not enhanced in diabetic patients.Furthermore, intrathecal introduction of aqueous ultrasound gel has been demonstrated to cause a distinct neuroinflammatory reaction. Finally, a large cohort study did not find the use of chlorhexidine gluconate for skin disinfection before neuraxial block to be associated with the risk of adhesive arachnoiditis.

SUMMARY

Clinical data suggest a high safety profile for intrathecal drugs and substances used for or in conjunction with spinal anesthesia. Recent experimental models for toxicity have provided further insight into the mechanisms and demonstrated possible, albeit clinically small differences in the relative neurotoxic potential of intrathecal drugs. This may contribute to a further increase in the safe use of spinal anesthesia in the clinical setting.

Magnesium as an adjuvant for caudal analgesia in children

BACKGROUND

There is a need for an adjuvant agent of caudal block that prolongs its duration and improves the analgesic efficacy to fasten functional recovery. Magnesium is an N-methyl-D-aspartate receptor antagonist that functions as an analgesic. This study was aimed to evaluate whether magnesium as an adjuvant for caudal block in children can improve postoperative analgesia and functional recovery.

METHODS

Eighty children, 2-6 years of age, undergoing inguinal herniorrhaphy, were included in this prospective, randomized, double-blinded study. For caudal block, Group R received ropivacaine 1.5 mg·ml(-1), 1 ml·kg(-1) and Group RM received the same dose of ropivacaine mixed with 50 mg of magnesium. The Parents' Postoperative Pain Measure (PPPM) score, analgesic consumption, functional recovery, and adverse effects were evaluated at 6, 24, 48, and 72 h after surgery, as well as daily thereafter until the child showed full functional recovery.

RESULTS

The PPPM score after hospital discharge was significantly lower for Group RM than for Group R at all times (P < 0.05). Children in Group RM required less fentanyl for rescue analgesia in the recovery area (16.2% vs 39.5%, P = 0.034) and less oral analgesics after discharge (20.5% vs 52.6%, P = 0.007). The time to return of normal functional activity was shorter in Group RM (P < 0.05). The incidence of adverse effects did not differ between groups.

CONCLUSIONS

As an adjuvant for caudal analgesia, 50 mg magnesium provided superior quality of analgesia and faster return of normal functional activity than local anesthetic alone in children.

Accidental intrathecal injection of magnesium sulfate for cesarean section

Magnesium sulfate is used frequently in the operation room and risks of wrong injection should be considered. A woman with history of pseudocholinesterase enzyme deficiency in the previous surgery was referred for cesarean operation. Magnesium sulfate of 700 mg (3.5 ml of 20% solution) was accidentally administered in the subarachnoid space. First, the patient had warm sensation and cutaneous anesthesia, but due to deep tissue pain, general anesthesia was induced by thiopental and atracurium. After the surgery, muscle relaxation and lethargy remained. At 8-10 h later, muscle strength improved and train of four (TOF) reached over 0.85, and then the endotracheal tube was removed. The patient was evaluated during the hospital stay and on the anesthesia clinic. No neurological symptoms, headache or backache were reported. Due to availability of magnesium sulfate, we should be careful for inadvertent intravenous, spinal and epidural injection; therefore before injection must be double checked.

Is intra-articular magnesium effective for postoperative analgesia in arthroscopic shoulder surgery?

As an N-methyl-D-aspartate receptor antagonist, magnesium has been hypothesized to have analgesic effects; in fact, several studies have demonstrated its efficacy for analgesia following intra-articular injection during knee surgery. In this study, intra-articular magnesium was administered during arthroscopic shoulder surgery and its analgesic efficacy was assessed according to pain intensity after surgery as well as postoperative consumption of pain medications.

BACKGROUND:

Various medications are used intra-articularly for postoperative pain reduction after arthroscopic shoulder surgery. Magnesium, a N-methyl-D-aspartate receptor antagonist, may be effective for reduction of both postoperative pain scores and analgesic requirements.

METHODS:

A total of 67 patients undergoing arthroscopic shoulder surgery were divided randomly into two groups to receive intra-articular injections of either 10 mL magnesium sulphate (100 mg/mL; group M, n=34) or 10 mL of normal saline (group C, n=33). The analgesic effect was estimated using a visual analogue scale 1 h, 2 h, 6 h, 8 h, 12 h, 18 h and 24 h after operation. Postoperative analgesia was maintained by intra-articular morphine (0.01%, 10 mg) + bupivacaine (0.5%, 100 mL) patient-controlled analgesia device as a 1 mL infusion with a 1 mL bolus dose and 15 min lock-out time; for visual analogue scale scores >5, intramuscular diclofenac sodium 75 mg was administered as needed during the study period (maximum two times).

RESULTS:

Intra-articular magnesium resulted in a significant reduction in pain scores in group M compared with group C 1 h, 2 h, 6 h, 8 h and 12 h after the end of surgery, respectively, at rest and with passive motion. Total diclofenac consumption and intra-articular morphine + bupivacaine consumption were significantly lower in group M. Postoperative serum magnesium levels were significantly higher in group M, but were within the normal range.

CONCLUSIONS:

Magnesium causes a reduction in postoperative pain in comparison to saline when administered intra-articularly after arthroscopic shoulder surgery, and has no serious side effects.

Effect of pre-emptive magnesium sulfate infusion on the post-operative pain relief after elective cesarean section

Background:

The aim of this study was to evaluate the analgesic efficacy of pre-operative single dose of intravenous (I.V.) magnesium sulfate infusion in patients undergoing elective Cesarean section.

Materials and Methods:

Seventy pregnant women who underwent elective Cesarean section were randomly divided into two groups. Before induction of anesthesia, the magnesium group (Group A) received magnesium sulfate 50 mg/kg I.V. in bolus dose. The control group (Group B) received the same volume of isotonic saline. The pain scores at rest and also upon movement were evaluated up to 24 h post-operatively and analgesic requirement was recorded during the first 24 h after operation.

Results:

Cumulative analgesic consumption (24 h after operation was 11.2 ± 6.3 mg in group A vs. 13.9 ± 3.9 mg in group B). Post-operative pain scores (24 h after operation was 1.8 ± 2.1 in group A vs. 2.9 ± 1.2 in group B) and shivering incidents (8.57 in group A vs. 14.28 in group B) were significantly lower in Group A (P < 0.05). Mean arterial pressure just after intubation and during the immediate post-operative period was significantly lower in Group A (P < 0.05).

Conclusion:

Pre-operative intravenous magnesium sulfate infusion decrease post-operation pain and requirement of analgesia in Cesarean section.