Comparison of Magnesium Sulfate and Ketamine with Ropivacaine in Supraclavicular Brachial Plexus Block: A Randomized Controlled Trial

Background:

Supraclavicular brachial plexus block offers good operating conditions with limited postoperative analgesia. Magnesium sulfate (MgSO₄) and ketamine block peripheral nociception mediated via N-methyl-D-aspartate receptors.

Aims:

The aim of this study was to evaluate the effect of MgSO₄ and ketamine on the duration of analgesia in brachial block.

Settings and Design:

This was a prospective, randomized, controlled double-blind study.

Materials and Methods:

One hundred and five adult patients were randomly divided into three groups: Group I = 27 mL of 0.5% ropivacaine; Group II = 27 mL of 0.5% ropivacaine + 250 mg MgSO₄; and Group II = 27 mL of 0.5% ropivacaine + 2 mg.kg⁻¹ ketamine. Normal saline was added to make a total volume of 30 mL. The onset and duration of the sensorimotor blockade, quality and duration of postoperative analgesia, and adverse effects were assessed.

Statistical Analysis:

Statistical analysis was performed using SPSS, version 17.0 software (SPSS, Inc., Chicago, IL, USA). Chi-square test was used for nonparametric and ANOVA for parametric data. Post hoc Student's paired t-test was applied wherever indicated. The results were expressed as mean and standard deviation or numbers (%). P < 0.05 was considered as statistically significant.

Results:

The duration of analgesia was significantly longer in Group II (8.78 ± 0.97 h) compared to Group I (6.76 ± 0.92 h; P < 0.001) and Group III (7.1 ± 0.89 h; P < 0.001). Intervention groups had lower postoperative visual analog scores at 8, 12, and 24 h compared to the control group. Sedation, nystagmus, and hallucinations were observed in Group III.

Conclusion:

The addition of MgSO₄ to ropivacaine in supraclavicular brachial plexus block significantly prolongs the duration of analgesia. MgSO₄ improves the quality of postoperative analgesia with lesser incidence of side effects when compared to ketamine.

Adjuvants in pain medicine. Selection of the drug depending on the desired effect – so which drug to choose?

To date, much research has focused on finding the ideal adjuvant for local anesthetics. Each of them can have different effects. In anesthesiology and pain medicine, depending on the purpose, one or another effect may be desirable. For example, in some situations it is desirable to accelerate the onset of action or prolong the duration of the block, in others the desired effect may be a “response to intravascular administration”, it should also be borne in mind that not all adjuvants are allowed for intrathecal administration.

Evaluation of magnesium as an adjuvant to ropivacaine-induced axillary brachial plexus block: A prospective, randomised, double-blind study

Background and Aims:

Axillary brachial plexus block is commonly performed for surgeries on the hand and forearm. However, there are very few studies on the use of magnesium sulphate in axillary brachial plexus block and, hence, the study was designed to evaluate magnesium as an adjuvant to ropivacaine-induced axillary block with respect to onset and duration of sensorimotor block and postoperative analgesia.

Methods:

Sixty patients of the American Society of Anesthesiologists (ASA) physical status I and II, undergoing surgeries on the hand and forearm were randomly recruited to receive ultrasound-guided axillary block with either 150 mg magnesium sulphate or 1 mL normal saline added to 0.5% ropivacaine. The primary outcome measure was to compare block characteristics including postoperative analgesia and the secondary outcome was to compare the use of rescue analgesia and the side-effect profile. Data were statistically analysed using Statistical Package for Social Sciences (SPSS version 21.0). Categorical variables were compared using the Chi-square test or Fisher's exact probability test; continuous variables compared using unpaired t-test or Mann-Whitney U test.

Results:

Onset of sensory (9.93 ± 1.31 vs 8.83 ± 1.12 min) as well as motor block (13.37 ± 1.63 vs 11.57 ± 1.30 min) was significantly hastened with addition of magnesium to ropivacaine (p < 0.001) and so was the duration (sensory 386.60 ± 18.26 vs 526.37 ± 27.43, motor 323.73 ± 15.17 vs 436.97 ± 18.99 min) (p < 0.001) and postoperative analgesia (425 ± 21.39 vs 572.83 ± 32.04 min) (p < 0.001) which reflected in decreased requirement of rescue analgesic and total postoperative analgesic dosage.

Conclusions:

Magnesium is an effective and safe adjuvant to local anaesthetics and improves all characteristics of axillary brachial plexus block along with postoperative analgesia.

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.

Analgesic effect of perineural magnesium sulphate for sciatic nerve block for diabetic toe amputation: A randomized trial

Background and objectives

High concentrations of local anesthetics may be neurotoxic for diabetic patients. Additive perineural administration of magnesium was reported to decrease the consumption of local anesthetics for nerve block. It was hypothesized that MgSO₄ added to dilute ropivacaine was equianalgesic to more concentrated ropivacaine for toe amputations in diabetic patients.

Methods

Seventy diabetic patients were allocated into 3 groups: 1) perineural 200 mg MgSO₄ added to 0.25% ropivacaine, 2) 0.25% ropivacaine alone, and 3) 0.375% ropivacaine alone. All patients underwent popliteal sciatic nerve block that was guided by ultrasonography using the respective regimens. Time of onset, duration of motor and sensory block were recorded. Spontaneous and evoked pain score, worst pain score, additional analgesic consumption, satisfaction score and initial time of analgesic requirement of each patient were documented up to 48 hours postoperatively.

Results

In comparison with 0.25% ropivacaine alone, magnesium supplement prolonged the duration of sensory block (p = 0.001), as well as better evoked pain score at 6 hour postoperatively (p = 0.001). In comparison with evoked pain score (1.6/10) in group of 0.375% ropivacaine, magnesium plus 0.25% ropivacaine presented a little higher score (2.5/10) at 6 hour postoperatively (p = 0.001), while lower worst pain score (p = 0.001) and less postoperative total analgesic consumption (p = 0.002).

Conclusions

The regimen of adding 200mg MgSO₄ to 0.25% ropivacaine for sciatic nerve block yields equal analgesic effect in comparison with 0.375% ropivacaine. These findings have suggested that supplemental MgSO₄ could not improve analgesic quality except reducing the total amount of local anesthetics requirement in diabetic toe amputations with sciatic nerve blocks.

Perineural Nalbuphine in Ambulatory Upper Limb Surgery: A Comparison of Effects of Levobupivacaine with and without Nalbuphine as Adjuvant in Supraclavicular Brachial Plexus Block - A Prospective, Double-blinded, Randomized Controlled Study

Background and Aims:

Various opioid additives have been trialed to prolong brachial plexus block. We evaluated the effect of adding nalbuphine hydrochloride to levobupivacaine for supraclavicular brachial plexus blockade. The primary end-points were the onset and duration of sensory and motor blocks and duration of analgesia.

Materials and Methods:

Seventy-eight patients (aged 25–45 years) posted for ambulatory forearm and hand surgery under supraclavicular brachial plexus block were divided into two equal groups (Groups LN and LC) in a randomized, double-blind fashion. In Group LN (n = 39), 30 ml 0.5% levobupivacaine + 10 mg (diluted in 2 ml 0.9% saline) nalbuphine hydrochloride, and in Group LC (n = 39), 30 ml 0.5% levobupivacaine + 2 ml normal saline (0.9%) were administered in supraclavicular block. Sensory and motor block onset times and block durations, time to first analgesic use, total analgesic need, postoperative visual analog scale (VAS), hemodynamics, and side effects were recorded for each patient.

Results:

Although with similar demographic profile and block (sensory and motor) onset time, sensory and motor block duration and time to first analgesic use were significantly longer and the total need for rescue analgesics was lower in Group LN (P < 0.05) than Group LC. Postoperative VAS value at 24 h was significantly lower in Group LN (P < 0.05). Intraoperative hemodynamics was comparable between two groups, and no any appreciable side effect was noted throughout the study period.

Conclusion:

It can be concluded that adding nalbuphine hydrochloride to supraclavicular brachial plexus block increases the sensory and motor block duration and time to first analgesic use, and decreases total analgesic use with no side effects.

Pain relief after ambulatory hand surgery: A comparison between dexmedetomidine and clonidine as adjuvant in axillary brachial plexus block: A prospective, double-blinded, randomized controlled study

BACKGROUND

For ages various adjuvants have been tried to prolong axillary brachial plexus block. We compared the effect of adding dexmedetomidine versus clonidine to ropivacaine for axillary brachial plexus blockade. The primary endpoints were the onset and duration of sensory and motor block and duration of analgesia.

MATERIALS AND METHODS

A total of 90 patients (20-40 years) posted for ambulatory elective hand surgery under axillary brachial plexus block were divided into two equal groups (groups ropivacaine dexmedetomidine [RD] and ropivacaine clonidine [RC]) in a randomized, double-blind fashion. In group RD (n = 45) 30 ml 0.5% ropivacaine + 100 μg of dexmedetomidine and group RC (n = 45) 30 ml 0.5% ropivacaine + 75 μg clonidine were administered in axillary plexus block. Sensory and motor block onset times and block durations, time to first analgesic use, total analgesic need, postoperative visual analog scale (VAS), hemodynamics and side-effects were recorded for each patient.

RESULTS

Though with similar demographic profile in both groups, sensory and motor block in group RD (P < 0.05) was earlier than group RC. Sensory and motor block duration and time to first analgesic use were significantly longer and the total need for rescue analgesics was lower in group RD (P < 0.05) than group RC. Postoperative VAS value at 18 h were significantly lower in group RD (P < 0.05). Intraoperative hemodynamics were insignificantly lower in group RD (P < 0.05) without any appreciable side-effects.

CONCLUSION

It can be concluded that adding dexmedetomidine to axillary plexus block increases the sensory and motor block duration and time to first analgesic use, and decreases total analgesic use with no side-effects.

Effect of addition of magnesium to local anesthetics for peribulbar block: A prospective randomized double-blind study

Background:

Magnesium sulphate has been used along with local anesthetics in different regional blocks and found to be effective in decreasing the time of onset of the block and increasing the duration of the block.

Objective:

To evaluate the effect of addition of magnesium sulfate to standard local anesthetics mixture on the time for onset of the globe and lid akinesia for peribulbar block in ophthalmic surgeries.

Materials and Methods:

Sixty patients with American Society of Anesthesiologists status I to III undergoing ophthalmic surgery under peribulbar block were included in this study. Patients were randomized into two groups. Both the groups received 4.5 ml of 2% lidocaine, 4.5 ml of 0.5% bupivacaine with150 IU hyaluronidase. Group NS received normal saline 1 ml in the peribulbar block and Group MS, magnesium sulfate 50 mg in 1 ml normal saline. The onset of akinesia, satisfactory block and complications were observed by an independent observer.

Results:

Demographic data was statistically similar. In the Group NS at 3, 5, 10 and 15 min after the block, complete akinesia was seen in 0, 2, 11 and 28 patients respectively. In the Group MS, at 3, 5, 10 and 15 min after the block, complete akinesia was seen in 13, 23, 27 and 28 patients respectively. Patients received magnesium sulfate showed the statistically significant rapid onset of lid and globe akinesia than the control group till 10 min (P < 0.000). None of the patients needed a supplementary block and had complications during the surgery.

Conclusion:

Addition of 50 mg of magnesium sulfate to the lidocaine-bupivacaine mixture for peribulbar block decreases the onset of akinesia without any obvious side effect.

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.

Effect of dexmedetomidine as adjuvant in ropivacaine-induced supraclavicular brachial plexus block: A prospective, double-blinded and randomized controlled study

Background and Aims:

Different additives have been used to prolong brachial plexus block. We evaluated the effect of adding dexmedetomidine to ropivacaine for supraclavicular brachial plexus blockade. The primary endpoints were the onset and duration of sensory and motor block and duration of analgesia.

Materials and Methods:

A total of 84 patients (20-50 years) posted for elective forearm and hand surgery under supraclavicular brachial plexus block were divided into two equal groups (Group R and RD) in a randomized, double-blind fashion. In group RD (n = 42) 30 ml 0.5% ropivacaine +1 ml (100 μg) of dexmedetomidine and group R (n = 42) 30 ml 0.5% ropivacaine +1 ml normal saline were administered in supraclavicular block. Sensory and motor block onset times and block durations, time to first analgesic use, total analgesic need, postoperative visual analog scale (VAS), hemodynamics and side-effects were recorded for each patient.

Results:

Though with similar demographic profile in both groups, sensory and motor block in group RD (P < 0.05) was earlier than group R. Sensory and motor block duration and time to first analgesic use were significantly longer and the total need for rescue analgesics was lower in group RD (P < 0.05) than group R. Post-operative VAS value at 12 h were significantly lower in group RD (P < 0.05). Intra-operative hemodynamics were significantly lower in group RD (P < 0.05) without any appreciable side-effects.

Conclusion:

It can be concluded that adding dexmedetomidine to supraclavicular brachial plexus block increases the sensory and motor block duration and time to first analgesic use, and decreases total analgesic use with no side-effects.

Evaluation of Magnesium as an adjuvant in Ropivacaine-induced supraclavicular brachial plexus block: A prospective, double-blinded randomized controlled study

Objective:

Different additives have been used to prolong brachial plexus block. We evaluated the effect of adding magnesium sulfate to ropivacaine for supraclavicular brachial plexus blockade. The primary endpoints were the onset and duration of sensory and motor block and duration of analgesia.

Methods:

One hundred patients (25–55 years) posted for elective forearm and hand surgeries under supraclavicular brachial plexus block were divided into two equal groups (Groups RM and RN) in a randomized, double-blind fashion. In group RM (n = 50), 30 ml 0.5% ropivacaine plus 150 mg (in 1 ml 0.9% saline) magnesium sulfate and in group RN (n = 50), 30 ml 0.5% ropivacaine plus 1 ml normal saline were administered in supraclavicular block. Sensory and motor block onset times and block durations, time to first analgesic use, total analgesic need, postoperative visual analog scale (VAS), hemodynamic variables, and side effects were recorded for each patient.

Findings:

Though with similar demographic profile and block (sensory and motor) onset time, the sensory and motor block duration and time to first analgesic use were significantly longer and the total need for rescue analgesics was lower in group RM (P = 0.026) than group RN. Postoperative VAS values at 24 h were significantly lower in group RM (P = 0.045). Intraoperative hemodynamics was comparable among two groups and no appreciable side effect was noted throughout the study period.

Conclusion:

It can be concluded from this study that adding magnesium sulfate to supraclavicular brachial plexus block may increase the sensory and motor block duration and time to first analgesic use, and decrease total analgesic needs, with no side effects.