Comparison of Dexmedetomidine and Dexamethasone as Adjuvants to Ultra-Sound Guided Interscalene Block in Arthroscopic Shoulder Surgery: A Double-Blinded Randomized Placebo-Controlled Study

The effect of perineural dexamethasone on nerve injury and recovery of nerve function after surgery: A randomized controlled trial

Background

While numerous studies have examined the influence of perineural dexamethasone on nerve block duration, its potential impact on postoperative nerve injury has not been adequately addressed.

Objective

This study aims to elucidate the effect of perineural dexamethasone on nerve injury and nerve function recovery after surgery.

Design

A prospective randomized double-blinded trial.

Setting

The First Affiliated Hospital of Chengdu Medical College, Chengdu, China. The study was conducted between 14 June and 30 December 2022.

Participants

Patients aged 18 - 80 years, ASA I - II, scheduled for elective orthopedic or burn and plastic surgery.

Interventions

Patients were randomized to receive either perineural dexamethasone (D group) or no dexamethasone (ND group).

Main outcome measures

Primary outcomes were the incidence and recovery of nerve injury. Secondary outcomes included postoperative pain scores, analgesic consumption, and adverse events.

Results

Initial postoperative nerve injury rates were similar between groups (D: 30.4 %, ND: 33.3 %, P > 0.05). At 12 weeks post-discharge, significantly more patients in the ND group recovered from nerve deficits (78.8 % vs 60.3 %; OR = 2.45, 95 % CI = 1.05 - 5.72, P < 0.05). No significant differences were observed in postoperative hyperglycemia or surgical site infection rates.

Conclusion

Perineural dexamethasone may impede nerve function recovery, suggesting caution in its use, particularly for patients with pre-existing nerve damage or diabetes. Further research is needed to elucidate the long-term effects of dexamethasone on nerve tissue recovery.

Trial registration

chictr.org.cn, ChiCTR2200059424.

Comparison of Dexmedetomidine and Ketamine in Serratus Anterior Plane Block for Postoperative Pain Control in Thoracotomy Patients: A Randomized Clinical Trial

Background

Postoperative pain control after thoracotomy is very important, and if not controlled, it can cause severe complications.

Objectives

This study aimed to compare dexmedetomidine and ketamine in serratus anterior plane block (SAPB) in pain control after thoracotomy.

Methods

This randomized clinical trial was conducted on 74 patients aged 18 to 60 years old with American Society of Anesthesiologists (ASA) class I or II who were referred to Imam Khomeini hospital in Ahvaz, Iran, for thoracotomy and randomly divided into two groups. After surgery, the SAPB with ultrasound-guided was performed. In the ropivacaine-ketamine (RK) group, ketamine 0.5 mg/kg and 0.4 cc/kg ropivacaine solution 0.25% and in the ropivacaine-dexmedetomidine (RD) group, in addition to 0.4 cc/kg ropivacaine 0.25%, dexmedetomidine 0.5 µg/kg was added. Verbal Numeric Scale (VNS), systolic blood pressure (SBP), diastolic blood pressure (DBP), respiratory rate (RR), heart rate (HR), and mean arterial blood pressure (MAP) were recorded.

Results

There was no significant difference in both groups in terms of demographic information (P < 0.05). The average VNS was lower in the ketamine group than in the dexmedetomidine group; however, there was a significant difference only at 1, 12, and 24 hours after surgery (P < 0.05). There was no statistically significant difference between the two groups in terms of SBP and DBP, HR, and MAP. There was a significant difference in the RR in the two groups at 12 and 24 hours after the operation (P < 0.05).

Conclusions

Dexmedetomidine and ketamine, which were used as supplements to ropivacaine for SAPB in patients undergoing elective thoracotomy, reduced the pain intensity after thoracotomy; nevertheless, the intensity of pain reduction was more and more effective in the group receiving ketamine.

Optimal concentration of ropivacaine for brachial plexus blocks in adult patients undergoing upper limb surgeries: a systematic review and meta-analysis

Aim of the Study: Brachial plexus block (BPB) is widely used for patients undergoing upper limb surgeries. Ropivacaine is the most commonly used local anesthetic for BPB. This study aimed to identify the optimal ropivacaine concentration for BPB in adult patients undergoing upper limb surgeries. Materials and Methods: PubMed, Embase, the Cochrane Library, and Web of Science were searched to identify randomized controlled trials (RCTs) that compared the effects of different concentrations of ropivacaine for BPB in adult patients undergoing upper limb surgeries. The primary outcomes were the onset time of sensory and motor block. RevMan 5.4 software was used for analysis. The GRADE approach was used to assess evidence quality. Results: Nine studies involving 504 patients were included. Compared to 0.5% ropivacaine, 0.75% ropivacaine shortened the onset time of sensory (WMD, -2.54; 95% CI; -4.84 to -0.24; <0.0001, moderate quality of evidence) and motor blockade (WMD, -2.46; 95% CI, -4.26 to -0.66; p = 0.01; moderate quality of evidence). However, 0.5% and 0.75% ropivacaine provided similar duration time of sensory (WMD, -0.07; 95% CI, -0.88 to 0.74; p = 0.81; high quality of evidence) and motor blockade (WMD, -0.24; 95% CI, -1.12 to 0.65; p = 0.55; high quality of evidence), as well as time to first request for oral analgesia (WMD, -1.57; 95% CI, -3.14 to 0.01; p = 0.5; moderate quality of evidence). Conclusion: Moderate-quality evidence suggested that, in terms of the onset time of sensory and motor blockade, 0.75% ropivacaine is a preferred concentration for BPB in upper limb surgeries. Systematic Review Registration: identifier CRD42023392145.

Comparison of dexmedetomidine and dexamethasone as adjuvants to the ultrasound-guided interscalene nerve block in arthroscopic shoulder surgery: a systematic review and Bayesian network meta-analysis of randomized controlled trials

Introduction

Interscalene block (ISB) is widely regarded as the gold standard treatment for acute pain following arthroscopic shoulder surgery. However, a single injection of a local anesthetic for ISB may not offer sufficient analgesia. Various adjuvants have been demonstrated to prolong the analgesic duration of the block. Hence, this study aimed to assess the relative efficacy of dexamethasone and dexmedetomidine as adjuncts to prolong the analgesic duration for a single- shot ISB.

Methods

The efficacy of adjuvants was compared using a network meta-analysis. The methodological quality of the included studies was evaluated using the Cochrane bias risk assessment tool. A comprehensive search of the PubMed, Cochrane, Web of Science, and Embase databases was conducted with a search deadline of March 1, 2023. Various adjuvant prevention randomized controlled trials have been conducted in patients undergoing interscalene brachial plexus block for shoulder arthroscopic surgery.

Results

Twenty-five studies enrolling a total of 2,194 patients reported duration of analgesia. Combined dexmedetomidine and dexamethasone (MD = 22.13, 95% CI 16.67, 27.58), dexamethasone administered perineurally (MD = 9.94, 95% CI 7.71, 12.17), high-dose intravenous dexamethasone (MD = 7.47, 95% CI 4.41, 10.53), dexmedetomidine administered perineurally (MD = 6.82, 95% CI 3.43, 10.20), and low-dose intravenous dexamethasone (MD = 6.72, 95% CI 3.74, 9.70) provided significantly longer analgesic effects compared with the control group.

Discussion

The combination of intravenous dexamethasone and dexmedetomidine provided the greatest effect in terms of prolonged analgesia, reduced opioid doses, and lower pain scores. Furthermore, peripheral dexamethasone in prolonging the analgesic duration and lowering opioid usage was better than the other adjuvants when used a single medication. All therapies significantly prolonged the analgesic duration and reduced the opioid dose of a single-shot ISB in shoulder arthroscopy compared with the placebo.

Dexmedetomidine improves lung compliance in patients undergoing lateral decubitus position of shoulder arthroscopy: A randomized controlled trial

BACKGROUND

The improvement of oxygenation and pulmonary mechanics in patients under general anesthesia can be achieved by dexmedetomidine (DEX) infusion. However, its role in patients undergoing lateral supine shoulder arthroscopy has not been thoroughly studied. This study aimed to evaluate the effect of DEX on lung compliance in patients undergoing shoulder arthroscopic surgery in a lateral decubitus position.

METHODS

The patients who underwent lateral recumbent shoulder arthroscopy under general anesthesia were randomly divided into the DEX group (group D) and the control group (group N). At the start of the trial, group D was given 0.5 μg/kg/hours continuous pumping until 30 minutes before the end of anesthesia; Group N was injected with normal saline at the same volume. The patients were recorded at each time point after intubation: supine position for 5 minutes (T0), lateral position for 5 minutes (T1), lateral position for 1 hour (T2), lateral position for 2 hours (T3), airway peak pressure, platform pressure, dynamic lung compliance, and static lung compliance, etc.

RESULTS

At the end of the drug infusion, the DEX group showed significant improved pulmonary mechanics and higher lung compliance than the control group. Compared with group N, group D's heart rate and mean arterial pressure were lower at all time points; there was no statistical difference in Tidal volume and Pressure end-tidal carbon dioxide data at each time point in Group D.

CONCLUSION

DEX can improve lung compliance and reduce airway pressure and platform pressure of patients undergoing shoulder arthroscopy in the lateral position under general anesthesia.

Current Strategies in Pain Regimens for Robotic Urologic Surgery: A Comprehensive Review

Context

Robotic surgery is becoming the most common approach in minimally invasive urologic procedures. Robotic surgery offers less pain to patients because of smaller keyhole incisions and less tissue retraction and stretching of fascia and muscular fibers. Tailored pain regimens have also evolved and allowed patients to feel minimal to no discomfort after robotic urologic surgery, allowing in parallel better surgical outcomes. This study aims to analyze the most current pain regimens in robotic urologic surgery and to evaluate the most current pain protocols and corresponding outcomes.

Evidence Acquisition

A literature review was performed of published manuscripts utilizing Pubmed and Google Scholar on pain protocols for patients undergoing robotic urologic surgery.

Results

Multimodal analgesia is gaining ground in robotic urologic surgery. Regional analgesia includes four major modalities: Neuroaxial analgesia, intercostal blocks, tranvsersus abdominis plane blocks, and paravertebral blocks. Each approach has a different injection site, region of analgesia coverage, and duration of coverage depending upon local anesthesia and/or adjuvant utilized with advantages and disadvantages that make each modality unique and efficacious.

Conclusions

Robotic urologic surgery has offered the advantage of smaller incisions, faster recovery, less postoperative opioid consumption, and better surgical outcomes. Neuraxial, intercostal, transversus abdominis plane, and quadratus lumborum blocks are the best and most adopted approaches which offer optimal outcomes to patients.

Effect of Intravenous Dexmedetomidine on Shivering in Cesarean Section under Intrathecal Anesthesia: Randomized Clinical Trial

Background

Shivering is one of the most common side effects after cesarean section (C-section) under spinal or epidural anesthesia. However, it is often not treated.

Objectives

The aim of this study was to evaluate the effectiveness of intravenous dexmedetomidine (DEX) in the prevention of shivering after intrathecal anesthesia in women undergoing C-sections.

Methods

This double-blind, placebo-controlled clinical trial was conducted on 80 women candidates for elective C-sections under intrathecal anesthesia who were referred to Imam Khomeini Governmental Hospital in Ahvaz, Iran, during 2020 - 2021. Patients were randomly divided into two groups of intravenous DEX (group D; 0.5 µg/kg) and normal saline (control, group C) and received the medications after umbilical cord clamping. All patients were evaluated during and after surgery for hemodynamic changes, the incidence and severity of shivering based on Chu and Tsai, side effects (e.g., nausea, vomiting), and sedation level based on the Ramsey scale.

Results

The incidence of shivering in group C was significantly higher than in group D (P = 0.003). Moreover, the severity of shivering on minutes 20, 30, and 45 in group C was significantly higher than in group D (P < 0.05). The mean sedation score during minutes 10 - 30 in group D was significantly higher than in group C (P < 0.05). Heart rate was not significantly different between the two groups (P < 0.05). Systolic and diastolic blood pressure were higher in group D than in group C (P < 0.05).

Conclusions

The administration of intravenous DEX effectively reduces the incidence and severity of shivering and provides appropriate sedation in patients undergoing C-sections, and it does not cause remarkable side effects.

Comparison of Intraperitoneal Versus Intravenous Dexamethasone on Postoperative Pain, Nausea, and Vomiting After Laparoscopic Cholecystectomy

Background

Despite all of the benefits provided by laparoscopic cholecystectomy, such as rapid recovery and shorter hospital stay for patients, the incidence of postoperative nausea and vomiting (PONV) and postoperative pain (POP) still remains high.

Objectives

This study was designed to compare the effects of intraperitoneal (IP) and intravenous (IV) dexamethasone on the reduction of PONV and POP.

Methods

This prospective, randomized, double-blind clinical trial was conducted on a study population of 86 adult patients who were scheduled for laparoscopic cholecystectomy with the American Society of Anesthesiologists class I-II. The patients were randomized into three groups, namely IP dexamethasone (n = 29), IV dexamethasone (n = 29), and control (n = 28) groups. The patients were followed for clinical outcomes, including PONV, POP, and consumption of antiemetics, and their hemodynamic status during the first 24 hours after the surgery.

Results

In the first 24 hours after the operation, no significant differences were observed in nausea (P = 0.41) and vomiting (P = 0.38) between the IP and IV dexamethasone groups. However, there was a lower severity of nausea in the IP group (P = 0.001). Additionally, the visual analog scale score representing POP was significantly reduced in the IP group (P = 0.02). No significant differences in the hemodynamic status were observed after the operation between all the three groups.

Conclusions

The administration of 8 mg IP dexamethasone was associated with significantly reduced pain and severity of nausea, but not PONV, after laparoscopic cholecystectomy.

Ultrasound-Guided Clavipectoral Block for Postoperative Analgesia of Clavicular Surgery: A Prospective Randomized Trial

Background

Clavicular fractures are commonly encountered in daily practice, and most cases are operated under general surgery. Until now, there has been a debate about the best approach to manage pain in such cases.

Objectives

We aimed to evaluate whether ultrasound-guided clavipectoral block [clavipectoral fascial plane block (CPB)] would be safe and effective in cases with clavicular fractures.

Methods

This prospective randomized study included a total of 40 patients with clavicular fractures; they were divided into 2 groups. Group 1 included 20 cases who underwent CPB, and group 2 included 20 cases who underwent placebo block. Pain score, duration of analgesia, total analgesic consumption, and procedure-related complications were noted and recorded.

Results

Despite the comparable demographic data between the 2 groups, pain scores were significantly lower in group 1 than in group 2, starting from postanesthesia care unit (PACU) admission until 12 hours after the operation. Group 1 showed a significant reduction in 24-hour opioid consumption and significant prolongation of the duration of analgesia compared to the placebo. Patient satisfaction was significantly better in group 1 than in group 2. No block-related adverse events were recorded.

Conclusions

CPB is a safe and effective regional technique that should be used for pain management after clavicular fixation surgery.

Novel Local Anesthetics in Clinical Practice: Pharmacologic Considerations and Potential Roles for the Future

The treatment of pain, both acute and chronic, has been a focus of medicine for generations. Physicians have tried to develop novel ways to effectively manage pain in surgical and post-surgical settings. One intervention demonstrating efficacy is nerve blocks. Single-injection peripheral nerve blocks (PNBs) are usually preferred over continuous PNBs, since they are not associated with longer lengths of stay. The challenge of single injection PNBs is their length of duration, which at present is a major limitation. Novel preparations of local anesthetics have also been studied, and these new preparations could allow for extended duration of action of anesthetics. An emerging preparation of bupivacaine, exparel, uses a multivesicular liposomal delivery system which releases medication in a steady, controlled manner. Another extended-release local anesthetic, HTX-011, consists of a combination of bupivacaine and low-dose meloxicam. Tetrodotoxin, a naturally occurring reversible site 1 sodium channel toxin derived from pufferfish and shellfish, has shown the potential to block conduction of isolated nerves. Neosaxitoxin is a more potent reversible site 1 sodium channel toxin also found in shellfish that can also block nerve conduction. These novel formulations show great promise in terms of the ability to prolong the duration of single injection PNBs. This field is still currently in development, and more researchers will need to be done to ensure the efficacy and safety of these novel formulations. These formulations could be the future of pain management if ongoing research continues to prove positive effects and low side effect profiles.

Comparison of the Effect of Propofol and Dexmedetomidine on Hemodynamic Parameters and Stress Response Hormones During Laparoscopic Cholecystectomy Surgery

Background

General anesthesia induces endocrine, immunologic, and metabolic responses. Anesthetic drugs affect the endocrine system by changing the level of stress hormones and hemodynamic variables of the patient.

Objectives

The purpose of this study was to compare the effects of propofol and dexmedetomidine on hemodynamic parameters and stress-induced hormones in laparoscopic cholecystectomy (LC) surgery.

Methods

Seventy patients of elective LC were included in this study. The patients were randomly assigned into two equal groups of propofol (75 µg/kg/min) and dexmedetomidine (0.5 µg/kg/hour) as anesthesia maintenance. Hemodynamic parameters (heart rate and mean atrial pressure), blood sugar, and serum epinephrine level were monitored and recorded from pre-anesthesia period to 10 min after entry to post-anesthesia care unit (PACU) according to a planned method.

Results

Heart rate and mean atrial pressure changes were significantly lower in dexmedetomidine group in all stages compared to propofol group (P < 0.001). Also, the rises in blood glucose and serum epinephrine levels in the dexmedetomidine group were significantly higher than in the propofol group (P < 0.001).

Conclusions

Anesthesia maintenance by dexmedetomidine showed a significant difference in hemodynamic parameters in comparison with propofol. While dexmedetomidine had better effects on controlling hemodynamic parameters, propofol showed better effects on decreasing stress hormones, and it can be suggested for LC surgery.

Hertling A. Adding Dexmedetomidine to Bupivacaine in Ultrasound-guided Thoracic Paravertebral Block for Pain Management after Upper Abdominal Surgery: A Double-blind Randomized Controlled Trial

Background

Paravertebral blocks are one of the possible postoperative pain management modalities after laparotomy. Adjuvants to local anesthetics, including alpha agonists, have been shown to lead to better pain relief and increased duration of analgesia.

Objectives

The aim of this study is to examine the effect of adding dexmedetomidine to bupivacaine for ultrasound-guided paravertebral blocks in laparotomy.

Methods

In this double-blind, randomized controlled trial (RCT), we enrolled 42 patients scheduled for T6 to T8 thoracic paravertebral block (TPVB) for analgesia after laparotomy. The patients were randomly assigned into two groups of BD (bupivacaine 2.5 mg/mL 20 mL plus dexmedetomidine 100 µg) and B (bupivacaine 20 mL alone). Following surgery, intravenous fentanyl patient-controlled analgesia was initiated. The numerical rating scale (NRS) for pain, sedation score, total analgesic consumption, time to first analgesic requirement, side effects (such as nausea and vomiting), respiratory depression, and patients’ satisfaction during the first 48 hours of evaluation were compared in the two groups.

Results

Pain scores and mean total analgesic consumption at the first 48 hours in the BD group were significantly lower than Group B (P = 0.03 and P < 0.001, respectively). The time of first analgesic request was significantly longer in BD group (P < 0.001). Sedation scores and side effects did not differ significantly between the two groups.

Conclusions

Adding dexmedetomidine to bupivacaine for TPVB after laparotomy yielded better postoperative pain management without significant complications.

Comparison of Intercostal Nerve Block with Ropivacaine and Ropivacaine-Dexmedetomidine for Postoperative Pain Control in Patients Undergoing Thoracotomy: A Randomized Clinical Trial

Background

Thoracotomy is one of the most painful surgeries, and failure to alleviate patients' pain can have dangerous consequences.

Objectives

This study aimed to evaluate the addition of dexmedetomidine to ropivacaine in the intercostal block for postoperative pain control in patients undergoing thoracotomy.

Methods

In this randomized clinical trial, 74 patients aged 18 to 60 years with ASA class I or II, BMI less than 40, and no severe systemic problems referred to a teaching hospital in Ahvaz to undergo thoracotomy were included in the study and randomly divided into two groups. After surgery, an ultrasound-guided intercostal block was done with ropivacaine (5 cc of 0.25% solution; group R) or ropivacaine (5 cc of 0.25% solution) plus dexmedetomidine (0.5 µg/kg; group RD) per dermatome. Two dermatomes above and two dermatomes below the level of surgical incision were used. Pain, total opioid consumption, length of ICU stays, time to first rescue analgesic, and time to get out of bed were compared between the two groups.

Results

The intercostal block significantly reduced pain in both groups (P < 0.0001). The pain was lower in the RD group than in the R group from six hours after the intervention up to 24 hours after (P < 0.001). The number of patients who needed rescue analgesia at 12 hours was significantly lower in the RD group (P < 0.05). The RD group also had lower total opioid consumption and a longer time to receive the first rescue analgesia (P < 0.01). There was no significant difference between the two groups in the length of hospitalization and the time to get out of bed.

Conclusions

Dexmedetomidine is an effective and safe choice to be used as an adjunct to ropivacaine in ICB, and it extends the duration of analgesia in combination with ropivacaine after thoracotomy.

Supraclavicular vs. Infraclavicular Brachial Plexus Nerve Blocks: Clinical, Pharmacological, and Anatomical Considerations

: Peripheral nerve blocks (PNB) have become standard of care for enhanced recovery pathways after surgery. For brachial plexus delivery of anesthesia, both supraclavicular (SC) and infraclavicular (IC) approaches have been shown to require less supplemental anesthesia, are performed more rapidly, have quicker onset time, and have lower rates of complications than other approaches (axillary, interscalene, etc.). Ultrasound-guidance is commonly utilized to improve outcomes, limit the need for deep sedation or general anesthesia, and reduce procedural complications. Given the SC and IC approaches are the most common approaches for brachial plexus blocks, the differences between the two have been critically evaluated in the present manuscript. Various studies have demonstrated slight favorability towards the IC approach from the standpoint of complications and safety. Two prospective RCTs found a higher incidence of complications in the SC approach – particularly Horner syndrome. The IC method appears to support a greater block distribution as well. Overall, both SC and IC brachial plexus nerve block approaches are the most effective and safe approaches, particularly under ultrasound-guidance. Given the success of the supraclavicular and infraclavicular blocks, these techniques are an important skill set for the anesthesiologist for intraoperative anesthesia and postoperative analgesia.

Novel Regional Nerve Blocks in Clinical Practice: Evolving Techniques for Pain Management

This review examines the use of novel US-guided nerve blocks in clinical practice. Erector spinae block is a regional anesthesia technique doing by injecting a local anesthetic among the erector spinae muscle group and transverse processes. The phrenic nerve is a branch of the cervical plexus, arising from the anterior rami of cervical nerves C3, C4, and C5. The quadratus lumborum muscle is located along the posterior abdominal wall. It originates from the transverse process of the L5 vertebral body, the iliolumbar ligament, and the iliac crest. US-guided peripheral nerve procedures have a considerable scope of use, including treating headaches and hiccups to abdominal surgical pain, cesarean sections, musculoskeletal pathologies. These nerve blocks have been an effective addition to clinical anesthesia practice. The use of peripheral nerve blocks has improved postoperative pain, lessened the use of opioids and their potential side effects, and decreased the incidence of sleep disturbance in patients. More research should be done to further delineate the potential benefits of these blocks.

Effect of Different Loading Doses of Dexmedetomidine on Controlled Hypotension and the Incidence of Bradycardia During Rhinoplasty: A Clinical Trial

Controlled hypotension, with a mean arterial pressure (MAP) of 60 mmHg - 70 mmHg, provides a bloodless and visible surgical field during rhinoplasty. It has been shown that dexmedetomidine, an α2-adrenoreceptor agonist, is a suitable choice in this regard. One of the disadvantages of this drug is the possibility of severe bradycardia during infusion. Therefore, we compared lower intravenous (IV) loading doses to determine whether the hypotensive effect of the drug was preserved and the bradycardia incidence decreased. In this randomized, double-blinded clinical trial, 81 patients aged 18 to 50 years with the American Society of Anesthesiologists physical status (ASA-PS) class I and II, scheduled for rhinoplasty randomly received 1.0, 0.9, and 0.8 µg/kg (named as groups 1.0, 0.9, and 0.8, respectively) of IV dexmedetomidine before the induction of anesthesia followed by infusion (0.3 - 0.7 µg/kg/h) during operation. The patients' heart rate (HR), MAP, the requirements for nitroglycerin (NTG) and extra fentanyl, as well as the incidence of bradycardia, were recorded. Bleeding and visibility of the surgical field were scored by the surgeon using a 6-point visual scale. MAPs, HRs, and consumption of NTG and extra fentanyl were similar in the studied groups. The surgical field was more visible and bloodless in group 1.0 compared to group 0.8 (P < 0.001); the differences were not significant between groups 1.0 and 0.9 (P = 0.605). The incidence (P = 0.027) and the severity of bradycardia (P = 0.017) were higher in the groups with higher loading doses. We concluded that dexmedetomidine is an acceptable agent to provide controlled hypotension. A loading dose of 0.9 µg/kg, but not 0.8 µg/kg, provides similar surgical field conditions as the dose of 1 µg/kg. Furthermore, despite the decrease in the incidence of bradycardia, the hypotensive effect of the drug is preserved.

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.

Adjuvant Drugs for Peripheral Nerve Blocks: The Role of NMDA Antagonists, Neostigmine, Epinephrine, and Sodium Bicarbonate

The potential for misuse, overdose, and chronic use has led researchers to look for other methods to decrease opioid consumption in patients with acute and chronic pain states. The use of peripheral nerve blocks for surgery has gained increasing popularity as it minimizes peripheral pain signals from the nociceptors of local tissue sustaining trauma and inflammation from surgery. The individualization of peripheral nerve blocks using adjuvant drugs has the potential to improve patient outcomes and reduce chronic pain. The major limitations of peripheral nerve blocks are their limited duration of action and dose-dependent adverse effects. Adjuvant drugs for peripheral nerve blocks show increasing potential as a solution for postoperative and chronic pain with their synergistic effects to increase the duration of action and decrease the required dosage of local anesthetic. N-methyl-d-aspartate (NMDA) receptor antagonists are a viable option for patients with opioid resistance and neuropathic pain due to their affinity to the neurotransmitter glutamate, which is released when patients experience a noxious stimulus. Neostigmine is a cholinesterase inhibitor that exerts its effect by competitively binding at the active site of acetylcholinesterase, which prevents the hydrolysis of acetylcholine and subsequently retaining acetylcholine at the nerve terminal. Epinephrine, also known as adrenaline, can potentially be used as an adjuvant to accelerate and prolong analgesic effects in digital nerve blocks. The theorized role of sodium bicarbonate in local anesthetic preparations is to increase the pH of the anesthetic. The resulting alkaline solution enables the anesthetic to more readily exist in its un-ionized form, which more efficiently crosses lipid membranes of peripheral nerves. However, more research is needed to show the efficacy of these adjuvants for nerve block prolongation as studies have been either mixed or have small sample sizes.