Adjuvants to local anesthetics: Current understanding and future trends

Quo Vadis PCA? A Review on Current Concepts, Economic Considerations, Patient-Related Aspects, and Future Development with respect to Patient-Controlled Analgesia

This review assesses four interrelating aspects of patient-controlled analgesia (PCA), a long-standing and still widely used concept for postoperative pain management. Over the years, anaesthesiologists and patients have appreciated the benefits of PCA alike. The market has seen new technologies leveraging noninvasive routes of administration and, thus, further increasing patient and staff satisfaction as well as promoting safety aspects. Pharmaceutical research focuses on the reduction or avoidance of opioids, side effects, and adverse events although influence of these aspects appears to be minor. The importance of education is still eminent, and new educational formats are tested to train healthcare professionals and patients likewise. New PCA technology can support the implementation of efficient processes to reduce workload and human errors; however, these new products come with a cost, which is not necessarily reflected through beneficial budget impact or significant improvements in patient outcome. Although first steps have been taken to better recognize the importance of postoperative pain management through the introduction of value-based reimbursement, in most western countries, PCA is not specifically compensated. PCA is still an effective and valued technique for postoperative pain management. Although there is identifiable potential for future developments in various aspects, this potential has not materialized in new products.

Outcomes of intrathecal analgesia in multiparous women undergoing normal vaginal delivery: A randomised controlled trial

Background and Aims

Although intrathecal analgesia is an effective option during labour, there is a need to establish sustainable and assured analgesia during the entire labour process. We aimed to assess the effect of adding dexmedetomidine, fentanyl or morphine to low-dose bupivacaine-dexamethasone for intrathecal labour analgesia in multiparous women.

Methods

This was a triple-blind, randomised controlled trial that included 140 multiparous women. Eligible women were randomly allocated to have intrathecal bupivacaine-dexamethasone with dexmedetomidine (group D), fentanyl (group F), morphine (group M) or saline (placebo) (group C). The duration of analgesia, intrathecal block characteristics and maternal and foetal outcomes were assessed and analysed.

Results

The longest analgesia duration and S1 regression time was recorded in group D followed by groups M, F and C, respectively, with statistical significance between all of them (P < 0.001). The shortest analgesia onset time and the highest sensory levels were recorded in group D followed by group F then group M with statistical significance between all of them (P < 0.001 and 0.003, respectively). Visual analogue scale values were comparable among groups M, F and D (P > 0.05) at most of the measurement time points and at the peak of the last uterine contraction before delivery while being significantly lower than those in group C (P < 0.001). However, there were similar motor block characteristics and normal neonatal outcomes in all groups.

Conclusion

In comparison to morphine and fentanyl, dexmedetomidine addition to intrathecal bupivacaine-dexamethasone significantly prolonged the duration and accelerated the onset of labour analgesia, with a good maternal and neonatal outcome.

Fetal and Maternal Responses to Dexmedetomidine Intrathecal Application During Cesarean Section: A Meta-Analysis

Background

Intrathecal dexmedetomidine (DEX) can improve the blockade of spinal anesthesia, but there is no clear conclusion on whether it has an effect on the fetus during cesarean section. Our meta-analysis evaluated the safety and efficacy of intrathecal DEX in cesarean delivery.

Material/Methods

We searched Cochrane, Embase, PubMed, and CBM for eligible studies, and used the Revised Cochrane Risk of Bias Tool (RoB 2.0) to assess the risk of bias of each study. RevMan was used for statistical analyses. We have registered this meta-analysis on PROSPERO (CRD42019120995).

Results

The meta-analysis included 10 RCTs, but only 5 were prospectively registered. The results of preregistration studies, including the 1- or 5-min Apgar score (mean difference [MD], −0.03; 95% confidence intervals [CI], −0.16 to 0.10; P=0.64 or MD, 0.00; 95% CI, −0.09 to 0.09; P=1), the umbilical arterial oxygen or carbon dioxide partial pressure (MD, 0.90; 95% CI, −4.92 to 6.72; P=0.76 or MD, 1.20; 95% CI, −2.06 to 4.46; P=0.47), and the cord blood pH (MD, −0.01; 95% CI, −0.05 to 0.03; P=0.72), showed that intrathecal DEX had no significant difference in neonatal outcomes compared with placebo. In maternal outcomes, intrathecal DEX significantly prolonged postoperative pain-free period and reduced the incidence of postoperative shivering, which did not increase spinal anesthesia-associated adverse effects.

Conclusions

Intrathecal DEX is safe for the fetus during cesarean section and can improve the blockade effects of spinal anesthesia on puerperae.

Post-operative analgesia techniques after total knee arthroplasty: A narrative review

Post-operative knee pain management has become a challenge to provide early relief and pain-free postoperative care to the patient. The major objectives of post-operative analgesic treatment are to reduce opioid requirements, post-operative pain, and adverse events related to opioid intake. This narrative review aimed to document post-operative analgesia techniques after total knee arthroplasty (TKA). The traditional approach involved high-dose opioid-based regimen, though opioid is considered strong analgesic, but are associated with a number of unwanted side effects to seek for alternative techniques. The role of sciatic nerve block in TKA pain is doubtful. Femoral Nerve Block (FNB) is still considered as the gold standard; however, FNB is associated with quadriceps weakness and risk of fall and sciatic block with foot drop. To overcome these drawback more distal nerve block techniques has evolved, namely saphenous nerve block in adductor canal, selective tibial which are claimed to provide comparable analgesia to that of femoral and sciatic nerve block. The combination of pre-emptive and multi-modal analgesia and technically well-delivered regional nerve blocks and postoperative physical therapy are an essential component which not only minimize the side effects of traditional opioid-based analgesia but also speed up functional recovery, increases patient satisfaction, and reduces the overall length of hospitalization and cost.

Review of adjuvants to local anesthetics in peripheral nerve blocks: Current and future trends

In recent anesthetic practice, peripheral nerve blocks (PNBs) are used extensively for surgical anesthesia and nonsurgical analgesia. PNBs offer many benefits over other anesthetic techniques in a certain population of patients, and in some specific clinical setting, that may contribute to faster and safer pain relief, increased patient satisfaction, reduced hospital stay, and decreased overall healthcare cost. The technique involves the injection of the anesthetic in the vicinity of a specific nerve or bundle of nerves to block the sensation of pain transmitting to a specific portion of the body. However, the length of analgesia when a single anesthetic is used for PNB may not last long. Therefore, the practice of adding an additional agent called adjuvant has been evolved to prolong the analgesic effect. There are many such adjuvants available that are clinically being used for this purpose imparting great efficacy and safety to the anesthetic process. The adjuvants molecules are generally classified as opioids, alpha-2 agonist, steroids, etc. Most of them are safe to use and show little or no adverse event related to neurotoxicity and tissue damage. Although there is extensive use of such adjuvants in the clinical field, none of the molecules is approved by the FDA and is used as an off-label drug. The risk to benefit ratio must be assessed while using such an agent. This review will try to delineate the basic need of adjuvant in peripheral nerve block and will discuss the advantages and limitations of using different adjuvants and will discuss the future prospect of such application.

Opiate Intoxication Caused by Epidural Infusion of Morphine: A Case Report of a Near Fatal Medication Error

INTRODUCTION

Epidural infusion of local anesthetics with opioids is widely used for pain control during the perioperative-and peripartum-periods. Selection of the opioid, appropriate dosing, and follow-up by the acute pain service are critical in providing safe postoperative epidural analgesia.

CASE REPORT SUMMARY

A 71-year-old man was scheduled for a parastomal hernia repair with midline laparotomy. The parastomal hernia was a complication from a previously performed colectomy for ulcerative colitis. Preoperatively, the patient received a lower thoracic epidural catheter. The epidural infusate (0.2% ropivacaine with 0.5 µg/mL sufentanil) was prepared and double-checked by holding area nurses. The fact that the right prescription medication label partially covered a morphine label went unnoticed. The intraoperative phase was characterized by stable parameters. Postoperatively, it was not possible to demonstrate an epidural nerve block. No pain was reported, and the patient could be transferred to the ward. The patient developed coma and delayed respiratory depression after discharge to the surgical ward, requiring intensive care unit admission and naloxone administration. Analysis of the syringe content revealed the presence of morphine (1 mg/mL).

DISCUSSION

Color-coded prefilled syringes combined with the use of an epidural specific syringe connector to prevent cross-connections should become standard practice. In addition, delayed respiratory depression should be considered after epidural administration of morphine.

Catheter use in regional anesthesia: pros and cons

Continuous peripheral nerve blocks refer to a local anesthetic solution administered via perineurally placed catheters in an effort to extend the benefits of a single-shot peripheral nerve block. They offer several advantages in the postoperative period including excellent analgesia, reduced opioid consumption and associated side effects, enhanced rehabilitation and improved patient satisfaction. The current trend towards less invasive, one-day surgery and enhanced recovery programs may decrease the requirement of catheter use. Prolonged motor block in particular is associated with undesirable outcomes. Should we routinely use continuous peripheral nerve blocks in our daily practice? This PRO-CON debate aims at answering the question from the experts' perspectives. Fascial compartment and wound catheters are outside the scope of this debate.

Recent advances in polymer-based drug delivery systems for local anesthetics

Local anesthetics, which cause temporary loss of pain by inhibiting the transmission of nerve impulses, have been widely used in clinical practice. However, neurotoxicity and short half-lives have significantly limited their clinical applications. To overcome those barriers, numerous drug delivery systems (DDS) have been designed to encapsulate local anesthetic agents, so that large doses can be released slowly and provide analgesia over a prolonged period. So far, multiple classes of local anesthetic carriers have been investigated, with some of them already on the market. Among those, polymer-based delivery platforms are the most extensively explored, especially in the form of polymeric nanoparticle carriers. This review gives a specific focus on the most commonly used natural and synthetic polymers for local anesthetics delivery, owing to their excellent biocompatibility, biodegradability and versatility. State-of-the-art studies concerning such polymer delivery systems have been discussed in depth. We also highlight the impact of those delivery platforms as well as some key challenges that need to be overcome for their broader clinical applications. STATEMENT OF SIGNIFICANCE: Currently, local anesthetics have been widely used in clinically practices to prevent transmission of nerve impulses. However, the applications of anesthetics are greatly limited due to their neurotoxicity and short half-lives. Moreover, it is difficult to maintain frequent administrations which can cause poor compliance and serious consequences. Numerous drug delivery systems have been developed to solve those issues. In this review, we highlight the recent advances in polymer-based drug delivery systems for local anesthetics. The advantages as well as shortcomings for different types of polymer-based drug delivery systems are summarized in this paper. In the end, we also give prospects for future development of polymer drug delivery systems for anesthetics.

Dexamethasone and dexmedetomidine as adjuvants to local anesthetic mixture in intercostal nerve block for thoracoscopic pneumonectomy: a prospective randomized study

BACKGROUND AND OBJECTIVES

Perineural dexamethasone or dexmedetomidine prolongs the duration of single-injection peripheral nerve block when added to the local anesthetic solution. In a randomized, controlled, double-blinded study in patients undergoing thoracoscopic pneumonectomy, we tested the hypothesis that combined perineural dexamethasone and dexmedetomidine prolonged the duration of analgesia as compared with either perineural dexamethasone or perineural dexmedetomidine after intercostal nerve block (INB).

METHODS

Eighty patients were randomized to receive INB using 28 mL 0.5% ropivacaine, with 2 mL normal saline (R group), with 10 mg dexamethasone in 2 mL (RS group) or 1 µg/kg dexmedetomidine in 2 mL (RM group), or with 1 µg/kg dexmedetomidine and 10 mg dexamethasone in 2 mL (RSM group) administrated perineurally. The INB was performed by the surgeon under thoracoscopic direct vision; a total of six intercostal spaces were involved, each with an injection of 5 mL. The primary outcome was the duration of analgesia. Secondary outcomes included total postoperative fentanyl consumption, visual analog scale pain score and safety assessment (adverse effects).

RESULTS

The duration of analgesia in RSM (824.2±105.1 min) was longer than that in RS (611.5±133.0 min), RM (602.5±108.5 min) and R (440.0±109.6 min) (p<0.001). Total postoperative fentanyl consumption was lower in RSM (106.0±84.0 µg) compared with RS (243.0±175.2 µg), RM (237.0±98.7 µg) and R (369.0±134.2 µg) (p<0.001). No significant difference was observed in the incidences of adverse effects between the four groups.

CONCLUSION

The addition of combined perineural dexmedetomidine and dexamethasone to ropivacaine for INB seemed to be an attractive method for prolonged analgesia with almost no adverse effects.

TRIAL REGISTRATION NUMBER

ChiCTR-IOR-17012183.

Peritubal Infiltration of Fentanyl Compared to Dexmedetomidine with Ropivacaine in Percutaneous Nephrolithotomy: A Randomized Comparative Analysis

Context:

Dexmedetomidine has been found as an effective adjuvant in various nerve blocks. Despite several studies on dexmedetomidine with ropivacaine, there is no study on comparing with fentanyl in peritubal infiltration in percutaneous nephrolithotomy (PCNL).

Aims:

The aim of this study was to compare the effect of the addition of dexmedetomidine or fentanyl in peritubal local anesthetic infiltration on pain scores and analgesic consumption in patients who underwent PCNL.

Settings and Design:

This was a prospective, randomized, double-blind, tertiary care center-based study.

Subjects and Methods:

A total of 60 American Society of Anesthesiologists Class I, II, and III patients were selected and randomly divided into two groups: Group RF ropivacaine and fentanyl (n = 30) and Group RD ropivacaine and dexmedetomidine (n = 30). Balanced general anesthesia was given. After completion of the surgery, peritubal infiltration was given at 6 and 12 O’clock positions under fluoroscopic guidance. Postoperative pain was assessed using the visual analog scale and dynamic visual analog scale rating 0–10 for initial 48 h. Postoperative sedation was assessed using five-point sedation score. Time to first rescue analgesic, number of doses of tramadol, and total consumption of tramadol required in 48 h were noted.

Statistical Analysis Used:

Descriptive data were expressed in mean and standard deviation for between-group comparisons; the Chi-square and Fisher's exact tests were used for categorical variables, whereas t-test and Mann–Whitney U-test were used to compare continuous variables between two groups.

Results:

Duration of analgesia in group RD (12.87 ± 3.85) is more prolonged than group RF (8.13 ± 3.28) h. Total dose of rescue analgesia required in 48 h in group RF was higher as compared to group RD.

Conclusions:

Addition of dexmedetomidine to ropivacaine is more effective than fentanyl in terms of prolongation of analgesic efficacy of local anesthetic in peritubal block along with short-lived mild sedation.

Efficacy of midazolam addition to local anesthetic in peribulbar block : Randomized controlled trial

BACKGROUND

Peribulbar block is considered a safe option for patients undergoing cataract surgery. The limited duration of regional eye blocks was shown to be the main problem. The objective of this study was to evaluate the effects of adjuvant midazolam (in two concentrations) to lidocaine in the peribulbar block.

MATERIAL AND METHODS

This study included 90 adult patients aged 40-70 years undergoing cataract surgery. Each patient was appointed to one of three groups. Group C received a single injection of a peribulbar block using a combination of lidocaine 2% and hyaluronidase 15 IU/ml, group M1 received a combination of lidocaine 2%, hyaluronidase 15 IU/ml plus midazolam 50 µg/ml and group M2 received lidocaine 2%, hyaluronidase 15 IU/ml plus midazolam 100 µg/ml.

RESULTS

The quality of the peribulbar block showed significant improvement among groups by one-way ANOVA (p = 0.002). The mean onset time of the sensory block was significantly shorter in the M2 and M1 groups (1.66 min and 2.17 min, respectively) compared to the control group C (2.52 min), while the onset of lid and globe akinesia lacked significance between the three groups (p = 0.23 and 0.06, respectively). Significance in mean values was found between the control (C) and M2 groups regarding orbicularis oculi function, digital spear pressure, topical anesthetic sting and the total score (P-values = 0.004, 0.016, 0.033 and 0.001, respectively). The duration of lid akinesia and sensory anesthesia were significantly different between the three groups (P = 0.048 and P<0.001, respectively) whereas the duration of globe akinesia was insignificant (P = 0.432).

CONCLUSION

Addition of midazolam to local anesthetic significantly improved the quality of peribulbar block, hastened the onset of sensory anesthesia, lid and globe akinesia and increased the duration of analgesia without notable side effects.

[Background and current use of adjuvants for regional anesthesia : From research to evidence-based patient treatment]

The discovery of the local anaesthetic effect by blocking sodium ion channels was a milestone in anaesthesia but was soon limited by sometimes life-threatening toxic effects of the local anaesthetics. By developing novel local anaesthetics and also by adding so-called adjuvants, attempts have been made to limit these life-threatening events. This article focuses on the historic background and the current state of the use of these adjuvants for regional anaesthesia. Adding epinephrine, clonidine or dexmedetomidine, but only as a single dose, results in a faster onset, longer duration of action and increased intensity of neuronal blockade of regional anaesthesia. The benefits of adding sodium bicarbonate, on the other hand, are relatively minor and, therefore, clinically negligible. Although increasing evidence in the literature suggests an improvement and prolongation of the analgesic effect after axonal administration of opioids, which can also be given continuously, systemic effects are not fully ruled out due to the increased incidence of central side effects. The partial local anaesthetic effects of opioids cannot always be distinguished from opioid receptor-specific effects. Mechanistic studies postulate a functional coupling of opioid receptors in injured rather than in intact peripheral nerves. Recent studies have identified glucocorticoid and mineralocorticoid receptors predominantly on peripheral nociceptive nerve fibers. This is consistent with numerous clinical reports of a marked prolongation of the local anaesthetic effect. In addition to the known genomic effects of steroids that occur via a change in gene expression of pain-sustaining protein structures, faster non-genomic effects are also discussed, which occur via a change in intracellular signaling pathways. In summary, new insights into mechanisms and novel results from clinical trials will help the anaesthesiologist in the decision to use adjuvants for regional anaesthesia which, however, requires to weigh the individual patient's benefits against the risks.

Efficacy of local wound infiltration analgesia with ropivacaine and dexmedetomidine in tubercular spine surgery - A pilot randomised double-blind controlled trial

Background and Aims:

Regional analgesic techniques are difficult to use in tubercular spine patients due to distorted spinal anatomy and presence of infection. This study was conducted with the aim to evaluate analgesic efficacy of local wound infiltration before wound closure in tubercular spine patients.

Methods:

This pilot randomised double-blind controlled study was conducted in 32 American Society of Anesthesiologists I-III patients, age ≥15 years, undergoing elective surgery for spinal tuberculosis. All the patients received general anaesthesia using standard technique and intravenous morphine for intraoperative analgesia. They received wound infiltration with either normal saline (group C) or local infiltration analgesia with 0.375% ropivacaine 3 mg/kg, adrenaline 5 μg/mL and dexmedetomidine 1 μg/kg in a total volume of 0.8 mL/kg (group LIA) before wound closure. Patient-controlled analgesia using intravenous morphine provided postoperative analgesia. The primary objective was to study 24-h morphine consumption, whereas the secondary objectives included pain scores, complications and patient satisfaction. Repeated measures analysis of variance, Chi-square test and Mann–Whitney U test were used for statistical analysis.

Results:

Morphine requirement was lower in group LIA (6.7 ± 2.7 mg) than in group C (27.7 ± 7.9 mg);P < 0.001. Group LIA also had lower pain scores (P < 0.001), longer time to rescue analgesic (P < 0.001), better patient satisfaction to pain relief (P = 0.001) and lower incidence of postoperative nausea and vomiting than group C.

Conclusion:

Wound infiltration with ropivacaine, adrenaline and dexmedetomidine before wound closure provided good postoperative analgesia with lower morphine requirement.

Comparative evaluation of anaesthetic efficacy and haemodynamic effects of a combination of isobaric bupivacaine with buprenorphine vs. isobaric levobupivacaine with buprenorphine for spinal anaesthesia - A double blinded randomised clinical trial

Background and Aims

Bupivacaine is the most frequently used local anaesthetic for spinal anaesthesia, however, use of levobupivacaine in clinical practice has advanced recently. This study aimed to compare the anaesthetic potency and haemodynamic effects of intrathecal bupivacaine with buprenorphine versus levobupivacaine with buprenorphine in infraumbilical surgeries.

Methods

This prospective randomised double blind study was conducted in seventy patients aged 18-65 years, American Society of Anesthesiologists grade I-II, scheduled for lower abdominal and lower limb surgery under spinal anaesthesia. The patients either received 0.5% isobaric racemic bupivacaine 3 ml with 2 μg/kg of buprenorphine (Group B) or 0.5% isobaric levobupivacaine 3 ml with 2 μg/kg of buprenorphine (Group L). The time for onset of sensory block between the two groups was the priomary end-point. Other measurements included haemodynamic variables, sensory and motor blockade characteristics, postoperative analgesia, and complications in the first 24 h.

Results

There was no significant difference in the onset of sensory block between the two groups. Sensory and motor blockade characteristics were similar between the two groups. However, there was significant fall in the heart rate at 5 min in Group B compared to Group L. There was statistically significant fall in systolic blood pressure in group B compared to Group L from 5 min up to 60 min and fall in diastolic blood pressure from 10 min to 45 min.

Conclusion

Our study showed that onset of sensory block is similar between isobaric levobupivacaine with buprenorphine 37 38 and isobaric bupivacaine with buprenorphine.

The effect of dexmedetomidine in coracoid approach brachial plexus block under dual stimulation

BACKGROUND

Coracoid approach brachial plexus block (CABPB) is safe and effective for clinical anesthesia and analgesia. Dual stimulation can enhance the block effect of CABPB when using nerve stimulator. Dexmedetomidine is a highly selective α-adrenoceptor agonist and it can prolong the duration of anesthesia when it is added into local anesthetics. The aim of this study was to assess the effects of dexmedetomidine on the duration of anesthesia and the effective postoperative analgesia time when it was mixed with ropivacaine for CABPB under dual stimulation.

METHODS

A total of 60 patients were randomly assigned into 2 groups (groups D and C), 30 patients in each group. CABPB were guided by nerve stimulator under dual stimulation. Each patient received 40 mL of 0.375% ropivacaine (group C), or 40 mL of 0.375% ropivacaine mixed with 1 μg/kg dexmedetomidine (group D). The duration of anesthesia, the effective postoperative analgesia time, sensory and motor block onset time, visual analog scale (VAS), and the cumulative dose of rescue tramadol were recorded.

RESULTS

Twenty-eight patients in each group were analyzed. The duration of anesthesia was longer in group D as compared with group C (759 vs 634 minutes, P < .05) and the effective postoperative analgesia time was longer in group D as compared with group C (986 vs 789 minutes, P < .05) too. The onset time of sensory and motor blocks were not significantly different between the 2 groups (P > .05). The VAS was similar in the 2 groups at 6 and 12 hours after block (P > .05), but it was lower in group D at 24 hours after block as compared to group C (P < .05). The cumulative dose of rescue tramadol during the first 48 hours postoperative period was significantly lower in group D as compared to group C (P < .05). No significant changes were observed in vital signs in either group.

CONCLUSION

The addition of 1 μg/kg dexmedetomidine to ropivacaine extends the duration of anesthesia and the effective postoperative analgesia time for CABPB under dual stimulation. The VAS at 24 hours after block and the demand for rescue tramadol during the first 48 hours postoperative period are lower as well without side effects in the study group.(Registered in ClinicalTrials.gov id. NCT02961361).

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.

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.