Regional Nerve Blocks-Best Practice Strategies for Reduction in Complications and Comprehensive Review

Environmental responsibility in resource utilization during the practice of regional anesthesia: a Canadian Anesthesiologists' Society Delphi consensus study

PURPOSE

Regional anesthesia (RA) is often perceived to be more environmentally sustainable than alternative forms of anesthesia. Nevertheless, the principles of sustainable RA remain ill-defined in the presence of variability of resource utilization within RA practice. Many infection prevention practices are based on low-level evidence, and recommendations vary internationally. We sought to conduct an evidence review and Delphi consensus study to provide guidance on aspects that lack high-quality evidence in RA practice to reconcile responsible resource stewardship and infection prevention in RA.

METHODS

We conducted a three-round modified Delphi process. After distributing an initial free-text questionnaire to all collaborators, we created structured questions, followed by two rounds of anonymized voting. We defined strong consensus as ≥ 75% agreement and weak consensus as ≥ 50% but < 75% agreement.

RESULTS

Forty-six experts agreed to take part in the study and 36 (78%) completed all the voting rounds. Regional anesthesia practice parameters with strong consensus included hand hygiene using alcohol scrub rather than soap and water, sterile gowns being unnecessary for single-injection RA techniques, only minimal equipment in the premade packs, and goal-directed use of sedation and supplemental oxygen.

DISCUSSION

We obtained consensus on the safe and environmentally responsible practice of RA for both single-injection and indwelling catheter techniques and identified areas of research focus. While more robust evidence is being generated, clinicians may use these findings as a guide to infection prevention and environmental sustainability in their anesthesia practice.

Analgesic Effects and Pharmacokinetics of Ropivacaine at Different Concentrations in Serratus Anterior Plane Block in Patients Undergoing Video-Assisted Thoracoscopic Surgery: A Prospective Randomized Trial

PURPOSE

Investigate the analgesia effects and pharmacokinetics of ropivacaine at different concentrations in Serratus Anterior Plane Block (SAPB) and assess the efficacy and safety.

METHODS

Thirty-six patients undergoing video-assisted thoracoscopic surgery (VATS) pulmonary resections were enrolled. Ultrasound-guided SAPB was induced with 3 mg/kg ropivacaine at different concentrations (0.25%, 0.5%, and 0.75%, referred to as Group L, Group M, and Group H, respectively). The concentration of ropivacaine in the plasma at 1, 15, 30, 45, 60 min, 2, 4, 8, 12, and 24 h after SAPB was determined by LC-MS/MS. Other evaluated measures included the Numerical Rating Scale (NRS) scores at rest and on movement, the frequency of dermatomes blocked, onset time and effective plane, Quality of Requirements(QoR)-15 scale, chronic postsurgical pain, and the level of IL-6 and IL-8.

FINDINGS

The NRS scores were significantly higher in Group L than those in other groups (P < 0.05), indicating that the analgesic effect of Group L was the worst among the three groups. Group H had a lower effective plane of anesthesia and significantly higher incidence of chronic postsurgical pain. The IL-8 level was significantly lower in Group H than in other groups at 1 min, 1 h, and 24 h after SAPB. The ropivacaine concentrations were the highest in Group H, followed by Group M and Group L. The high blood concentration of ropivacaine in Group H may increase the risk of systemic toxicity from local anesthetics. Compared to Group L and Group H, Group M had superior analgesic effects and better safety. Among the three groups, Cmax, t1/2, and AUC0-∞ differed significantly.

IMPLICATIONS

For patients undergoing VATS, using 0.5% ropivacaine for SAPB is recommended.

Letter to the editor: The use of XperGuide® needle guidance software for CT guided thoracic sympathetic block

With the introduction of modern cone beam computed tomography in the operating room, the benefits of imaging modalities in daily practice are recognized by an increasing number of clinicians. Newer generation imaging modalities include CT needle guidance software, which can aid the operator place the needle correctly during percutaneous intervention. This technique has several advantages over traditional percutaneous interventions, especially for high risk procedures like thoracic sympathectomy. We describe and discuss outcomes and possible advantages of applying CT guided needle placement using needle guidance software (XperGuide®) for percutaneous thoracic sympathetic blockade in 8 patients. Based on our findings, we conclude that the use of high quality imaging and needle guidance software such as XperGuide® may improve patient outcomes, and reduce the risk of adverse effects, providing a relatively easy, safe, and valuable alternative treatment strategy for thoracic sympathectomies.

Incidence of nerve injury following acupuncture treatments in Taiwan

OBJECTIVE

Acupuncture, a widely employed traditional therapeutic modality known for its efficacy in pain alleviation and diverse condition management, may inadvertently result in mechanical nerve injury due to its invasive nature. This research aimed to ascertain the incidence of nerve injuries post-acupuncture, identify associated risk factors, and map the distribution of nerve injury sites.

METHODS

A case-control study nested in the National Health Insurance Research Database (NHIRD) 2000-2018 two million cohort was conducted. Patients previously diagnosed with nerve injury, surgery, or degeneration before acupuncture were excluded. Cases were defined as patients receiving acupuncture and seeking medical attention for nerve injury (ICD9-CM code 950-957) within 14 days post-procedure, while control groups comprised patients undergoing acupuncture without subsequent adverse events. Invasive treatments prior to adverse events and adverse events occurring more than 14 days post-acupuncture were excluded. To ensure case-control comparability, factors such as age, gender, socioeconomic status, and medical facility environment were controlled using propensity score matching.

RESULTS

The study encompassed 14,507,847 acupuncture treatments administered to 886,753 patients, with 8361 instances of post-acupuncture nerve injury identified, representing an incidence rate of approximately 5.76 per 10,000 procedures. Age emerged as a significant risk factor, with the adjusted odds ratios escalating with age. Several comorbidities including diabetes, hypothyroidism, liver cirrhosis, chronic kidney disease, herpes zoster, hepatitis virus, rheumatoid arthritis, systemic lupus erythematosus, dementia, and cerebrovascular accidents were associated with an elevated risk of nerve injury post-acupuncture.

CONCLUSION

This study underscores the importance of meticulous patient profiling and cautious therapeutic approach in acupuncture, considering the evident influence of various demographic, systemic, and treatment-related factors on the incidence of nerve injuries.

Double-Edge, Single-Edge, and Intermediate-Edge Ultrasound Sign and Correlation With Fascial Plane Block Efficacy: An Experimental Study

Introduction Ultrasound-guided fascial plane blocks are nowadays the gold standard technique for regional anesthesia and postoperative analgesia. Despite their high success rate, cases of partial or total failure of this method have been reported. This experimental study aims to address the corresponding ultrasound signs and their association with fascial plane block efficacy. Methods After capturing the appropriate sonographic image that included muscle layers and their fasciae, an 18-gauge epidural needle penetrated the cadaveric porcine tissue and was forwarded until the tip of the needle reached the target fascial plane. The infusion of methylthioninium chloride or methylene blue dye was performed, causing tissue hydro dissection. The documentation of the generated ultrasound images was followed by surgical exposure of the tip of the needle. Results The distribution of the dye into the plane of interest (double-edge sign) was equivalent to block success, whereas the single-edge sign (accumulation of the dye between fascia and epimysium) indicated total block failure. The intermediate-edge sign, a combination of the previous ultrasound signs, is related to partial failure of block performance. Conclusion The identification of the three novel sonographic signs is an accurate predictive factor of peripheral nerve block efficacy. The respective data are expected to aid the rapid improvement of interfascial plane block accuracy and techniques, leading to their more effective execution and simultaneously eliminating the failure rates. Thereby, the amelioration of intra and postoperative analgesia will be accomplished, expediting the patient's hospital discharge and reducing or even avoiding opioid consumption.

Micro-pharmacokinetics of lidocaine and bupivacaine transfer across a myelinated nerve fiber

BACKGROUND

The aim of the present study was to predict the time to onset and duration of action of two local anesthetics (lidocaine and bupivacaine) based on experimental dimensions of a typical nerve and experimental octanol/water partition coefficients.

METHODS

We began our compilation of experimental data with a numerical solution of the Smoluchowski equation for the transfer of lidocaine and bupivacaine across the axon membrane in the region of the node of Ranvier (axolemma) and across the Schwann cell. The difference between the aqueous and lipid environments of the neuron was simulated by including the coordinate-dependent chemical potential. In the second step, the permeation rates calculated using the diffusion equation were used to solve a system of four ordinary differential equations. This approach allowed us to simulate the cellular environment for a longer time and to compare our model with pharmacokinetic properties (time to onset and duration of action) of local anesthetics from the literature. The behavior of local anesthetics under physiological conditions and in case of local acidosis was also simulated.

RESULTS

We demonstrated that local anesthetics cross the axolemma in a time span of less than 1 μs. The time to onset of action, controlled by diffusion from the epineurium to an axon with a typical distance of 500 μm, was 167 s and 186 s for lidocaine and bupivacaine, respectively. The calculated half-life, which is a measure of the duration of action, was 41 min and 328 min for lidocaine and bupivacaine, respectively.

CONCLUSIONS

Duration of action is controlled by the storage capacity of lipophilic compartments around the axon, which is higher for bupivacaine but lower in local acidosis. For the latter case, the literature, including textbooks, provides a misinterpretation, namely that protonated species cannot penetrate the membrane.

Antioxidant activity of lidocaine, bupivacaine, and ropivacaine in aqueous and lipophilic environments: an experimental and computational study

Introduction: Local anesthetics are widely recognized pharmaceutical compounds with various clinical effects. Recent research indicates that they positively impact the antioxidant system and they may function as free radical scavengers. We hypothesize that their scavenging activity is influenced by the lipophilicity of the environment. Methods: We assessed the free radical scavenging capacity of three local anesthetics (lidocaine, bupivacaine, and ropivacaine) using ABTS, DPPH, and FRAP antioxidant assays. We also employed quantum chemistry methods to find the most probable reaction mechanism. The experiments were conducted in an aqueous environment simulating extracellular fluid or cytosol, and in a lipophilic environment (n-octanol) simulating cellular membranes or myelin sheets. Results: All local anesthetics demonstrated ABTS˙⁺ radical scavenging activity, with lidocaine being the most effective. Compared to Vitamin C, lidocaine exhibited a 200-fold higher half-maximal inhibitory concentration. The most thermodynamically favorable and only possible reaction mechanism involved hydrogen atom transfer between the free radical and the -C-H vicinal to the carbonyl group. We found that the antioxidant activity of all tested local anesthetics was negligible in lipophilic environments, which was further confirmed by quantum chemical calculations. Conclusion: Local anesthetics exhibit modest free radical scavenging activity in aqueous environments, with lidocaine demonstrating the highest activity. However, their antioxidant activity in lipophilic environments, such as cellular membranes, myelin sheets, and adipose tissue, appears to be negligible. Our results thus show that free radical scavenging activity is influenced by the lipophilicity of the environment.

Effect of Ultrasound-Guided Fascia Iliac Compartment Block with Nalbuphine and Ropivacaine on Preoperative Pain in Older Patients with Hip Fractures: A Multicenter, Triple-Blinded, Randomized, Controlled Trial

INTRODUCTION

Pain management for older patients with hip fractures is challenging. This study aimed to investigate the effect of ultrasound-guided fascia iliac compartment block (UGFICB) using different doses of nalbuphine in combination with ropivacaine on preoperative analgesia in older patients with hip fractures.

METHODS

In this multicenter randomized controlled trial, 280 elderly patients with hip fracture were randomly allocated into four UGFICB groups (n = 70 in each group): a ropivacaine group (30 mL 0.1% ropivacaine + 0.9% normal saline) and three ropivacaine plus nalbuphine groups (5, 10, and 20 mg nalbuphine, respectively). The primary outcomes were the duration of analgesia at rest and on passive movement. Secondary outcomes included sensory block area, side effects, and vital signs. The doses of rescue analgesia with parecoxib sodium were also analyzed.

RESULTS

The addition of nalbuphine dose-dependently increased the duration of analgesia at rest and on passive movement (P < 0.05) and expanded the area of sensory block (P < 0.05). Compared with the ropivacaine group, the pain scores at rest and on movement at 6 and 8 h after the block were lower in three ropivacaine plus nalbuphine groups (P < 0.05), without between-group differences at 2, 4, and 12 h. The four groups had comparable side effects (nausea and vomiting) and vital signs (P > 0.05).

CONCLUSIONS

UGFICB with 5, 10, and 20 mg nalbuphine added to ropivacaine prolonged the analgesia duration, increased sensory block area, reduced pain, and decreased the doses of rescue parecoxib sodium for older patients after hip fracture, without obvious side effects. Among these three doses, nalbuphine 20 mg in combination with ropivacaine provided the longest duration of analgesia and the largest sensory block area.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2000029934).

The Influence of Diabetic Peripheral Neuropathy on the Duration of Sciatic Nerve Block with 1.3% Liposomal Bupivacaine and 0.25% Bupivacaine Hydrochloride in a Mouse Model

Little is known regarding the pharmacological properties of extended-release local anesthetics in the setting of diabetic peripheral neuropathy. We investigated and compared the duration of sciatic nerve block following administration of clinically relevant concentrations of liposomal bupivacaine (LB) and bupivacaine hydrochloride (BH) in diabetic mice with peripheral neuropathy. In this prospective, randomized, and double-blind study, twenty-four female C57BL/6J-OlaHsd mice were assigned to a streptozotocin-induced type 1 diabetes group and a control group without diabetes. The presence of peripheral neuropathy was established by assessing the duration of thermal latency of the plantar and tail-flick tests, following which both groups were subdivided into two subgroups in which 35 mg/kg of 1.31% LB and 7 mg/kg of 0.25% BH were respectively administered for sciatic nerve block. The average sensory block duration with BH was 106 min and 117.1 min in the control and diabetic groups, respectively. With LB, the average sensory block duration was 118 min in the control mice, while in mice with diabetic peripheral neuropathy, the average block duration was significantly longer and above the 270 min limit set in our study. Accordingly, sensory block duration was longer with LB compared to BH, and diabetic peripheral neuropathy significantly increased sciatic nerve block duration with LB.

Determination of bupivacaine tissue concentration in human biopsy samples using high-performance liquid chromatography with mass spectrometry

In the present study, we developed a simple and rapid analytical method for the quantification of bupivacaine hydrochloride in human biopsy samples of adipose, muscle, neural, connective and cartilage tissue using liquid chromatography-mass spectrometry. Anesthetics were extracted from the tissue samples using 0.1% formic acid in acetonitrile for protein denaturation and hexane for removal of lipophilic impurities. Analytes were separated adequately on Phenomenex Luna Omega polar C18 column using a gradient mobile phase 0.1% formic acid in water and 0.1% formic acid in acetonitrile. The lower limits of quantification were ≤ 97 ng g^-1 tissue for all studied tissues. Intra-day recoveries were between 48.2% and 82.1% with relative standard deviations (RSDs) between 1.47% and 14.28%, whereas inter-day recoveries were between 52.2% and 77.6% with RSDs between 2.98% and 14.79%. The calibration curve showed a linear fit with R² higher than 0.99 in the concentration range from 0.16 to 100 μg g^-1 . Lidocaine hydrochloride was tested as internal standard because its recoveries and matrix effects were comparable to bupivacaine hydrochloride. Post-analytical corrections of measured bupivacaine tissue concentrations can accordingly be made based on recovery of lidocaine as internal standard, with recoveries between 51.2% and 86.9% and RSDs between 1.99% and 16.88%. The developed method could be used to study time-dependent spread of bupivacaine locally or to more distant locations across tissue barriers.

Cadaveric Model Simulations for Training in Ultrasound-Guided Percutaneous Placement of a Novel Peripheral Nerve Stimulation Electrode

Peripheral nerve stimulation (PNS) electrodes are used to treat intractable painful conditions involving peripheral nerves. Methods for performing PNS continue to evolve, from open surgical to minimally invasive placement of electrodes. A PNS system consisting of subcutaneously implanted leads with an integrated anchor and electrodes, and an external pulse generator to produce peripheral neuromodulation, is now available for use in the clinical setting. This novel system allows either surgical or percutaneous lead positioning, and avoids the use of long leads or extensions crossing the joints, which are exposed to mechanical stress and damage. To identify methods for successfully inserting these electrodes, we investigated if a cadaver model could be an effective educational tool for teaching PNS electrode placement using ultrasound guidance. Six cadavers were studied in an attempt to find an ideal approach for ultrasound-guided electrode placement into the upper and lower extremities and cervical spine, and to describe the unique anatomy of the peripheral nerves relative to percutaneous stimulation-electrode placement. The use of cadaveric model simulations offers opportunities to practice percutaneous placement of PNS electrodes under stress-free conditions without patient discomfort, to acquire skill and confidence in performing these surgical approaches. Ultrasound-guided percutaneous placement of PNS electrodes should be learned in a simulation laboratory before such placement is performed in actual patients.

AAV2/9-mediated silencing of PMP22 prevents the development of pathological features in a rat model of Charcot-Marie-Tooth disease 1 A

Charcot-Marie-Tooth disease 1 A (CMT1A) results from a duplication of the PMP22 gene in Schwann cells and a deficit of myelination in peripheral nerves. Patients with CMT1A have reduced nerve conduction velocity, muscle wasting, hand and foot deformations and foot drop walking. Here, we evaluate the safety and efficacy of recombinant adeno-associated viral vector serotype 9 (AAV2/9) expressing GFP and shRNAs targeting Pmp22 mRNA in animal models of Charcot-Marie-Tooth disease 1 A. Intra-nerve delivery of AAV2/9 in the sciatic nerve allowed widespread transgene expression in resident myelinating Schwann cells in mice, rats and non-human primates. A bilateral treatment restore expression levels of PMP22 comparable to wild-type conditions, resulting in increased myelination and prevention of motor and sensory impairments over a twelve-months period in a rat model of CMT1A. We observed limited off-target transduction and immune response using the intra-nerve delivery route. A combination of previously characterized human skin biomarkers is able to discriminate between treated and untreated animals, indicating their potential use as part of outcome measures.

Comparison of ultrasound-guided and nerve stimulator-guided interscalene blocks as a sole anesthesia in shoulder arthroscopic rotator cuff repair: A retrospective study

Ultrasound-guided interscalene block (US-ISB) and nerve stimulator-guided interscalene block (NS-ISB) have both been commonly used for anesthesia in shoulder arthroscopic surgery.This study aims to compare which method provides surgical block as a sole anesthesia. In this retrospective study, 1158 patients who underwent shoulder arthroscopic rotator cuff tear repair surgery under ISB between October 2002 and March 2018 were classified into either the US-ISB or NS-ISB anesthesia groups. Demographic and anesthetic characteristics and intraoperative medications were analyzed after propensity score matching and compared between the 2 groups.There was a 0.5% rate of conversion to general anesthesia in the US-ISB group and a 6.7% rate in the NS-ISB group (P < .001). The volume of local anesthetics used for ISB was 29.7 ± 8.9 mL in the US-ISB group versus 38.1 ± 4.8 mL in the NS-ISB group (P < .001). The intraoperative use of analgesics and sedatives such as fentanyl, midazolam and propofol in combination was significantly lowered in the US-ISB group (P < .001).US-ISB is a more effective and safer approach for providing intense block to NS-ISB because it can decrease the incidence of conversion to general anesthesia and reduce the use of analgesics and sedatives during arthroscopic shoulder surgery.

Landmark Technique vs Ultrasound-Guided Approach for Posterior Tibial Nerve Block in Cadaver Models

BACKGROUND

The use of ultrasound for peripheral nerve blocks has proven extremely useful for improving the accuracy and efficacy of many regional anesthetic techniques. There remain a few nerve blocks which have lagged behind in employing the assistance of ultrasound consistently, one of which is the ankle block. This block is commonly utilized for either surgical anesthesia or post-operative analgesia for a variety of foot and ankle procedures. The objective of this study was to compare the accuracy of traditional anatomical landmark-guided technique with an ultrasound-guided approach for ankle block by assessing the spread of injectate along the posterior tibial nerve (PTN) in cadaver models.

MATERIALS AND METHODS

Ten below-knee cadaver specimens were used for this study. Five were randomly chosen to undergo anatomical landmark-guided PTN blocks, and five were selected for ultrasound-guided PTN blocks. The anatomical landmark technique was performed by identifying the medial malleolus and Achilles tendon and inserting the needle (4 cm long, 21G Braun® Stimuplex) at the midpoint of the two structures, aiming toward the medial malleolus and advancing until bone was contacted. The ultrasound technique was performed with a linear probe identifying the medial malleolus and the PTN, with the needle subsequently advanced in-plane with a posterior to anterior trajectory until the tip was adjacent to the nerve. Each specimen was injected with 2 mL of acrylic dye. All the specimens were dissected following injection to determine which nerves had been successfully coated with dye.

RESULTS

The PTN was successfully coated with dye in all five (100%) ultrasound-guided blocks. In the anatomical landmark group, two (40%) PTN were successfully coated with dye. Of the three unsuccessful attempts, two specimens were noted to have dye injected posterior to the PTN; dye was injected into the flexor digitorum longus tendon in one.

CONCLUSION

The base of evidence has dramatically increased in recent years in support of the use of ultrasound in regional anesthesia. This study substantiates the superiority of ultrasound guidance for ankle block by demonstrating a 100% success rate of delivering a simulated nerve block to the correct anatomic location.