Research priorities in regional anaesthesia: an international Delphi study.

BACKGROUND: Regional anaesthesia use is growing worldwide, and there is an increasing emphasis on research in regional anaesthesia to improve patient outcomes. However, priorities for future study remain unclear. We therefore conducted an international research prioritisation exercise, setting the agenda for future investigators and funding bodies. METHODS: We invited members of specialist regional anaesthesia societies from six continents to propose research questions that they felt were unanswered. These were consolidated into representative indicative questions, and a literature review was undertaken to determine if any indicative questions were already answered by published work. Unanswered indicative questions entered a three-round modified Delphi process, whereby 29 experts in regional anaesthesia (representing all participating specialist societies) rated each indicative question for inclusion on a final high priority shortlist. If ≥75% of participants rated an indicative question as 'definitely' include in any round, it was accepted. Indicative questions rated as 'definitely' or 'probably' by <50% of participants in any round were excluded. Retained indicative questions were further ranked based on the rating score in the final Delphi round. The final research priorities were ratified by the Delphi expert group. RESULTS: There were 1318 responses from 516 people in the initial survey, from which 71 indicative questions were formed, of which 68 entered the modified Delphi process. Eleven 'highest priority' research questions were short listed, covering themes of pain management; training and assessment; clinical practice and efficacy; technology and equipment. CONCLUSIONS: We prioritised unanswered research questions in regional anaesthesia. These will inform a coordinated global research strategy for regional anaesthesia and direct investigators to address high-priority areas.

Recommendations for anatomical structures to identify on ultrasound for the performance of intermediate and advanced blocks in ultrasound-guided regional anesthesia.

Recent recommendations describe a set of core anatomical structures to identify on ultrasound for the performance of basic blocks in ultrasound-guided regional anesthesia (UGRA). This project aimed to generate consensus recommendations for core structures to identify during the performance of intermediate and advanced blocks. An initial longlist of structures was refined by an international panel of key opinion leaders in UGRA over a three-round Delphi process. All rounds were conducted virtually and anonymously. Blocks were considered twice in each round: for "orientation scanning" (the dynamic process of acquiring the final view) and for "block view" (which visualizes the block site and is maintained for needle insertion/injection). A "strong recommendation" was made if ≥75% of participants rated any structure as "definitely include" in any round. A "weak recommendation" was made if >50% of participants rated it as "definitely include" or "probably include" for all rounds, but the criterion for strong recommendation was never met. Structures which did not meet either criterion were excluded. Forty-one participants were invited and 40 accepted; 38 completed all three rounds. Participants considered the ultrasound scanning for 19 peripheral nerve blocks across all three rounds. Two hundred and seventy-four structures were reviewed for both orientation scanning and block view; a "strong recommendation" was made for 60 structures on orientation scanning and 44 on the block view. A "weak recommendation" was made for 107 and 62 structures, respectively. These recommendations are intended to help standardize teaching and research in UGRA and support widespread and consistent practice.

Combined proximal or distal nerve blocks for postoperative analgesia after total knee arthroplasty: a randomised controlled trial.

BACKGROUND: Many regional anaesthetic techniques have been proposed to manage pain after total knee arthroplasty, but the best approach is unclear. We compared opioid consumption in the first 48 h between two different regional anaesthesia strategies in patients undergoing total knee arthroplasty. METHODS: In this single-centre, prospective study, we randomly allocated 90 patients to a combination of IPACK (interspace between popliteal artery and capsule of the posterior knee), triangle femoral and obturator nerve blocks (distal group), or a combination of sciatic, femoral, obturator, and lateral femoral cutaneous nerve blocks (proximal group). All patients received an opioid-sparing general anaesthesia regimen. The primary outcome was opioid consumption in the first 48 h. Secondary outcomes included opioid consumption in the first 24 h and verbal rating pain scores in the first 48 h. RESULTS: There was no difference in median cumulative oral morphine equivalent consumption at 48 h between the distal and the proximal block groups (33 [18-78] mg vs 30 [22-51] mg, respectively; P=0.29). Median oral morphine equivalent consumption at 24 h was higher in the distal group compared with the proximal group (30 [13-59] vs 15 [0-18], respectively; P<0.001). Verbal rating pain scores were lower in the proximal group compared with the distal group on arrival to the postanaesthesia care unit and at 6 and 12 h. CONCLUSIONS: In patients undergoing total knee arthroplasty under total intravenous general anaesthesia with a multimodal analgesia regimen, proximal nerve blocks resulted in improved pain scores in the first 12 h and reduced opioid consumption in the first 24 h when compared with distal nerve blocks. No difference in pain scores or opioid consumption was seen at 48 h. CLINICAL TRIAL REGISTRATION: NCT04499716.

Recommendations for effective documentation in regional anesthesia: an expert panel Delphi consensus project.

BACKGROUND AND OBJECTIVES: Documentation is important for quality improvement, education, and research. There is currently a lack of recommendations regarding key aspects of documentation in regional anesthesia. The aim of this study was to establish recommendations for documentation in regional anesthesia. METHODS: Following the formation of the executive committee and a directed literature review, a long list of potential documentation components was created. A modified Delphi process was then employed to achieve consensus amongst a group of international experts in regional anesthesia. This consisted of 2 rounds of anonymous electronic voting and a final virtual round table discussion with live polling on items not yet excluded or accepted from previous rounds. Progression or exclusion of potential components through the rounds was based on the achievement of strong consensus. Strong consensus was defined as ≥75% agreement and weak consensus as 50%-74% agreement. RESULTS: Seventy-seven collaborators participated in both rounds 1 and 2, while 50 collaborators took part in round 3. In total, experts voted on 83 items and achieved a strong consensus on 51 items, weak consensus on 3 and rejected 29. CONCLUSION: By means of a modified Delphi process, we have established expert consensus on documentation in regional anesthesia.

International consensus on anatomical structures to identify on ultrasound for the performance of basic blocks in ultrasound-guided regional anesthesia.

There is no universally agreed set of anatomical structures that must be identified on ultrasound for the performance of ultrasound-guided regional anesthesia (UGRA) techniques. This study aimed to produce standardized recommendations for core (minimum) structures to identify during seven basic blocks. An international consensus was sought through a modified Delphi process. A long-list of anatomical structures was refined through serial review by key opinion leaders in UGRA. All rounds were conducted remotely and anonymously to facilitate equal contribution of each participant. Blocks were considered twice in each round: for "orientation scanning" (the dynamic process of acquiring the final view) and for the "block view" (which visualizes the block site and is maintained for needle insertion/injection). Strong recommendations for inclusion were made if ≥75% of participants rated a structure as "definitely include" in any round. Weak recommendations were made if >50% of participants rated a structure as "definitely include" or "probably include" for all rounds (but the criterion for "strong recommendation" was never met). Thirty-six participants (94.7%) completed all rounds. 128 structures were reviewed; a "strong recommendation" is made for 35 structures on orientation scanning and 28 for the block view. A "weak recommendation" is made for 36 and 20 structures, respectively. This study provides recommendations on the core (minimum) set of anatomical structures to identify during ultrasound scanning for seven basic blocks in UGRA. They are intended to support consistent practice, empower non-experts using basic UGRA techniques, and standardize teaching and research.

Obturator nerve block does not provide analgesic benefits in total hip arthroplasty under multimodal analgesic regimen: a randomized controlled trial.

BACKGROUND AND OBJECTIVES: Although regional analgesia is considered an important component of optimal pain management, use of peripheral nerve blocks for total hip arthroplasty remains controversial. Since the obturator nerve innervates the anteromedial part of the joint capsule, we hypothesized that an obturator nerve block would decrease the opioid consumption after total hip arthroplasty. METHODS: In this single center, prospective, triple blinded study, we randomly allocated 60 patients undergoing total hip arthroplasty under opioid-sparing total intravenous general anesthesia to a preoperative obturator nerve block or a sham block (placebo group) using 20 mL of ropivacaine 0.2% or saline, respectively. All patients received a multimodal analgesic regimen with non-opioid analgesics including periarticular local infiltration analgesia. The primary outcome was the intravenous opioid consumption in the post-anesthesia care unit. RESULTS: Median (IQR) intravenous oxycodone consumption in the post-anesthesia care unit was 4 (2, 7.5) mg in the obturator nerve block group and 3 (0, 4) mg in the placebo group (p=0.05). There were no differences in pain scores between groups in the first 24 hours except at arrival on the surgical ward with significant higher pain scores in the placebo group (p=0.03). The ability to stand up and walk within 24 hours was comparable between groups as was the time to first walk (180 (90, 720) vs 240 (120, 780) min for the obturator nerve block and placebo groups, respectively; p=0.62). CONCLUSIONS: Obturator nerve block did not improve postoperative opioid consumption after total hip arthroplasty performed under general anesthesia with a multimodal analgesic regimen. TRIAL REGISTRATION NUMBER: NCT04085640.

Total knee arthroplasty under quadruple nerve block with ropivacaine 0.32%: effect of addition of intravenous dexmedetomidine to intravenous dexamethasone on analgesic duration.

BACKGROUND AND OBJECTIVES: Peripheral nerve blocks reduce postoperative pain and enhance recovery after total knee arthroplasty (TKA). This study aims to assess the benefits of addition of intravenous dexmedetomidine (DexM) to intravenous dexamethasone on the analgesic duration of quadruple nerve blocks. METHODS: This double-blind, randomized, controlled trial prospectively enrolled 90 patients scheduled for TKA under quadruple nerve blocks (sciatic, femoral, obturator, and lateral femoral cutaneous nerves blocks) with 70 mL, 0.32% ropivacaine. All patients received systemic dexamethasone 10 mg. Patients were randomized to receive DexM (2 µg/kg, intravenous) or placebo (1:1 ratio). The primary endpoint was the duration of analgesia defined as the time to first request for rescue analgesia (oxycodone). RESULTS: Kaplan-Meier curves for the first analgesic request were similar between groups (log-rank test; p=0.27). Median (IQR) duration of analgesia was similar between placebo (1575 min (1211-1952)) and DexM (1470 min (1263-1700)) groups (p=0.56). Cumulative consumption of oxycodone at the 48th hour was 20 mg (10-30) and 30 mg (20-40) in placebo and DexM groups, respectively (p=0.14). The day after surgery, 93% and 89% of patients were able to walk in placebo and DexM groups, respectively (p=0.46). Intravenous DexM was associated with bradycardia, hypotension and longer recovery room stay (p<0.05 for all comparisons). CONCLUSIONS: In a multimodal analgesic regimen, addition of systemic DexM (2 µg/kg) to systemic dexamethasone does not prolong the analgesic duration of quadruple nerve block with ropivacaine 0.32% after TKA. TRIAL REGISTRATION NUMBER: NCT03834129.

Deep visual nerve tracking in ultrasound images.

Ultrasound-guided regional anesthesia (UGRA) becomes a standard procedure in surgical operations and pain management, offers the advantages of nerve localization, and provides region of interest anatomical structure visualization. Nerve tracking presents a crucial step for practicing UGRA and it is useful and important to develop a tool to facilitate this step. However, nerve tracking is a very challenging task that anesthetists can encounter due to the noise, artifacts, and nerve structure variability. Deep-learning has shown outstanding performances in computer vision task including tracking. Many deep-learning trackers have been proposed, where their performance depends on the application. While no deep-learning study exists for tracking the nerves in ultrasound images, this paper explores thirteen most recent deep-learning trackers for nerve tracking and presents a comparative study for the best deep-learning trackers on different types of nerves in ultrasound images. We evaluate the performance of the trackers in terms of accuracy, consistency, time complexity, and handling different nerve situations, such as disappearance and losing shape information. Through the experimentation, certain conclusions were noted on deep learning trackers performance. Overall, deep-learning trackers provide good performance and show a comparative performance for tracking different kinds of nerves in ultrasound images.

Ultrasound-guided ankle block. History revisited.

Following forefoot surgery, compared to the traditional multimodal approach, regional anesthesia and analgesia provides high quality pain relief, decreases opioids consumption and leads to very high satisfaction scores. Traditional regional techniques relied either on wound infiltration, landmark technique ankle blocks or popliteal sciatic nerve block. Numerous anatomic variations of the different nerves might lead to failure following a blind technique. The current evolution towards ambulatory care will push surgical teams to favor techniques that simplify postoperative treatment and encourages immediate ambulation. The development of Ultrasound Guided Blocks has enabled us to perform very selective and precise nerve blocks. Ankle blocks provide excellent intraoperative anesthesia as well as long postoperative pain relief. Complications are rare using regional anesthesia for postoperative analgesia even after extensive foot surgery. Revival of ankle blocks is a perfect example of the high impact of new technological advances in improving ambulatory surgical care after foot surgery.

Perioperative Use of Intravenous Lidocaine.

Lidocaine is an amide local anaesthetic initially used intravenously as an antiarrhythmic agent. At some point it was proposed that intravenous lidocaine (IVL) had an analgesic effect that could be potentially beneficial in perioperative settings. Since these preliminary reports, a large body of evidence confirmed that IVL had anti-inflammatory and opiate-sparing effects, a combination of characteristics leading to an array of effects such as a decrease in postoperative pain and opiate consumption, and a reduction in the duration of digestive ileus. Additional studies demonstrated IVL to possess antithrombotic, antimicrobial and antitumoral effects. Beneficial effects of IVL have been characterized in abdominal surgery but remain controversial in other types of surgeries. Because the quality of evidence was limited, due to inconsistency, imprecision and study quality, recent conclusions from meta-analysis pooling together all types of surgery stated the uncertainty about IVL benefits. Additional indications such as the prevention of propofol-induced injection pain, prevention of hyperalgesia, protection against bronchial reactivity by bronchotracheal relaxation during surgery, and the increase in depth of general anaesthesia have since emerged. IVL is rapidly distributed in the body and metabolized by the liver. With the commonly recommended doses, lidocaine's therapeutic index remains very high and the plasma concentrations stay largely below the cardiotoxic and neurotoxic threshold levels, a notion that may be used by clinicians to draw conclusions on the benefit-risk profile of IVL in comparison to other analgesic strategies. The purpose of this review is to address the pharmacokinetic and pharmacodynamic properties of lidocaine in healthy and pathological conditions.

Adaptive median binary patterns for fully automatic nerves tracking in ultrasound images.

BACKGROUND AND OBJECTIVE: In the last decade, Ultrasound-Guided Regional Anesthesia (UGRA) gained importance in surgical procedures and pain management, due to its ability to perform target delivery of local anesthetics under direct sonographic visualization. However, practicing UGRA can be challenging, since it requires high skilled and experienced operator. Among the difficult task that the operator can face, is the tracking of the nerve structure in ultrasound images. Tracking task in US images is very challenging due to the noise and other artifacts. METHODS: In this paper, we introduce a new and robust tracking technique by using Adaptive Median Binary Pattern(AMBP) as texture feature for tracking algorithms (particle filter, mean-shift and Kanade-Lucas-Tomasi(KLT)). Moreover, we propose to incorporate Kalman filter as prediction and correction steps for the tracking algorithms, in order to enhance the accuracy, computational cost and handle target disappearance. RESULTS: The proposed method have been applied on real data and evaluated in different situations. The obtained results show that tracking with AMBP features outperforms other descriptors and achieved best performance with 95% accuracy. CONCLUSIONS: This paper presents the first fully automatic nerve tracking method in Ultrasound images. AMBP features outperforms other descriptors in all situations such as noisy and filtered images.

Perineural Versus Systemic Dexamethasone in Front-Foot Surgery Under Ankle Block: A Randomized Double-Blind Study.

BACKGROUND AND OBJECTIVES: Among the different adjuvants, dexamethasone is one of the most accepted to prolong the effect of local anesthetics. This study aims to determine the superiority of perineural over systemic dexamethasone administration after a single-shot ankle block in metatarsal osteotomy. METHODS: We performed a prospective, double-blind, randomized study. A total of 100 patients presenting for metatarsal osteotomy with an ankle block were randomized into 2 groups: 30 mL ropivacaine 0.375% + perineural dexamethasone 4 mg (1 mL) + 2.5 mL of systemic saline solution (PNDex group, n = 50) and 30 mL ropivacaine 0.375% + 1 mL of perineural saline solution + intravenous dexamethasone 10 mg (2.5 mL) (IVDex group, n = 50). The primary end point was the duration of analgesia defined as the time between the performance of the ankle block and the first administration of rescue analgesia with tramadol. RESULTS: Time period to first rescue analgesia with tramadol was similar in the IVDex group and the PNDex group. Data are expressed as mean (SD) or median (range). Duration of analgesia was 23.2 (9.5) hours in the IVDex group and 19 (8.2) hours in the PNDex group (P = 0.4). Consumption of tramadol during the first 48 hours was 0 mg (0-150 mg) in the IVDex group versus 0 mg (0-250 mg) in the PNDex group (P = 0.59). Four (8%) and 12 (24%) patients reported nausea or vomiting in the IVDex group and the PNDex group, respectively (P = 0.03). CONCLUSIONS: In front-foot surgery, perineural and systemic administrations of dexamethasone are equivalent for postoperative pain relief when used as an adjuvant to ropivacaine ankle block. CLINICAL TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov, identifier NCT02904538.

Diaphragmatic paralysis in obese patients in arthroscopic shoulder surgery: consequences and causes.

PURPOSE: Ambulatory process in arthroscopic shoulder surgery has boomed over past decades. Some anesthetic techniques such as interscalene block (ISB) and its surrogates are associated with diaphragmatic paralysis and might compromise outpatient procedure. HYPOTHESIS: This study aims to assess consequences of diaphragmatic paralysis in obese patients. METHODS: This prospective observational study screened patients with body mass index (BMI) ≥ 30 kg/m2 undergoing acromioplasty or supraspinatus tendon repair. Surgery was performed using brachial plexus block, and the method of brachial plexus block was left at the discretion of attending anesthesiologists. Post-operative hemidiaphragmatic paralysis was evaluated using M-mode ultrasonography and its consequences on patient ventilation were assessed: occurrence of hypoxic episode defined as oxygen saturation less than 90% (by pulse oximeter) in room air, dyspnea and failure of ambulatory procedure. Causes of diaphragmatic paralysis were also analyzed. RESULTS: Ninety-one patients were screened, 82 patients were included in this study and 37 patients (45%) presented diaphragmatic paralysis. Compared to patients without diaphragmatic paralysis, diaphragmatic paralysis was associated with dyspnea [10 (27%) versus 1 (2%); p = 0.0019], occurrence of patients presenting at least one hypoxic episode [6 (16%) versus 1 (2%); p = 0.02] and failure of ambulatory process [10 (27%) versus 1 (2%); p = 0.009]. The combination of axillary and suprascapular nerve blocks, but also low volume ISB, was found to be protective against diaphragmatic paralysis when compared to high volume ISB [Odds ratios 0.0019 (0.001-0.026) and 0.0482 (0.008-0.27), respectively; p < 0.001]. CONCLUSION: In patients with BMI ≥ 30 kg/m2 undergoing arthroscopic shoulder surgery, diaphragmatic paralysis is associated with dyspnea, occurrence of hypoxic episodes and failure of ambulatory procedure. High volume ISB and also, to a lesser extent, low volume ISB were found to be responsible for diaphragmatic paralysis. TRIAL REGISTRY NUMBER: Registration n° 2014-202.

Fortuitous Diagnosis of Preexisting Neuropathy During Ultrasound-Guided Regional Anesthesia Performance: A Case Report.

Ultrasound-guided regional anesthesia requires the anesthesia provider to interpret new information. This article reports on the case of a 38-year-old man scheduled for a fifth metacarpal fracture repair. Ultrasound nerve examination revealed abnormal pathology of the axillary brachial plexus consisting of an increased volume of the terminal nerves of the brachial plexus. Ultrasound scanning initiated the subsequent diagnosis of multifocal motor neuropathy. Regional anesthesia was abandoned in favor of general anesthesia. Ultrasonography training needs to be expanded in the coming years to include awareness of the abnormal pathology, as it might impact the choice of anesthetic procedure and patient outcome.

Phase-based probabilistic active contour for nerve detection in ultrasound images for regional anesthesia.

Ultrasound guided regional anesthesia (UGRA) is steadily growing in popularity, owing to advances in ultrasound imaging technology and the advantages that this technique presents for safety and efficiency. The aim of this work is to assist anaesthetists during the UGRA procedure by automatically detecting the nerve blocks in the ultrasound images. The main disadvantage of ultrasound images is the poor quality of the images, which are also affected by the speckle noise. Moreover, the nerve structure is not salient amid the other tissues, which makes its detection a challenging problem. In this paper we propose a new method to tackle the problem of nerve zone detection in ultrasound images. The method consists in a combination of three approaches: probabilistic, edge phase information and active contours. The gradient vector flow (GVF) is adopted as an edge-based active contour. The phase analysis of the monogenic signal is used to provide reliable edges for the GVF. Then, a learned probabilistic model reduces the false positives and increases the likelihood energy term of the target region. It yields a new external force field that attracts the active contour toward the desired region of interest. The proposed scheme has been applied to sciatic nerve regions. The qualitative and quantitative evaluations show a high accuracy and a significant improvement in performance.