Efficacy of adjuvant dexmedetomidine on penile block for pediatric hypospadias repair

INTRODUCTION

The management of postoperative pain, particularly in younger children, presents a challenge due to their limited ability to articulate the intensity of pain, lower pain threshold, and restricted availability of approved analgesics for pediatric use. Peripheral nerve blocks may be favored over neuraxial blocks because they allow quicker mobilization after surgery.

OBJECTIVE

The present study aims to investigate the potential impact of adding dexmedetomidine to a local anesthetic (bupivacaine) on the analgesic efficacy in dorsal penile nerve block in hypospadias repair surgery.

METHOD

In this prospective double-blinded clinical trial, 50 children aged between 6 months and 6 years old undergoing hypospadias repair surgery participated. Analgesia was administered through a dorsal penile nerve block (DPNB) at the end of surgery. Participants were divided into two groups; one received bupivacaine alone, and the other received dexmedetomidine and bupivacaine in DPNB. Pain and sedation levels were assessed with FLACC score and MOAA/S score, respectively, at 0,1,2 and 4 h after surgery. Vital signs and adverse effects were also recorded, including hemodynamic changes, nausea, and vomiting.

RESULT

There was no statistically significant difference in demographic variables. As illustrated in Figure, the median of FLACC score in group BD was significantly lower compared to group B at every measured time point. MOAA/S score was significantly lower in group BD than in group B (p < 0.001), indicating a higher sedation level. None of the participants in either group experienced any adverse effect except for vomiting, which was not statistically significant (8 % in group B vs. 4 % in group BD, p > 0.999).

DISCUSSION

Several studies have documented the supplementary analgesic properties of dexmedetomidine when used in conjunction with local anesthetic during various surgical procedures and nerve blocks. The present study provides evidence for the additional analgesic efficacy of dexmedetomidine and bupivacaine in the context of dorsal penile nerve block during hypospadias repair surgery while not yielding any significant adverse outcomes. Although the patients in our study were monitored for 4 h in the postanesthesia care unit (PACU), conducting a more comprehensive assessment of patients is advisable.

CONCLUSION

The findings of our study indicate that incorporating dexmedetomidine alongside bupivacaine in dorsal penile nerve block during hypospadias repair surgery may lead to enhanced management of postoperative pain. The lack of adverse effects implies it may be a potentially safe supplementary pain reliever for surgical procedures.

How Do We Treat Children with Anterior Cutaneous Nerve Entrapment Syndrome and Is the Biopsychosocial Model Also Being Applied? A Scoping Review

Background

Evidence-based guidelines for managing anterior cutaneous nerve entrapment syndrome (ACNES) in children are absent. The primary aim of this review was to scrutinize the evidence supporting currently used treatment interventions. In accordance with the World Health Organization (WHO) guidelines for managing chronic pain in children, these patients and their families and caregivers should be treated within the context of the biopsychosocial model; pain should not be treated purely as a biomedical problem. Therefore, our second aim was to evaluate whether these interventions are applied within the context of the biopsychosocial model, utilizing an inter- or multidisciplinary approach.

Materials and Methods

A scoping review of the literature was conducted to explore treatment strategies for ACNES in children. To ensure a comprehensive overview of published literature on this topic, the search was not restricted based on study type. Two reviewers independently assessed titles and abstracts. After excluding records unrelated to children, full texts were screened for inclusion. Any discrepancies in judgement were resolved through discussion with a third reviewer.

Results

Out of 35 relevant titles, 22 were included in this review. Only 4 articles provided information on long-term outcomes. The overall quality of the review was deemed low. The majority of reports did not address treatment or education within the psychological and social domains. A structural qualitative analysis was not feasible due to the substantial heterogeneity of the data.

Conclusion

The evidence supporting current treatment strategies in children with ACNES is of low quality. More research is needed to establish an evidence-based treatment algorithm for patients with this challenging pain problem. In line with the WHO recommendation, greater emphasis should be placed on a biopsychosocial approach. The ultimate goal should be the development of a generic treatment algorithm outlining an approach to ACNES applicable to all professionals involved.

The effect of warming ropivacaine on ultrasound-guided subgluteal sciatic nerve block: a randomized controlled trial

BACKGROUND

There is a long latent period for the sciatic nerve block before a satisfactory block is attained. Changes in the temperature of local anesthetics may influence the characters of the peripheral nerve block. This study was designed to evaluate the effect of warming ropivacaine on the ultrasound-guided subgluteal sciatic nerve block.

METHODS

Fifty-four patients for distal lower limbs surgery were randomly allocated into warming group (group W, n = 27) or room tempeture group (group R, n = 27) with the ultrasound-guided subgluteal sciatic nerve block. The group W received 30 ml of ropivacaine 0.5% at 30℃ and the group R received 30 ml of ropivacaine 0.5% at 23℃. The sensory and motor blockade were assessed every 2 min for 30 min after injection. The primary outcome was the onset time of limb sensory blockade.

RESULTS

The onset time of sensory blockade was shorter in group W than in group R (16 (16,18) min vs 22 (20,23) min, p < 0.001), and the onset time of motor blockade was also shorter in group W than in group R (22 (20,24) min vs 26 (24,28) min, p < 0.001). The onset time of sensory blockade for each nerve was shorter in group W than in group R (p < 0.001). No obvious differences for the duration of sensory and motor blockade and the patient satisfaction were discovered between both groups. No complications associated with nerve block were observed 2 days after surgery.

CONCLUSIONS

Warming ropivacaine 0.5% to 30℃ accelerates the onset time of sensory and motor blockade in the ultrasound-guided subgluteal sciatic nerve block and it has no influence on the duration of sensory and motor blockade.

TRIAL REGISTRATION

The trial was registered on October 3, 2022 in the Chinese Clinical Trial Registry ( https://www.chictr.org.cn/bin/project/edit?pid=181104 ), registration number ChiCTR2200064350 (03/10/2022).

Perineural low dexamethasone dose as adjuvant in supraclavicular brachial plexus block for arteriovenous fistula creation in end stage renal disease: a randomized controlled trial

BACKGROUND AND AIMS

Dexamethasone as adjunct to local anesthetic solution improves the quality of brachial plexus block (BPB). However, evidence for its efficacy at low doses (< 4 mg) is lacking. This study was designed to evaluate the duration of analgesia attained with low dose dexamethasone as adjuvant to local anesthetic for creation of arteriovenous fistula (AVF) under BPB.

METHODS

Sixty-six patients scheduled for AVF creation were randomly allocated to receive either saline (control) or 2 mg dexamethasone, together with 0.5% ropivacaine and 0.2% lignocaine. The primary outcome was duration of analgesia, defined as time from performing the block to the first analgesic request. The secondary outcomes were time from injection to complete sensory block, time from injection to complete motor block, duration of motor block, postoperative analgesic consumption, and fistula patency at three months.

RESULTS

All the blocks were effective. In the group that received dexamethasone, the time to first analgesic request was significantly delayed (432 ± 43.8 minutes vs. 386.4 ± 40.2 minutes; p < 0.01). The onset of sensory and motor blockade occurred faster in dexamethasone group and overall analgesic consumption was also reduced. However, dexamethasone addition did not prolong the duration of motor block. There was no statistically significant difference in the patency of fistulas between the two groups at three months. (p = 0.34).

CONCLUSION

Addition of low-dose perineural dexamethasone to local anesthetic solution significantly prolonged the duration of analgesia. Further trials are warranted to compare the adverse effects between dexamethasone doses of 4 mg and lower.

Dexmedetomidine versus sufentanil as adjuvants to bupivacaine for brachial plexus block during upper extremity surgery: a randomized clinical trial

BACKGROUND

Brachial plexus block (BPB) has been accepted as a reliable alternative for general anesthesia in upper limb surgeries. Adding adjuvant drugs like dexmedetomidine and sufentanil has been shown to have clinical and pharmacologic advantages. In this randomized parallel clinical trial, we aim to compare the effects of these two adjuvants for bupivacaine in BPB.

METHODS

In this double-blinded study, by using computer-assisted block randomization, 40 patients ranged from 20 to 65 years old and scheduled for elective upper limb surgeries were assigned to two equal study groups (n = 20), receiving 1 mL of 5 ..g.mL-1 sufentanil (group S) or 1 mL of 100 ..g.mL-1 dexmedetomidine (group D) in adjunction to 30 mL of 0.5% bupivacaine for supraclavicular BPB under the guidance of ultrasonography. Characteristics of local anesthesia and postoperative analgesia were evaluated (n = 40).

RESULTS

The duration of blocks significantly improved in group S (sensory: estimated median difference (EMD) [95%CI] = 100.0 [70.0...130.0], p < 0.001; motor: EMD [95%CI] = 120.0 [100.0...130.0], p < 0.001). Group S also had significantly longer postoperative analgesia and lower opioid consumption within 24 hours after the surgery (EMD [95%CI] = 4.0 [3.0...7.0], p < 0.001; EMD [95%CI] = -5.0 [-5.0...-5.0], p < 0.001; respectively). None of the patients showed adverse effects concerning vital signs, nausea, or vomiting.

CONCLUSION

Our study showed that during ultrasound-guided supraclavicular BPB, sufentanil is a fairly better choice than dexmedetomidine as an adjuvant for bupivacaine and can provide preferable sensory and motor blocks. No significant side effects were seen in either of the study groups.

Comparison between the effects of epidural lidocaine, tramadol, and lidocaine-tramadol on postoperative pain in cats undergoing elective orchiectomy

BACKGROUND

In veterinary clinical practice, orchiectomy is one of the most common surgical procedures for cats and is performed mainly in young animals. The purpose of this study was to compare three different epidural (EP) analgesic protocols used in cats undergoing orchiectomy in order to determine which protocol resulted in superior outcomes in terms of perioperative analgesia. Twenty-one client-owned male cats were premedicated with a combination of dexmedetomidine (10 µg/kg) and midazolam (0.2 mg/kg) injected intramuscularly. Anesthesia was induced intravenously with propofol. Cats were randomly divided in three treatment groups of seven animals each: Group L received EP lidocaine (2 mg/kg), Group T received EP tramadol (1 mg/kg), and Group LT received EP lidocaine (2 mg/kg) plus tramadol (1 mg/kg). The post-operative pain level was assessed using two different scales: the Glasgow Composite Measure Pain Scale-Feline (CMPS-F) and the Feline Grimace Scale (FGS). Rescue analgesia was administered when the CMPS-F total score was ≥5 or the FGS total score was ≥4.

RESULTS

No adverse effects related to tramadol or lidocaine were observed. Based on post-operative pain assessments, significant differences between groups were observed according to both pain scoring systems. In particular, in Group LT, the CMPS-F and FGS scores decreased significantly in the first six hours following castration.

CONCLUSIONS

Based on our results, EP lidocaine plus tramadol provided the best post-operative analgesic effects in cats submitted to orchiectomy lasting 6 h and could also be a choice to consider for longer surgical procedures.

Successful remimazolam sedation-epidural block in an older patient with severe chronic obstructive pulmonary disease: A case report

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with high morbidity and mortality rates worldwide. Older patients have a degenerative cardiopulmonary function, weak compensatory capacity, and poor surgical tolerance. Therefore, the mode of anesthesia must be optimized. Remimazolam is a new ultrashort-acting benzodiazepine with a rapid onset of action, rapid metabolism, and mild effects on pulmonary circulation. Remimazolam sedation combined with an epidural block has not been reported in hypertensive older adults with severe COPD and inguinal mass resection.

CASE SUMMARY

We report the case of a 73-year-old man with hypertension and severe COPD, who underwent resection of an enlarged inguinal mass that he had noticed more than 7 mo before presentation. The patient presented with a “right inguinal mass” and was recommended to undergo an enlarged inguinal mass resection. Surgery was relatively challenging, due to the large mass (13 cm × 8 cm × 7 cm), hard texture, and poor mobility. Considering the advanced age of the patient, grade III hypertension, and severe COPD, we administered remimazolam combined with an epidural block for anesthesia to ensure perioperative safety and careful consideration. The anesthetic effect was precise; the procedure was performed smoothly without any complications, and the patient was successfully anesthetized. However, anesthetic management in such cases has not yet been reported by previous studies.

CONCLUSION

Remimazolam sedation combined with an epidural block is safe and effective in older patients with hypertension and severe COPD.

Naphazoline and oxymetazoline are superior to epinephrine in enhancing the cutaneous analgesia of lidocaine in rats

This study observed the cutaneous analgesic effect of adrenergic agonists when combined with lidocaine. We aimed at the usefulness of four adrenergic agonists and epinephrine as analgesics or as tools to prolong the effect of local anesthetics using a model of cutaneous trunci muscle reflex (pinprick pain) in rats. We showed that subcutaneous four adrenergic agonists and epinephrine, as well as the local anesthetic bupivacaine and lidocaine, developed a concentration-dependent cutaneous analgesia. The rank order of the efficacy of different compounds (ED₅₀ ; median effective dose) was epinephrine [0.013 (0.012-0.014) μmol] > oxymetazoline [0.25 (0.22-0.28) μmol] > naphazoline [0.42 (0.34-0.53) μmol] = bupivacaine [0.43 (0.37-0.50) μmol] > xylometazoline [1.34 (1.25-1.45) μmol] > lidocaine [5.86 (5.11-6.72) μmol] > tetrahydrozoline [6.76 (6.21-7.36) μmol]. The duration of full recovery caused by tetrahydrozoline, oxymetazoline, or xylometazoline was greater (P < 0.01) than that induced via epinephrine, bupivacaine, lidocaine, or naphazoline at equianesthetic doses (ED₂₅ , ED₅₀ , and ED₇₅ ). Co-administration of lidocaine (ED₅₀ ) with four adrenergic agonists or epinephrine enhanced the cutaneous analgesic effect. We observed that four adrenergic agonists and epinephrine induce analgesia by themselves, and such an effect has a longer duration than local anesthetics. Co-administration of lidocaine with the adrenergic agonist enhances the analgesic effect, and the cutaneous analgesic effect of lidocaine plus naphazoline (or oxymetazoline) is greater than that of lidocaine plus epinephrine.

Drug Permeability: From the Blood-Brain Barrier to the Peripheral Nerve Barriers

Drug delivery into the peripheral nerves and nerve roots has important implications for effective local anesthesia and treatment of peripheral neuropathies and chronic neuropathic pain. Similar to drugs that need to cross the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB) to gain access to the central nervous system (CNS), drugs must cross the peripheral nerve barriers (PNB), formed by the perineurium and blood-nerve barrier (BNB) to modulate peripheral axons. Despite significant progress made to develop effective strategies to enhance BBB permeability in therapeutic drug design, efforts to enhance drug permeability and retention in peripheral nerves and nerve roots are relatively understudied. Guided by knowledge describing structural, molecular and functional similarities between restrictive neural barriers in the CNS and peripheral nervous system (PNS), we hypothesize that certain CNS drug delivery strategies are adaptable for peripheral nerve drug delivery. In this review, we describe the molecular, structural and functional similarities and differences between the BBB and PNB, summarize and compare existing CNS and peripheral nerve drug delivery strategies, and discuss the potential application of selected CNS delivery strategies to improve efficacious drug entry for peripheral nerve disorders.

Comparison of plasma levobupivacaine concentrations with and without epinephrine following erector spinae plane block for breast cancer surgery: a randomized controlled trial

Background

The erector spinae plane (ESP) block requires a large volume of local anesthetic to provide effective analgesia, which has the potential to cause local anesthetic systemic toxicity (LAST). Adjunctive epinephrine slows the entry of local anesthetic into the plasma and decreases its toxic effect on vulnerable tissues. We compared plasma levobupivacaine concentrations with and without epinephrine after ESP blocks for breast cancer surgery.

Methods

In this prospective, double-blinded, randomized controlled trial, 35 patients who underwent elective unilateral partial mastectomy with sentinel lymph node biopsy were enrolled. The patients were randomized to group L (ESP block with 2 mg/kg levobupivacaine) or LE (ESP block with 2 mg/kg levobupivacaine and 5 μg/mL epinephrine). Blood samples were obtained at 2.5, 5, 7.5, 10, 12.5, 15, 30, 60, and 120 min after the ESP block, and plasma concentrations of levobupivacaine were compared.

Results

Twenty-nine patients were included in the analysis. The maximum plasma concentration (C_max) and the time to maximum concentration (T_max) were, respectively, 1.24 μg/mL and 6.0 min in group L and 0.62 μg/mL and 7.2 min in group LE. The two groups showed no significant differences in the numerical rating scale scores immediately after extubation and 5 and 9 h after the ESP block, or in the interval from the ESP block to the first rescue analgesia. No patient developed symptoms suggestive of LAST.

Conclusions

A single bolus of 2 mg/kg levobupivacaine in the ESP block resulted in a short T_max with high C_max. Adding epinephrine to levobupivacaine decreased the C_max and delayed the T_max after ESP blocks but had no effect on postoperative analgesia.

Trial registration

UMIN Clinical Trials Registry, UMIN000034479. The trial was retrospectively registered on October 13, 2018.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01632-6.

Buprenorphine versus dexamethasone as perineural adjuvants in femoral and adductor canal nerve blocks for total knee arthroplasty: a randomized, non-inferiority clinical trial

BACKGROUND

Optimal control of acute postoperative pain and prevention of chronic persistent pain in total knee arthroplasty (TKA) remain a challenge.

METHODS

A randomized, non-inferiority clinical trial (385 patients) evaluated every hour immediate postoperative pain during 24 h, using a verbal rating 11-point scale for patient self-reporting of pain (VRS11). All patients received subarachnoid anesthesia and were randomly allocated in 4 groups: single shots femoral (FNB) or adductor canal blocks (ACB), both with dexamethasone (dex) and buprenorphine (bup). Patients received intravenous analgesia (metamizole magnesium, dexketoprofen) and rescue analgesia when needed: intravenous (paracetamol and morphine) and/or regional (femoral and sciatic nerve blocks). Demographics and adverse effects were also recorded.

RESULTS

A 45.7% of patients had pain: bupACB 56.3%, bupFNB 50.0%, dexACB 40.6% and dexFNB 36.1% (p=0.022). Rescue analgesia was needed in 37.7% of patients (p=0.128). There were statistical differences in percentage of timepoints without pain (95.0±7.9%, p=0.014) and mean VRS11 (0.18±0.3, p=0.012) but no differences in distribution of intensity periods of pain. There were no significant differences in the need of rescue analgesia excepting the use of intravenous morphine (p=0.025).

CONCLUSIONS

buprenorphine is in the present trial inferior to dexamethasone by less than the established non-inferiority limit when used as perineural adjuvant in femoral nerve or adductor canal blocks in total knee arthroplasty analgesia. So, it could be considered an alternative in patients where dexamethasone is contraindicated, such as diabetics.

Analgesic Efficacy of Addition of Magnesium Sulfate to Bupivacaine in Wound Infiltration Technique in Perianal Surgeries

BACKGROUND

In peripheral nerve blocks, magnesium sulfate is an excellent adjuvant to local anesthetics. The use of magnesium sulfate as an adjuvant in wound infiltration for postoperative analgesia needs to be investigated.

AIMS

This study was conducted to evaluate the analgesic efficacy of magnesium sulfate as an adjuvant when added to bupivacaine in wound infiltration technique in perianal surgeries.

SETTINGS AND DESIGN

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

MATERIALS AND METHODS

Sixty patients undergoing perianal surgeries were randomly divided into two groups, Group M and Group C. Following perianal surgery, Group M patients received a local wound infiltration of injection magnesium sulfate 750 mg (1.5 mL of injection 50% magnesium sulfate) added to 0.5% bupivacaine 13.5 mL making a total volume of 15 mL, whereas Group C patients received a local wound infiltration of injection 0.5% bupivacaine 13.5 mL and 1.5 mL normal saline. Postoperative vitals and pain scores were assessed.

STATISTICAL ANALYSIS USED

Student's t-test for normally distributed continuous data, Mann-Whitney U-test for ordinal data, and Chi-square test or Fisher's exact test, whichever is appropriate for categorical data, were used.

RESULTS

The magnesium sulfate group had a lower postoperative pain score, a longer duration of postoperative analgesia, and a lesser number of rescue analgesic doses in the first 24 h.

CONCLUSION

We conclude that magnesium sulfate is an effective adjuvant to bupivacaine for wound infiltration in terms of postoperative analgesia quality and duration following perianal surgeries.

Evaluation of the paw withdrawal latency for the comparison between tramadol and butorphanol administered locally, in the plantar surface of rat, preliminary study

The aim of the study was to evaluate the analgesic efficacy of tramadol compared to butorphanol administered locally in ventral surface of the hind paw of rats. Prospective, randomized experimental study; twenty-one adult male Wistar rats were selected. Heart rate (beats minute^-1), respiratory rate (breaths minute^-1), and paw withdrawal latency (onset of radiant heat until paw withdrawal/seconds) were measured prior (T⁰) and after (T⁵, T¹⁰, T¹⁵, T²⁰) intraplantar injection with saline solution 0,9% (group S), butorphanol 1 mg kg^-1 (group B), and tramadol 1 mg kg^-1 (group T). Shapiro-Wilk normality test and Friedman test were used to analyze the data expressed by median and range. Statistical significance was set at p < 0.05. Statistical analysis of heart rate showed that there were significant differences between groups at different monitoring times. There were no significant differences in respiratory rate after intraplantar injection in any of the treatment groups. The paw withdrawal latency values at T5, T10, and T15 minutes after intraplantar injection in the group B were significantly higher compared to baseline value and to the values of the other groups. The paw withdrawal latency were no significant changes in the measurements of intragroup in S and T. Intraplantar administration of butorphanol provides a good analgesia and significantly increases paw withdrawal latency compared to tramadol. Intraplantar injection of butorphanol could be useful and safe and safe technique to achieve local analgesia for minor surgical procedures in rats.

The emergency medicine management of clavicle fractures

BACKGROUND

Clavicle fractures are common. An emergency physician needs to understand the diagnostic classifications of clavicle fractures, have a plan for immobilization, identify associated injuries, understand the difference between treating pediatric and adult patients, and have an approach to multimodal pain control. It is also important to understand when expert orthopedic consultation or referral is indicated.

OBJECTIVE OF THE REVIEW

To provide an evidence-based review of clavicle fracture management in the emergency department.

DISCUSSION

Clavicle fractures account for up to 4% of all fractures evaluated in the emergency department. They can be separated into midshaft, distal, and proximal fractures. They are also classified in terms of their degree of displacement, comminution and shortening. Emergent referral is indicated for open fractures, posteriorly displaced proximal fractures, and those with emergent associated injuries. Urgent referral is warranted for fractures with greater than 100% displacement, fractures with >2 cm of shortening, comminuted fractures, unstable distal fractures, and floating shoulder. Nondisplaced or minimally displaced fractures with no instability or associated neurovascular injury are managed non-operatively with a sling. Pediatric fractures are generally managed conservatively, with adolescents older than 9 years-old for girls and 12 years-old for boys being treated using algorithms that are similar to adults.

CONCLUSIONS

When encountering a patient with a clavicle fracture in the emergency department the fracture pattern will help determine whether emergent consultation or urgent referral is indicated. Most patients can be discharged safely with sling immobilization and appropriate outpatient follow-up.

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

BACKGROUND

Interscalene block is one of the popular methods for decreasing pain and analgesic consumption after shoulder arthroscopic surgeries.

OBJECTIVES

The objective is to compare the analgesic duration of effects of dexmedetomidine and dexamethasone as adjuvants to 0.5% ropivacaine in ultrasound-guided interscalene blocks for arthroscopic shoulder surgery in an ambulatory setting.

METHODS

In this randomized controlled trial, 117 adult patients candidate for ambulatory arthroscopic shoulder surgery under general anesthesia were divided into three groups to perform an ultra-sound guided interscalene block before the surgery. The ropivacaine (control) group received ropivacaine 0.5% 20 mL, group Dexamethasone received ropivacaine 0.5% 20 mL plus 4mg dexamethasone, and group dexmedetomidine received ropivacaine 0.5% 20 mL plus 75 mcg of dexmedetomidine. Time to return of sensory function, of motor function, of first pain sensation, amount of opioid medication consumed at 24 hours and 48 hours post-operatively were measured.

RESULTS

The 24-hour median (25th- 75th percentile) opioid consumption in morphine equivalents was similar between groups 22.5 mg (10 - 30), 15 mg (0 - 30), and 15 mg (0 - 20.6) in the ropivacaine, dexmedetomidine, and dexamethasone groups, respectively (P = 0.130). The median (25th- 75th percentile) 48 hours post-operatively, the median opioid consumption in morphine equivalents was 40 mg (25 - 67.5) in the ropivacaine group, 30 mg (22 - 50.6) in the dexamethasone group, and 52.5 mg (30 - 75) in the dexmedetomidine group (P = 0.278). The median 24-hour pain scores were 6 (5 - 8) in the ropivacaine control group, 7 (5.5 - 8) in the dexamethasone group, and 7 (4 - 9) in the dexmedetomidine group (P = 0.573).

CONCLUSIONS

There was no statistical difference in opioid consumption at 24 and 48 hours post-operatively when comparing dexmedetomidine, dexamethasone, and no adjuvant. However, intraoperative opioid use was significantly lower with dexmedetomidine compared to dexamethasone and plain 0.5% ropivacaine. The safe side effect profile of dexmedetomidine makes it a reasonable alternative as an adjuvant for peripheral nerve blockade when dexamethasone use may be contraindicated.

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.

Nanogels with High Loading of Anesthetic Nanocrystals for Extended Duration of Sciatic Nerve Block

The development of thermoresponsive nanogels loaded with nanocrystals of the local anesthetic bupivacaine nanocrystals (BNCs) for prolonged peripheral nerve pain relief is reported here. BNCs were prepared using the antisolvent precipitation method from the hydrophobic form of bupivacaine (bupivacaine free base). The as-prepared BNCs were used stand-alone or encapsulated in temperature-responsive poly(ethylene glycol) methyl ether methacrylate (OEGMA)-based nanogels, resulting in bupivacaine NC-loaded nanogels (BNC-nanogels) of monodisperse size. The synthesis protocol has rendered high drug loadings (i.e., 93.8 ± 1.5 and 84.8 ± 1.2 wt % for the NC and BNC-nanogels, respectively) and fast drug dissolution kinetics in the resulting composite material. In vivo tests demonstrated the efficacy of the formulation along with an extended duration of sciatic nerve block in murine models of more than 8 h with a formulation containing only 2 mg of the local anesthetic thanks to the thermoresponsive character of the polymer, which, at body temperature, becomes hydrophobic and acts as a diffusion barrier for the encapsulated drug nanocrystals. The hydrophobicity of the encapsulated bupivacaine free base probably facilitates its pass through cell membranes and also binds strongly to their hydrophobic lipid bilayer, thereby protecting molecules from diffusion to extracellular media and to the bloodstream, reducing their clearance. When using BNC-nanogels, the duration of the anesthetic blockage lasted twice as long as compared to the effect of just BNCs or a conventional bupivacaine hydrochloride solution both containing equivalent amounts of the free drug. Results of the in vivo tests showed enough sensory nerve block to potentially relieve pain, but still having mobility in the limb, which enables motor function when required. The BNC-nanogels presented minimal toxicity in the in vivo study due to their sustained drug release and excellent biocompatibility. The encapsulation of nano-sized crystals of bupivacaine provides a prolonged regional anesthesia with reduced toxicity, which could be advantageous in the management of chronic pain.

The addition of clonidine to ropivacaine in rectus sheath nerve blocks for pediatric patients undergoing laparoscopic appendectomy: A double blinded randomized prospective study

STUDY OBJECTIVE

The primary goal of this study was to determine if the addition of clonidine to ropivacaine prolonged periumbilical numbness compared to ropivacaine alone in pediatric patients receiving ultrasound guided rectus sheath nerve blocks for laparoscopic appendectomy. The secondary goals were to evaluate differences in perioperative pain scores, analgesic consumption, sedation, anxiolysis, and hemodynamic effects from clonidine.

DESIGN

This was a single center, randomized, double-blinded prospective study.

SETTING

This study was conducted within the pediatric operating rooms at the Children's Hospital of Pittsburgh, a large university-based academic medical center.

PATIENTS

Fifty pediatric patients (ages 10-17 years old) without pre-existing cognitive impairment, developmental delay or chronic pain undergoing laparoscopic appendectomy during weekday hours were enrolled and randomized to control versus intervention groups.

INTERVENTION

Ultrasound guided rectus sheath nerve block injections were performed at the beginning of surgery with either ropivacaine 0.5% plus normal saline or ropivacaine 0.5% plus clonidine (2 mcg/kg, maximum of 100 mcg).

MEASUREMENTS

The duration of periumbilical numbness, Numeric Pain Rating Scale scores, University of Michigan Sedation Scale, State-Trait Anxiety Inventory for Children, analgesic consumption, heart rate, blood pressure, and mean arterial pressures, were recorded for each patient at several time points in the perioperative setting.

MAIN RESULTS

There were no significant differences in demographic characteristics between groups. The median duration of periumbilical numbness did not significantly differ between the ropivacaine only and the ropivacaine plus clonidine groups 540.0 minutes [360.0 -1015.0] (median [interquartile range (IQR)]) versus 823.5 minutes [509.5- 1080.0], p = 0.451. There were no significant differences in perioperative analgesic consumption, pain and anxiety scores, PACU sedation, or hemodynamic instability.

CONCLUSIONS

The addition of clonidine did not significantly prolong rectus sheath nerve block duration and was well tolerated in pediatric patients. Perioperative analgesia, hemodynamics, anxiety, and PACU sedation did not differ between groups.

TRIAL REGISTRATION

Clinical Trials NCT02439281.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.

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.

Comparison of postoperative analgesic effects in response to either dexamethasone or dexmedetomidine as local anesthetic adjuvants: a systematic review and meta-analysis of randomized controlled trials

This review compares the effects of peripheral dexamethasone and dexmedetomidine on postoperative analgesia. We included six randomized controlled trials (354 patients) through a systematic literature search. We found that analgesia duration was comparable between dexamethasone and dexmedetomidine (58.59 min, 95% CI (confidence interval), -  66.13, 183.31 min) with extreme heterogeneity. Secondary outcome was also compared and no significant difference was observed in sensory block onset and duration and motor block duration and also for postoperative nausea and vomiting. It is noteworthy that dexamethasone reduced analgesic consumption (fentanyl) by 29.12 mcg compared with dexmedetomidine. We performed subgroup analyses and found no significant difference between the following: (1) lidocaine vs ropivacaine (P = 0.28), (2) nerve block vs nerve block + general anesthesia (P = 0.47), and (3) upper limb surgery vs thoracoscopic pneumonectomy (P = 0.27). We applied trial sequential analysis to assess the risks of type I and II errors and concluded that the meta-analysis was insufficiently powered to answer the clinical question, and further analysis is needed to establish which adjuvant is better. In conclusion, we believe that existing research indicates that dexamethasone and dexmedetomidine have equivalent analgesic effects in peripheral nerve blocks.

SBA 2020: Regional anesthesia safety recommendations update

The purpose of the Brazilian Society of Anesthesiology (SBA)’s Regional Anesthesia Safety Recommendations Update is to provide new guidelines based on the current relevant clinical aspects related to safety in regional anesthesia and analgesia. The goal of the present article is to provide a broad overview of the current knowledge regarding pre-procedure asepsis and antisepsis, risk factors, diagnosis and treatment of infectious complications resulting from anesthetic techniques. It also aims to shed light on the use of reprocessed materials in regional anesthesia practice to establish the effects of aseptic handling of vials and ampoules, and to show cost-effectiveness in the preparation of solutions to be administered continuously in regional blockades. Electronic databases were searched between January 2011 (final date of the literature search for the past SBA recommendations for safety in regional anesthesia) and September 2019. A total of 712 publications were found, 201 of which were included for further analysis, and 82 new publications were added into the review. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system was used to assess the quality of each study and to classify the strength of evidence. The present review was prepared by members of the SBA Technical Standards Committee.

[SBA 2020: Regional anesthesia safety recommendations update]

The purpose of the Brazilian Society of Anesthesiology's (SBA) Regional Anesthesia Safety Recommendations Update is to provide new guidelines based on the current relevant clinical aspects related to safety in regional anesthesia and analgesia. The goal of the present article is to provide a broad overview of the current knowledge regarding pre-procedure asepsis and antisepsis, risk factors, diagnosis and treatment of infectious complications resulting from anesthetic techniques. It also aims to shed light on the use of reprocessed materials in regional anesthesia practice to establish the effects of aseptic handling of vials and ampoules, and to show cost-effectiveness in the preparation of solutions to be administered continuously in regional blockades. Electronic databases were searched between January 2011 (final date of the literature search for the past SBA recommendations for safety in regional anesthesia) and September 2019. A total of 712 publications were found, 201 of which were included for further analysis, and 82 new publications were added into the review. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system was used to assess the quality of each study and to classify the strength of evidence. The present review was prepared by members of the SBA Technical Standards Committee.

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.

A novel LC-MS/MS analytical method for detection of articaine and mepivacaine in blood and its application to a preliminary pharmacokinetic study

Local anaesthetics (LAs) are commonly used in surgery, especially in dentistry. They cause a transitory inhibition of nerve signal due to the blockade of the voltage-gated sodium channels. LAs are administrated alone or with vasoconstriction agents, such as adrenaline. Toxicity of LAs is associated to neurological and cardiovascular alterations. Tachycardia, arrhythmia, tremors, tonic-clonic seizure and respiratory depression (at high doses) are the main symptoms of intoxication by LAs. Lidocaine, articaine and mepivacaine are among the most used anaesthetics. This study aimed to fully validated a new method for the simultaneous detection of articaine and mepivacaine in whole blood. Sample treatment consisted in a liquid-liquid extraction with phosphate buffer (pH 8, 0.1 M) and ethyl-acetate. Analysis was performed by liquid chromatography-tandem mass spectrometry in multiple reaction monitoring mode (transitions: articaine, 285→8658 m/z; mepivacaine, 247→9870 m/z; lidocaine - internal standard -, 235→8658 m/z). The method proved to be highly sensitive with limit of quantifications for articaine and mepivacaine of 0.8 and 0.1 ng/mL, respectively. Accuracy and precision were always within the acceptance criteria. The new procedure was also successfully applied to a preliminary pharmacokinetics study.

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.

Morphological reasoning of paraaortal surgical access for an abdominal aortic neural plexus in pet dogs

Despite a great number of studied and development of new treatment of various diseases, there is a lack of effective surgical access pathways to an abdominal autonomic nerve in small predatory animals. The study is purposed to develop a morphologically reasonable, species-specific surgical access of paraaortic injection of local anesthetics into an area of localization of abdominal autonomic nerves in pet dogs. The subjects of the study were corpses of mature mesomorphic pet dogs fallen of non-communicable diseases. The complex of morphological methods used in this research is as follows: normal and subtle dissection on the academic Vorobyov’s method, classic methods of production of light-optical histological medications, morphometry. With the aim of developing injection access to abdominal autonomic nerves, an injection of colored latex solution with its further dissection was used. In our investigations skeletonangiotopical relations, macro-microanatomical and histological constitution of abdominal nerves of aortal plexus were studied. Epineural structures was in pet dogs were characterized. The results of macromicroanatomical and histological studies allowed to develop a technique of paraaortal surgical access to an abdominal aortal nervous plexus in pet dogs. The proposed technique of paraaortal surgical access for a block of an abdominal aortal nervous plexus allows for full coverage an area where the sources of abdominal organs innervation are located.

The Influence of Vasoconstritor Use in Local Anesthesia in Individuals with Chronic Renal Failure

AbstractIndividuals with chronic renal failure (CRD) undergo hemodialysis to compensate for systemic-based disease and often develop systemic arterial hypertension (SAH). Such individuals, when needing dental treatment, carry with them the consideration of which type of anesthetic to be used in clinical and surgical interventions. The objective of this study was to evaluate the action of anesthetics with vasoconstrictor (AwV) and without vasoconstrictor (AoV) in individuals with chronic renal failure. Research subjects needed dental treatment, with dental restorations, on the right and left lower dental arch in premolars and / or molars, thus receiving the model of a split-mouth clinical study. In a randomized study, each side of the mandible was subjected to an anesthetic infiltration with only one 1.8 mL tube in two different moments with a minimum interval of 7 days (for one moment with AwV and another AoV moment). The parameters of oxygen saturation (SaO2), heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured 5 minutes before anesthesia, 5, 15 and 30 minutes after anesthesia. The results found in this study showed statistical difference only in SaO2 in the time of 5 minutes after the anesthesia in comparison of the AwV and AoV group, this same result was obtained when only those individuals who, besides nephropathies, had a diagnosis of SAH, were evaluated. The findings of this study highlight the safety of the use of anesthetics, with or without vasoconstrictors since in small amounts, in individuals with CRF with or without associated SAH.Keywords: Renal Insufficiency. Hypertension. Anesthetics, Local.ResumoIndivíduos com insuficiência renal crônica (IRC) em geral são submetidos à hemodiálise para compensação da doença de base sistêmica e frequentemente desenvolvem a hipertensão arterial sistêmica (HAS). Tais indivíduos, ao necessitarem de tratamento odontológico, levam consigo a ponderação de qual tipo de anestésico a ser utilizado em intervenções clínicas e cirúrgicas. O objetivo deste estudo foi avaliar a ação de anestésicos com vasoconstritor (ACV) e sem vasoconstritor (ASV) em indivíduos com insuficiência renal crônica. Os indivíduos da pesquisa tinham necessidade de tratamento odontológico, com restaurações dentárias, no arco dentário inferior direito e esquerdo em pré-molares e/ou molares, recebendo assim o modelo de estudo clínico de boca dividida. De forma aleatória, os hemiarcos inferiores foram submetidos, em dois diferentes momentos com intervalo mínimo de 7 dias, a infiltração anestésica com apenas um tubete de 1,8 mL (para um momento com ACV e outro momento ASV). Foi feita aferição dos parâmetros de saturação de oxigênio (SaO2), frequência cardíaca  (FC), pressão arterial sistólica (PAS) e diastólicas (PAD), 5 minutos antes da anestesia, 5, 15 e 30 minutos após a anestesia. Os resultados encontrados neste estudo demonstraram diferença estatística apenas na SaO2 no tempo de 5 minutos após a anestesia em comparação do grupo ACV e ASV, esse mesmo resultado foi obtido quando avaliados apenas os indivíduos que, além de nefropatas, apresentavam diagnóstico de HAS. Os achados deste estudo ressaltam a segurança do uso de anestésicos, com ou sem vasoconstritores desde que em pequenas quantidades, em indivíduos com IRC com ou sem HAS associada.Palavras-chave: Insuficiência Renal. Hipertensão. Anestésicos Locais.

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

BACKGROUND AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

TRIAL REGISTRATION NUMBER

ChiCTR-IOR-17012183.

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.

Greater palatine block for V2 trigeminal neuralgia: Case report

AIMS

This study describes a novel nerve block directed at the maxillary (V2) division of the fifth cranial nerve as treatment for medication-refractory trigeminal neuralgia (TN).

METHODS AND RESULTS

The authors present three cases of TN treated with V2 nerve block using commonly available local anesthetics injected through the greater palatine foramen. Patients' medications were noted before and after the procedure. Following the injection, patients were followed over time and outcome was assessed. Patients experienced rapid and long-lasting pain relief allowing for significant reduction in antineuralgia medications. This was done with the objective of breaking the pain cycle with subsequent discontinuation or reduction of analgesic medications.

CONCLUSION

This technique may be an effective treatment for medication-refractory V2 TN. By interrupting the pain cycle, this renders the condition amenable to long-term control using diminished doses of standard antineuralgia pharmaceuticals. The practical implications of the described procedure are that it is simple, safe, and well-tolerated with few or no adverse effects. This novel technique is a diagnostic feature for the dentist to differentiate between sources of facial pain.

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

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

Single-Injection Adductor Canal Block With Multiple Adjuvants Provides Equivalent Analgesia When Compared With Continuous Adductor Canal Blockade for Primary Total Knee Arthroplasty: A Double-Blinded, Randomized, Controlled, Equivalency Trial

BACKGROUND

Peripheral nerve blockade is used to provide analgesia for patients undergoing total knee arthroplasty. This study compared a single-injection adductor canal block (SACB) with adjuvants to continuous adductor canal blockade (CACB). The hypothesis was that the 2 groups would have equivalent analgesia at 30 hours after neural blockade.

METHODS

This was a double-blinded, randomized, controlled, equivalency trial. Sixty patients were randomized to either the SACB group (20 mL of 0.25% bupivacaine, 1.67 mcg/mL of clonidine, 2 mg of dexamethasone, 150 mcg of buprenorphine, and 2.5 mcg/mL of epinephrine) or the CACB group (20 mL 0.25% of bupivacaine injection with 2.5 mcg/mL of epinephrine followed by an 8 mL/h infusion of 0.125% bupivacaine continued through postoperative day 2). The primary outcome was movement pain scores at 30 hours using the numeric rating scale (NRS). The secondary outcomes included serial postoperative NRS pain scores (rest and movement every 6 hours), opioid consumption, time to first opioid administration, ability to straight leg raise, patient satisfaction, length of stay, and the incidence of nausea/vomiting.

RESULTS

An intention-to-treat analysis included 59 patients. The NRS pain scores with movement were equivalent at 30 hours (SACB 5.5 ± 2.8 vs CACB 5.7 ± 2.9 [mean NRS ± standard deviation]; mean difference 0.2 [-1.5 to 1.0 {90% confidence interval}]). All NRS pain scores were equivalent until 42 hours (rest) and 48 hours (rest and movement) with the CACB group having lower pain scores. Other secondary outcomes were not statistically different.

CONCLUSION

An SACB provides equivalent analgesia for up to 36 hours after block placement when compared with a CACB for patients undergoing total knee arthroplasty, though a CACB was favored at 42 hours and beyond.

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.

Local Anesthetic Systemic Toxicity

Local anesthetics are commonly used in the perioperative environment to facilitate surgical procedures or to provide postoperative pain management for patients. The use of local anesthetics, however, introduces the risk of complications resulting from local anesthetic systemic toxicity and the risks of increased morbidity and mortality for the surgical patient. Systemic toxicity from the injection or overdose of local anesthetics is a rare but potentially fatal complication that occurs in less than 1 in 1,000 patients. This article provides the perioperative nurse with information about local anesthetics, the signs and symptoms of local anesthetic systemic toxicity, and the information needed to manage a patient experiencing this complication.

Dexamethasone and Clonidine, but not Epinephrine, Prolong Duration of Ropivacaine Brachial Plexus Blocks, Cross-Sectional Analysis in Outpatient Surgery Setting

Objective

The primary aim of this study is to determine the effect of adding dexamethasone, clonidine or both with and without epinephrine to ropivacaine and bupivacaine brachial plexus blocks.

Design

Observational study of prospectively collected data.

Setting

Single academic outpatient surgery center.

Methods

We evaluated 5,515 patient entries who received brachial plexus block (BPB). Multiple, rescue, unsuccessful, and distal nerve blocks of the upper extremity were excluded. The duration was calculated from the time the block was performed until the resolution of the block by patient report. Block durations were compared using Analysis of Variance.

Results

After exclusions, 3,706 nerve blocks were analyzed. The median concentration of ropivacaine used was 0.5%. Both clonidine and dexamethasone significantly increased block duration by 1.1 and 3.0 hours, respectively. Combining clonidine and dexamethasone with ropivacaine increased block duration by 6.2 hours (p<0.001) when compared to ropivacaine alone. Dexamethasone and Clonidine increased block duration by 5.2 hours (p<0.001) when compared to clonidine alone and by 3.2 hours (p<0.001) compared to dexamethasone alone. The addition of epinephrine to any of the adjuvants made no statistically significant difference to the duration of action except when it was added to dexamethasone.

Summary

For brachial plexus blocks, epinephrine did not affect the duration of analgesia when added to ropivacaine. Epinephrine did not enhance the observed increase of block duration induced by clonidine or the combination of clonidine and dexamethasone. The most block duration enhancement was observed when combination of clonidine and dexamethasone were added to ropivacaine.

Precision-guided long-acting analgesia by Gel-immobilized bupivacaine-loaded microsphere

Peripheral nerve blockade (PNB) is a conventional strategy for the management of acute postoperative pain. However, the short duration of the associated analgesia and the potential systemic toxicity due to the low molecular weights of local anesthetics limit their application. Methods: An in situ forming injectable Gel-microsphere (Gel-MS) system consisting of PLGA-PEG-PLGA Gel (Gel) and Gel-immobilized bupivacaine-loaded microsphere (MS/BUP) was prepared for precision-guided long-acting analgesia. A series of in vitro characterizations, such as scanning electron microscopy, rheology analysis, confocal laser scanning microscopy, drug release, and erosion and degradation, were carried out. After that, the in vivo analgesia effect of the Gel-MS system, the immobilization effect of Gel on the MS, and biocompatibility of the system were evaluated using a sciatic nerve block model. Results: The BUP release from the Gel-MS system was regulated by both the inner MS and the outer Gel matrix, demonstrating sustained BUP release in vitro for several days without an initial burst release. More importantly, incorporation of the Gel immobilized the MS and hindered the diffusion of MS from the injection site because of its in situ property, which contributed to a high local drug concentration and prevented systemic side effects. In vivo, a single injection of Gel-MS/BUP allowed rats to maintain sensory and motor blockade significantly longer than treatment with MS/BUP (P < 0.01) or BUP-loaded Gel (Gel-BUP, P < 0.01). Histopathological results demonstrated the excellent biodegradability and biocompatibility of the Gel-MS system without neurotoxicity. Conclusion: This precision-guided long-acting analgesia, which provides an in situ and sustained release of BUP, is a promising strategy for long-acting analgesia, and could represent a potential alternative for clinical pain management.

Perineural dexamethasone successfully prolongs adductor canal block when assessed by objective pinprick sensory testing: A prospective, randomized, dose-dependent, placebo-controlled equivalency trial

STUDY OBJECTIVE

To determine whether perineural dexamethasone prolongs peripheral nerve blockade (PNB) when measured objectively; and to determine if a 1 mg and 4 mg dose provide equivalent PNB prolongation compared to PNB without dexamethasone.

SETTING

Multiple studies have reported that perineural dexamethasone added to local anesthetics (LA) can prolong PNB. However, these studies have relied on subjective end-points to quantify PNB duration. The optimal dose remains unknown. We hypothesized that 1 mg of perineural dexamethasone would be equivalent in prolonging an adductor canal block (ACB) when compared to 4 mg of dexamethasone, and that both doses would be superior to an ACB performed without dexamethasone.

DESIGN

This was a prospective, randomized, double-blind, placebo-controlled equivalency trial involving 85 patients undergoing a unicompartmental knee arthroplasty.

INTERVENTIONS

All patients received an ACB with 20 ml of 0.25% bupivacaine with 1:400,000 epinephrine. Twelve patients had 0 mg of dexamethasone (placebo) added to the LA mixture; 36 patients had 1 mg of dexamethasone in the LA; and 37 patients had 4 mg of dexamethasone in the LA.

MEASUREMENTS

The primary outcome was block duration determined by serial neurologic pinprick examinations. Secondary outcomes included time to first analgesic, serial pain scores, and cumulative opioid consumption.

MAIN RESULTS

The 1 mg (31.8 ± 10.5 h) and 4 mg (37.9 ± 10 h) groups were not equivalent, TOST [Mean difference (95% CI); 6.1 (-10.5, -2.3)]. Also, the 4 mg group was superior to the 1 mg group (p-value = 0.035), and the placebo group (29.7 ± 6.8 h, p-value = 0.011). There were no differences in opioid consumption or time to analgesic request; however, some pain scores were significantly lower in the dexamethasone groups when compared to placebo.

CONCLUSION

Dexamethasone 4 mg, but not 1 mg, prolonged the duration of an ACB when measured by serial neurologic pinprick exams.

CLINICAL TRIAL REGISTRATION

NCT02462148.

Low-dose NSAIDs reduce pain via macrophage targeted nanoemulsion delivery to neuroinflammation of the sciatic nerve in rat

Neuroinflammation involving macrophages elevates Prostaglandin E₂, associated with neuropathic pain. Treatment with non-steroidal anti-inflammatory drugs (NSAIDs) inhibits cyclooxygenase, reducing PGE₂. However, NSAIDs cause physiological complications. We developed nanoemulsions incorporating celecoxib and near infrared dye. Intravenous injected nanoemulsion is incorporated into monocytes that accumulate at the injury; revealed in live animals by fluorescence. A single dose (celecoxib 0.24 mg/kg) provides targeted delivery in chronic constriction injury rats, resulting in significant reduction in the visualized inflammation, infiltration of macrophages, COX-2 and PGE₂. Animals exhibit relief from hypersensitivity persisting at least four-days. The total body burden of drug is reduced by >2000 fold over oral drug delivery.