Anaesthetic Agents for Advanced Regional Anaesthesia

Levobupivacaine versus ropivacaine for brachial plexus block: A systematic review and meta-analysis of randomised controlled trials

Background and Aims

Brachial plexus block (BPB) is advantageous for elective orthopaedic or reconstructive upper limb surgery. However, the optimal local anaesthetic in BPB remains debatable. Therefore, we aim to investigate the efficacy and safety of levobupivacaine versus ropivacaine in BPB for upper limb surgery.

Methods

A systematic review and meta-analysis synthesising randomised controlled trials (RCTs), retrieved by systematically searching PubMed, EMBASE, WOS, SCOPUS, Google Scholar, and CENTRAL since inception till June 2024. Continuous and dichotomous outcome variables were pooled using mean difference (MD) and risk ratio (RR), with a 95% confidence interval (CI), using Stata v. 17. We assessed heterogeneity using the Chi-square test and I2 statistic.

Results

Sixteen RCTs and 939 patients were included. Levobupivacaine was significantly associated with a longer sensory block duration [MD: 1.66 (95% CI: 1.43, 1.89), P < 0.001] and motor block duration [MD: 1.18 (95% CI: 0.11, 2.26), P = 0.03]. However, there was no difference between both groups in time to sensory block [MD: -0.30 (95% CI: -1.31, 0.71), P = 0.56], time to motor block [MD: -0.29 (95% CI: -1.26, 0.67), P = 0.55], pain score [MD: -0.48 (95% CI: -2.13, 1.16), P = 0.56], rescue analgesia rate [RR: 0.94 (95% CI: 0.74, 1.20), P = 0.64], and complications [RR: 0.47 (95% CI: 0.20, 1.13), P = 0.09].

Conclusions

Levobupivacaine is significantly associated with a longer duration of sensory and motor block in patients undergoing BPB for upper limb surgery compared to ropivacaine, with a similar safety profile. However, there was no difference regarding the time to onset of the sensory or motor block.

Clinical and Antinociceptive Effects of Distal Inferior Alveolar Nerve Block in Ponies With Tramadol 5% or Lidocaine 2

This study aimed to compare the antinociceptive effects of tramadol 5% and lidocaine 2% on mental nerve block in horses of the Brazilian Pony breed. Eight adult non-pregnant mares were used in this study. The ponies were tranquilized with acepromazine (5 µg kg^-1, IV), and the infiltration of the mental foramen was performed in Treatment 1- tramadol 5% (T, 150 mg) or Treatment 2- lidocaine 2% (L, 60 mg), both at a total dose of 3 ml in each foramen. Heart rate (HR), respiratory rate (RR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP), mean arterial pressure (MAP), rectal temperature (RT), and formation of skin lesions (SL) were evaluated. Evaluation of nociception of the outer lip (OL), inner lip (IL), and gingiva (GG) were performed using an electronic von Frey device with the evaluation of the ponies' reactions to each stimulus. From these reactions, we determined latency time (LT) and duration of antinociception (DAN). Analysis of variance with 16 observations was performed for HR, RR, SAP, DAP, MAP, LT and DAN. Data were expressed as mean ± standard deviation and the means were compared by the SNK and Student's t-test (P< 0.05). Changes in HR, RR, SAP, DAP, and MAP between evaluation times were associated with the effects of acepromazine (P>0.05). No formation of skin lesions was observed. Latency time did not differ between treatments (P>0.05). Both lidocaine 2% and tramadol 5% produced an antinociceptive effect. We conclude that the duration of the antinociceptive effect of tramadol 5% is longer than that of lidocaine 2%.

Intravenous versus perineural dexmedetomidine in prolongation of analgesia with regional anesthesia: a meta-analysis and systematic review

Background and Objective. It is unclear whether perineural administration offers advantages when compared to intravenous dexmedetomidine in local anesthesia. To compare the efficacy of perineural versus intravenous dexmedetomidine as local anesthetic adjuvant, we conducted the meta analysis and systematic review. Materials and Methods. Two researchers searched MEDLINE, OVID, PubMed, Embase, Cochrane Central, Web of Science and Wanfang data for randomized controlled trials comparing the effect of intravenous versus perineural dexmedetomidine as local anesthetic adjuvant without any language restrictions. Results. We identified 14 randomized controlled trials (801 patients). The results revealed that the duration of analgesia (SMD: -1.76, 95 % CI, [-2.7, -0.83] P = 0.000, I2 = 96 %), the duration of sensory block (SMD:- 3.99, 95 % CI, [-5.88, -2.0], P = 0.000, I2 = 97.6 %), the duration of motor block (SMD: -1.6, 95 % CI, [-2.78, -0.41] P = 0.008, I 2 = 95.5 %) were significantly longer in the perineural group, when compared to systematic dexmedetomidine. The onset time of sensory block (SMD: 1.55, 95 % CI, [0.16, 2.94] P = 0.028, I2 = 96.7 %) and the onset time of motor block (SMD: 0.84, 95 % CI, [0.17, 1.5] P = 0.013, I2 = 88.3 %) were shorter in perineural group compared to intrave nous dexmedetomidine. Meanwhile, analgesic consumption in 24 hours (SMD: 0.37, 95 % CI, [0.05, 0.69] P = 0.023, I 2 = 55.6 %) and the incidence of patients of Ramsay Sedation Scale > 3 (RR: 3.8, 95 % CI, [1.45, 9.97] P = 0.000, I 2 = 26.9 %), hypotension (RR: 1.74, 95 % CI, [1.15, 2.65] P= 0.009, I2 = 32.7 %) and bradycardia (RR: 3.71, 95 % CI, [1.27, 10.86] P = 0.017, I2 = 0 %) were lower in perineural dexmedetomidine compared to the intravenous group. Conclusions. Our meta-analysis generates the evidence that perineural dexmedetomidine is a superior adminstration for prolonging the duration of analgesia. Perineural dexmedetomidine also shows the advantages in duration of sensory block and the onset time of sensory and motor block, when compared to the intravenous administration. Simultaneously, dexmedetomidine as a local anesthetic adjuvant for perineural injection may be much safer than intravenous application because of the lower incidence of patients of Ramsay Sedation Scale > 3 and lower incidence of hypotension and bradycardia.

Comparison Between the Effects of Bupivacaine and Levobupivacaine for Spinal Anesthesia on QT Dispersion

BACKGROUND

Bupivacaine and Levobupivacaine are frequently used local anesthetic drugs in spinal anesthesia practice. Both agents have arrhythmic effects on the heart. However, there is no clear information about which agent is more arrhythmogenic.

OBJECTIVE

The aim of this article is to investigate the effects of bupivacaine and its S (-)-enantiomer, levobupivacaine, on cardiac arrhythmias in patients.

METHODS

The study included 40 patients scheduled for inguinal hernia surgery. Patients were randomly divided into the following two groups using a sealed envelope method: Group I, the bupivacaine group (n = 20); and Group II, the levobupivacaine group (n = 20). The QT values were taken preoperatively and during the 10th of the spinal block, the 10th of the surgical incision, and the 10th postoperative minute. Additionally, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), oxygen saturation (SO₂), and heart rate (HR) values, in addition to motor block (Bromage scale) levels and durations, were recorded for each patient.

RESULTS

HR values measured at 10 min after spinal block were significantly higher than the baseline values in the levobupivacaine group (p < 0.05). The corrected QT interval (QTc) values increased significantly at 10 minutes after spinal block and at 10 min postoperatively in the bupivacaine group (p < 0.05). QTd and QTcd measurements were taken at the 10th minute of spinal anesthesia, the 10th minute of the incision, and the 10th minute postoperatively. When compared to the levobupivacaine group, a statistically significant increase was found in the bupivacaine group (p < 0.05).

CONCLUSION

Levobupivacaine allows greater hemodynamic stability, while bupivacaine affects QTc and QTd measurement times more. As such, we believe that levobupivacaine may be a better alternative to bupivacaine during clinical practice, particularly in patients with cardiac problems.

Clonidine as an Adjuvant to Bupivacaine for Suprazygomatic Maxillary Nerve Blocks in Cleft lip and Palate Repair: A Randomized, Prospective, Double-Blind Study

OBJECTIVES

Does clonidine, as adjuvant to bupivacaine for suprazygomatic maxillary nerve blocks, reduce emergence agitation in patients undergoing cleft lip and cleft palate surgery?

DESIGN

Randomized, controlled, and double-blind study.

SETTING

Guwahati Comprehensive Cleft Care Center, Guwahati (Assam, India).

PARTICIPANTS

A total of 124 patients; with a median age of 5 years in the clonidine group (CLG) and 7 years in the control group (CG), who underwent cleft lip or cleft palate surgery were included. Exclusion criteria included lack of consent from patients or their guardians, allergy to local anesthetics, coagulation disorders, local infection at the puncture site before performing the block, and language difficulties or cognitive disorders.

INTERVENTIONS

Patients were randomized into 2 groups to receive bilateral suprazygomatic maxillary nerve blocks with either a bupivacaine/clonidine mixture for the CLG or bupivacaine alone in the CG.

MAIN OUTCOME MEASURE

The primary end point was the incidence of emergence agitation.

RESULTS

There was a statistically significant difference in the incidence of emergence agitation (30.2% in the CG compared to 15.2% in the CLG; difference of incidences: 15%, 95% CI: 0.1-30.1). The percentage of patients requiring intraoperative Fentanyl was lower in the CLG (10.6% compared to 26.4%; difference of incidences: 15.8%, 95% CI: 1.8-29). No other differences were observed. Further research in a more typically aged children population undergoing cleft surgery is needed.

CONCLUSIONS

The use of clonidine as an adjuvant to bupivacaine in maxillary nerve block reduces the incidence of emergence agitation and intraoperative opioid consumption without hemodynamic or sedative side effects in patients undergoing cleft lip and palate surgery.

Analgesic sparing effect of dexamethasone with levobupivacaine in quadratus lumborum block in patients undergoing unilateral inguinal hernia repair: A prospective randomised controlled trial

Background

Quadratus lumborum block (QLB) provides somatic and visceral analgesia to the lower thoracic and abdominal wall. The aim was to investigate the analgesic effect of dexamethasone with levobupivacaine in QLB in patients undergoing unilateral inguinal hernia repair surgery.

Methods

A total of 90 patients of American Society of Anaesthesiologists (ASA) I/II were randomly divided into two groups. Group L received 0.25% levobupivacaine (20 ml) + normal saline (1 ml) and group D received 0.25% levobupivacaine (20 ml) + 4 mg dexamethasone (1 ml) in QL plane on the operated side using ultrasound, after completion of surgery under spinal anaesthesia. The primary objective was to compare time for first rescue analgesia. The secondary objectives were total rescue analgesic consumption and numeric rating scale (NRS) in the first 24 h.

Results

The demographic data age, sex, height, weight and ASA were comparable in both groups. The mean time to request for first rescue analgesia was longer in group D compared to group L (1016.02 ± 205.97 min versus 640 ± 132.96 min; P < 0.0001). The mean total tramadol consumption in the first 24 h was lower in group D compared to group L (233.55 ± 86.92 mg versus 328.22 ± 78.74 mg; P < 0.0001). Patients in group D had significantly lower NRS scores at rest and on movement as compared to group L.

Conclusions

The addition of dexamethasone to levobupivacaine in QLB results in prolonged duration of postoperative analgesia, less rescue analgesic requirements and better quality of analgesia as compared to levobupivacaine in unilateral inguinal hernia repair surgery.

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.

The impact of peripheral nerve blocks on perioperative outcome in hip and knee arthroplasty-a population-based study

The role of anesthesia techniques on perioperative outcomes on a population level has recently gained widespread interest. Although mainly neuraxial vs general anesthesia has been addressed, population-level data on the impact of peripheral nerve blocks (PNBs) are still lacking. Therefore, we investigated the association between PNB use and outcomes using retrospective data on 1,062,152 recipients of hip and knee arthroplasties (total hip arthroplasty [THA]/total knee arthroplasty [TKA]) from the national Premier Perspective database (2006-2013). Multilevel multivariable logistic regression models measured associations between PNB use and outcomes. Complications included cardiac, pulmonary, gastrointestinal and renal complications, cerebrovascular events, infections, wound complications, thromboembolic complications, inpatient falls, and mortality. Resource utilization variables included blood transfusions, intensive care unit admissions, opioid consumption, cost, and length of stay. Overall, 12.5% of patients received a PNB, with an increase over time particularly among TKAs. Peripheral nerve block use was associated with lower odds for most adverse outcomes mainly among patients with THA. Notable beneficial effects were seen for wound complications (odds ratio 0.60 [95% confidence interval, 0.49-0.74]) among THA recipients and pulmonary complications (odds ratio 0.83 [95% confidence interval, 0.72-0.94]) in patients with TKA. Peripheral nerve block use was significantly (P < 0.0001) associated with a -16.2% and -12.7% reduction in opioid consumption for patients with THA and TKA, respectively. In conclusion, our results indicate that PNBs might be associated with superior perioperative population-level outcomes. In light of the inability to establish a causal relationship and the presence of residual confounding, we strongly advocate for further prospective investigation, ideally in multicenter, randomized trials, to establish the potential impact of PNBs on outcomes on a population level.

Ropivacaine versus levobupivacaine in peripheral nerve block: A PRISMA-compliant meta-analysis of randomized controlled trials

BACKGROUND

To determine which is more potent in peripheral nerve block between ropivacaine and levobupivacaine.

METHODS

A literature search was performed in the EMBASE, Medline, the Cochrane Library, and the Web of Science. The trials that were found were then evaluated for eligibility. The Cochrane Collaboration's Review Manager software was used to perform the meta-analyses.

RESULTS

Twelve studies including 556 patients were included for final analysis. No statistically significant difference was observed between the 2 drugs with respect to onset time of surgical anesthesia, onset time of sensory block, onset time of motor block, duration of motor block, and patients overall satisfaction. Levobupivacaine provided more long-term anesthesia (weighted mean difference [WMD], -2.94; 95% confidence interval [CI], -5.56 to -0.32; I = 93%) and significantly lower incidence of postoperative rescue analgesia (odds ratio [OR], 2.11; 95% CI 1.18-3.74; I = 21%) than ropivacaine. There was a trend toward greater duration of sensory block in the levobupivacaine group (WMD, -1.16; 95% CI, -1.89 to -0.43; I = 14%).

CONCLUSION

Levobupivacaine is more potent than ropivacaine in peripheral nerve block to some extent. Otherwise, more rigorous randomized control trials are required in the future.

Resonance Rayleigh scattering technique as a detection method for the RP-HPLC determination of local anaesthetics in human urine

A highly selective and sensitive method of reversed phase high-performance liquid chromatography (RP-HPLC) coupled with resonance Rayleigh scattering (RRS) was developed for the determination of procaine, bupivacaine and tetracaine. Separation of three local anaesthetics was achieved at 35 °C on a C₁₈ column. The mobile phase was 30: 70 (v/v) acetonitrile/triethylamine-phosphoric acid buffer (pH 2.9) at flow rate of 0.3 mL/min. The RRS detection was conducted by taking advantage of the strong RRS enhancement of the local anaesthetics with erythrosine reaction in an acidic medium. Under optimum conditions, the limit of detection (S/N = 3) values were in the range of 2.4-11.2 ng/mL. Recoveries from spiked human urine samples were 95.8%-104.5%. The proposed method applied to the determination of local anaesthetics in human urine achieved satisfactory results. In addition, the mechanism of the reaction is fully discussed. Copyright © 2016 John Wiley & Sons, Ltd.

Incidence of cardiovascular complications in knee arthroplasty patients before and after implementation of a ropivacaine local infiltration analgesia protocol: A retrospective study

BACKGROUND

Local infiltration analgesia (LIA) during total knee arthroplasty has been shown to give statistically significant reduction in post-operative pain. The effects of using high volumes of ropivacaine combined with adrenaline as LIA on cardiovascular parameters in knee replacement have not been described before. The objective of this study was to investigate the cardiovascular safety of ropivacaine as part of high volume local infiltration analgesia (LIA) in total knee replacement surgery.

METHODS

This is a retrospective observational comparative cohort study conducted in two independent cohorts, one treated without and one treated with a local infiltration analgesia protocol, containing a total of 744 patients with a mean age of 68years (42 to 89) and 68years (21 to 88) respectively with a follow-up of 12months.

RESULTS

No statistical difference in bradycardia during surgery, post-operative cardiovascular complications, and mortality was found after use of LIA. A statistically significant lower incidence of hypotension was found in the LIA group (P<0.01). This result has to be interpreted with care, due to the use of adrenaline in the LIA mixture, which could mask possible hypotension. No statistical difference was found in the occurrence of hypertension or tachycardia, despite the addition of adrenaline to the LIA mixture. No difference in mortality was found between the two groups (P=0.11).

CONCLUSION

These results show safe use of high volume ropivacaine with adrenaline as local infiltration analgesia during total knee replacement surgery.

Tracking local anesthetic effects using a novel perceptual reference approach

Drug effects of loco-regional anesthetics are commonly measured by unidimensional pain rating scales. These scales require subjects to transform their perceptual correlates of stimulus intensities onto a visual, verbal, or numerical construct that uses a unitless cognitive reference frame. The conceptual understanding and execution of this magnitude estimation task may vary among individuals and populations. To circumvent inherent shortcomings of conventional experimental pain scales, this study used a novel perceptual reference approach to track subjective sensory perceptions during onset of an analgesic nerve block. In 34 male subjects, nociceptive electric stimuli of 1-ms duration were repetitively applied to left (target) and right (reference) mandibular canines every 5 s for 600 s, with a side latency of 1 ms. Stimulus strength to the target canine was programmed to evoke a tolerable pain intensity perception and remained constant at this level throughout the experiment. A dose of 0.6 ml of articaine 4% was submucosally injected at the left mental foramen. Subjects then reported drug effects by adjusting the stimulus strength (in milliamperes) to the reference tooth, so that the perceived intensity in the reference tooth was equi-intense to the target tooth. Pain and stimulus perception offsets were indicated by subjects. Thus, the current approach for matching the sensory experience in one anatomic location after regional anesthesia allows detailed tracking of evolving perceptual changes in another location. This novel perceptual reference approach facilitates direct and accurate quantification of analgesic effects with high temporal resolution. We propose using this method for future experimental investigations of analgesic/anesthetic drug efficacy.

Regional anesthesia for pediatric knee surgery: a review of the indications, procedures, outcomes, safety, and challenges

The indications for surgery on the knee in children and adolescents share some similarity to adult practice in that there are an increasing number of sports-related injuries requiring surgical repair. In addition, there are some unique age-related conditions or congenital abnormalities that may present as indications for orthopedic intervention at the level of the knee. The efficacy and safety of peripheral nerve blocks (PNBs) for postoperative analgesia following orthopedic surgery has been well established in adults. Recent studies have also demonstrated earlier functional recovery after surgery in patients who received PNBs. In children, PNB is gaining popularity, and increasing data are emerging to demonstrate the feasibility, efficacy, and safety in this population. In this paper, we will review some of the most common indications for surgery involving the knee in children and the anatomy of knee, associated dermatomal and osteotomal innervation, and the PNBs most commonly used to produce analgesia at the level of the knee. We will review the evidence in support of regional anesthesia in children in terms of both the quality conferred to the immediate postoperative care and the role of continuous PNBs in maintaining effective analgesia following discharge. Also we will discuss some of the subtle challenges in utilizing regional anesthesia in the pediatric patient including the use of general anesthesia when performing regional anesthesia and the issue of monitoring for compartment syndrome. Finally, we will offer some thoughts about areas of practice that are in need of further investigation.

Bedside ultrasound procedures: musculoskeletal and non-musculoskeletal

The widespread availability of ultrasound (US) technology has increased its use for point of care applications in many health care settings. Focused (point of care) US is defined as the act of bringing US evaluation to the bedside for real-time performance. These images are collected immediately by the practitioner, allowing for direct integration into the physician's medical decision-making process. The real-time bedside diagnostic ability of US becomes a key tool for the management of patients. The purpose of this review is to (1) provide a general description of the use of focused US for bedside procedures; (2) specify the indications and common techniques used in bedside US procedures; and (3) describe the techniques used for each bedside intervention.

Update on the clinical utility and practical use of ropivacaine in Chinese patients

We reviewed the Chinese and English literature for efficacy and tolerability data as well as pharmacological properties of ropivacaine in Chinese patients. Ropivacaine is a long-acting amide local anesthetic agent that elicits nerve block via reversible inhibition of sodium ion influx in nerve fibers. The available evidence in the literature on anesthesia practice indicates that ropivacaine produces equally surgical sensory block and postoperative and obstetrics analgesia with good maternal and fetal outcome to those of bupivacaine or levobupivacaine. It appears to be associated with comparable onset, quality, and duration of sensory block, but with a lower incidence or grade of motor block, compared to bupivacaine. The satisfaction of both patients and surgeons is high when ropivacaine is used. Thus, ropivacaine appears to be an important option for regional anesthesia and for the management of postoperative and labor pain, with its enhanced sensorimotor differentiation blockage at lower concentrations and enhanced safety at higher concentrations.

Medical management of acute pain in patients with chronic pain

The number of patients with chronic pain has increased over the years, as well as the number of patients who manage chronic pain with opioids. As prescribed opioid use has increased, so has its abuse and misuse. It has also been estimated that the number of people using opioids illicitly has doubled worldwide over the last 20 years. Management of chronic pain with opioids is associated with pathophysiological phenomena such as tolerance, dependence and hyperalgesia. They can become a problem when chronic pain patients present for a surgical procedure. Furthermore, patients who are on opioids on a regular basis require higher amounts during the perioperative period. The perioperative management of the chronic pain patient is difficult and complex. Developing an appropriate plan that can fulfill patients' and surgical team's needs requires skills and experience. The aim of this review is to describe the options available for the optimal perioperative management of acute pain in patients with a history of chronic pain.

Duration of upper and lower extremity peripheral nerve blockade is prolonged with dexamethasone when added to ropivacaine: a retrospective database analysis

BACKGROUND

Dexamethasone, when added to local anesthetics, has been shown to prolong the duration of peripheral nerve blocks; however, there are limited studies utilizing large numbers of patients. The purpose of this study was to examine the effect of adding dexamethasone to ropivacaine on duration of nerve blocks of the upper and lower extremity.

METHODS

We reviewed 1,040 patient records collected in an orthopedic outpatient surgery center that had received an upper or lower extremity peripheral nerve block with ropivacaine 0.5% with or without dexamethasone and/or epinephrine. The primary outcome was duration of analgesia in upper or lower extremity blocks containing dexamethasone as an adjunct. Secondary outcomes included postoperative patient pain scores, satisfaction, and the incidence of block related complications. Linear and ordinal logistic regression models were used to examine the independent effect of dexamethasone on outcomes.

RESULTS

Dexamethasone was observed to increase median block duration by 37% (95% confidence interval: 31-43%). The increased block duration persisted within body regions (upper and lower) and across a range of block types. Dexamethasone was also observed to reduce pain scores on the day of surgery (P = 0.001) and postoperative day 1 (P < 0.001). There was no significant difference in duration of nerve blocks when epinephrine (1:400,000) was added to 0.5% ropivacaine with or without dexamethasone.

CONCLUSION

The addition of dexamethasone to 0.5% ropivacaine prolongs the duration of peripheral nerve blocks of both the upper and lower extremity.

Intravenous lipid administration for drug-induced toxicity: a critical review of the existing data

Following the discovery that administration of intravenous lipid emulsion (ILE) may reverse the cardiac and neurological toxicity of certain local anesthetic agents, ILE's potential role has recently been explored in the setting of toxicity attributed to a variety of different drugs. The potential mechanisms, safety and efficacy of this approach are considered in this review. Data are reviewed from 76 published reports involving ILE administration for severe drug toxicity, including 55 where toxicity was due to nonanesthetic agents. ILE was reported to exert a positive therapeutic effect in only a proportion of the reported cases, with greatest evidence of efficacy concerning local anesthetic agents. Administration has typically involved bolus administration followed by continuous maintenance infusion, and a number of different mechanisms are proposed, from preferential partitioning of the drug from cardiac tissue to the circulating lipid fraction and direct inotropic effects related to carnitine pathways and fatty acid oxidative metabolism. No major adverse effects have been encountered, but too few data exist to adequately address the safety profile of ILE.

Articaine: a review of its use for local and regional anesthesia

Articaine is an intermediate-potency, short-acting amide local anesthetic with a fast metabolism due to an ester group in its structure. It is effective with local infiltration or peripheral nerve block in dentistry, when administered as a spinal, epidural, ocular, or regional nerve block, or when injected intravenously for regional anesthesia. In comparative trials, its clinical effects were not generally significantly different from those of other short-acting local anesthetics like lidocaine, prilocaine, and chloroprocaine, and there is no conclusive evidence demonstrating above-average neurotoxicity. Articaine proved to be suitable and safe for procedures requiring a short duration of action in which a fast onset of anesthesia is desired, eg, dental procedures and ambulatory spinal anesthesia, in normal and in special populations.

Postoperative analgesia for the surgical correction of congenital clubfoot: comparison between peripheral nerve block and caudal epidural block

BACKGROUND AND OBJECTIVES

Correction of congenital clubfoot (CCF) is associated with severe postoperative pain. Caudal epidural block associated with general anesthesia is the anesthetic technique used more often in children, but it is limited by the short duration of the postoperative analgesia. Peripheral nerve blocks are associated with a low incidence of complications and prolonged analgesia. The objective of this study was to compare the duration of analgesia in peripheral nerve blocks and caudal block, as well as morphine consumption in the first 24 hours after correction of CCF in children.

METHODS

This is a randomized, double-blind study with children undergoing surgeries for posteromedial release of CCF, who were divided in four groups according to the anesthetic technique: caudal (ACa), sciatic and femoral block (IF), sciatic and saphenous block (IS), and sciatic block and local anesthesia (IL), associated with general anesthesia. In the first 24 hours, patients received oral dypirone and acetaminophen, and they were evaluated by anesthesiologists who were unaware of the technique used. Oral morphine (0.19 mg x kg(1) per day) was administered according to the scores of the CHIPPS (Children's and infants' postoperative pain scale) scale.

RESULTS

One hundred and eighteen children separated into four groups: ACa (30), IF (32), IS (28), and IL (28) participated in this study. The mean time between the blockade and the first dose of morphine was 6.16 hours in group ACa, 7.05 hours in group IF, 7.58 in IS, and 8.18 hours in IL. Morphine consumption was 0.3 mg.kg-1 per day in all four groups. Significant differences were not observed among the groups.

CONCLUSIONS

peripheral nerve blocks did not promote longer lasting analgesia or a decrease in morphine consumption in the first 24 hours in children undergoing CCF correction when compared to caudal epidural block.

Ultrasound guidance for pediatric peripheral nerve blockade

There is an increasing trend in the use of peripheral nerve blockade for postoperative analgesia in children, and the use of ultrasound guidance to perform peripheral nerve blocks is gaining popularity. A thorough knowledge of anatomy will help in performing the appropriate block, and will also aid in better use and understanding of ultrasound guidance. In this article, we briefly review the use of ultrasound guidance to perform common upper and lower extremity and truncal blocks.

Host-guest complexations of local anaesthetics by cucurbit[7]uril in aqueous solution

The cucurbit[7]uril (CB[7]) host molecule forms very stable host-guest complexes with the local anaesthetics procaine (K(CB[7]) = (3.5 +/- 0.7) x 10(4) dm(3) mol(-1)), tetracaine (K(CB[7]) = (1.5 +/- 0.4) x 10(4) dm(3) mol(-1)), procainamide (K(CB[7]) = (7.8 +/- 1.6) x 10(4) dm(3) mol(-1)), dibucaine (K(CB[7]) = (1.8 +/- 0.4) x 10(5) dm(3) mol(-1)) and prilocaine (K(CB[7]) = (2.6 +/- 0.6) x 10(4) dm(3) mol(-1)) in aqueous solution (pD = 4.75). The stability constants are 2-3 orders of magnitude greater than the values reported for binding by the comparably sized beta-cyclodextrin host molecule. The inclusion by CB[7] raises the first pK(a) values of the anaesthetics by 0.5-1.9 pK units, as the protonated forms are bound more strongly in acidic solution. The complexation-induced chemical shift changes in the guest proton resonances provide an indication of the site(s) of binding and the effects of protonation on the location of the binding sites.

Clonidine and analgesic duration after popliteal fossa nerve blockade: randomized, double-blind, placebo-controlled study

BACKGROUND

We tested the hypothesis that 100 microg clonidine added to 0.375% bupivacaine would prolong the duration of analgesia from popliteal fossa nerve blockade.

METHODS

Ninety-nine patients scheduled for hospital admission after foot or ankle surgery entered this randomized, double-blind, placebo-controlled trial. Patients received a popliteal fossa block (nerve stimulator technique, via the posterior approach) using 30 mL 0.375% bupivacaine, with epinephrine. Patients were randomized to receive no clonidine, 100 microg clonidine IM, or 100 microg clonidine with bupivacaine for the popliteal block. Patients also received a combined spinal-epidural anesthetic, a saphenous nerve block, and postoperative IV patient-controlled analgesia. The primary outcome was patient-reported duration of analgesia.

RESULTS

Duration of analgesia was statistically longer in the block clonidine group (18 +/- 6 h for clonidine with bupivacaine vs 14 +/- 7 h for IM clonidine and 15 +/- 7 h for control, P = 0.016 for control vs clonidine with bupivacaine). Pain scores, analgesic use, and side effects attributable to pain management were similar among groups.

CONCLUSIONS

Clonidine significantly prolongs the analgesic duration after popliteal fossa nerve blockade with bupivacaine.

The effects of general anesthesia on the central nervous and cardiovascular system toxicity of local anesthetics

BACKGROUND

Local anesthetic toxicity is often studied experimentally in acutely prepared, anesthetized laboratory animals. We determined the influence of halothane/O(2) anesthesia on cardiovascular and central nervous system (CNS) toxic responses to six amide-type local anesthetics administered i.v..

METHODS

Behavioral, cardiovascular, and pharmacokinetic responses were determined in previously instrumented ewes (approximately 45-50 kg, n = 18), on separate occasions when conscious and anesthetized, to bupivacaine (100 mg), levobupivacaine (125 mg), ropivacaine (150 mg), lidocaine (350 mg), mepivacaine (350 mg), prilocaine (350 mg), and saline (control) infused i.v. over 3 min.

RESULTS

The local anesthetics caused convulsions in conscious sheep, but no overt CNS effects in anesthetized sheep. Negative inotropy and slight bradycardia without changes in arterial blood pressure occurred initially in conscious sheep, followed by positive inotropy, tachycardia, and hypertension at the abrupt onset of CNS excitotoxicity, along with widening of QRS complexes. Fatal cardiac arrhythmias occurred in, respectively, 3 of 11, 2 of 12, and 2 of 13 conscious sheep infused with bupivacaine, levobupivacaine, and ropivacaine; in 1 of 9 with prilocaine, electromechanical dissociation (followed by polymorphic ventricular tachycardia) caused death. In anesthetized sheep, cardiovascular depression, preexisting from the general anesthesia, was exacerbated by all local anesthetics, and increased QRS width was prolonged; concurrent blood local anesthetic concentrations were doubled. Nevertheless, all anesthetized animals survived.

CONCLUSIONS

General anesthesia produced physiological perturbations, exacerbated local anesthetic-induced cardiovascular depression, and changed the pharmacokinetics of toxic doses of local anesthetics. However, cardiovascular fatalities from local anesthetics occurred only in conscious animals.

Useful adjuvants for postoperative pain management

Adjuvants are compounds which by themselves have undesirable side-effects or low potency but in combination with opioids allow a reduction of narcotic dosing for postoperative pain control. Adjuvants are needed for postoperative pain management due to side-effects of opioid analgesics, which hinder recovery, especially in the increasingly utilized ambulatory surgical procedures. NMDA antagonists have psychomimetic side-effects at high doses, but at moderate doses do not cause stereotypic behavior but allow reduction in opioid dose to obtain better pain control. Alpha-2 adrenergic agonists cause sedation, hypotension and bradycardia at moderate doses, but at low doses can be opioid sparing especially in spinal administration. Gabapentin-like compounds have low potency against acute pain, but in combination with opioids allow a reduction in opioid dose with improved analgesia. Corticosteroids may have only a limited role as adjuvants while acetylcholine esterase inhibitors may have too many side-effects. Newer adjuvants will be needed to reduce opioid dose and concomitant side-effects, even more as same day surgeries become more routine.

The Effects of Clonidine on Postoperative Analgesia After Peripheral Nerve Blockade in Children

BACKGROUND

The effect of clonidine on the duration of sensory blockade after peripheral nerve blockade is controversial. We evaluated the effects of clonidine on the duration of sensory and motor block and analgesia time in children who underwent a variety of peripheral nerve blocks.

METHODS

We reviewed the regional anesthesia database that contains data on children who underwent an infraclavicular, lumbar plexus, femoral, fascia iliaca or sciatic nerve block for postoperative analgesia at The Children's Hospital of Philadelphia between October 2002 and December 2005. Patients were prospectively followed after the nerve block.

RESULTS

Two hundred fifteen patients (47%) received either bupivacaine or ropivacaine local anesthetic (LA) and 220 (53%) a combination of local anesthetic and clonidine (LAC). The duration of sensory block was significantly longer in the LAC (17.2 +/- 5 h) compared with that in the LA group (13.2 +/- 5 h) (P = 0.0001). The increase in duration was independent from the type of peripheral nerve block, local anesthetic used and operation performed. The motor block duration was significantly longer in the LAC group (9.6 +/- 5 vs 4.3 +/- 4 h, P = 0.014). Two patients in the LAC and one in the LA group experience prolonged numbness (max 72 h). No paresthesia or dysesthesia was observed.

CONCLUSION

The addition of clonidine to bupivacaine and ropivacaine can extend sensory block by a few hours, and increase the incidence of motor blocks.

Some current controversies in paediatric regional anaesthesia

PURPOSE OF REVIEW

Controversial topics in paediatric regional anaesthesia are discussed.

RECENT FINDINGS

The performance of blocks under general anaesthesia, new local anaesthetics, adjuvants, location techniques, and risks of masking compartment syndromes are contemplated.

SUMMARY

The performance of regional blocks in anaesthetized patients is generally contra-indicated in adults but accepted in children. Levobupivacaine displays the same pharmacokinetic profile as racemic bupivacaine with possibly less cardiac toxicity. Ropivacaine undergoes slower absorption and, in some studies, concomitant increase in peak plasma concentration in infants. Conversely, continuous infusion of ropivacaine offers the safest therapeutic index. Many adjuvants have been used but only epinephrine, clonidine, and preservative-free ketamine offer clear advantages. Midazolam and neostigmine are effective but have potential drawbacks and raise safety questions. Needle and catheter positioning is critical. Electrocardiogram guidance and electrical stimulation occasionally help identify the migration of epidural catheters. Stimulating catheters might be useful for continuous peripheral blockade. Ultrasonography will probably become the reference technique for peripheral catheter placement. Patients at risk of compartment syndrome must be monitored (measurement of compartmental pressures); adequate pain management does not 'hide' this complication but, on the contrary, can facilitate early diagnosis since the increase in requirement for pain medication precedes other clinical symptoms by an average of 7.3 h.

Effects of regional anesthesia with ropivacaine on arterial pressure and heart rate in healthy subjects

The anesthetic, ropivacaine, has been used extensively in clinical practice, but few studies have evaluated this long-acting local anesthetic in dentistry. In this study we evaluated the effects of ropivacaine alone and ropivacaine + vasoconstrictor on the cardiovascular system when used as a dental anesthetic in volunteers. Thirty-two healthy subjects received two consecutive infiltrations of 1.8 ml of either 0.75% ropivacaine or ropivacaine + epinephrine into the pterygomandibular region. Pain sensation, numbness of the lip, arterial pressure, heart rate, and electrocardiogram changes were monitored for 2 h. The onset of anesthesia was 10 min after the injection and lasted for more than 2 h, and numbness of the lip lasted for approximately 8 h. Ropivacaine alone did not cause significant changes in the cardiovascular parameters, but ropivacaine + epinephrine caused a transient increase in arterial pressure and heart rate 2 min postinjection. We conclude that ropivacaine alone injected into the pterygomandibular region does not affect the cardiovascular system and that the addition of epinephrine has no beneficial effect. This finding may be relevant to dentists endeavoring to find an anesthetic of minimal cardiovascular risk to produce regional anesthesia for long-lasting procedures without the need of a vasoconstrictor.