Closing the gap: artificial intelligence applied to ultrasound-guided regional anaesthesia.

The role of artificial intelligence in ultrasound-guided regional anaesthesia is explored in a recent study by Bowness and colleagues, published in the British Journal of Anaesthesia. The investigators showed that non-expert ability to identify key sono-anatomical structures was improved with the assistance of proprietary artificial intelligence software. Whether such software could increase learning efficiency, and thereby patient access, to regional anaesthesia, will require further study.

Patient-maintained versus anaesthetist-controlled propofol sedation during elective primary lower-limb arthroplasty performed under spinal anaesthesia: a randomised controlled trial.

BACKGROUND: Patient-maintained propofol TCI sedation (PMPS) allows patients to titrate their own target-controlled infusion (TCI) delivery of propofol sedation using a handheld button. The aim of this RCT was to compare PMPS with anaesthetist-controlled propofol TCI sedation (ACPS) in patients undergoing elective primary lower-limb arthroplasty surgery under spinal anaesthesia. METHODS: In this single-centre open-label investigator-led study, adult patients were randomly assigned to either PMPS or ACPS during their surgery. Both sedation regimes used Schnider effect-site TCI modelling. The primary outcome measure was infusion rate adjusted for weight (expressed as mg kg-1 h-1). Secondary outcomes measures included depth of sedation, occurrence of sedation-related adverse events and time to medical readiness for discharge from the postanaesthsia care unit (PACU). RESULTS: Eighty patients (48 female) were randomised. Subjects using PMPS used 39.3% less propofol during the sedation period compared with subjects in group ACPS (1.56 [0.57] vs 2.57 [1.33] mg kg-1 h-1; P<0.001), experienced fewer discrete episodes of deep sedation (0 vs 6; P=0.0256), fewer airway/breathing adverse events (odds ratio [95% confidence interval]: 2.94 [1.31-6.64]; P=0.009) and were ready for discharge from PACU more quickly (8.94 [5.5] vs 13.51 [7.2] min; P=0.0027). CONCLUSIONS: Patient-maintained propofol sedation during lower-limb arthroplasty under spinal anaesthesia results in reduced drug exposure and fewer episodes of sedation-related adverse events compared with anaesthetist-controlled propofol TCI sedation. To facilitate further investigation of this procedural sedation technique, PMPS-capable TCI infusion devices should be submitted for regulatory approval for clinical use. CLINICAL TRIAL REGISTRATION: ISRCTN29129799.

Patient-maintained propofol sedation for adult patients undergoing surgical or medical procedures: a scoping review of current evidence and technology.

Patient-maintained propofol sedation (PMPS) is the delivery of procedural propofol sedation by target-controlled infusion with the patient exerting an element of control over their target-site propofol concentration. This scoping review aims to establish the extent and nature of current knowledge regarding PMPS from both a clinical and technological perspective, thereby identifying knowledge gaps to guide future research. We searched MEDLINE, EMBASE, and OpenGrey databases, identifying 17 clinical studies for analysis. PMPS is described in the context of healthy volunteers and in orthopaedic, general surgical, dental, and endoscopic clinical settings. All studies used modifications to existing commercially-available infusion devices to achieve prototype systems capable of PMPS. The current literature precludes rigorous generalisable conclusions regarding the safety or comparative clinical effectiveness of PMPS, however cautious acknowledgement of efficacy in specific clinical settings is appropriate. Based on the existing literature, together with new standardised outcome reporting recommendations for sedation research and frameworks designed to assess novel health technologies research, we have made recommendations for future pharmacological, clinical, behavioural, and health economic research on PMPS. We conclude that high-quality experimental clinical trials with relevant comparator groups assessing the impact of PMPS on standardised patient-orientated outcome measures are urgently required.

Effect of mental rotation skills training on ultrasound-guided regional anaesthesia task performance by novice operators: a rater-blinded, randomised, controlled study.

BACKGROUND: The effect of mental rotation training on ultrasound-guided regional anaesthesia (UGRA) skill acquisition is currently unknown. In this study we aimed to examine whether mental rotation skill training can improve UGRA task performance by novice operators. METHODS: We enrolled 94 volunteers with no prior experience of UGRA in this randomised controlled study. After a baseline mental rotation test, their performance in a standardised UGRA needling task was independently assessed by two raters using the composite error score (CES) and global rating scale (GRS). Volunteers with low baseline mental rotation ability were randomised to a mental rotation training group or a no training group, and the UGRA needling task was repeated to determine the impact of the training intervention on task performance. The study primary outcome measure was UGRA needling task CES measured before and after the training intervention. RESULTS: Multivariate analyses controlling for age, gender, and previous performance showed that participants exposed to the training intervention made significantly fewer errors (CES B=-0.66 [standard error, se=0.17]; P<0.001; 95% confidence interval [CI], -0.92 to -0.26) and displayed improved overall performance (GRS B=6.15 [se=2.99], P=0.048, 95% CI=0.06 to 12.13) when undertaking the UGRA needling task. CONCLUSIONS: A simple training intervention, based on the manipulation and rotation of three-dimensional models, results in improved technical performance of a UGRA needling task in operators with low baseline mental rotation skills.

A Prototype Patient-Maintained Propofol Sedation System Using Target Controlled Infusion for Primary Lower-Limb Arthroplasty.

Each year, many operations in the UK are performed with the patient awake, without the use of general anaesthesia. These include joint replacement procedures, and in order to reduce patient anxiety, the supervising anaesthetist delivers the sedative propofol intravenously using a target-controlled infusion (TCI) device. However, it is clinically challenging to judge the required effect-site concentration of sedative for an individual patient, resulting in patient care issues related to over or under-sedation. To improve the process, patient-maintained propofol sedation (PMPS), where the patient can request an increase in concentration through a hand-held button, has been considered as an alternative. However, due to the proprietary nature of modern TCI pumps, the majority of PMPS research has been conducted using prototypes in research studies. In this work, a PMPS system is presented that effectively converts a standard infusion pump into a TCI device using a laptop with TCI software. Functionally, the system delivers sedation analogous to a modern TCI pump, with the differences in propofol consumption and dosage within the tolerance of clinically approved devices. Therefore, the Medicines and Healthcare products Regulatory Agency (MHRA) has approved the system as a safe alternative to anaesthetist-controlled TCI procedures. It represents a step forward in the consideration of PMPS as a sedation method as viable alternative, allowing further assessment in clinical trials.

Visuospatial Ability as a Predictor of Novice Performance in Ultrasound-guided Regional Anesthesia.

BACKGROUND: Visuospatial ability correlates positively with novice performance of simple laparoscopic tasks. The aims of this study were to identify whether visuospatial ability could predict technical performance of an ultrasound-guided needle task by novice operators and to describe how emotional state, intelligence, and fear of failure impact on this. METHODS: Sixty medical student volunteers enrolled in this observational study. The authors used an instructional video to standardize training for ultrasound-guided needle advancement in a turkey breast model and assessed volunteers' performance independently by two assessors using composite error score (CES) and global rating scale (GRS). The authors assessed their "visuospatial ability" with mental rotation test (MRT), group embedded figures test, and Alice Heim group ability test. Emotional state was judged with UWIST Mood Adjective Checklist (UMACL), and fear of failure and general cognitive ability were judged with numerical reasoning test. RESULTS: High CES scores (high error rate) were associated with low MRT scores (ρ = -0.54; P < 0.001). Better GRS scores were associated with better MRT scores (ρ = 0.47; P < 0.001). Regarding emotions, GRS scores were low when anxiety levels were high (ρ = -0.35; P = 0.005) and CES scores (errors) were low when individuals reported feeling vigorous and active (ρ = -0.30; P = 0.01). CONCLUSIONS: An MRT predicts novice performance of an ultrasound-guided needling task on a turkey model and as a trait measure could be used as a tool to focus training resources on less-able individuals. Anxiety adversely affects performance. Therefore, both may prove useful in directing targeted training in ultrasound-guided regional anesthesia.

A randomised controlled trial of the efficacy of ultrasound-guided transversus abdominis plane (TAP) block in laparoscopic colorectal surgery.

BACKGROUND: Optimal analgesia following laparoscopic colorectal resection is yet to be determined; however, recent studies have questioned the role of postoperative epidural anaesthesia, suggesting other analgesic modalities may be preferable. The aim of this randomised controlled trial was to assess the effect of transversus abdominis plane (TAP) blocks on opioid requirements in patients undergoing laparoscopic colorectal resection. METHODS: After appropriate trial registration ( www.clinicaltrials.gov NCT 00830089) and local medical ethics review board approval (REC 09/H0407/10), all adult patients who were to undergo laparoscopic colorectal surgery at a single centre were randomised into the intervention group receiving bilateral TAP blocks or the control group (no TAP block). The blocks were administered prior to surgery after the induction of a standardised anaesthetic by an anaesthetist otherwise uninvolved with the case. The patient, theatre anaesthetist, surgeon, and ward staff were blinded to treatment allocation. All patients received postoperative analgesia of paracetamol and morphine as a patient-controlled analgesia (PCA). Cumulative opioid consumption and pain scores were recorded at 2, 4, 6, and 24 h postoperatively and compared between the groups as were clinical outcomes and length of stay. RESULTS: The intervention (TAP block) group (n = 33) and the control group (n = 35) were comparable with respect to characteristics, specimen pathology, and type of procedure. The TAP block group's median cumulative morphine usage (40 mg [IQR = 25-63]) was significantly less than that of the control group (60 mg [IQR = 39-81]). Pain scores and median length of stay (LOS) were similar between the two groups. CONCLUSION: Preoperative TAP blocks in patients undergoing laparoscopic colorectal resection reduced opioid use in the first postoperative day in this study.

Standardizing nomenclature in regional anesthesia: an ASRA-ESRA Delphi consensus study of upper and lower limb nerve blocks.

BACKGROUND: Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks. METHODS: We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%-74% agreement. RESULTS: A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research. CONCLUSIONS: We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.

Erector Spinae Plane Blocks for the Early Analgesia of Rib Fractures in Trauma (ESPEAR): protocol for a multicentre pilot randomised controlled trial with feasibility and embedded qualitative assessment.

INTRODUCTION: Patients with rib fractures commonly experience significant acute pain and are at risk of hypoxia, retained secretions, respiratory failure and death. Effective analgesia improves these outcomes. There is widespread variation in analgesic treatments given to patients including oral, intravenous and epidural routes of administration. Erector spinae plane (ESP) blockade, a novel regional analgesic technique, may be effective, but high-quality evidence is lacking. METHODS AND ANALYSIS: To determine if a definitive trial of ESP blockade in rib fractures is possible, we are conducting a multicentre, randomised controlled pilot study with feasibility and qualitative assessment. Fifty adult patients with rib fractures will be randomised in a 1:1 ratio to ESP blockade with multimodal analgesia or placebo ESP blockade with multimodal analgesia. Participants and outcome assessors will be blinded. The primary feasibility outcomes are recruitment rate, retention rate and trial acceptability assessed by interview. ETHICS AND DISSEMINATION: The study was approved by the Oxford B Research Ethics Committee on 22 February 2022 (REC reference: 22/SC/0005). All participants will provide written consent. Trial results will be reported via peer review and to grant funders. TRIAL REGISTRATION NUMBER: ISRCTN49307616.

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.

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.

Real-time three-dimensional ultrasound-guided central venous catheter placement.

We present the first description of real-time 3-dimensional ultrasound for insertion of a central venous catheter in a surgical patient. An HD11 XE™ ultrasound machine with a V8-4 transducer (Philips Medical Systems, Bothell, WA) was used throughout. Three-dimensional multiplanar and volume-rendered views allowed us to simultaneously view the neck anatomy in 3 orthogonal planes. Needle entry into the vein and subsequent catheter placement were also visualized. We were able to rotate the views in real time, thereby enabling visualization of the catheter within the lumen of the vein. The ability to see simultaneous real-time short- and long-axis views along with volume perspective without altering transducer position is an exciting development with the potential to confer a safety benefit to the patient. Although the operator is required to assimilate more information, the limitations we encountered were mainly related to processing power and transducer size, which we expect will be overcome with advancing technology.

Efficacy of transversus abdominis plane blocks in laparoscopic colorectal resections.

BACKGROUND: The increasing use of laparoscopic techniques for colorectal resections means that the issue of postoperative analgesia needs to be reassessed. This nonrandomized comparative study aimed to assess the efficacy of the transversus abdominis plane (TAP) block in laparoscopic colorectal resections. METHODS: Prospectively collected data from consecutive patients undergoing laparoscopic colorectal resections were used. Analgesia usage and outcome data for patients who had a TAP block and a postoperative morphine patient-controlled analgesia pump (PCA) were compared with those for patients who had a PCA alone. RESULTS: Data for 74 patients were used in the final analysis (40 TAP/PCA and 34 PCA alone). There was a significant reduction in overall intravenous opiate use in the TAP/PCA group (31.3 vs. 51.8 mg; P = 0.03). The TAP/PCA group showed a slight trend toward a shorter hospital stay (3 vs. 4 days; P = 0.17) but no difference in postoperative complications or any other outcome measure. There was no procedure-related morbidity relating to the use of TAP blocks. CONCLUSIONS: It appears that TAP blocks reduce postoperative analgesia use of patients undergoing laparoscopic colorectal resections within an enhanced recovery program, and this may have an impact on their postoperative hospital length of stay.

Impact of video games on ultrasound-guided regional anesthesia skills.

BACKGROUND: There is an association between video game practice and laparoscopic expertize in trainee surgeons. Ultrasound-guided regional anesthesia has many parallels with laparoscopic surgery. The aim of this study was to explore whether video game experience is associated with enhanced performance in a simulated ultrasound-guided task in novice operators. METHODS: In this prospective observational study, 60 medical student volunteers were recruited. Following characterization of video game experience, they underwent an assessment of visuospatial abilities. Following standardized teaching, the recruits' technical performance of an ultrasound-guided needle task was assessed for overall quality by global rating scale (GRS). RESULTS: Out of a total possible GRS score of 35, gamers compared with non-gamers demonstrated 5.2 (95% CI 1.9 to 8.4) units of better performance. Gamers also performed better in mental rotation test scores (difference 4.1, 95% CI 1.2 to 7.0) . CONCLUSION: Video game practice is associated with increased mental rotation ability and enhanced technical performance in a simulated ultrasound-guided task.

Delineation of distal ulnar nerve anatomy using ultrasound in volunteers to identify an optimum approach for neural blockade.

BACKGROUND AND OBJECTIVE: Ultrasound can provide novel approaches to neural blockade independent of surface landmarks. We elucidated the sonoanatomy of the ulnar nerve in the forearm of healthy volunteers in order to identify an optimum site for neural blockade. METHODS: One hundred forearms were scanned; the shape, depth from skin and cross-sectional area of the nerve were noted at the elbow, forearm and wrist. RESULTS: The nerve was visualized in all volunteers and had a maximum depth of 18.9 mm from the skin. The mean distance between the nerve and artery, 2 cm proximal to the point where the two structures met in the forearm, was 8.5 mm (95% confidence interval 8.1-8.9 mm). This was approximately at the junction between the proximal 2/5 and distal 3/5 of the forearm. CONCLUSION: Our study demonstrates that ultrasound can be utilized to identify the ulnar nerve and artery in the forearm. This implies that traditional landmarks will not be required prior to neural blockade. We have suggested a point for blockade of the nerve to reduce risk of vascular puncture.

Anaesthetist-controlled versus patient-maintained effect-site targeted propofol sedation during elective primary lower-limb arthroplasty performed under spinal anaesthesia (ACCEPTS): study protocol for a parallel-group randomised comparison trial.

BACKGROUND: The clinical efficacy of effect-site targeted patient-maintained propofol sedation (PMPS) compared to anaesthetist-controlled propofol sedation (ACPS) for patients undergoing awake joint replacement surgery is currently unknown. There is no commercially available medical device capable of delivering PMPS so we have designed and built such a device. We plan a clinical trial to compare PMPS to ACPS and to collect data relating to the safety of our prototype device in delivering sedation. METHODS: The trial is an open-label, randomised, controlled superiority trial recruiting adults who are undergoing elective primary lower-limb arthroplasty with sedation by propofol infusion by effect-site targeting into two equal-sized parallel arms: PMPS and ACPS. The primary research objective is to compare the body-weight-normalised rate of propofol consumption when sedation for surgery on adults undergoing elective primary lower-limb arthroplasty under spinal anaesthesia is patient-maintained versus when it is anaesthetist-controlled. The study primary null hypothesis is that there is no difference in the rate of propofol consumption when sedation is patient-maintained versus anaesthetist-controlled. DISCUSSION: This is the first trial to test the superiority of effect-site-targeted patient-maintained propofol sedation versus anaesthetist-controlled propofol sedation in terms of total propofol consumption during the sedation period. The results of this trial will help inform clinicians and device manufacturers of the clinical efficacy and safety of patient-maintained propofol sedation applied to a common operative setting. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number Registry, ISRCTN29129799 . Prospectively registered on 12 June 2018.