Additives to local anesthetics for peripheral nerve blockade. Int Anesthesiol Clin. 2011;49:104-116. [PMID: 21956081 DOI: 10.1097/aia.0b013e31820e4a49]

Local Anesthetics, Local Anesthetic Systemic Toxicity (LAST), and Liposomal Bupivacaine

Local anesthetics have played a vital role in the multimodal analgesia approach to patient care by decreasing the use of perioperative opioids, enhancing patient satisfaction, decreasing the incidence of postoperative nausea and vomiting, decreasing the length of hospital stay, and reducing the risk of chronic postsurgical pain. The opioid-reduced anesthetic management for perioperative analgesia has been largely successful with the use of local anesthetics during procedures such as peripheral nerve blocks and neuraxial analgesia. It is important that practitioners who use local anesthetics are aware of the risk factors, presentation, and management of local anesthetic systemic toxicity (LAST).

Implementation of an Ultrasound-Guided Regional Anesthesia Program in the Emergency Department of a Community Teaching Hospital

STUDY OBJECTIVE

We sought to initiate an emergency department (ED)-based ultrasound-guided regional anesthesia (UGRA) program in our community teaching hospital system. Here, we present our development process and protocol. We also sought to assess the types, indications, and associated adverse event rates for the UGRA procedures in this study.

METHODS

We conducted a retrospective analysis of prospectively collected quality assurance data from a case series of patients who underwent an UGRA procedure in the ED. In August 2020, we developed an UGRA program for our community teaching hospital and its 2 affiliated freestanding EDs. For quality assurance purposes, we tracked all UGRA procedures performed in the ED, and we specifically assessed adverse events using structured follow-up. We subsequently obtained approval from our institutional review board to perform chart reviews of the patients in our dataset to abstract additional data and formally perform a research study. We determined the frequency with which different UGRA procedures were performed, and we calculated the adverse event rate.

RESULTS

Between August 24, 2020, and July 15, 2022, a total of 18 different sonographers performed and documented 229 UGRA procedures on 206 unique patients. This included 28 different types of procedures. Follow-up after disposition was successful in 82.0% of patients. In 2 cases, the patient reported no pain relief at all from the procedure, but no patients reported complications related to the procedure.

CONCLUSION

We successfully initiated a robust ED-based UGRA program in our community teaching hospital system. Among patients with successful follow-up, no adverse events were identified.

Advances in Anesthesia for Shoulder Surgery: A Comprehensive Review of Dexmedetomidine-Enhanced Interscalene Brachial Plexus Block

Surgical procedures on the shoulder pose distinctive challenges in managing pain during the perioperative period, underscoring the importance of exploring innovative anesthesia techniques. This comprehensive review article delves into integrating dexmedetomidine, an alpha-2 adrenergic agonist, within interscalene brachial plexus blocks for shoulder surgery. The review initiates by underscoring the pivotal role of effective anesthesia in shoulder surgery and elucidates the rationale behind investigating dexmedetomidine as an adjunct. It meticulously examines the anatomy and physiology of the brachial plexus, emphasizing its critical significance in shoulder surgery. Furthermore, the article expounds on dexmedetomidine's mechanisms of action and pharmacokinetics, encompassing its safety profile and potential side effects. The conventional interscalene brachial plexus block techniques, along with their limitations and challenges, are discussed, laying the foundation for the integration of dexmedetomidine. The review subsequently delves into exploring the role of dexmedetomidine in regional anesthesia, covering previous studies, mechanisms of action, and the potential advantages of incorporating it into nerve blocks. The review's core concentrates on the practical application of dexmedetomidine-enhanced interscalene brachial plexus blocks. This includes discussions on administration techniques, dosage guidelines, and compelling evidence supporting its utilization. Clinical scenarios where this approach proves most advantageous are thoroughly explored, comparing its effectiveness with traditional techniques in terms of pain control and patient outcomes. A comprehensive examination of relevant clinical trials and case studies highlights the evidence supporting its efficacy. The review also underscores safety considerations associated with dexmedetomidine. It proposes strategies for mitigating risks to ensure patient safety. Insights into future directions and research are provided, encompassing ongoing studies, areas necessitating further investigation, and potential refinements in technique. Finally, the article summarizes key findings, emphasizing the practicality of dexmedetomidine-enhanced interscalene brachial plexus blocks in shoulder surgery and its far-reaching implications for clinical practice and patient care.

"Knowing It Before Blocking It," the ABCD of the Peripheral Nerves: Part B (Nerve Injury Types, Mechanisms, and Pathogenesis)

Selander emphatically said, "Handle these nerves with care," and those words still echo, conveying a loud and clear message that, however rare, peripheral nerve injury (PNI) remains a perturbing possibility that cannot be ignored. The unprecedented nerve injuries associated with peripheral nerve blocks (PNBs) can be most tormenting for the unfortunate patient and a nightmare for the anesthetist. Possible justifications for the seemingly infrequent occurrences of PNB-related PNIs include a lack of documentation/reporting, improper aftercare, or associated legal implications. Although they make up only a small portion of medicolegal claims, they are sometimes difficult to defend. The most common allegations are attributed to insufficient informed consent; preventable damage to a nerve(s); delay in diagnosis, referral, or treatment; misdiagnosis, and inappropriate treatment and follow-up care. Also, sufficient prospective studies or randomized trials have not been conducted, as exploring such nerve injuries (PNB-related) in living patients or volunteers may be impractical or unethical. Understanding the pathophysiology of various types of nerve injury is vital to dealing with them further. Processes like degeneration, regeneration, remyelination, and reinnervation can influence the findings of electrophysiological studies. Events occurring in such a process and their impact during the assessment determine the prognosis and the need for further interventions. This educational review describes various types of PNB-related nerve injuries and their associated pathophysiology.

Anesthetic efficacy of buffered 4% articaine for mandibular first molar infiltration: a crossover clinical trial

Background

The limited studies on the effect of buffering on the clinical efficacy of articaine have reported controversial results. The purpose of this study was to clinically compare the pain of injection, anesthetic success, onset, and duration of pulpal anesthesia of buffered 4% articaine with epinephrine 1:100000 versus a non-buffered 4% articaine with epinephrine 1:100000 formulation for buccal infiltration of the mandibular first molar.

Methods

Sixty-three volunteers were enrolled in the study. All volunteers received two injections consisting of a single mandibular first molar buccal infiltration with 1.8 ml of 4% articaine with epinephrine 1:100000 and 1.8 ml of 4% articaine with epinephrine 1:100000 buffered with 8.4% sodium bicarbonate. The infiltrations were applied in two separate appointments spaced at least one week apart. After injection of the anesthetic solution at the examined site, the first molar was pulp-tested every 2 min for the next 60 min.

Results

Successful pulpal anesthesia was recorded in 69.8% of cases using non-buffered articaine solution and 76.2% of cases using buffered articaine solution, with no significant difference between the formulations (P = 0.219). The mean time of anesthesia onset for the volunteers with successful anesthetic outcome in both formulations (n = 43) was 6.6 ± 1.6 min for the non-buffered articaine solution and 4.5 ± 1.6 min for the buffered solution, which differed significantly (P = 0.001). In the same volunteers, the mean duration of pulpal anesthesia was 28.4 ± 7.1 min for non-buffered articaine solution and 30.2 ± 8.5 min for buffered articaine solution, with no significant difference between the formulations (P = 0.231). Considering the pain of injection, regardless of the anesthetic success, the mean values of VAS were 11.3 ± 8.2 mm for the non-buffered articaine solution and 7.8 ±6.5 mm for the buffered articaine solution, which differed significantly (P = 0.001 < 0.05).

Conclusion

According to the present study, 4% articaine with epinephrine can benefit from buffering and provide better anesthetic behavior, with improved onset and less pain during injection.

Peripheral Regional Anesthesia Using Local Anesthetics: Old Wine in New Bottles?

During the past decade, numerous efforts were undertaken aiming at prolonging the analgesic effect of regional anesthesia. With the development of extended-release formulations and enhanced selectivity for nociceptive sensory neurons, a very promising contribution to the development of pain medications has been achieved. At present, liposomal bupivacaine is the most popular, non-opioid, controlled drug delivery system, but its duration of action, which is still controversially discussed, and its expensiveness have decreased initial enthusiasm. Continuous techniques can be seen as an elegant alternative for providing a prolonged duration of analgesia, but for logistic or anatomical reasons, they are not always the best choice. Therefore, focus has been directed towards the perineural and/or intravenous addition of old and established substances. As for perineural application, most of these so-called 'adjuvants' are used outside their indication, and their pharmacological efficacy is often not or only poorly understood. This review aims to summarize the recent developments for prolonging the duration of regional anesthesia. It will also discuss the potential harmful interactions and side effects of frequently used analgesic mixtures.

Safety and Duration of Low-Dose Adjuvant Dexamethasone in Regional Anesthesia for Upper Extremity Surgery: A Prospective, Randomized, Controlled Blinded Study

BACKGROUND

Orthopedic procedures concerning the upper extremity commonly use a brachial plexus nerve block to achieve postoperative analgesia. The addition of dexamethasone to peripheral nerve blocks has been shown to significantly prolong its effect. We hypothesize that 1 mg doses of dexamethasone will prolong brachial plexus nerve block with similar efficacy to 4 mg and better than ropivacaine alone.

METHODS

Seventy-nine patients who received a brachial plexus nerve block prior to undergoing upper extremity surgery were randomized to 1 of 4 treatment groups: group 1 received only 30 mL of 0.5% ropivacaine without dexamethasone (control); groups 2, 3, and 4 received 4, 2, and 1 mg of dexamethasone, respectively, added to 30 mL of 0.5% ropivacaine.

RESULTS

Comparison of block duration, specifically "first signs of the block wearing off" to the 0-mg group, referencing the 1-, 2-, and 4-mg groups (P = .02, .04, and .01, respectively) that received steroid adjuvant therapy demonstrated a significant increase in time until the block began to wear off. All study groups receiving steroids also demonstrated a significant increase in duration of the block prior to its effects being completely gone when compared with the control group (P < .01 for all groups).

CONCLUSIONS

Our findings demonstrate that adjuvant dexamethasone can prolong brachial plexus nerve blocks effectively at low doses compared with high doses, in addition to prolonging analgesia compared with local anesthetic alone.

The Effect of Sugammadex on Time of Sciatic Block by Perineural Bupivacaine in Rats

OBJECTIVES

We aimed to investigate the effect of sugammadex on the motor, sensory and deep sensory block in the sciatic nerve created by bupivacaine in rats.

MATERIALS AND METHODS

18 Sprague-Dawley adult male rats treated with unilateral sciatic nerve block by bupivacaine (0.2 ml) were randomly divided into three groups. Control group (Group C, n = 6, 1.5 mL saline) perineural sugammadex group (Group PNS, n = 6, 16 mg/kg) and intraperitoneal sugammadex group (Group IPS, n = 6, 16 mg/kg) Motor, sensory, and deep sensory functions were evaluated every 10 minutes by a blind researcher. 6 tissue samples each belonging to the sciatic nerve, 1.5 cm in length and 0.2 cm in diameter, were taken from paraffin blocks. Sections of 3-4 micrometers were stained with Hematoxylin + Eosin, Masson Trichrome dyes and examined under a light microscope.

RESULTS

There was no statistically significant difference between 3 groups in terms of the time to return to normal motor, sensory and deep sensory function. There was also no significant difference in edema, extracellular matrix, and myelin. Inflammatory cells were seen in all groups, mainly epineurium, epineurium, and perineurium.

CONCLUSION

There are findings of no histological effects or effects on local block of sugammadex in rats undergoing sciatic nerve block.

Comparison Between Dexamethasone and Fentanyl as an Adjuvant to Bupivacaine and Lignocaine in Supraclavicular Brachial Plexus Block for Upper Limb Surgery

Background:

Interest in supraclavicular brachial plexus blocks has been rekindled using sonographic guidance to locate the brachial plexus. Various adjuncts have been suggested to potentiate the anesthetic and analgesic effects of local anesthetic agents. We designed this randomized double-blind controlled study to compare the effects of dexamethasone and fentanyl when added to a mixture of bupivacaine and lignocaine in supraclavicular blocks in patients undergoing forearm surgeries.

Methods:

Sixty-six patients aged between 20 to 60 years old belonging to ASA one or two were recruited prospectively, double-blinded, and randomized way. Supraclavicular block under sonographic guidance was performed in the three groups by using injection bupivacaine (0.5%) 20 cc + injection lignocaine (2%) 10 cc + injection 0.9% normal saline; 2ml (Group S), injection bupivacaine (0.5%) 20 cc + injection lignocaine (2%) 10 cc + injection dexamethasone 8 mg (Group D), and injection bupivacaine (0.5%) 20 cc + injection lignocaine (2%) 10 cc + injection fentanyl 50 µgm (Group F). The onset time of sensory and motor block, duration of sensory and motor block, and hemodynamic variables were recorded.

Results:

Group D showed a significantly greater sensory and motor block duration than other groups ( P = .001). Comparison of hemodynamic variables failed to reveal any statistically significant differences between all groups.

Conclusion:

Both dexamethasone and fentanyl are good adjuvants in the supraclavicular block, but dexamethasone is better, given faster onset and duration of analgesia.

Local Anesthetics, Local Anesthetic Systemic Toxicity (LAST), and Liposomal Bupivacaine

Local anesthetics have played a vital role in the multimodal analgesia approach to patient care by decreasing the use of perioperative opioids, enhancing patient satisfaction, decreasing the incidence of postoperative nausea and vomiting, decreasing the length of hospital stay, and reducing the risk of chronic postsurgical pain. The opioid-reduced anesthetic management for perioperative analgesia has been largely successful with the use of local anesthetics during procedures such as peripheral nerve blocks and neuraxial analgesia. It is important that practitioners who use local anesthetics are aware of the risk factors, presentation, and management of local anesthetic systemic toxicity (LAST).

Epinephrine and Dexamethasone as Adjuvants in Upper Extremity Peripheral Nerve Blocks in Pediatric Patients

Introduction: Regional anesthesia in children in recent years has been accepted worldwide. The increased interest in it is partly due to the use of ultrasonography which provides confidence and accuracy to the anesthesiologic team. Adjuvants are used to extend the duration of the sensory and motor blocking, limiting the cumulative dose of local anesthetics. The use of adjuvants in peripheral nerve blocks in the pediatric population is still under research. Aim: To observe the effect of epinephrine and dexamethasone as adjuvants to local anesthetics in peripheral upper extremity nerve blocks in pediatric patients. Materials and methods: The study included 63 patients, aged group 4-14 years, admitted to the University Clinic of Pediatric Surgery for surgical treatment of upper limb fractures in the period of January 2020 until March 2021. Patients were randomized into three groups, and all patients in the groups received analgo-sedation prior to peripheral nerve block. Patients in group 1 (21 patients) received supraclavicular, or interscalene block with 2 ml lidocaine 2% and bupivacaine 0.25% (max 2mg/kg) with a total volume of 0.5ml/kg. In group 2, the patients (21) received 25 μg of epinephrine in 2 ml of 2% solution of lidocaine and 0.25% bupivacaine (max 2 mg/kg) with a total volume of 0.5 ml/kg, and in group 3, the patients (21) received 2% lidocaine 2ml and 0.25% bupivacaine (max 2mg/kg) in combination with 2mg dexamethasone with a total volume of 0.5ml/kg. Results: Results showed that in patients in group 1, the average duration of the sensory block was 7 hours, while the duration of the motor block was 5 hours and 30 minutes. In group 2 (epinephrine), the durations of both sensory and motor block were prolonged for about 30 minutes on average compared to the first group. In group 3 (dexamethasone) the duration of the sensory and motor block was significantly longer compared with the first two groups (p<0.0001). Conclusion: Epinephrine and dexamethasone prolong the duration of action of local anesthetics in peripheral nerve blocks of the upper extremity in pediatric patients and thus reduce the need for analgesics in the postoperative period.

Analgesic Efficacy and Safety of Local Infiltration Following Lumbar Decompression Surgery: A Systematic Review of Randomized Controlled Trials

This systematic review aims to appraise available clinical evidence on the efficacy and safety of wound infiltration with adjuvants to local anesthetics (LAs) for pain control after lumbar spine surgery. A database search was conducted to identify randomized controlled trials (RCTs) pertinent to wound infiltration with analgesics or miscellaneous drugs adjunctive to LAs compared with sole LAs or placebo. The outcomes of interest were postoperative rescue analgesic consumption, pain intensity, time to first analgesic request, and the occurrence of adverse events. Twelve double-blind RCTs enrolling 925 patients were selected for qualitative analysis. Most studies were of moderate-to-good methodological quality. Dexmedetomidine reduced analgesic requirements and pain intensity within 24 h postoperatively, while prolonged pain relief was reported by one RCT involving adjunctive clonidine. Data on local magnesium seem promising yet difficult to interpret. No clear analgesic superiority could be attributed to steroids. Τramadol co-infiltration was equally effective as sole tramadol but superior to LAs. No serious adverse events were reported. Due to methodological inconsistencies and lack of robust data, no definite conclusions could be drawn on the analgesic effect of local infiltrates in patients undergoing lumbar surgery. The probable positive analgesic efficacy of adjunctive dexmedetomidine and magnesium needs further evaluation.

Pharmacological and clinical implications of local anaesthetic mixtures: a narrative review

Various techniques have been explored to prolong the duration and improve the efficacy of local anaesthetic nerve blocks. Some of these involve mixing local anaesthetics or adding adjuncts. We did a literature review of studies published between 01 May 2011 and 01 May 2021 that studied specific combinations of local anaesthetics and adjuncts. The rationale behind mixing long- and short-acting local anaesthetics to hasten onset and extend duration is flawed on pharmacokinetic principles. Most local anaesthetic adjuncts are not licensed for use in this manner and the consequences of untested admixtures and adjuncts range from making the solution ineffective to potential harm. Pharmaceutical compatibility needs to be established before administration. The compatibility of drugs from the same class cannot be inferred and each admixture requires individual review. Precipitation on mixing (steroids, non-steroidal anti-inflammatory drugs) and subsequent embolisation can lead to serious adverse events, although these are rare. The additive itself or its preservative can have neurotoxic (adrenaline, midazolam) and/or chondrotoxic properties (non-steroidal anti-inflammatory drugs). The prolongation of block may occur at the expense of motor block quality (ketamine) or block onset (magnesium). Adverse effects for some adjuncts appear to be dose-dependent and recommendations concerning optimal dosing are lacking. An important confounding factor is whether studies used systemic administration of the adjunct as a control to accurately identify an additional benefit of perineural administration. The challenge of how best to prolong block duration while minimising adverse events remains a topic of interest with further research required.

Dexmedetomidine Added to Ropivacaine for Ultrasound-guided Erector Spinae Plane Block Prolongs Analgesia Duration and Reduces Perioperative Opioid Consumption After Thoracotomy: A Randomized, Controlled Clinical Study

OBJECTIVES

Single-injection erector spinae plane block (ESPB) provides good control of pain relief after open thoracotomy surgeries. However, the duration of pain relief does not last long. For this purpose, we hypothesized that adding α2-adrenoceptor agonist, dexmedetomidine, for interfascial nerve blockade may increase the duration of analgesia. There are only few studies using dexmedetomidine for interfasical nerve blocks in humans. In this study, our aim is to investigate whether addition of dexmedetomidine to ropivacaine for ESPB could effectively prolong the duration of postoperative analgesia and reduce opioid consumption after open thoracotomy.

MATERIALS AND METHODS

Sixty patients with esophageal cancer were randomized to receive ESPB using 28 mL of 0.5% ropivacaine, with 2 mL of normal saline (group R) or 0.5 µg/kg dexmedetomidine in 2 mL (group RD) administered interfascially. ESPB was performed at the fifth thoracic level under ultrasound guidance. The primary outcome was the duration of analgesia. The secondary outcomes were total postoperative sufentanil consumption, Numeric Rating Scale pain scores, Ramsay Sedation Scale scores and adverse effects.

RESULTS

The duration of analgesia in group RD (505.1±113.9) was longer than that in group R (323.2±75.4) (P<0.001). The total postoperative sufentanil consumption was lower in group RD (23.3±10.0) than in group R (33.8±13.8) (P=0.001). There was no significant difference in the incidence of adverse effects between the 2 groups.

CONCLUSION

After open thoracotomy, addition of dexmedetomidine to ropivacaine for ESPB effectively prolonged the duration of postoperative analgesia and reduced opioid consumption without increasing additional incidence of adverse effects.

Effect on analgesia duration and pain intensity of adding dexamethasone to lidocaine in digital nerve block in patients with finger trauma

Digital nerve block is one of the multimodal analgesia methods used in finger trauma cases. According to some studies, dexamethasone needs further investigation before being used routinely. We therefore investigated dexamethasone's effect on the parameters of digital nerve block. In this double-blind clinical study, 60 patients were allocated to two groups: lidocaine alone and lidocaine + dexamethasone. Groups were compared for pain intensity, analgesia duration and demographic characteristics. Patients in the intervention group received 3 cc 2% lidocaine + 1 cc (equivalent to 4 mg) dexamethasone and patients in the control group received 3 cc lidocaine 2% + 1 cc normal saline. The two groups were comparable for age and gender. In the lidocaine + dexamethasone group, postoperative pain severity was significantly lower and the pain-free period was longer (P < 0.05). Dexamethasone as an adjuvant in digital nerve block after trauma reduced the severity of postoperative pain and increased the pain-free period.

Adjuvant Drugs for Peripheral Nerve Blocks: The Role of Alpha-2 Agonists, Dexamethasone, Midazolam, and Non-steroidal Anti-inflammatory Drugs

Adjuvant drugs for peripheral nerve blocks are a promising solution to acute postoperative pain and the transition to chronic pain treatment. Peripheral nerve blocks (PNB) are used in the brachial plexus, lumbar plexus, femoral nerve, sciatic nerve, and many other anatomic locations for site-specific pain relief. However, the duration of action of a PNB is limited without an adjuvant drug. The use of non-opioid adjuvant drugs for single-shot peripheral nerve blocks (sPNB), such as alpha-2 agonists, dexamethasone, midazolam, and non-steroidal anti-inflammatory drugs, can extend the duration of local anesthetics and reduce the dose-dependent adverse effects of local anesthetics. Tramadol is a weak opioid that acts as a central analgesic. It can block voltage-dependent sodium and potassium channels, cause serotonin release, and inhibit norepinephrine reuptake and can also be used as an adjuvant in PNBs. However, tramadol's effectiveness and safety as an adjuvant to local anesthetic for PNB are inconsistent. The effects of the adjuvants on neurotoxicity must be further evaluated with further studies to delineate the safety in their use in PNB. Further research needs to be done. However, the use of adjuvants in PNB can be a way to help control postoperative pain.

Intraoperative Administration of Dexmedetomidine and Dexamethasone in Local Anesthetic Infiltration to Improve Postoperative Pain Control After Posterior Cervical Fusion

Dexmedetomidine, a selective and potent α2-adrenoceptor agonist, is used for its anxiolytic, sedative, and analgesic properties. Dexamethasone is a high-potency, long-acting glucocorticoid that has been shown to provide analgesic and anti-inflammatory effects. At present, little has been published with regard to the effectiveness of these drugs as dual agents with local anesthetics for analgesia. In this report, a case of a 50-year-old man who underwent a cervical spine orthopedic procedure is described, in which an intraoperative injection of ropivacaine was administered with the adjuvants dexmedetomidine and dexamethasone, providing extended postoperative pain relief. In summary, we present a patient who had an injection of ropivacaine with dexmedetomidine and dexamethasone into the erector spinae muscles in the cervical region, which provided improvement in postoperative pain and reduced opioid consumption for five days post-surgery, demonstrating additive and/or synergistic effects beyond the normal local anesthetic duration.

Comparison of morphine, dexmedetomidine and dexamethasone as an adjuvant to ropivacaine in ultrasound-guided supraclavicular brachial plexus block for postoperative analgesia-a randomized controlled trial

Background and Aims:

An ideal adjuvant to local anesthetic in a nerve block should prolong the duration of analgesia, and hasten the onset of sensory and motor blockade without significant adverse effects. The aim of this study was to compare morphine, dexmedetomidine, and dexamethasone as an additive to ropivacaine in ultrasound-guided supraclavicular brachial plexus block (SBPB) for postoperative analgesia.

Material and Methods:

In this randomized, double-blinded study, 150 patients undergoing upper extremity surgery were randomly divided into three groups: group A (morphine 5 mg), group B (dexmedetomidine 50 μg), and group C (dexamethasone 8 mg). The additives were added to 30 ml of 0.5% ropivacaine solution and administered in SBPB. The duration of postoperative analgesia, onset of sensory and motor blockade, sedation, and adverse effects were observed. The pain was assessed by visual analog scale (VAS) and sedation by Ramsay sedation score. The duration of postoperative analgesia was taken as time consumed from block completion to administration of rescue analgesia (VAS >3).

Results:

The demographic profile was similar in both groups. The duration of analgesia was significantly longer in dexamethasone (867.2 ± 217.6 min) than morphine (739. 2 ± 162.5 min) and dexmedetomidine (654.2 ± 179.9 min) (P < 0.001). The onset of sensory and motor blockade was quicker with dexmedetomidine than dexamethasone and morphine. Three cases of block failure were reported with morphine. No major adverse effects were reported.

Conclusion:

Dexamethasone is an ideal adjuvant to ropivacaine in brachial plexus block to prolong postoperative analgesia and devoid of adverse effects. Dexmedetomidine has a quicker onset of sensory and motor blockade.

Does local anesthetic temperature affect the onset and duration of ultrasound-guided infraclavicular brachial plexus nerve block?: a randomized clinical trial

Background

Infraclavicular brachial plexus nerve block is a commonly performed anesthesiology technique in the upper extremity. Local anesthetics may be administered at different temperatures for both neuraxial and peripheral nerve blocks. We aimed to evaluate the effects of the temperature of the local anesthetic at the time of administration on the onset and duration of sensory and motor blocks in infraclavicular brachial plexus nerve block.

Methods

A total of 80 patients undergoing elective upper extremity surgery were randomly assigned to one of the following groups using a computer-based randomization software; low temperature (4 °C) (Group L, n = 26), room temperature (25 °C) (Group R, n = 27) and warmed (37 °C) (Group W, n = 27). A 1:1 mixture of 2% lidocaine and 0.5% bupivacaine was used as local anesthetic. Infraclavicular brachial plexus nerve block was performed under ultrasound guidance in all patients preoperatively. The onset and duration of sensory and motor blocks were recorded.

Results

Each group had different onset of motor (p < 0.001) and sensory (p < 0.001) blocks. The duration of motor block was similar between groups (p = 221). However, a significant difference was found in the duration of sensory block between group L (399.1 ± 40.8 min) and group R (379.6 ± 27.6 min) (p = 0.043). There was no complication related to nerve block procedure.

Conclusions

The administration of the local anesthetic at lower temperatures may prolong the onset of both motor and sensory blocks in infraclavicular brachial plexus nerve block.

Nalbuphine Versus Ketorolac as an Adjuvant to Local Wound Infiltration Anesthesia in Open Colorectal Surgery: A Prospective Randomized Controlled Study

INTRODUCTION

Adding adjuvants to local wound infiltration (LWI) provides long analgesic duration with fewer adverse effects. We aimed to compare the clinical effects of nalbuphine and ketorolac as an adjuvant to LWI in patients undergoing open colorectal cancer surgery.

METHOD

A total of 126 ASA I-III patients aged ≥ 18 years who were scheduled for open colorectal cancer surgery were included. Patients were randomly assigned to receive LWI using 10 mL 0.75% ropivacaine, with 20 mL normal saline (group R), 10 mg nalbuphine in 1 mL (group RN), or 25 mg ketorolac in 0.8 mL (group RK). Analgesia duration was the primary outcome. The total 48-h postoperative morphine-equivalent consumption and additional rescue analgesia rates were recorded as key secondary outcomes.

RESULTS

Among 126 patients randomized, 124 completed the trial. The duration until the first press of the analgesia pump was significantly shorter in group R (median: 320.0 min) compared with group RN (median: 829.5 min) and group RK (median: 820.0 min) (P < 0.001). The median difference in morphine consumption was 113.0 mg for group R vs. group RN (P < 0.001), and 115.5 mg for group R vs. group RK (P < 0.001). The proportion of patients using additional morphine within the first day after surgery in group R showed a higher relative risk (RR) compared with group RN (RR, 3.89; P = 0.001) and group RK (RR, 3.17; P = 0.001). There were no apparent differences between the RN and RK groups in any outcomes, whether in adjusted or unadjusted analysis.

CONCLUSIONS

Among patients undergoing open colorectal cancer surgery, both nalbuphine and ketorolac infiltration achieved equally prolonged duration of analgesia and reduced morphine consumption compared with ropivacaine alone after surgery, suggesting that the equivalent analgesic dose of nalbuphine and ketorolac as local anesthetic adjuvants in LWI could have a similar analgesic effect.

TRIAL REGISTRATION

ChiCTR1800019209.

HTX-011 (bupivacaine and meloxicam) for the prevention of postoperative pain - clinical considerations

HTX-011 is an extended-release, dual-acting local anesthetic consisting of bupivacaine (sodium-channel blocker) and low-dose meloxicam (non-steroidal anti-inflammatory drug [NSAID]) applied needle-free during surgery. Introducing low-dose meloxicam addresses the limited efficacy of liposomal bupivacaine in acidic inflamed tissues and allows enhanced analgesic effects over three days. It has great promise to be an extremely effective postoperative pain regimen and produce an opioid-free surgical recovery, as it has consistently significantly reduced pain scores and opioid consumption through 72 h. This manuscript provides an updated, concise narrative review of the pharmacology, clinical efficacy, safety and tolerability of this drug and its applications to prevent postoperative pain.

Analgesic Effect of the Topical Use of Dexamethasone in Ultrasound-Guided Axillary Brachial Plexus Blockade: A Prospective, Randomized, Double-Blind, Placebo-Controlled Study

Introduction

Increasing the duration of regional anesthesia in orthopedic surgery is of vital importance, as it prolongs postoperative analgesia, allowing faster rehabilitation of patients. Dexamethasone has been found to extend the block duration in animal and human studies. The aim of this study is the assessment of the effect of the addition of dexamethasone to ropivacaine on the onset and duration of axillary brachial plexus block, along with the intensity of postoperative pain.

Methods

Forty patients undergoing below-elbow surgery under ultrasound-guided axillary brachial plexus block were randomly allocated to receive either 30 mL ropivacaine 0.75% with 2 mL of saline (Group A, n = 20) or 30 mL ropivacaine 0.75% with 2 mL of dexamethasone (4 mg) (Group B, n = 20). Sensory and motor blockade were assessed, with the use of the pinprick test and the modified Bromage scale, at five, 10, 15, and 20 min after the block. The duration of analgesia, intensity of postoperative pain, postoperative opioid consumption, overall satisfaction, and perioperative complications were compared between the two groups.

Results

We found no difference at the mean onset time of the sensory and motor block between the two groups. The mean duration of postoperative analgesia was three hours higher in the dexamethasone group (15.85 ± 4.82 versus 11.75 ± 6.81, p-value = 0.035). Pain intensity was lower in the dexamethasone group, at six and 12 hours after surgery (3.45 ± 1.79 versus 4.65 ± 1.79, p-value = 0.040). Postoperative opioid consumption, patient overall satisfaction, and perioperative complications were not significantly different between groups.

Conclusions

Dexamethasone prolongs the duration of ropivacaine in an axillary brachial plexus block and decreases postoperative pain in patients subjected to below-elbow surgery.

Dexmedetomidine combined with suprascapular nerve block and axillary nerve block has a synergistic effect on relieving postoperative pain after arthroscopic rotator cuff repair

PURPOSE

Suprascapular nerve block (SSNB) is the most commonly used block for the relief of postoperative pain from arthroscopic rotator cuff repair and can be used in combination with axillary nerve block (ANB). Dexmedetomidine (DEX) is a type of alpha agonist that can elongate the duration of regional block. The aim of this study was to compare the effects of the use of dexmedetomidine combined with SSNB and ANB with those of the use of SSNB and ANB alone on postoperative pain, satisfaction, and pain-related cytokines within the first 48 h after arthroscopic rotator cuff repair.

METHODS

Forty patients with rotator cuff tears who had undergone arthroscopic rotator cuff repair were enrolled in this single-center, double-blinded randomized controlled trial study. Twenty patients were randomly allocated to group 1 and received ultrasound-guided SSNB and ANB using a mixture of 0.5 ml (50 μg) of DEX and 9.5 ml of 0.75% ropivacaine preemptively. The other 20 patients were allocated to group 2 and underwent ultrasound-guided SSNB and ANB alone using a mixture of 0.5 ml of normal saline and 9.5 ml of ropivacaine. The visual analog scale (VAS) for pain and patient satisfaction (SAT) scores were postoperatively checked within 48 h. The plasma interleukin (IL)-6, IL-8, IL-1β, cortisol, and serotonin levels were also postoperatively measured within 48 h.

RESULTS

Group 1 showed a significantly lower mean VAS (visual analog scale of pain) score 1, 3, 6, 12, 18 and 24 h after operation, and a significantly higher mean SAT (patient satisfaction) score 1, 3, 6, 12, 18, 24 and 36 h after the operation than group 2. Group 1 showed a significantly lower mean plasma IL-8 level 1 and 48 h after the operation, and a significantly lower mean IL-1β level 48 h after the operation than group 2. Group 1 showed a significantly lower mean plasma serotonin level 12 h after the operation than group 2. The mean timing of rebound pain in group 1 was significantly later than that in group 2 (36 h > 23 h, p = 0.007). Six patients each in groups 1 and 2 showed rebound pain. The others did not show rebound pain.

CONCLUSIONS

Ultrasound-guided SSNA and ANB with DEX during arthroscopic rotator cuff repair resulted in a significantly lower mean VAS score and a significantly higher mean SAT score within 48 h after the operation than SSNB and ANB alone. Additionally, SSNB and ANB with DEX tended to result in a later mean timing of rebound pain accompanied by significant changes in IL-8, IL-1β, and serotonin levels within 48 h after the operation. The present study could provide the basis for selecting objective parameters of postoperative pain in deciding the optimal use of medication for relieving pain.

LEVEL OF EVIDENCE

Level I.

TRIAL REGISTRATION

2015-20, ClinicalTrials.gov Identifier: NCT04398589.

IRB NUMBER

2015-20, Hallym University Chuncheon Sacred Heart Hospital.

Efficacy of Local Anesthetic Wound Infiltration in Temporomandibular Joint Ankylosis Surgery for Control of Postoperative Pain: A Prospective, Randomized Controlled, and Double-Blinded Trial

PURPOSE

This study aimed to compare the analgesic efficacy of wound infiltration with ropivacaine alone or with adjuvants clonidine or dexamethasone for postoperative pain in temporomandibular joint ankylosis (TMJA) surgery.

MATERIALS AND METHODS

The investigators implemented a randomized controlled trial with 3 parallel groups, among the patients of bilateral TMJA visiting the maxillofacial surgery unit between March 12, 2015 and February 5, 2017. At the completion of surgery, wound infiltration was done with 0.25% of ropivacaine (R group), 0.25% of ropivacaine with 0.5 mcg/kg of clonidine (RC group), 0.25% of ropivacaine with 0.1 mg/kg of dexamethasone (RD group), and 0.2 mL/kg of drug volume on each side. The primary outcome variables were total opioid consumption (fentanyl in micrograms/kilogram) and visual analog scale for pain at rest and movement for 24 hours after surgery. The secondary outcome variables were time (minutes) to first rescue analgesic requirement and patient satisfaction scores. The patients, surgeons, and anesthesiologists collecting the data were blinded to the group allocation. Continuous and qualitative data were summarized using mean (standard deviation) and frequency distribution, respectively.

RESULTS

About 45 patients were randomized into 3 equal groups. Mean age of the sample was 17.6 ± 8.04 years (males = 24 [53%]; females = 21 [47%]). Surgery for TMJA included gap arthroplasty (n = 17), interpositional arthroplasty (n = 24), and total TMJ replacement (n = 4). Total fentanyl (micrograms) consumption during 24 hours was comparable between all the 3 groups and statistically not significant (P = .40). The pain scores (visual analog scale at rest and movement) were comparable at all time points. No significant difference was noted for time to first rescue analgesic requirement (P = .31). Patient satisfaction was higher in RC group as compared with R group (P = .009). No adverse effects were noted in any group.

CONCLUSIONS

Within the confines of the sample size and the absence of power calculation, the study implies that wound infiltration with ropivacaine was as efficacious as when mixed with adjuvants, either clonidine or dexamethasone, for control of postoperative pain for 24 hours.

Effects of Dexamethasone on Bupivacaine-Induced Peripheral Nerve Injection Injury in the Rat Sciatic Model

INTRODUCTION

The aim of this study was to investigate the effect of perineural dexamethasone against intraneural bupivacaine.

MATERIAL AND METHODS

Rats were divided into 9 groups with 6 animals in each group; Group 1 (Intraneural saline 600 µL-2ndday), Group 2 (Intraneural saline 600 µL-7th day), Group 3 (Intraneural saline 600 µL + perineural dexamethasone 0.5 mg/kg-2nd day), Group 4 (Intraneural saline 600 µL + perineural dexamethasone 0.5 mg/kg-7th day), Group 5 (Intraneural bupivacaine 10 mg/kg-2nd day), Group 6 (Intranueral bupivacaine 10 mg/kg-7th day), Group 7 (Intraneural bupivacaine 10 mg/kg + perineurald exam ethasone 0.5 mg/kg-2nd day), Group 8 (Intraneural bupivacaine 10 mg/kg + perineural dexamethasone 0.5 mg/kg-7th day), Group 9 (Control group). At the end of the application period, histopathological and immunohistochemical examinations were analyzed.

RESULTS AND CONCLUSION

It was observed that caspase 3 levels significantly increased in the 5th and 6th groups compared to the 1st and 2nd groups (p < 0.01). However, in the 7th and 8th groups, these levels were similar with 1st and 2nd groups. While a significant decrease in S 100 levels was detected in group 6 (p < 0.05), a significant increase occurred in Group 8 and reached the same levels as Group 2. According to histopathological evaluation, edema, vacuolization and myelin degeneration were significantly increased in groups 5 and 6 (p < 0.05). However, in the 8th group, the mentioned data showed a significant decrease and reached the same levels as group 2. As a result, perineural dexamethasone was found to have protective effects against intraneural bupivacaine induced sciatic nerve damage.

Dexmedetomidine combined with interscalene brachial plexus block has a synergistic effect on relieving postoperative pain after arthroscopic rotator cuff repair

PURPOSE

Interscalene brachial plexus block (ISB) is one of the most commonly used regional blocks in relieving postoperative pain after arthroscopic rotator cuff repair. Dexmedetomidine (DEX) is an alpha 2 agonist that can enhance the effect of regional blocks. The aim of this study was to compare the effects of DEX combined with ISB with ISB alone on postoperative pain, satisfaction, and pain-related cytokines within the first 48 h after arthroscopic rotator cuff repair.

METHODS

Fifty patients with rotator cuff tears who had undergone arthroscopic rotator cuff repair were enrolled in this single center, double-blinded randomized controlled trial study. Twenty-five patients were randomly allocated to group 1 and received ultrasound-guided ISB using a mixture of 1 ml (100 μg) of DEX and 8 ml of 0.75% ropivacaine preemptively. The other 25 patients were allocated to group 2 and underwent ultrasound-guided ISB alone using a mixture of 1 ml of normal saline and 8 ml of ropivacaine. The visual analog scale (VAS) for pain and patient satisfaction (SAT) scores were checked within 48 h postoperatively. The plasma interleukin (IL)-6, -8, -1β, cortisol, and substance P levels were also measured within 48 h, postoperatively.

RESULTS

Group 1 showed a significantly lower mean VAS score and a significantly higher mean SAT score than group 2 at 1, 3, 6, 12, and 18 h postoperatively. Compared with group 2, group 1 showed a significantly lower mean plasma IL-6 level at 1, 6, 12, and 48 h postoperatively and a significantly lower mean IL-8 level at 1, 6, 12, 24, and 48 h postoperatively. The mean timing of rebound pain in group 1 was significantly later than that in group 2 (12.7 h > 9.4 h, p = 0.006).

CONCLUSIONS

Ultrasound-guided ISB with DEX in arthroscopic rotator cuff repair led to a significantly lower mean VAS score and a significantly higher mean SAT score within 48 h postoperatively than ISB alone. In addition, ISB with DEX showed lower mean plasma IL-6 and IL-8 levels than ISB alone within 48 h postoperatively, with delayed rebound pain.

LEVEL OF EVIDENCE

I.

TRIAL REGISTRATION

2013-112, ClinicalTrials.gov Identifier: NCT02766556.

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.

Adding Dexmedetomidine to Articaine Increases the Latency of Thermal Antinociception in Rats

Articaine is a low-toxicity local anesthetic that is widely used in dentistry. Typically, epinephrine is added to prolong the duration of articaine local anesthesia; however, epinephrine exhibits adverse effects. Low-dose dexmedetomidine (DEX), an α₂-adrenoreceptor agonist, reportedly prolongs local anesthesia without notable adverse cardiovascular effects. The purpose of this study was to assess whether a combination of low-dose DEX and articaine would provide a low-toxicity local anesthetic option for dental procedures without adverse cardiovascular effects. Thus, this study investigated whether DEX could prolong the local anesthetic effect of articaine using a rat model of pain. Adult male Wistar rats (N = 44; 11 per group) received a 50-μL subcutaneous injection into the plantar surface of the hind paws; injections were composed of either normal saline, 4% articaine (2 mg articaine), combined 5 μg/kg DEX and 4% articaine (1.25 μg DEX + 2 mg articaine), or combined epinephrine (1:100,000) and 4% articaine (0.9 μg epinephrine + 2 mg articaine). Subsequent acute pain perception was determined by paw withdrawal movement in response to infrared radiant heat stimulation of the plantar region. Paw withdrawal latency was tested at 5-minute intervals. Paw withdrawal latency values at 35 and 40 minutes were 3.83 ± 1.76 and 3.29 ± 1.43 seconds for articaine alone, 7.89 ± 2.72 and 7.25 ± 3.37 seconds for DEX and articaine, and 8.95 ± 2.28 and 8.17 ± 3.01 seconds for epinephrine and articaine. DEX prolonged the paw withdrawal latency of articaine for up to 35 minutes (p = .015) but not 40 minutes after injection (p = .052) when compared to articaine alone. The combination of DEX and articaine can provide effective local anesthesia for up to 35 minutes after injection.

Adjuncts to local anesthetic wound infiltration for postoperative analgesia: a systematic review

Local anesthetics (LAs) are commonly infiltrated into surgical wounds for postsurgical analgesia. While many adjuncts to LA agents have been studied, it is unclear which adjuncts are most effective for co-infiltration to improve and prolong analgesia. We performed a systematic review on adjuncts (excluding epinephrine) to local infiltrative anesthesia to determine their analgesic efficacy and opioid-sparing properties. Multiple databases were searched up to December 2019 for randomized controlled trials (RCTs) and two reviewers independently performed title/abstract screening and full-text review. Inclusion criteria were (1) adult surgical patients and (2) adjunct and LA agents infiltration into the surgical wound or subcutaneous tissue for postoperative analgesia. To focus on wound infiltration, studies on intra-articular, peri-tonsillar, or fascial plane infiltration were excluded. The primary outcome was reduction in postoperative opioid requirement. Secondary outcomes were time-to-first analgesic use, postoperative pain score, and any reported adverse effects. We screened 6670 citations, reviewed 126 full-text articles, and included 89 RCTs. Adjuncts included opioids, non-steroidal anti-inflammatory drugs, steroids, alpha-2 agonists, ketamine, magnesium, neosaxitoxin, and methylene blue. Alpha-2 agonists have the most evidence to support their use as adjuncts to LA infiltration. Fentanyl, ketorolac, dexamethasone, magnesium and several other agents show potential as adjuncts but require more evidence. Most studies support the safety of these agents. Our findings suggest benefits of several adjuncts to local infiltrative anesthesia for postoperative analgesia. Further well-powered RCTs are needed to compare various infiltration regimens and agents.

Protocol registration

PROSPERO (CRD42018103851) (https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=103851)

Comparing post-operative analgesic effects of varying doses of dexmedetomidine as an adjuvant to ropivacaine for ultrasound-guided dual transversus abdominis plane block following laparotomy for gynecologic malignancies

The aim of the present study was to determine the analgesic effects of ropivacaine combined with different doses of dexmedetomidine for ultrasound-guided transversus abdominis plane (TAP) block immediately following laparotomy in patients with gynecologic malignancies. A further aim was to determine the appropriate clinical dose of dexmedetomidine as an adjuvant for ropivacaine. Patients with gynecologic malignancies scheduled for laparotomy were randomly assigned to group R (TAP block with 0.3% ropivacaine), group RD1 (TAP block with ropivacaine and 0.5 µg/kg dexmedetomidine), group RD2 (TAP block with ropivacaine and 1 µg/kg dexmedetomidine) and group RD3 (TAP block with ropivacaine and 2 µg/kg dexmedetomidine). TAP blocks were performed post-operatively. The four groups all received patient-controlled intravenous analgesia (PCIA) after the operation. The numerical rating scale (NRS) as well as the Ramsay sedation scale (RSS) scores, the first request time for PCIA bolus, oxycodone hydrochloride consumption, the plasma concentration of ropivacaine, the incidence of post-operative complications and adverse events, and patient satisfaction were recorded. Post-operative NRS scores at rest exhibited significant differences between the R group and all the RD groups at 24 h after surgery (P<0.05). Compared with the other groups, the NRS score in the RD3 group was decreased (P<0.05). The RSS scores were higher in all of the RD groups compared with those in the R group at 2 h (P<0.05) and were highest in the RD3 group compared with those in all other groups at 4 h (P<0.05). The first request time for PCIA was significantly longer in the RD3 group compared with that in the RD2, RD1 and R groups (510.47±102.67, 595.47±100.11, 682.43±104.46 and 776.42±143.91 min, respectively; P<0.05). Cumulative opioid consumption based on the number of PCIA bolus requested at 24 and 48 h post-operatively indicated that the total number of PCIA boluses was significantly lower in the RD groups compared with those in the R group at 24 and 48 h (P<0.05). The ropivacaine concentration did not differ among the four groups. There was no significant difference between groups with respect to post-operative nausea and vomiting, bradycardia and hypotension; however, all RD groups had a higher patient satisfaction than group R (P<0.05). Compared with that in the other groups, the duration of post-anesthesia care unit stay in group RD3 was relatively longer due to excessive sedation (P<0.05). In conclusion, TAP blockade using 0.5-2 µg/kg dexmedetomidine combined with 0.3% ropivacaine is a safe and effective treatment for analgesia in laparotomy procedures for gynecologic malignancies. The study was registered in the Chinese Clinical Trial Registry (CHICTR; www.chictr.org.cn) on January 15th, 2019 (registration no. ChiCTR1900020995).

[Stocktaking of local anesthetics 2020]

For decades local anesthetics have proven to be safe and effective drugs in the clinical practice, crucially promoting the enormous achievements in regional anesthesia. Meanwhile, it is a well-known fact that local anesthetics are much more than just "simple" sodium channel blockers. They also interact with numerous other ion channels and subcellular structures, enhancing nerve blockade and resulting in systemic "alternative" effects, which can sometimes even be clinically used. By the simultaneous administration of various adjuvants (e.g., opioids, corticosteroids and α₂-receptor agonists) attempts are made to prolong the time of action of local anesthetics after a single administration in order to achieve the best possible improvement in postoperative analgesia. In this context, ultralong-acting local anesthetics, such as liposomal bupivacaine, which at least theoretically can provide a sensory nerve block for several days, have been developed and clinically introduced. The coming years will show whether these approaches will develop into genuine alternatives to the personnel and cost-intensive continuous nerve blockades.Local anesthetic-induced systemic toxicity is meanwhile rare but still a potentially life-threatening event, frequently resulting from accidental intravascular injection or extensive systemic resorption. Consequently, slow and fractional application of these agents with intermittent aspiration helps to prevent toxic sequelae. If toxic symptoms occur, however, the intravenous infusion of 20% lipid solutions in addition to basic treatment measures can enhance the success of treatment.

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.

Pain Management for Orthopedic Injuries

Pain management in acute orthopedic injury needs to be tailored to the presentation and patient. Subjective and objective assessment, in conjunction with pathophysiology, should be used to provide symptom control. Ideally, treatment should be administered in an escalating fashion, attempting to manage pain with the lowest dose of the safest medication available. There are also adjunctive therapies, including those that are nonpharmacologic, that can provide additional relief.

Peripheral nerve catheters: A critical review of the efficacy

Continuous peripheral nerve blocks are commonly used for postoperative analgesia after surgery. However, catheter failure may occur due to either primary (incorrect insertion) or secondary reasons (displacement, obstruction, disconnection). Catheter failure results in unanticipated pain, need for opioid use, and risk of readmission or delay in hospital discharge. This review aimed to assess definition and frequency of catheter failure, and discuss the alternatives to prolong duration of single-shot nerve blocks. A literature search was performed on peripheral catheters reporting failure as the main outcome measure. Thirty-three studies met the selection criteria, comprising 2711 catheters. Literature review suggests that peripheral nerve catheters have clinically significant failure rate when the assessment is performed using an objective (imaging) method. Subjective methods of assessment (without imaging) may underestimate the incidence of catheter failure.

Comparison of the effect of three different adjuvants on the analgesic duration of single injection interscalene brachial plexus block: a prospective, randomized, triple blinded clinical trial

BACKGROUND AND OBJECTIVES

Use of regional anesthesia can result in faster recovery and better patient satisfaction. Addition of perineural adjuncts to local anesthetics may improve the duration of analgesia, but there is a paucity of data comparing them in a single randomized trial. We compared the effects of three adjuncts clonidine, dexamethasone, and buprenorphine, on the duration of analgesia of interscalene brachial plexus block.

METHODS

160 patients, undergoing elective shoulder surgery, were randomized to four groups to receive an interscalene block with one of the following solutions: ropivacaine alone, ropivacaine with clonidine 75 µg, ropivacaine with dexamethasone 8 mg, or ropivacaine with buprenorphine 300 µg. The primary outcome variable was the duration of analgesia; secondary outcome measures were time to onset of the block, and the duration of sensory and motor blocks.

RESULTS

There was no statistically significant difference in the total analgesia time among the four groups; p=0.11. The pairwise comparison in analgesic time and 99% CI were: control versus clonidine (-1.94 hours (-7.33 to 3.12)), control versus dexamethasone (-4.16 hours (-9.50 to 0.58)) and control versus buprenorphine (-1.1 hours (-5.34 to 3.23)). There was no differences in block set-up time, or total sensory and motor block duration among the groups.

CONCLUSION

There was no significant improvement in the duration of analgesia with addition of any of the three adjuncts to interscalene blocks. However, there was a larger than expected variability in patient response, hence the study may have been underpowered for the primary outcome.

Capsazepine prolongation of the duration of lidocaine block of sensory transmission in mice may be mediated by modulation of HCN channel currents

Background and objectives

Hyperpolarization-activation cyclic nucleotide-gated (HCN) channels contribute to the effects of lidocaine. Capsazepine (CPZ), a competitive inhibitor of capsaicin of transient receptor potential vanilloid-1 channel, has also been found to inhibit HCN channel currents (I _h). This study was designed to investigate whether CPZ could prolong durations of lidocaine in regional anesthesia.

Methods

Mouse HCN1 and HCN2 channels were expressed in human embryonic kidney 293 (HEK 293) cells. The effect of CPZ on I _h was measured by whole-cell patch-clamping recording. Sciatic nerve block model in mice was used for the study in vivo. The mice were randomly divided into seven groups, respectively, receiving lidocaine, CPZ, ZD7288 (HCN channel blocker), CPZ + lidocaine, ZD7288 + lidocaine, ZD7288 + CPZ + lidocaine, forskolin (an activator of adenylyl cyclase) + CPZ + lidocaine. Regional anesthetic durations of lidocaine were determined. Voltage-gated sodium channel currents (I _Na) and I _h were recorded in dorsal root ganglion neurons of mice. The effects of CPZ on I _Na and I _h with or without Cyclic adenosine monophosphate (cAMP) were assessed. Isolated mice sciatic nerve was prepared to evaluate the effect of CPZ on the compound action potentials (CAP).

Results

Capsazepine non-selectively inhibited transfected mHCN1 and mHCN2 channel currents in HEK 293 cells. In sciatic nerve block in vivo, compared to lidocaine alone, adding CPZ extended the durations of lidocaine for noxious sensory block (35.1 ± 3.3 vs. 20.3 ± 1.7 min), tactile sensory block (25.5 ± 4.4 vs. 20.0 ± 3.7 min), thermal sensory block (39.6 ± 6.6 vs. 26.8 ± 5.5 min), and motor function block (28.6 ± 4.1 vs. 20.9 ± 4.2 min). Duration of thermal sensory block was longer in CPZ + lidocaine group than that of ZD7288 + lidocaine group (39.6 ± 6.6 vs. 33.4 ± 4.5 min). Forskolin reversed the prolongation by CPZ on lidocaine durations. CPZ or ZD7288 alone did not produce typical regional anesthetic effects. Increased intracellular concentration of cAMP reversed the inhibition of CPZ on I _h. Although CPZ alone inhibited I _Na at the concentration more than 30 μM, it did not inhibit the CAP amplitudes in isolated sciatic nerves. CPZ dose-dependently enhanced the inhibitory effect of 1% lidocaine on the CAP amplitudes.

Conclusions

Capsazepine may prolong durations of lidocaine in peripheral nerve block by modulation of HCN channel currents.

Regional Anesthesia for Ambulatory Anesthesiologists

Proper pain control is critical for ambulatory surgery. Regional anesthesia can decrease postoperative pain, improve patient satisfaction, and expedite patient discharge. This article discusses the techniques, clinical pearls, and potential pitfalls associated with those blocks, which are most useful in an ambulatory perioperative setting. Interscalene, supraclavicular, infraclavicular, axillary, paravertebral, erector spinae, pectoralis, serratus anterior, transversus abdominis plane, femoral, adductor canal, popliteal, interspace between the popliteal artery and capsule of the knee, and ankle blocks are described.

Lower extremity regional anesthesia: essentials of our current understanding

The advent of ultrasound guidance has led to a renewed interest in regional anesthesia of the lower limb. In keeping with the American Society of Regional Anesthesia and Pain Medicine's ongoing commitment to provide intensive evidence-based education, this article presents a complete update of the 2005 comprehensive review on lower extremity peripheral nerve blocks. The current review article strives to (1) summarize the pertinent anatomy of the lumbar and sacral plexuses, (2) discuss the optimal approaches and techniques for lower limb regional anesthesia, (3) present evidence to guide the selection of pharmacological agents and adjuvants, (4) describe potential complications associated with lower extremity nerve blocks, and (5) identify informational gaps pertaining to outcomes, which warrant further investigation.

Effect of Perineural and Intravenous Dexamethasone on Duration of Analgesia in Supraclavicular Brachial Plexus Block with Bupivacaine: A Comparative Study

Background:

Perineural dexamethasone has been shown to improve analgesia in single injection supraclavicular block. Systemic mechanism of action of dexamethasone along with safety concerns of perineural route of administration has prompted the investigation of intravenous route as an alternative.

Aims:

We aim to compare the effects of dexamethasone as an additive to local anesthetic when used via perineural and intravenous route in terms of duration of analgesia and onset of motor and sensory block.

Settings and Design:

The study was done as a prospective comparative observational study conducted in a tertiary care hospital in India among 50 patients during a period of 1 year.

Materials and Methods:

Twenty-five patients aged 18–60 years, belonging to the American Society of Anesthesiologists physical status Classes I and II, receiving supraclavicular block with 0.5% bupivacaine and perineural dexamethasone were compared with similar number of patients receiving the block along with intravenous dexamethasone. Duration of analgesia, onset of sensory block, and onset of motor block were studied.

Statistical Analysis:

The results were analyzed using Chi-square test for qualitative variables and unpaired t-test for quantitative variables.

Results:

The duration of analgesia in the group receiving perineural dexamethasone (Group DP) 817.2 ± 88.011 min was comparable to the group receiving intravenous dexamethasone (Group DI) 858.00 ± 86.168, with a P = 0.104. Time to onset of sensory block in Group DP (10.20 ± 1.443 min) was significantly faster than that of Group DI (11.60 ± 1.443) with a P = 0.001. Time to onset of motor block in Group DP (13.92 ± 1.754 min) was significantly earlier than that of Group DI (14.96 ± 1.274 min) with a P = 0.02.

Conclusion:

It is concluded from this study that intravenous and perineural dexamethasone equally prolongs the duration of analgesia in supraclavicular block. However, perineural dexamethasone resulted in a faster onset of motor and sensory blockade.

Effects of hyaluronidase on ropivacaine or bupivacaine regional anaesthesia of the canine pelvic limb

OBJECTIVE

To determine the effect of hyaluronidase on time to onset and offset of anaesthesia in ropivacaine or bupivacaine femoral-ischiatic nerve blocks.

STUDY DESIGN

Blinded randomized crossover trial.

ANIMALS

Eight dogs.

METHODS

Each dog underwent four treatments separated into two blocks - initially, the ropivacaine treatment block: RS (ropivacaine 0.5% plus saline 0.9%) and RH (ropivacaine 0.5% plus hyaluronidase 100 IU mL^-1), followed 3 weeks later by the bupivacaine treatment block: BS (bupivacaine 0.5% plus saline) and BH (bupivacaine 0.5% plus hyaluronidase). The local anaesthetics were administered at 0.1 mL kg^-1 per site. Hyaluronidase and saline were administered at 0.02 mL kg^-1 per site. Performance of femoral-ischiatic blocks was aided by a combined ultrasound-electrolocation technique. The mechanical nociceptive threshold was measured, until offset or 360 minutes, using an algometer to ascertain baseline, onset and offset of anaesthesia. Onset and offset of anaesthesia were defined as a 25% increase above and as a return to <25% above baseline nociceptive threshold readings, respectively.

RESULTS

The median (range) onset of anaesthesia for RS and RH was 21 (3-60) and 12 (3-21) minutes, respectively (p = 0.141), and offset was 270 (90-360) and 180 (30-300) minutes, respectively (p = 0.361). By contrast, the median (range) onset of anaesthesia for BS and BH was 24 (3-60) and 9 (3-27) minutes, respectively (p = 0.394), and offset was 360 (240-360) and 330 (210-360) minutes, respectively (p = 0.456).

CONCLUSION AND CLINICAL RELEVANCE

Hyaluronidase had no effect on the onset and offset times of ropivacaine and bupivacaine femoral-ischiatic nerve blocks in dogs compared with saline. The onset and offset times were highly variable in all treatments. Clinically, the high variability of the onset and offset times of the regional anaesthesia of these local anaesthetic drugs means that clinicians must monitor the animal's response and, if required, provide additional analgesic drugs.

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.

Opiate-Free Pain Therapy Using Carbamazepine-Loaded Microparticles Provides Up to 2 Weeks of Pain Relief in a Neuropathic Pain Model

INTRODUCTION

Opioids remain a mainstay in the treatment of acute and chronic pain, despite numerous and potentially dangerous side effects. There is a great unmet medical need for alternative treatments for patients suffering from pain that do not result in addiction or adverse side effects. Anticonvulsants have been shown to be effective in managing pain, though high systemic levels and subsequent side effects limit their widespread usage. Our goal was to determine if the incorporation of an anticonvulsant, carbamazepine, into a biodegradable microparticle for local sustained perineural release would be an efficacious analgesic following a peripheral injury.

METHODS

Following induction of the chronic constriction injury model in Sprague-Dawley rats, mechanical allodynia testing was performed using von Frey filaments and thermal allodynia was evaluated using the Hargreaves method. Histology and blood work were performed to evaluate toxicity as well as to monitor drug and metabolite presence over time.

RESULTS

A 2-fold increase in hindpaw withdrawal thresholds in animals receiving carbamazepine-loaded microparticles relative to controls was observed for up to 14 days after treatment. Drug and metabolite had a peak blood concentration of 54.7 ng/mL and dropped off exponentially to < 5 ng/mL over a few days.

CONCLUSION

This formulation reduced systemic exposure to carbamazepine over 1,000-fold relative to traditional analgesic dosing regimens. This 2-component drug delivery system has been specifically engineered to release a controlled amount of carbamazepine over a 14-day period, providing significant pain relief with no toxicological or observable adverse events via behavioral or histochemical analysis.

Optimal dose of perineural dexmedetomidine for interscalene brachial plexus block to control postoperative pain in patients undergoing arthroscopic shoulder surgery: A prospective, double-blind, randomized controlled study

BACKGROUND

Adjuvant perineural dexmedetomidine can be used to prolong the analgesic effect of interscalene brachial plexus block (ISB). We investigated the optimal dose of dexmedetomidine in ISB for postoperative analgesia in patients undergoing arthroscopic shoulder surgery.

METHODS

One hundred patients scheduled for elective shoulder arthroscopic surgery were enrolled in this randomized, double-blind study. Ultrasound-guided ISB was performed before general anesthesia using 22 mL of ropivacaine 0.5% combined with 1, 1.5, or 2 μg/kg of dexmedetomidine (group D1, D2, and D3, respectively) or with normal saline as a control (group R, n = 25 per group). The primary outcome was the duration of analgesia (DOA), numeric pain rating scale (NRS), and consumption of additional analgesics during 36 h after ISB. Secondary outcome included durations of motor and sensory block (DOM and DOS), hemodynamic variables and sedation and dyspnea scores.

RESULTS

Ninety-seven patients completed the study. The DOS, DOM, and DOA were significantly longer in the dexmedetomidine groups than in group R. The DOA was significantly longer in group D3 than in groups D1 (P = .026) and D2 (P = .039). The DOA was 808.13 ± 179.97, 1032.60 ± 288.14, 1042.04 ± 188.13, and 1223.96 ± 238.06 min in groups R, D1, D2, and D3, respectively. The NRS score was significantly higher in group R than in the dexmedetomidine groups 12 h after ISB (P < .001) and significantly lower in group D3 than in the other groups 18 h after ISB (P = .02). The incidence of hypotension was higher in groups D2 and D3 than in group R during surgery (P = .008 and P = .011, respectively). There were no significant differences in consumption of rescue analgesics, sedation, and dyspnea scores between the study groups.

CONCLUSION

Perineural dexmedetomidine 2 μg/kg could be the optimal dose in ISB for arthroscopic shoulder surgery in that it provides an adequate DOA. However, this dose was associated with increased risk of hypotension.

Is amalgamated ligno-bupivacaine an answer to complicated minor oral surgical anesthesia? A randomized split-mouth double-blind clinical trial

PURPOSE

The purpose of this study was to find a suitable anesthetic combination for complicated and protracted minor oral surgical procedures.

METHODS

Fifty patients with bilaterally impacted deep-seated mandibular third molars were included in this study and randomly divided on the basis of anesthetic used into two groups. Group A received 2% lignocaine with 1:200,000 adrenaline while in group B, amalgamated mixture of 2% lignocaine and 0.5% bupivacaine was used. The onset time, duration of anesthetic effect, supplementary injections, pain (during local anesthetic deposition, intra and postoperatively), and postoperative analgesia were the study parameters. Chi-square and unpaired t tests were used to compare means.

RESULTS

The onset time in both the groups was comparable and showed statistically significant difference between the duration of anesthetic effect with notable requirement of supplemental anesthetic injections in group A (54%) (p < 0.05). Pain scores also revealed a statistically significant intergroup difference (p < 0.05). Requirement of postoperative analgesics was delayed in group B.

CONCLUSIONS

The amalgamated mixture of lignocaine and bupivacaine had equivocally rational onset and provided a more profound and in-depth anesthesia especially in complicated and protracted minor oral surgical procedures. Though this mixture is widely used in other surgical fields, its efficacy still remains unexploited and undocumented in oral and maxillofacial surgical procedures.