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.

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.

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.

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.

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.

Three-dimensional, multiplanar, ultrasound-guided, radial nerve block.

OBJECTIVE: We describe the use of 3-dimensional, multiplanar ultrasound imaging for peripheral nerve block. CASE REPORT: To illustrate the potential usefulness of the technique, we present a case in which real-time 3-dimensional, multiplanar ultrasound was used to assist in the performance of a radial nerve block. CONCLUSIONS: Three-dimensional, multiplanar ultrasound in real-time has the potential to improve nerve identification and accuracy of needle placement in regional anesthesia.

Ultrasound anatomy of the radial nerve in the distal upper arm.

BACKGROUND AND OBJECTIVES: We aimed to describe the ultrasound appearance of the radial nerve in the lateral aspect of the distal upper arm. This procedure was done to identify potential novel sites for ultrasound-guided radial-nerve block. METHODS: We scanned the lateral aspect of the distal upper arm in both arms of 50 healthy adult volunteers (equal gender distribution), using a 38 mm, 5 to 10 MHz, linear ultrasound probe (SonoSite MicroMaxx, Hitchen, UK). Three points were defined: A, midway between the anterior process of the acromion and lateral epicondyle of the humerus; B, one third of the distance between A and the lateral epicondyle; C, two thirds of the distance between A and the lateral epicondyle. Subjects' arms were scanned between A and C. We measured the maximal transverse (parallel to skin) and anteroposterior (perpendicular to skin) diameters of the radial nerve and calculated its cross-sectional area. Depth of the radial nerve from the skin surface was measured, and its shape and appearance were noted. RESULTS: At point B, the radial nerve lay in the spiral groove of the humerus, closely associated with the profunda brachii artery and vein. At point C, the nerve had passed through the lateral intermuscular septum and lay between brachioradialis and brachialis muscles. In 99% of arms, the radial nerve was not visible at point A, but became visible between points A and B in 93% of arms. The depth at point B was significantly less than at point C (mean +/- SD: 1.21 +/- 0.35 vs. 1.71 +/- 0.35 cm; P < .001). The measured depth of the nerve was positively correlated (P < .001) with body mass index and with arm circumference, but not with gender. The radial nerve was oval-shaped at both sites, with a cross-sectional area of 3.1 +/- 0.7 mm(2) at point B and 2.9 +/- 0.7 mm(2) at point C. CONCLUSIONS: Points B and C may represent convenient, novel sites for ultrasound-guided radial-nerve block. The nerve is clearly visualized and has not yet divided into superficial and deep branches. Point C may be the optimal site for radial-nerve block because of the smaller risk of vessel puncture. Our observations also demonstrate the ability of ultrasound to identify nerves at sites not clearly defined by surface anatomic landmarks.

Anesthesiologists' perception of patients' anxiety under regional anesthesia.

The aim of this survey is to report anesthesiologists' perception of patients' anxiety under regional anesthesia, its frequency, effects and causes, and the strategies employed to reduce it. Electronic questionnaires were sent to all grades of anesthesiologists in Nottingham, UK. The response rate for the survey was 79%. Over half of the anesthesiologists in our region believe that anxiety during regional anesthesia is not common. Surgery and anesthesia, followed by block failure were reported by anesthesiologists as the most common causes of patients' anxiety. Frequently employed techniques to manage anxiety were communication or sedation. Most respondents felt that regional anesthesia provides good analgesia and patient satisfaction. However, 20% felt that regional anesthesia is painful or unpleasant for patients, perhaps explaining the reluctance by some anesthesiologists to perform regional anesthesia.

Patient satisfaction with perioperative care among patients having orthopedic surgery in a university hospital.

This survey aimed to validate the English version of the multidimensional Leiden Perioperative Patient Satisfaction questionnaire (LPPSq) and use it to assess patient satisfaction with perioperative care and the influence of type of anesthesia. One hundred patients having orthopedic surgery under regional and general anesthesia verbally consented to participate. Different aspects of satisfaction were assessed (eg, provision of information, and staff-patient relationship). The reliability estimate of the LPPSq (Cronbach's-α) was good (0.94). Overall, patient satisfaction score was 86.7%, lowest was for information (80.8%) and highest for staff-patient relationships (90.3%). Patients were more satisfied with the provision of information regarding regional anesthesia.