Epidural magnesium reduces postoperative analgesic requirement

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.

Comparative effect of transforaminal injection of Magnesium sulphate versus Ozone on oxidative stress biomarkers in lumbar disc related radicular pain

BACKGROUND

We aimed to investigate the effect of transforaminal injection of Magnesium sulphate versus Ozone on pain intensity, functional disability and the oxidative stress biomarkers; superoxide dismutase (SOD) and Glutathione (GSH) in patients with lumbar disc prolapse.

METHODS

This randomized controlled trial was conducted on 135 patients having symptomatic lumbar disc prolapse, received either transforaminal injection of Magnesium sulphate with steroids, Ozone with steroids, or steroids alone. Assessment of pain severity and functional disability were done before intervention, 2 weeks, 1, 3, and 6 months after intervention. Serum SOD and GSH were measured for all included patients before and 2 weeks after intervention.

RESULTS

There was a statistically significant improvement in pain intensity and functional disability 2 weeks after intervention in the three groups, but at 1-month and 3-months after intervention, the significant improvement was in Mg sulphate and Ozone groups only. At 6-months follow up, Mg sulphate group only showed a significant improvement. There was a statistically significant increase in SOD and GSH serum levels, 2-weeks after intervention in both Magnesium sulphate (P-value = 0.002, 0.005 respectively) and ozone groups (P-value < 0.001, < 0.001), but there was no statistically significant change in SOD and GSH serum levels in control group.

CONCLUSION

Transforaminal injection of Mg sulphate in patients with lumbar disc prolapse causes significant long-term improvement (up to 6 months) in pain intensity and functional disability. The serum levels of SOD and GSH were significantly increased at 2 weeks following both transforaminal injection of Mg sulphate and ozone.

Intra-articular magnesium to alleviate postoperative pain after arthroscopic knee surgery: a meta-analysis of randomized controlled trials

Objective

We aimed to evaluate the safety and efficacy of intra-articular (IA) magnesium (Mg) for postoperative pain relief after arthroscopic knee surgery.

Methods

We searched PubMed, Embase, Medline, Cochrane library, and Web of Science to identify randomized controlled trials that compared postoperative pain outcomes with or without IA Mg after knee arthroscopy. The primary outcomes were pain intensity at rest and with movement at different postoperative time points and cumulative opioid consumption within 24 h after surgery. Secondary outcomes included the time to first analgesic request and side effects.

Results

In total, 11 studies involving 677 participants met the eligibility criteria. Pain scores at rest and with movement 2, 4, 12, and 24 h after surgery were significantly lower, doses of supplementary opioid consumption were smaller, and the time to first analgesic requirement was longer in the IA Mg group compared with the control group. No significant difference was detected regarding adverse reactions between the groups.

Conclusions

Intra-articular magnesium is an effective and safe coadjuvant treatment for relieving postoperative pain intensity after arthroscopic knee surgery.

Protocol registration at PROSPERO: CRD42020156403.

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.

Magnesium Sulfate as a Preemptive Adjuvant to Levobupivacaine for Postoperative Analgesia in Lower Abdominal and Pelvic Surgeries under Epidural Anesthesia(Randomized Controlled Trial)

Background:

Magnesium (Mg) has been evaluated as an adjuvant to local anesthetics for prolongation of postoperative epidural and intrathecal analgesia but not with epidural levobupivacaine in lower abdominal surgeries.

Aim of the Study:

The aim of the study was to evaluate the preemptive analgesic effect of Mg added to epidural levobupivacaine anesthesia in infraumbilical abdominal surgeries.

Settings and Design:

This study design was a prospective randomized controlled trial.

Patients and Methods:

Two groups, each with fifty patients undergoing lower abdominal and pelvic surgeries with epidural anesthesia. Group M received 15 ml of a mixture of 14 ml levobupivacaine 0.5%, 0.5 ml magnesium sulfate 10% (50 mg), and 0.5 ml 0.9 NaCl at induction. Group L received 15 ml of 14 ml levobupivacaine 0.5% and 1 ml 0.9 NaCl at induction. Then, continuous infusion was used as 5 ml/h of the specific mixture of each group till the end of the surgery.

Statistical Analysis:

Chi-square test, unpaired t-test or Mann–Whitney, and Wilcoxon sign rank test were used.

Results:

No statistically significant difference between the two groups regarding intraoperative hemodynamics (P > 0.05). Sensory and motor block onset was significantly shorter in Group M (14.5 [±1.51] and 12.42 [±1.69]) compared to Group L (19.86 [±1.39] and 19.34 [±1.62]) (P = 0.001). Group M showed lower visual analog scale (VAS) pain score compared to Group L from the 2^nd to the 5^th h postoperatively. Time for first analgesic dose was longer in Group M (294.98 [±21.67]) compared to Group L (153.96 [±10.04]) (P = 0.001).

Conclusions:

Preoperative and intraoperative epidural Mg infusion with levobupivacaine resulted in prolonged postoperative analgesia and lower VAS.

Adjuvants to local anesthetics: Current understanding and future trends

Although beneficial in acute and chronic pain management, the use of local anaesthetics is limited by its duration of action and the dose dependent adverse effects on the cardiac and central nervous system. Adjuvants or additives are often used with local anaesthetics for its synergistic effect by prolonging the duration of sensory-motor block and limiting the cumulative dose requirement of local anaesthetics. The armamentarium of local anesthetic adjuvants have evolved over time from classical opioids to a wide array of drugs spanning several groups and varying mechanisms of action. A large array of opioids ranging from morphine, fentanyl and sufentanyl to hydromorphone, buprenorphine and tramadol has been used with varying success. However, their use has been limited by their adverse effect like respiratory depression, nausea, vomiting and pruritus, especially with its neuraxial use. Epinephrine potentiates the local anesthetics by its antinociceptive properties mediated by alpha-2 adrenoreceptor activation along with its vasoconstrictive properties limiting the systemic absorption of local anesthetics. Alpha 2 adrenoreceptor antagonists like clonidine and dexmedetomidine are one of the most widely used class of local anesthetic adjuvants. Other drugs like steroids (dexamethasone), anti-inflammatory agents (parecoxib and lornoxicam), midazolam, ketamine, magnesium sulfate and neostigmine have also been used with mixed success. The concern regarding the safety profile of these adjuvants is due to its potential neurotoxicity and neurological complications which necessitate further research in this direction. Current research is directed towards a search for agents and techniques which would prolong local anaesthetic action without its deleterious effects. This includes novel approaches like use of charged molecules to produce local anaesthetic action (tonicaine and n butyl tetracaine), new age delivery mechanisms for prolonged bioavailability (liposomal, microspheres and cyclodextrin systems) and further studies with other drugs (adenosine, neuromuscular blockers, dextrans).

Association between the use of magnesium sulfate as neuroprotector in prematurity and the neonatal hemodynamic effects

PURPOSE

Cerebral palsy is often associated with prematurity and magnesium sulfate (MgSO₄) has been used as a neuroprotector, with favorable results. However, its mechanism of action has not been fully elucidated. This study aimed to evaluate the association between MgSO₄ at the imminent premature delivery and neonatal hemodynamic effects.

MATERIALS AND METHODS

A cross-sectional study involving 94 newborns (NB) between 24 and 32 weeks at a Brazilian hospital was performed. Bivariate analysis between the use or the non-use of MgSO₄ and hemodynamic characteristics was performed, using the Chi-square test.

RESULTS

NB were evaluated between those who received MgSO₄ (27.7) and those who did not (72.3%). Normal heart rate was verified in 62.8% of NB, normal respiratory rate in 70.2%, and normal temperature in 22.3%. Oxygen saturation higher or equal than 95% was evidenced in 85.1% of NB, normal hemoglucotest in 74.5%, and hemoglobin greater or equal than 16.4 g/dL in 30.9%. Non-invasive ventilation was performed in 48.9% of NB, while 51.1% were submitted to endotracheal ventilation. There was no significance relation detected between the use of MgSO₄ and the hemodynamic characteristics.

CONCLUSIONS

MgSO₄ does not appear to influence hemodynamic factors as a cause of the neuroprotection in premature NB.

Single bolus dose of epidural magnesium prolongs the duration of analgesia in cardiac patients undergoing vascular surgeries

Background and Aims:

Magnesium, a physiological antagonist of calcium and N-methyl-d-aspartate, has a role in the prevention of pain in patients undergoing surgery for peripheral vascular diseases with cardiac comorbidities such as ischaemic heart disease and coronary artery disease. The objective of our study was assessment of effects of epidural magnesium in cardiac patients undergoing vascular surgery.

Methods:

Sixty patients of either sex American Society of Anesthesiologists physical status III undergoing surgeries for peripheral vascular diseases were enrolled. The control group had 30 patients who received levobupivacaine 0.25% 10 ml with fentanyl 50 μg while 30 patients in study group received levobupivacaine 0.25% 10 ml with fentanyl 50 μg and magnesium 100 mg. The primary outcome was duration of analgesia. Sedation score, pain assessment using visual analogue scale (VAS), systolic blood pressure (SBP) and diastolic blood pressure (DBP), heart rate (HR), respiratory rate (RR) and fentanyl consumption were also recorded. Statistical analyses were performed using Minitab 15 statistical software.

Results:

Both groups were similar demographically and with respect to baseline HR, SBP, DBP and RR. In the study group, compared to the control group, duration of analgesia was 4.17 ± 1.07 h versus 1.55 ± 0.47 h (P < 0.01), sedation score were\ better (P = 0.003) and the VAS scores was lower (P < 0.01).

Conclusion:

Epidural magnesium, added to levobupivacaine and fentanyl as a single bolus dose effectively prolongs the duration of analgesia in high-risk cardiac patients undergoing peripheral vascular surgery.

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.

The Effect of Intravenous Magnesium Sulfate on Post-Operative Analgesia During Laminectomy

Background and Objectives:

Post-operative pain control is an important concern for both patients and physicians. Magnesium is being used as an adjuvant for anesthesia and analgesia during and after various surgeries. We aimed to investigate the effects of intravenous magnesium sulfate on post-operative analgesia after laminectomy.

Methods Materials:

In this randomized double-blind controlled clinical trial, we enrolled 40 adult patients aged 18-60 with American Society of Anesthesiologists (ASA)  Class I-II who were candidates for elective laminectomy. The patients were randomly assigned in two control groups and were similarly anesthetized. In the case group, after the induction of anesthesia, a loading dose of magnesium sulfate (30 mg/kg) was administered within five to 10 minutes followed by a maintenance dose of 10 mg/kg/hr up to the end of the surgery; while, the patients in the control group received the same volume of saline. After the surgery, all patients received a patient-controlled intravenous analgesia (PCA) pump containing morphine. The first time of using PCA, the amount of consumed morphine during the first 24 hours, and pain score were recorded at 6,12,18 and 24 hours in the post-operative period.

Results:

There was no significant difference between the two groups with respect to the amount of morphine consumed in 24 hours after the surgery (P value =0.23), the first time of using of PCA pump (P value =0.79) and pain intensity (P value=0.52).

Conclusion:

The infusion of Magnesium Sulfate during laminectomy had no effect on patients’ pain and opioid requirement during the first 24 hours after the surgery.

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

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.

Cold bupivacaine versus magnesium sulfate added to room temperature bupivacaine in sonar-guided femoral and sciatic nerve block in arthroscopic anterior cruciate ligament reconstruction surgery

BACKGROUND

Cooling of local anesthetic potentiates its action and increases its duration. Magnesium sulfate (MgSo₄) added to local anesthetic prolongs the duration of anesthesia and postoperative analgesia with minimal side effects.

AIM

The aim of this prospective, randomized, double-blind study was to compare the effect of cold to 4°C bupivacaine 0.5% and Mg added to normal temperature (20-25°C) bupivacaine 0.5% during sonar-guided combined femoral and sciatic nerve blocks on the onset of sensory and motor block, intraoperative anesthesia, duration of sensory and motor block, and postoperative analgesia in arthroscopic anterior cruciate ligament (ACL) reconstruction surgery.

PATIENTS AND METHODS

A total of 90 American Society of Anesthesiologists classes I and II patients who were scheduled to undergo elective ACL reconstruction were enrolled in the study. The patients were randomly allocated to 3 equal groups to receive sonar-guided femoral and sciatic nerve blocks. In Group I, 17 ml of room temperature (20-25°C) 0.5% bupivacaine and 3 ml of room temperature saline were injected for each nerve block whereas in Group II, 17 ml of cold (4°C) 0.5% bupivacaine and 3 ml of cold saline were injected for each nerve block. In Group III, 17 ml of room temperature 0.5% bupivacaine and 3 ml of MgSo₄ 5% were injected for each nerve block. The onset of sensory and motor block was evaluated every 3 min for 30 min. Surgery was started after complete sensory and motor block were achieved. Intraoperatively, the patients were evaluated for heart rate and mean arterial pressure, rescue analgesic and sedative requirements plus patient and surgeon satisfaction. Postoperatively, hemodynamics, duration of analgesia, resolution of motor block, time to first analgesic, total analgesic consumption, and the incidence of side effects were recorded.

RESULTS

There was no statistically significant difference in demographic data, mean arterial pressure, heart rate, and duration of surgery. Onset of both sensory and motor block was significantly shorter in both Groups II and III compared to Group I. Intraoperative anesthetic quality was comparable between groups with good patient and surgeon satisfaction. The time to first analgesia was significantly longer in Groups II and III compared to Group I with nonsignificant difference between each other. Moreover, the total opioid consumption was significantly lower in Groups II and III and duration of analgesia and motor block were significantly longer in Groups II and III compared to Group I. There was no difference in the incidence of side effects.

CONCLUSIONS

The use of cold 0.5% bupivacaine or the addition of Mg to normal temperature 0.5% bupivacaine prolongs the sensory and motor block duration without increasing side effects and enhances the quality of intra- and post-operative analgesia with better patient satisfaction in sonar-guided femoral and sciatic nerve block for arthroscopic ACL reconstruction surgery.

A randomized double-blind study to evaluate efficacy and safety of epidural magnesium sulfate and clonidine as adjuvants to bupivacaine for postthoracotomy pain relief

Background:

The aim of the study was to compare postoperative pain relief in patients undergoing an elective thoracotomy with thoracic epidural analgesia using single shot magnesium and clonidine as adjuvants to bupivacaine.

Methods:

In a randomized prospective study, 60 patients of American Society of Anesthesiologists physical status I–III of either sex, between 20 and 60 years undergoing elective unilateral thoracotomy, were allocated to three equal groups of 20 patients. Each patient received thoracic epidural analgesia using bupivacaine alone (Group A) or with magnesium (Group B) or clonidine (Group C) at the end of surgery during skin closure. Postoperatively, pain was measured using a visual analog scale (VAS). Rescue analgesia (50 mg tramadol intravenous) was given at a VAS score of ≥4. Duration of analgesia and total dose of rescue analgesic during 24 h was calculated. Postoperative sedation and other side effects if any were recorded.

Results:

All the groups were homogeneous with respect to their demographics. The 24 h cumulative mean VAS score in Groups A, B, and C was 3.12 ± 0.97, 2.86 ± 0.43, and 1.83 ± 0.59, respectively. The duration of analgesia was prolonged in Group C (165 ± 49.15 min), followed by Group B (138 ± 24.6 min), and Group A (118.5 ± 52.8 min). The duration of analgesia was significantly prolonged in the clonidine group as compared to the control group (P = 0.001). The number of rescue analgesia doses were more in Group A (3.3 ± 1.65) followed by Group B (2.35 ± 0.98) and Group C (1.75 ± 0.71). The sedation scores were significantly higher in Group C. However, shivering was seen in Group A (40%) and Group C (20%) and absent in Group B (P = 0.003).

Conclusion:

Thoracic epidural analgesia using bupivacaine with clonidine is an efficient therapeutic modality for postthoracotomy pain. Magnesium as an adjuvant provided quality postoperative analgesia decreasing the need for postoperative rescue analgesia and incidence of postoperative shivering without causing sedation.

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.

Enhancement of ropivacaine caudal analgesia using dexamethasone or magnesium in children undergoing inguinal hernia repair

BACKGROUND

Caudal analgesia is the most commonly used technique providing intra- and postoperative analgesia for various pediatric infraumbilical surgical procedures but with the disadvantage of short duration of action after single injection. Caudal dexamethasone and magnesium could offer significant analgesic benefits. We compared the analgesic effects and side-effects of dexamethasone or magnesium added to caudal ropivacaine in pediatric patients undergoing inguinal hernia repair.

MATERIALS AND METHODS

A total of 105 (1-6 years) were randomly assigned into three groups in a double-blinded manner. After a standardized sevoflurane in oxygen anesthesia, each patient received a single caudal dose of ropivacaine 0.15% 1.5 mL/kg combined with either magnesium 50 mg in normal saline 1 mL (group RM), dexamethasone 0.1 mg/kg in normal saline 1 mL (group RD), or corresponding volume of normal saline (group R) according to group assignment. Postoperative analgesia, use of analgesics, and side-effects were assessed during the first 24 h.

RESULTS

Addition of magnesium or dexamethasone to caudal ropivacaine significantly prolonged analgesia duration 8 (5-11) h and 12 (8-16) h, respectively compared with 4 (3-5) h with the use of ropivacaine alone. The incidence of postoperative rescue analgesia was significantly higher in group R compared with groups RM and RD. The time to 1(st) analgesic dose was significantly longer in groups RM and RD (500 ± 190 and 730 ± 260 min) respectively compared with group R (260 ± 65 min). Group R patients achieved significantly higher Children's Hospital of Eastern Ontario Pain Scale and Faces Legs Activity Cry Consolability scores (4(th) hourly) compared with groups RM and RD patients (8(th) and 12(th) hourly, respectively).

CONCLUSION

The addition of dexamethasone or magnesium to caudal ropivacaine significantly prolonged the duration of postoperative analgesia in children undergoing inguinal hernia repair. Also the time to 1(st) analgesic dose was longer and the need for rescue postoperative analgesic was reduced and without increase in incidence of side effects.

Study of patient pain management after heart surgery

PURPOSE

To investigate postoperative pain control and analgesic use after heart surgery.

METHODS

20 patients undergone heart surgery, randomly entered the study. Each patient was asked to score his pain intensity on visual analog scale (VAS) at four different occasions.

RESULTS

120 patients aged 59 year-old; including 81 male were enrolled in the study. 69.2% had coronary artery disease and 16.7% had heart-valve problem. Main types of surgeries were coronary artery bypass surgery (70.5%) and valve repairement (23%). Duration of ICU stay was 4.78±2.7 days and duration of intubations was 17.38 ± 36.46 hours. Pre-surgery pain relief was administrated to 42% of the subjects and morphine and promethazine was the main pre-surgery analgesia medication. Post surgery analgesic included morphine (injection), petidine (injection) and NSAIDS (oral or rectal). According to VAS, mean pain level, 1 and 4 hours after extubation, and before and one hour after transferring to wards was 5.05±2.5, 4.09±2.0, 3.52±1.8, 2.36±1.89, respectively. Although the level of pain reported was mostly moderate, 80% were reported satisfaction with their post-surgery pain management.

CONCLUSION

A closer pain management control is needed for patients after heart surgery. Introduction of newer pain management techniques, medications and dosages could reduce the pain and suffering.

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.

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

Eighteen published trials have examined the use of neuraxial magnesium as a peri-operative adjunctive analgesic since 2002, with encouraging results. However, concurrent animal studies have reported clinical and histological evidence of neurological complications with similar weight-adjusted doses. The objectives of this quantitative systematic review were to assess both the analgesic efficacy and the safety of neuraxial magnesium. Eighteen trials comparing magnesium with placebo were identified. The time to first analgesic request increased by 11.1% after intrathecal magnesium administration (mean difference: 39.6 min; 95% CI 16.3-63.0 min; p = 0.0009), and by 72.2% after epidural administration (mean difference: 109.5 min; 95% CI 19.6-199.3 min; p = 0.02) with doses of between 50 and 100 mg. Four trials monitored for neurological complications: of the 140 patients included, only a 4-day persistent headache was recorded. Despite promising peri-operative analgesic effect, the risk of neurological complications resulting from neuraxial magnesium has not yet been adequately defined.

A comparison of epidural magnesium and/or morphine with bupivacaine for postoperative analgesia after cesarean section

BACKGROUND

Magnesium can potentiate the antinociceptive effect of morphine. This prospective randomized double-blinded study was undertaken to establish the analgesic effect of adding magnesium to epidural morphine during cesarean section.

METHODS

Two hundred patients undergoing cesarean section under combined spinal-epidural anesthesia were recruited. After administration of intrathecal bupivacaine 10mg, patients were randomly assigned to receive one of four epidural study solutions: 0.1% bupivacaine 10 mL (Group B); 0.1% bupivacaine 10 mL and morphine 1.5mg (Group B+Mor); 0.1% bupivacaine 10 mL and magnesium 500 mg (Group B+Mg); or 0.1% bupivacaine 10 mL morphine 1.5mg and magnesium 500 mg (Group B+Mor+Mg). The primary outcome was the area under the curve for visual analog scale pain scores during 36 h postoperatively. Secondary outcomes included time to the use of rescue analgesics, patient satisfaction and side effects.

RESULTS

Patients in Group B+Mor+Mg had lower for pain scores and area under the curve pain scores both at rest and on movement, increased time for first analgesic request, and increased satisfaction score at 24h after surgery.

CONCLUSION

Addition of magnesium 500 mg and morphine 1.5mg to epidural 0.1% bupivacaine 10 mL reduced postoperative pain compared with addition of morphine or magnesium alone or no additive.

Evaluation of single epidural bolus dose of magnesium as an adjuvant to epidural fentanyl for postoperative analgesia: A prospective, randomized, double-blind study

OBJECTIVE

Magnesium has been used as an adjuvant by various routes, including intravenous, intrathecal, and epidural in different dosage regimens. The effect of single bolus dose of magnesium as an adjuvant to fentanyl for postoperative analgesia has not been studied. This prospective randomized controlled trial was done to evaluate the efficacy of single bolus administration of magnesium epidurally as an adjuvant to epidural fentanyl for postoperative analgesia in patients undergoing total hip replacement under combined spinal epidural anesthesia.

METHODS

Sixty patients received combined spinal-epidural anesthesia with 2 mL of 0.5% hyperbaric bupivacaine intrathecally. After the surgery, patients were randomized into Group F [epidural fentanyl (1 μg/kg) in 10 mL saline] and Group FM [epidural magnesium (75 mg) along with fentanyl (1 μg/kg) in 10 mL saline]. Supplementary analgesia was provided by 50 mg intravenous tramadol if Verbal Rating Score (VRS) >4. Patient's first analgesic requirement and duration of analgesia were recorded.

RESULTS

The duration of analgesia was significantly longer for Group FM, 340±28.8 min, compared with Group F, 164±17.1 min (P=0.001). The frequency of rescue analgesics required in 24-h postoperative period in Group FM (2.3±0.5) was significantly less than that in Group F (4.3±0.5) (P=0.001). VRS was significantly lower in Group FM up to 4 h in the postoperative period (P=0.001). Bromage scale was statistically insignificant at all points of time.

CONCLUSIONS

The administration of magnesium (75 mg) as an adjuvant to epidural fentanyl (1 μg/ kg) for postoperative analgesia results in significantly lower VRS with prolonged duration of analgesia as compared with epidural fentanyl (1 μg/kg) alone. Concomitant administration of magnesium also reduces the requirement of breakthrough analgesics with no increased incidence of side effects.

Comparison of postoperative analgesic effect of intrathecal magnesium and fentanyl added to bupivacaine in patients undergoing lower limb orthopedic surgery

OBJECTIVE

To compare the analgesic efficacy and side effects of magnesium and fentanyl as an additive to intrathecal bupivacaine.

METHODS

Ninety adult patients scheduled for femur surgery under spinal anesthesia were randomly allocated to one of the following three groups to receive intrathecally: bupivacaine 15 mg combined with 0.5 mL magnesium 10%; bupivacaine 15 mg combined with 0.5 mL fentanyl; or bupivacaine 15 mg combined with 0.5 mL distilled water (control). The time to first analgesic request, sensory and motor blockade onset time, duration of sensory and motor blockade, analgesic requirement in the first 12 hours after surgery, and the incidences of hypotension, bradycardia, hypoxemia and ephedrine were recorded.

RESULTS

Magnesium caused a significant delay in the onset of both sensory and motor blockade compared with the fentanyl (95% CI 3 to 4; p < 0.001) and control (95% CI 3.5-5; p < 0.001) groups. The duration of spinal analgesia in group F (fentanyl) was significantly greater than in group C (control) (95% CI 365-513; p < 0.001) and group M (magnesium) (95% CI 385-523; p < 0.001). The total amount of methadone consumption over 12 hours was significantly lower in the magnesium and fentanyl groups than in the control group (5 mg vs. 5.666 ± 1.728 mg; p = 0.04).

CONCLUSION

Addition of intrathecal magnesium sulfate to spinal anesthesia induced by bupivacaine significantly prolonged the onset of both sensory and motor blockade compared with fentanyl. Although magnesium failed to prolong the time to first analgesic requirement as seen with fentanyl, it reduced the total consumption of opioids in the first 12 hours postoperatively compared with the control group.

Lumbosacral epidural magnesium prolongs ketamine analgesia in conscious sheep

PURPOSE: To determine the analgesic, motor, sedation and systemic effects of lumbosacral epidural magnesium sulphate added to ketamine in the sheep. METHODS: Six healthy adult male mixed-breed sheep; weighing 43 ± 5 kg and aged 20-36 months. Each sheep underwent three treatments, at least 2 weeks apart, via epidural injection: (1) ketamine (KE; 2.5 mg/kg), (2) magnesium sulphate (MG; 100 mg), and (3) KE + MG (KEMG; 2.5 mg/kg + 100 mg, respectively). Epidural injections were administered through the lumbosacral space. Analgesia, motor block, sedation, cardiovascular effects, respiratory rate, skin temperature, and rectal temperature were evaluated before (baseline) and after drug administration as needed. RESULTS: The duration of analgesia with the lumbosacral epidural KEMG combination was 115 ± 17 min (mean ± SD), that is, more than twice that obtained with KE (41 ± 7 min) or MG (29 ± 5 min) alone. KE and KEMG used in this experiment induced severe ataxia. The heart rate and arterial blood pressures changes were no statistical difference in these clinically health sheep. CONCLUSION: The dose of magnesium sulphate to lumbosacral epidural ketamine in sheep is feasible, and can be used in procedures analgesics in sheep.

Multimodal pain management after total joint arthroplasty

Adequate postoperative pain control in patients who have undergone total joint arthroplasty allows faster rehabilitation and reduces the rate of postoperative complications. Multimodal pain management involves the introduction of adjunctive pain control methods in an attempt to control pain with less reliance on opioids and fewer side effects. Current research suggests that traditional nonsteroidal anti-inflammatory drugs (NSAIDs) and the associated cyclooxygenase type-2 (COX-2) inhibitors improve pain control in most cases. Nearly all multimodal pain management modalities have a safe side-effect profile when they are added to existing methods. The exception is the administration of DepoDur (extended-release epidural morphine) to elderly or respiratory-compromised patients because of a potential for hypoxia and cardiopulmonary events.

Relief of postherpetic neuralgia with transforaminal epidural injection of magnesium -a case report-

Although postherpetic neuralgia (PHN) is a common chronic pain syndrome, the pathophysiology of this disorder is not well known and management is often very difficult. N-Methyl-D-Aspartate (NMDA) receptor antagonists are known to be effective in PHN, and magnesium, a physiological blocker of NMDA receptors, is widely used to treat various chronic pain disorders. Here, we present a case of the PHN refractory to conventional treatment, which was treated successfully with transforaminal epidural injection of magnesium sulphate at the affected dermatome.

Is magnesium sulfate by the intrathecal route efficient and safe?

The polypharmacological approach to the treatment of postoperative pain has become routine in an attempt to minimize the adverse side effects of opioids. Magnesium sulphate is a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) receptor and thus can modify nociceptive modulation. Intravenous administration of magnesium sulphate can improve postoperative analgesia and decrease the requirement for postoperative opiates, but the effects are inconsistent and have not been reliably accompanied by a reduction in the incidence of morphine-related adverse events. Several studies have shown that the administration of magnesium by the intrathecal route is safe and, in combination with opiates, extends the effect of spinal anaesthesia in both animal and human studies. The analysis of these studies justifies further investigation of the use of magnesium sulphate by the intrathecal route.

The effect of adding magnesium sulphate to epidural bupivacaine and fentanyl in elective caesarean section using combined spinal-epidural anaesthesia: a prospective double blind randomised study

BACKGROUND

Combined spinal-epidural anaesthesia is commonly used for elective caesarean section. Intrathecal injection produces rapid onset with minimal doses of local anaesthetic and epidural administration can be used to prolong the block. Our study examined the effects of adding magnesium sulphate to epidural bupivacaine and fentanyl in patients undergoing elective caesarean section using combined spinal-epidural anaesthesia.

METHODS

Women ASA physical status I or II at term were recruited. All received 2 mL intrathecal 0.5% hyperbaric bupivacaine, 10 mL epidural 0.25% plain bupivacaine with fentanyl 100 μg, and were randomly allocated to receive either 10 mL of epidural 0.9% sodium chloride or 10 mL epidural 5% magnesium sulphate. The quality of surgical anaesthesia, incidence of hypotension, Apgar scores, intraoperative pain assessment, onset of postoperative pain, sedation scores and side effects were recorded in the postoperative period.

RESULTS

Ninety women were recruited. There was no difference in the time taken for the block to reach T4 sensory level, time to reach the highest level of sensory block, time interval between first neuraxial injection and onset of surgery between the groups. Women who received magnesium had greater motor block and muscle relaxation (P<0.05). Apgar scores were 7 or more in almost all neonates in both groups. There was no significant difference in the incidence of hypotension, nausea and vomiting and duration of motor blockade between the groups. Women who received magnesium showed less shivering and later onset of post operative pain (P<0.05).

CONCLUSION

The addition of magnesium to epidural bupivacaine and fentanyl in women undergoing elective caesarean section with combined spinal-epidural anaesthesia improved intraoperative conditions and the quality of postoperative analgesia.