An ultra-low dose of naloxone added to lidocaine or lidocaine-fentanyl mixture prolongs axillary brachial plexus blockade

The effect of adjuvants added to local anaesthetics for single-injection upper extremity peripheral regional anaesthesia: A systematic review with network meta-analysis of randomised trials

BACKGROUND

Peripheral regional anaesthesia is frequently used for upper extremity surgery. To prolong the duration of analgesia, adjuvants can be added to single-injection local anaesthetics. Despite attempts to compare several adjuvants in pairwise meta-analyses, a comprehensive comparison is still missing.

OBJECTIVE

The objective of this network meta-analysis was to determine the effectiveness of adjuvants in upper extremity peripheral nerve blocks.

DESIGN

A systematic review of randomised controlled trials with network meta-analyses.

DATA SOURCES

A literature search in Embase, CENTRAL, MEDLINE and Web of Science was performed up to March 2023.

ELIGIBILITY CRITERIA

Randomised trials comparing different adjuvants injected perineurally in peripheral upper extremity nerve blocks were eligible. Frequentist network meta-analysis was conducted using a random effects model with physiological saline as the comparator. The primary endpoint was the ratio of means (ROM) of the duration of analgesia.

RESULTS

The review included 242 randomised controlled trials with a total of 17 391 patients. Twenty-eight adjuvants were compared in the largest networks. Most network estimations consisted of a high proportion of direct evidence. Fourteen adjuvants increased the duration of analgesia significantly by the following factors, ROM [95% confidence interval (CI)]: dexamethasone 1.95 (1.79 to 2.13), buprenorphine 1.83 (1.51 to 2.24), butorphanol 1.84 (1.41 to 2.39), potassium chloride 1.89 (1.15 to 3.11), dexmedetomidine 1.70 (1.59 to 1.81), sufentanil 1.70 (1.27 to 2.29), ketorolac 1.68 (1.24 to 2.27), midazolam 1.55 (1.24 to 1.94), tramadol 1.52 (1.32 to 1.75), nalbuphine 1.50 (1.30 to 1.72), morphine 1.43 (1.09 to 1.88), magnesium sulfate 1.42 (1.20 to 1.67), clonidine 1.36 (1.24 to 1.50) and fentanyl 1.23 (1.08 to 1.40). Inconsistency in network meta-analysis was substantial. Overall side effect rates were low with all adjuvants.

CONCLUSION

The best interventions to prolong the duration of analgesia were dexamethasone, followed by dexmedetomidine, opioids, electrolytes, ketorolac and midazolam. There are general concerns about the quality of underlying studies and the risk of publication bias.

TRIAL REGISTRATION

PROSPERO 2018 CRD42018115722.

Effect of Fentanyl as an Adjuvant to Brachial Plexus Block for Upper Extremity Surgeries: A Systematic Review and Meta-Analysis of RCTs

Objective

To assess if the addition of fentanyl to brachial plexus block has an impact on anesthetic outcomes and complication rates in patients undergoing upper extremity surgeries.

Methods

We explore the PubMed, Embase, ScienceDirect, CENTRAL, and Google Scholar databases for all randomized controlled trials (RCTs) comparing adjuvant fentanyl with placebo/no drug for patients undergoing upper extremity surgery under brachial plexus block. Outcomes assessed were onset, duration of sensory and motor anesthesia, complications, and postoperative analgesia scores. Meta-analysis was conducted utilizing a random-effects model. The risk of bias was assessed using the Cochrane Collaboration's risk of bias assessment tool 2. Certainty of evidence was assessed using GRADE. Subgroup analysis was conducted depending upon the approach of brachial plexus block and type of local anesthetic.

Results

Twelve RCTs with 660 patients were included. Addition of fentanyl had no effect on onset of sensory anesthesia (11 studies; MD: 0.48; 95% CI: -1.81, 0.85; I 2 = 96%; p=0.48) but significantly shortened onset of motor anesthesia (8 studies; MD: -2.36; 95% CI: -3.99, -0.74; I 2 = 96%; p=0.48). Duration of sensory anesthesia (9 studies; MD: 82.81; 95% CI: 41.81, 123.81; I 2 = 99%; p < 0.0001) and motor anesthesia (7 studies; MD: 93.41; 95% CI: 42.35, 144.46; I 2 = 99%; p=0.0003) was significantly increased with addition of fentanyl. The certainty of evidence-based on GRADE was deemed to be moderate for both onset and duration of anesthesia. The incidence of overall complications (nausea/vomiting and pruritis) was significantly higher in the fentanyl group (7 studies; OR: 2.14; 95% CI: 1.04, 4.40; I 2 = 8%; p=0.04) but with low certainty of evidence.

Conclusions

Adjuvant fentanyl with brachial plexus block improves the onset of motor anesthesia but not sensory anesthesia. The duration of both sensory and motor anesthesia is significantly prolonged with fentanyl by around 83-93 minutes. However, clinicians should be aware that complications such as nausea/vomiting and pruritis are increased twofold with the addition of the drug. Current evidence is limited risk of bias in the RCTs and high heterogeneity in the meta-analyses.

A Low Dose of Naloxone Added to Ropivacaine Prolongs Femoral Nerve Blockade: A Randomized Clinical Trial

Femoral nerve blocks (FNBs) are used as safe and useful procedures to control severe postoperative pain from total knee arthroplasty (TKA). Various adjuvants have been used to prolong the duration of the local anesthetic blockade. This study evaluated whether a low dose of naloxone administered with local anesthetics prolongs the duration of FNB. A prospective, randomized double-blind controlled study was conducted with 74 patients undergoing unilateral TKA. Through a single-bolus administration guided by ultrasound, the control group (group C) received 20 mL of 0.375% ropivacaine, while the naloxone group (group N) received 20 mL of 0.375% ropivacaine with 100 ng of naloxone. The time elapsed before the first analgesia request, the total amount of opioids consumed at 24 h postoperatively, the onset time of the sensory blockade, the visual analog pain scale (VAS) scores after arriving at the recovery room, after 6, 12, 18, and 24 h at rest and after 12, 18, and 24 h of activity, the quadricep strength before the FNB procedure and at 12 and 24 h postoperatively, the quality of sleep on the first night after surgery, the satisfaction score, and the incidence of postoperative complications were recorded. The time elapsed before the first analgesia request was significantly longer in group N (735.5 ± 187.2 min) than that in group C (602.6 ± 210.4 min) (P=0.003). The total dose of supplementary opioids consumed at 24 h postoperatively was significantly lower in group N (312.4 ± 141.7 μg) than that in group C (456.5 ± 279.5 μg) (P=0.007). Lower VAS scores were recorded in group N than that in group C at rest and during knee activity (rest, 12 h, P=0.001, 18 h, P=0.043; activity, 12 h, P=0.001). The addition of a low dose of naloxone to ropivacaine for FNB significantly delayed the first request for rescue analgesia and decreased the opioid consumption within 24 h, without significant complications.

Comparative Study of Intravenous Dexmedetomidine Sedation With Perineural Dexmedetomidine on Supraclavicular Approach Brachial Plexus Block in Upper Limb Orthopaedic Surgery

Background

Dexmedetomidine is being used as an adjuvant analgesic, both as intravenous (IV) and intrathecal infusion. The role of perineural (P) dexmedetomidine has evoked attention recently. The aim of this study was to compare the effect of IV dexmedetomidine and P dexmedetomidine as an adjunct to supraclavicular brachial plexus block in upper limb orthopaedic surgery. 

Methods

Patients were randomly divided into two equal groups (n=20). Group I (IV dexmedetomidine) received dexmedetomidine 1 mcg/kg IV as loading dose over 10 minutes, followed by continuous infusion of dexmedetomidine 0.4 mcg/kg/hr IV. Group P (P dexmedetomidine) received dexmedetomidine at 1 mcg/kg perineurally. After adequate motor response with the aid of peripheral nerve stimulator a supraclavicular block with 40 ml solution containing 5 mg/kg lignocaine (2%) with adrenaline (1:200,000) and 2 mg/kg of bupivacaine (0.5%) was injected to both the groups. Group P also received dexmedetomidine perineurally with block. Onset and duration of sensory and motor block, Ramsay sedation score, hemodynamic parameters, and postoperative analgesia requirement were assessed along with side effects. The data obtained were recorded as mean ± SD, ranges, numbers, and ratios. Results were analyzed using the chi-square test, the Mann-Whitney test for non-parametric data, and an unpaired ‘t’-test for parametric data. Statistical analysis was carried out using the SPSS (version 10, 2002; SPSS Inc., Chicago, IL, USA) for Windows statistical package. P value less than 0.05 was considered statistically significant. 

Results

Mean onset of sensory block was earlier in group I than in group P (p<0.05) although mean onset of motor block was not significantly different (p>0.05). Duration of sensory and motor blockade was longer in group I (p<0.05). Patients in group I demonstrated lower pulse rate and lower systolic and diastolic blood pressures throughout the period with comparable SpO₂ values. There was no difference in intraoperative Ramsay sedation scores in both groups, but postoperative Ramsay sedation scores at 9, 12, and 15 hours were better in group I (p<0.05). The average time to rescue analgesia (visual analogue scale >4) was higher in group I (p>0.05).

Conclusion

IV dexmedetomidine produced early onset of sensory block, longer duration of sensory and motor block, and longer duration of analgesia as compared with P dexmedetomidine as an adjuvant to supraclavicular block with 5 mg/kg lignocaine (2%) and 2 mg/kg bupivacaine (0.5%) in upper limb orthopaedic surgeries.

Small dose of naloxone as an adjuvant to bupivacaine in intrapleural infiltration after thoracotomy surgery: a prospective, controlled study

Background

Severe pain always develops after thoracotomy; intrapleural regional analgesia is used as a simple, safe technique to control it. This study was performed to evaluate whether a small dose of naloxone with local anesthetics prolongs sensory blockade.

Methods

A prospective, randomized double-blinded controlled study was conducted on 60 patients of American Society of Anesthesiologists statuses I and II, aged 18 to 60 years, scheduled for unilateral thoracotomy surgery. After surgery, patients were randomly divided into two groups: through the intrapleural catheter, group B received 30 ml of 0.5% bupivacaine, while group N received 30 ml of 0.5% bupivacaine with 100 ng of naloxone. Postoperative pain was assessed using the visual analog pain scale (VAS). Time for the first request for rescue analgesia, total amount consumed, and incidence of postoperative complications were also recorded.

Results

The VAS score significantly decreased in group N, at 6 h and 8 h after operation (P < 0.001 for both). At 12 h after injection, the VAS score increased significantly in group N (P < 0.001). The time for the first request of rescue analgesia was significantly longer in group N compared to group B (P < 0.001). The total amount of morphine consumed was significantly lower in group N than in the bupivacaine group (P < 0.001).

Conclusions

Addition of a small dose of naloxone to bupivacaine in intrapleural regional analgesia significantly prolonged pain relief after thoracotomy and delayed the first request for rescue analgesia, without significant adverse effects.

Low-Dose Naltrexone (LDN)-Review of Therapeutic Utilization

Naltrexone and naloxone are classical opioid antagonists. In substantially lower than standard doses, they exert different pharmacodynamics. Low-dose naltrexone (LDN), considered in a daily dose of 1 to 5 mg, has been shown to reduce glial inflammatory response by modulating Toll-like receptor 4 signaling in addition to systemically upregulating endogenous opioid signaling by transient opioid-receptor blockade. Clinical reports of LDN have demonstrated possible benefits in diseases such as fibromyalgia, Crohn’s disease, multiple sclerosis, complex-regional pain syndrome, Hailey-Hailey disease, and cancer. In a dosing range at less than 1 μg per day, oral naltrexone or intravenous naloxone potentiate opioid analgesia by acting on filamin A, a scaffolding protein involved in μ-opioid receptor signaling. This dose is termed ultra low-dose naltrexone/naloxone (ULDN). It has been of use in postoperative control of analgesia by reducing the need for the total amount of opioids following surgery, as well as ameliorating certain side-effects of opioid-related treatment. A dosing range between 1 μg and 1 mg comprises very low-dose naltrexone (VLDN), which has primarily been used as an experimental adjunct treatment for boosting tolerability of opioid-weaning methadone taper. In general, all of the low-dose features regarding naltrexone and naloxone have been only recently and still scarcely scientifically evaluated. This review aims to present an overview of the current knowledge on these topics and summarize the key findings published in peer-review sources. The existing potential of LDN, VLDN, and ULDN for various areas of biomedicine has still not been thoroughly and comprehensively addressed.

Does co-treatment with ultra-low-dose naloxone and morphine provide better analgesia in renal colic patients?

OBJECTIVE

This study attempted to evaluate the efficacy of ultra-low-dose intravenous (IV) naloxone combined with IV morphine, as compared to IV morphine alone, in terms of reducing pain and morphine-induced side effects in patients with renal colic.

METHODS

In this double-blind clinical trial, 150 patients aged 34 to 60 years old who presented to the emergency department (ED) with renal colic were randomly allocated to either an intervention group that received ultra-low-dose IV naloxone combined with IV morphine or to a control group that received morphine plus a placebo. The severity of pain, sedation, and nausea were assessed and recorded for all patients at entrance to the ED (T1), then at 20 (T2), 40 (T3), 60 (T4), 120 (T5), and 180 (T6) minutes after starting treatment. The Numeric Rating Scale (NRS) was used for the assessment of pain and nausea intensities, and the Ramsay Sedation Scale (RSS) was used to assess sedation.

RESULTS

A GEE model revealed that patients in the naloxone group had non-significantly reduced pain scores compared to those in the morphine group (coefficient = -0.68; 95% CI: -1.24 to -0.11, Wald X2 (1) = 5.41, p = 0.02). The sedation outcome demonstrated no statistically significant differences at T1 to T4 among patients with renal colic compared to the ones who only received morphine. At T5 and T6, 1.5% vs. 20% and 1.5% vs. 16.9% of subjects from the naloxone group versus the morphine group obtained RSS scores equal to 3, respectively (p = 0.001 and p = 0.004, respectively).

CONCLUSIONS

Compared to patients who only received IV morphine, co-treatment of ultra-low-dose naloxone with morphine could not provide better analgesia and sedation/agitation states in renal colic patients.

Naloxone added to bupivacaine or bupivacaine-fentanyl prolongs motor and sensory block during supraclavicular brachial plexus blockade: a randomized clinical trial

BACKGROUND

In this study, the effect of naloxone on duration of supraclavicular brachial plexus block was evaluated. It was hypothesized that naloxone can increase the duration of neural blockade.

METHODS

Sixty-eight patients scheduled for surgery under supraclavicular brachial plexus block were randomly assigned to receive 30 ml bupivacaine (Group C); 30 ml bupivacaine with 100 μg of fentanyl (Group F); 30 ml bupivacaine with 100 ng naloxone (Group N); or 30 ml bupivacaine with 100 μg of fentanyl and 100 ng naloxone (Group N + F). Sensory and motor blockade were recorded at 5, 15, and 30 min following the block, and every 10 min following the end of surgery. Duration of sensory and motor block was considered to be the time interval between the complete block and the first postoperative pain and complete recovery of motor functions.

RESULTS

Sensory and motor onset times were the same in all groups. The duration of sensory and motor block in Group C (11.3 ± 1.7 h and 4.56 ± 1.0 h) and Group F (12.8 ± 3.3 h and 5.1 ± 2.0 h) were less than in the other groups (18.1 ± 2.2 h and 6.18 ± 1.0 h in Group N, and 15.8 ± 2.9 h and 6.53 ± 1.1 h in Group N + F, P < 0.0001).

CONCLUSION

Addition of naloxone to bupivacaine in supraclavicular brachial plexus block prolonged the duration of the neural blockade.

Effect of ketamine as an adjuvant in ultrasound-guided supraclavicular brachial plexus block: A double-blind randomized clinical trial study

Background:

Supraclavicular brachial plexus block is one of the most effective anesthetic procedures in operations for the upper extremity. Ketamine has been reported to enhance the analgesic effects of local anesthetics. We have conducted this study to assess whether coadministration of ketamine can prolong the local analgesic effect of lidocaine in the supraclavicular brachial plexus block for patients undergoing elective upper extremity surgery.

Materials and Methods:

Sixty adult patients undergoing elective surgery of the elbow, forearm, wrist or hand were randomly allocated in two groups of 30 patients each. Group 1 (ketamine group) received 5 mg/kg lidocaine 1.5% plus 2 mg/kg ketamine, Group 2 (control group) received 5 mg/kg lidocaine 1.5% and saline. The outcome measures included severity of pain by using visual analog scale (VAS, 0 = no pain 10 cm = the most severe pain), time of first request for analgesia, and total dose of postoperative opioid administration. The data was analyzed using the χ² test, student's t-test, Kaplan-Meier survival analysis, and Multivariate analysis tests.

Results:

Patients in the control group had a higher VAS than patients who received ketamine, at all time points during the first 24 hours after surgery (all P < 0.05). The time of first request for analgesia in the ketamine group was significantly more than in the control group (8.93 ± 1.0 vs. 7.30 ± 1.9, respectively, P < 0.001).

Conclusion:

The addition of ketamine to lidocaine in the ultrasound-guided brachial plexus block could decrease the postoperative pain and need for analgesic. Therefore, it could be considered as an option in the brachial plexus block to enhance the analgesic action of lidocaine.

Liposomal bupivacaine as a single-injection peripheral nerve block: a dose-response study

BACKGROUND

Currently available local anesthetics approved for single-injection peripheral nerve blocks have a maximum duration of <24 hours. A liposomal bupivacaine formulation (EXPAREL, Pacira Pharmaceuticals, Inc., San Diego, CA), releasing bupivacaine over 96 hours, recently gained Food and Drug Administration approval exclusively for wound infiltration but not peripheral nerve blocks.

METHODS

Bilateral single-injection femoral nerve blocks were administered in healthy volunteers (n = 14). For each block, liposomal bupivacaine (0-80 mg) was mixed with normal saline to produce 30 mL of study fluid. Each subject received 2 different doses, 1 on each side, applied randomly in a double-masked fashion. The end points included the maximum voluntary isometric contraction (MVIC) of the quadriceps femoris muscle and tolerance to cutaneous electrical current in the femoral nerve distribution. Measurements were performed from baseline until quadriceps MVIC returned to 80% of baseline bilaterally.

RESULTS

There were statistically significant dose responses in MVIC (0.09%/mg, SE = 0.03, 95% confidence interval [CI], 0.04-0.14, P = 0.002) and tolerance to cutaneous current (-0.03 mA/mg, SE = 0.01, 95% CI, -0.04 to -0.02, P < 0.001), however, in the opposite direction than expected (the higher the dose, the lower the observed effect). This inverse relationship is biologically implausible and most likely due to the limited sample size and the subjective nature of the measurement instruments. While peak effects occurred within 24 hours after block administration in 75% of cases (95% CI, 43%-93%), block duration usually lasted much longer: for bupivacaine doses >40 mg, tolerance to cutaneous current did not return to within 20% above baseline until after 24 hours in 100% of subjects (95% CI, 56%-100%). MVIC did not consistently return to within 20% of baseline until after 24 hours in 90% of subjects (95% CI, 54%-100%). Motor block duration was not correlated with bupivacaine dose (0.06 hour/mg, SE = 0.14, 95% CI, -0.27 to 0.39, P = 0.707).

CONCLUSIONS

The results of this investigation suggest that deposition of a liposomal bupivacaine formulation adjacent to the femoral nerve results in a partial sensory and motor block of >24 hours for the highest doses examined. However, the high variability of block magnitude among subjects and inverse relationship of dose and response magnitude attests to the need for a phase 3 study with a far larger sample size, and that these results should be viewed as suggestive, requiring confirmation in a future trial.

Opioid antagonists for pain

INTRODUCTION

Opioid receptor antagonists are well known for their ability to attenuate or reverse the effects of opioid agonists. This property has made them useful in mitigating opioid side effects, overdose and abuse. Paradoxically, opioid antagonists have been reported to produce analgesia or enhance analgesia of opioid agonists. The authors review the current state of the clinical use of opioid antagonists as analgesics.

AREAS COVERED

Published clinical trials, case reports and other sources were reviewed to determine the effectiveness and safety of opioid antagonists for use in relieving pain. The results are summarized. Postulated mechanisms for how opioid antagonists might exert an analgesic effect are also briefly summarized.

EXPERT OPINION

Since the comprehensive review by Leavitt in 2009, few new studies on the use of opioid antagonists for pain have been published. The few clinical trials generally consist of small populations. However, there does appear to be a trend of effectiveness of low doses (higher doses antagonize opioid agonist effects). How opioid antagonists can elicit an analgesic effect is still unclear, but a number of possibilities have been suggested. Although the data do not yet support recommendation of widespread application of this off-label use of opioid antagonists, further study appears worthwhile.

Preventive analgesia by local anesthetics: the reduction of postoperative pain by peripheral nerve blocks and intravenous drugs

The use of local anesthetics to reduce acute postoperative pain has a long history, but recent reports have not been systematically reviewed. In addition, the need to include only those clinical studies that meet minimum standards for randomization and blinding must be adhered to. In this review, we have applied stringent clinical study design standards to identify publications on the use of perioperative local anesthetics. We first examined several types of peripheral nerve blocks, covering a variety of surgical procedures, and second, we examined the effects of intentionally administered IV local anesthetic (lidocaine) for suppression of postoperative pain. Thirdly, we have examined publications in which vascular concentrations of local anesthetics were measured at different times after peripheral nerve block procedures, noting the incidence when those levels reached ones achieved during intentional IV administration. Importantly, the very large number of studies using neuraxial blockade techniques (epidural, spinal) has not been included in this review but will be dealt with separately in a later review. The overall results showed a strongly positive effect of local anesthetics, by either route, for suppressing postoperative pain scores and analgesic (opiate) consumption. In only a few situations were the effects equivocal. Enhanced effectiveness with the addition of adjuvants was not uniformly apparent. The differential benefits between drug delivery before, during, or immediately after a surgical procedure are not obvious, and a general conclusion is that the significant antihyperalgesic effects occur when the local anesthetic is present during the acute postoperative period, and its presence during surgery is not essential for this action.