Background: Traumatic rib fractures cause significant acute pain. Patients are at risk of hypoventilation, atelectasis, hypoxia, retained secretions, pneumonia, respiratory failure, and death. Effective analgesia is thought to reduce these adverse outcomes. There is widespread variation in analgesic treatments given to patients including oral, intravenous, and epidural routes of administration. Erector spinae plane (ESP) block, a novel regional analgesic technique, may be effective, but high-quality evidence is lacking. Methods: To determine if a definitive trial of ESP block and catheter in rib fractures is possible, we conducted a multicentre, randomised, controlled pilot study with feasibility assessment. Adults with rib fractures were randomised in a 1:1 ratio to either (i) ESP blockade and catheter, or (ii) placebo ESP blockade and catheter, both for 72 h. In addition, all participants received multimodal analgesia. Participants and outcome assessors were blinded. The primary feasibility outcomes were recruitment rate (target: ≥1.11 participants/site/month), retention rate (target: ≥80%), and trial acceptability assessed by staff interview. Pre-specified red–amber–green criteria were agreed to determine feasibility of a future definitive clinical trial on this topic. Results: Twenty-five participants (mean [standard deviation] age 57 [16] yr, number of rib fractures 5 [3]) were recruited from three UK major trauma centres at a rate of 0.69 participants per site per month. Retention to 6-week follow-up was 80%. Based on our criteria, the current study design is not feasible for adoption into a definitive trial. For future research in this area, we recommend substantial modification to (i) the intervention, (ii) means of bias reduction, and (iii) timing and nature of outcome measure assessments. Conclusions: Based on pre-specified criteria, a definitive examination of the clinical effectiveness of ESP block in the analgesic management of adults after blunt force chest wall injury is only feasible if substantial amendments to trial processes piloted in this study are undertaken. An open-label assessment of single-shot ESP block, applying patient-reported average pain intensity of the first 24 h as the primary outcome, and conducted at sites with established ESP analgesic pathways, may overcome the most significant feasibility barriers identified by the present study. Clinical trial registration: ISRCTN49307616.

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.

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.

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.

IntroductionPatients 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 analysisTo 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 disseminationThe 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 numberISRCTN49307616.

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.

This article explains some of the background to the new national standardised operating procedure to prevent wrong side block, developed by a working party of the Safe Anaesthesia Liaison Group (SALG). However, the document may seem a little unusual, since it is not presented as a barrier to wrong side block. Rather, its main aim is to standardise practice across hospitals so that any future events can be analysed against a common framework; hence the designation as a standardised operating procedure and not a guideline. We think as a result the incidence of wrong side blocks will diminish, but not be eliminated. ‘Prep, stop, block’ describes the process to be followed; enhancing the message of ‘stop before you block’ that the stop moment should occur just before needle insertion. Conceived in 2011 [1], ‘stop before you block’ is a wonderfully catchy phrase emphasising the importance of stopping and checking the correct side before inserting the needle to prevent a wrong side block. Although intuitive, it does not seem to have worked. Data presented elsewhere confirm that the incidence of wrong side block (deemed a Never Event in the UK) has remained doggedly unchanged at between 1 in 6250 and 1 in 7812 [2, 3]. This is not a deficiency with ‘stop before you block’ as a principle but rather, as we have since learned, with the manner in which it is practised. The original guidance encouraged local flexibility in its application. This was understandable, as being a new initiative with no supportive evidence, local variation might have enhanced experiences helping to shape guideline evolution. The original initiative was disseminated via websites of the main national anaesthetic organisations [1] but did not reach the academic literature until several years later [4] and then appears to have been the focus of only about a dozen papers in total (several being correspondence items). However, this very flexibility has, we believe, become the main problem. As part of an analysis by SALG, hospital Trusts were invited to share their local policies to prevent wrong side block and 24 did so (see also online Supporting Information, Table S1). The heterogeneity that has evolved is striking. Several Trusts have no specific policy at all, or at most a ‘policy’ consisting only of the original ‘stop before you block’ poster [1]. In many Trusts, the policy is merged with those designed to prevent other errors, such as retention of guide wires. A few Trusts require the use of an additional mark, such as a sticker, to the surgical site mark. These additional marks have themselves led to wrong side block [5], especially as some literature recommends placing such marks or stickers on the side not to be blocked, leading to further confusion [6]. The colour, shape and type of stickers, where used, were inconsistent across Trusts (see also online Supporting Information, Table S1). In summary, the original hope that the practice of ‘stop before you block’ would converge to a common process through practice and research has been replaced by a wide divergence of rules and recommendations, the majority of which have been associated with wrong side block (see also online Supporting Information, Table S1). Further evidence has emerged that, even when anaesthetists performed a ‘stop’ moment, they often did so at the wrong time, often only at the World Health Organization (WHO) sign-in when the patient arrives in the anaesthetic room [7]. A survey found that after a wrong side block, anaesthetists felt genuine surprise, as they recalled having duly ‘stopped’ [7]. Some Trust policies explicitly align the ‘stop’ moment with the WHO sign-in, or before skin cleaning, both of which can occur sometime before needle insertion (see also online Supporting Information, Table S1). Equally for blocks of multiple nerves at different sites, some anaesthetists appeared to assume that only one stop moment was necessary for the first, even when the subsequent injections required re-prepping the skin or turning the patient [7]. Regrettably, there remains a minority of anaesthetists who admitted to not complying with ‘stop before you block’ in any form, and this includes several who themselves have performed a wrong side block [7]. Many of these issues were underlined in the very first investigation by the then newly created Healthcare Safety Investigation Branch in 2018, which focused on wrong side block. The report described a single case and, while not making any specific practice recommendations, formally invited SALG to formulate a new standard with less, if any, room for local variation [8]. The new standardised operating procedure (available in Fig. 1 and see also online Supporting Information, Appendix S1) has been through various drafts in a modified Delphi process, and the acknowledgements lists the organisations that have reviewed, modified and approved it. Further supportive evidence including results of a 3-month adoption trial and a formative observational study are available in the online Supporting Information (Appendix S2). The main principle of the new standardised operating procedure is to deconstruct the act of performing a block into three distinct phases: preparation; the stop moment; and finally the local anaesthetic injection. These may commonly be practised seamlessly but now the stop moment is a clear interruption, punctuating the end of preparation. Preparation may begin before or after the WHO sign-in, and also before, after or in absence of general anaesthesia. It may include: drawing up all drugs and equipment (needles, syringes, nerve stimulator, ultrasound pre-scan etc.); positioning the patient and oneself; gloving (and gowning where needed); and cleaning the skin over the block site area. The standardised operating procedure enhances the role of the assistant, to whom the prepared drug tray is handed over at the end of preparation phase, out of reach of the person performing the injection (termed the ‘blocker’ to acknowledge that non-anaesthetists may be performing blocks). To obtain the needle/syringe/tray to perform the block, the blocker should verbalise the completion of preparation and in turn, the assistant should acknowledge this. User feedback obtained by SALG (see also online Supporting Information, Appendix S2) indicated that some practitioners found this uncomfortable initially, but it should cause no more embarrassment or difficulty than saying ‘cricoid off’ in a rapid sequence induction, ‘3-2-1, turn’ when positioning a patient or verbal confirmation of end-tidal carbon dioxide after tracheal intubation. At this point, both assistant and blocker should confirm that the site prepared coincides with the surgical site mark and again (having once done this at sign-in), with what is noted on the consent form. Only after confirmation of this process does the assistant hand the drug tray back to the blocker, who then immediately performs the block. We cannot specify what ‘immediately’ means in strict chronological terms, but we can stress that the longer the interval between the receipt of the drug tray and insertion of needle, the greater will be the risk of wrong side block. Delays might be caused by: patient instability and need for corrective intervention (e.g. hypotension, hypoxia); patient movement; ultrasound or nerve stimulator failure; noticing drug errors; or distractive interruptions from people entering the room or telephone calls. Passage of time is in the minds of individuals, and if the blocker or assistant feel that the immediacy of needle insertion is impaired, they should stop and begin the process again at the preparation phase. This may require the assistant speaking up to provide challenge, so there will need to be human factors training to strengthen application of the standardised operating procedure over time [9]. The evidence supporting the new standardised operating procedure is not conclusive, but it is far greater than that which accompanied the original ‘stop before you block’ guidance or any of the existing policies (see also online Supporting Information, Table S1). We anticipate further research might focus on questions such as: how to help people remember to follow the procedure?; how robust is the process for unusual blocks or scenarios (e.g. where there is no assistant)?; how can interruptions to the process be best managed?; or will assistants feel able to speak up if the blocker is not complying or misses a step [9]? To some individuals, this new process will not present much, if any, change to practice. Others who pride themselves on speed may be more challenged. Some Trusts will need to change their policies radically, especially those that have invested heavily in special site-marking stickers. There should be no site mark in addition to the surgical site mark (but anaesthetic-only blocks will need a site mark and, of course, dedicated consent). The new policy should be stand-alone and not merged with other safety initiatives. Previous aids such as flaps obscuring the ultrasound screen or ‘stop before you block’ syringe stickers may not directly interfere with the ‘prep, stop, block’ process (although some individuals may find these a helpful reminder, these do not form part of the standardised operating procedure). Feedback revealed that colleagues perform blocks in the most surprising ways or in the most unusual circumstances. No guidance can comprehensively encompass all the clinical practice that exists. The standardised operating procedure described is for what we regard as the most common situation of a peripheral nerve block in an anaesthetic or block room before surgery. Hence, the full document includes an extensive ‘frequently asked questions’ section (available in the online Supporting Information, Appendix S1). This addresses situations such as where: there is no surgical site mark at all because it is an ‘anaesthetic-only’ procedure; the block is performed after surgery and the site mark has disappeared; there are multiple surgical site marks; the surgical site mark is placed on the correct side but at some distance from the site of injection; and there is no assistant. A guiding principle is the recognition that these are all situations of increased risk where extra vigilance is needed. One interesting question concerned blocks near the midline (e.g. erector spinae block). Here, a surgical mark may be clearly on one side of the body and visible, but the anatomical side of injection may only be confirmed using ultrasound. Since the assistant cannot be expected to interpret ultrasound images, they cannot verify the block is being placed on the correct side. Our suggestion is to delineate the surface anatomy by marking, but this is distinct from an extra site mark. Rather, it serves to help the assistant verify the side. By boiling down the act of performing a block injection into three component parts, the new standardised operating procedure is simple. We did not recommend a more complex technical solution, although we are aware of several possibilities in principle. Nerve stimulators or ultrasound machines might be constructed with alarms to trigger a stop moment or they may fail to activate unless a stop moment is undertaken [10]. Drug trays or boxes that can be locked and a voice-activated unlocking system has been suggested, opening only when a stop moment is verbalised [11]. Difficulties with technical solutions include the lack of any evidence and the need for product development, investment, CE marking and adoption [12]. Where more than one product or solution exists, organisations like SALG are constrained in recommending one over the other. Regardless, the new standardised operating procedure should not be viewed as a restrictive straitjacket that puts an end to critical enquiry, innovation or research. Rather, offering a common framework going forward, it can serve as a stable reference against which further developments can be mapped. The main aim of the new standardised operating procedure is to replace the existing patchwork of failed policies. Never Events are known to occur randomly [13], so it is likely that wrong side blocks will arise despite adherence to the new procedure. However, the common framework should enable us to identify exactly where future improvements in the guidance need to be made. Further detailed information including a video is available at the SALG website (https://www.salg.ac.uk) and the RA-UK website (https://ra-uk.org). The authors thank Dr H. Young for assistance in obtaining the data for Table S1 and Dr D. Luff for assistance with creating the training video on the SALG website. They thank Dr M. Richardson and Dr S. Traill for assistance with the formative observational study in Appendix S2. They thank the Working Party members: Dr C. McCartney, Mid Essex Hospital Services NHS Trust, Chelmsford (representing the Faculty of Pain Medicine); Dr L, Wee, Manchester University NHS Foundation Trust and Dr T. Brunning, Worcestershire Acute Hospitals Foundation Trust (both representing the Royal College of Anaesthetists’ Simulation Working Party); Dr C. Frerk, Northampton University Hospital; Mr B. Patel, Royal College of Anaesthetists Lay Committee; Ms J. Russell and Ms F. Watts (representing NHS Improvement). They also thank all those who participated in the feedback contributing to Table S1 and to the data in Appendix S2. In addition to the individuals and organisations mentioned above, the following have contributed to the new standardised operating procedure: RA-UK; Council of the Royal College of Anaesthetists; Association of Anaesthetists Safety Committee; and the Board of the Association of Anaesthetists. There has also been supportive input from NHS Improvement, Medicines and Healthcare products Regulatory Agency and Healthcare Safety Investigations Branch. JP is co-Chair, Safe Anaesthesia Liaison Group, Royal College of Anaesthetists. NH is Honorary Secretary of RA-UK. NB helped conceive and introduce the original ‘Stop before you block’ guidance. No other competing interests declared. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Background and AimsThere has been a significant impact on anaesthetic teaching and training within the UK owing to the COVID-19 pandemic. Most of the teaching needs are met using virtual methods. Hands on skills such as regional anaesthesia are not suitable for a virtual teaching format. Therefore, we aimed to continue and provide regional anaesthesia training in a large tertiary teaching hospital in a COVID-safe manner.MethodsWe implemented training of ‘Plan A’ blocks1. This included dedicated theatre space, ultrasound equipment and use of HDMI technology for projection. The training was delivered in small groups in a safe and socially distanced manner. Information about the delivery of content, participant satisfaction and confidence in block performance were collected using a survey. All teaching was delivered by a Consultant and trainee with interest in regional anaesthesia. Approval was obtained form the local audit department.ResultsData was collated after a four-month cycle of teaching. Attendees ranged from core trainees (67%) to junior registrars (33%). 95% participants found the content, hands on experience and presenters’ knowledge to be excellent. 86% of participants felt they had better confidence in their block skills after the training. Overall satisfaction with delivery of the training was recorded as excellent in 95% of candidates.ConclusionsContinuing regional anaesthesia training in the COVID-19 pandemic has been beneficial for trainees in terms of improvement in skills and to boost their morale. This has been particularly relevant as there has been a drive to reduce aerosol generating procedures and improve safety for anaesthetists and theatre staff2.

Background and Aims Recent opinion has suggested focusing training on a small number of ‘ Plan A blocks ’ to improve basic regional anaesthesia competence amongst non-regional enthusiasts 1 . We assessed trainee confidence performing Plan A blocks with indirect supervision. We also sort trainee opinion regarding which techniques should be designated as essential competencies and how our regional anaesthesia training could be improved. Methods We performed an email survey of all anaesthetic trainees within the East Midlands School of Anaesthesia exploring their confidence in performing regional anaesthesia. Results We received 40 trainee responses (7 CT1-CT2, 13 ST3-ST5, 20 ST6-ST7). Trainees confident in performing plan A blocks under indirect supervision were (numbers are expressed as% responses/total responding]): Interscalene 60 [24/40]; axillary 60 [24/40]; [NB1] femoral 87.5 40]; adductor canal 42.5 [17/40]; popliteal erector spinae 10 [4/40]; rectus sheath blocks 42.5 Trainees responding that individual blocks should be included as core competencies: Interscalene 87.2 [34/40]; axillary [33/40]; femoral 87.5 [35/40]; adductor canal 56.4 [22/40]; popliteal 76.9 [30/40]; erector spinae 10 rectus sheath [27/40].80% for regular local and to of essential

Background and AimsThere has been a significant impact on anaesthetic teaching and training within the UK owing to the COVID-19 pandemic. Most of the teaching needs are met using virtual methods. Hands on skills such as regional anaesthesia are not suitable for a virtual teaching format. Therefore, we aimed to continue and provide regional anaesthesia training in a large tertiary teaching hospital in a COVID-safe manner.MethodsWe implemented training of ‘Plan A’ blocks1. This included dedicated theatre space, ultrasound equipment and use of HDMI technology for projection. The training was delivered in small groups in a safe and socially distanced manner. Information about the delivery of content, participant satisfaction and confidence in block performance were collected using a survey. All teaching was delivered by a Consultant and trainee with interest in regional anaesthesia. Approval was obtained form the local audit department.ResultsData was collated after a four-month cycle of teaching. Attendees ranged from core trainees (67%) to junior registrars (33%). 95% participants found the content, hands on experience and presenters’ knowledge to be excellent. 86% of participants felt they had better confidence in their block skills after the training. Overall satisfaction with delivery of the training was recorded as excellent in 95% of candidates.ConclusionsContinuing regional anaesthesia training in the COVID-19 pandemic has been beneficial for trainees in terms of improvement in skills and to boost their morale. This has been particularly relevant as there has been a drive to reduce aerosol generating procedures and improve safety for anaesthetists and theatre staff2.

Background and Aims Anaesthesia and post-operative analgesia for patients undergoing total knee arthroplasty (TKA) has evolved over the last 20 years. Our aim was to carry out a quality improvement project to assess the benefit of motor sparing nerve blocks which includes the IPACK and low femoral triangle blocks1. We aimed to assess post-operative pain scores and analgesic requirements2. Methods We carried out a retrospective analysis of patients undergoing TKA including 46 patients after seeking approval from the local audit committee. We used medical notes to obtain patient characteristics, method of anaesthesia and analgesia provision, opiate consumption, and pain scores. Results 100% of patients had a spinal anaesthetic with 1 patient requiring conversion to GA. 41% of patients had a combined IPACK and low femoral triangle block. The remainder received LAI by the surgeon. The mean request for first opiate dose was earlier by 20 min in the block group. Opiate consumption was significantly lower in the first 24 hours by 21 mg OME. 90% had no to mild pain at 24 hours in the block group compared to 63% in the LIA group. Pain scores at 48 hours were similar in both groups. A multimodal approach to analgesia was used for all patients. Conclusions Motor sparing nerve blocks for patients undergoing TKA is beneficial in the first 24 hours with improved pain scores, reduced opiate consumption as well as surgeon satisfaction. We have implemented recommendations to add these to our ERAS pathway and aim to train anaesthetists in performing these blocks for all TKA patients.

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.

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.

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.

Key points•Shoulder surgery can be associated with severe postoperative pain.•Interscalene brachial plexus blockade is used to provide anaesthesia, analgesia, or both for shoulder surgery.•The beach chair position carries risks of compromising haemodynamic and cerebral function.•Selective peripheral nerve blockade provides alternative analgesia to interscalene blockade.•Operative pathways should integrate preoperative patient education, intraoperative regional anaesthesia, and multimodal postoperative analgesia.Learning objectivesBy reading this article you should be able to:•Plan the intraoperative conduct of shoulder surgery with the patient either awake, sedated, or using general anaesthesia.•Describe the steps required to safely perform interscalene brachial plexus blockade for shoulder surgery.•Describe the complications and adverse effects of interscalene nerve block.•Discuss the differences between regional anaesthetic techniques performed for anaesthesia to facilitate awake surgery and techniques used to provide postoperative analgesia. •Shoulder surgery can be associated with severe postoperative pain.•Interscalene brachial plexus blockade is used to provide anaesthesia, analgesia, or both for shoulder surgery.•The beach chair position carries risks of compromising haemodynamic and cerebral function.•Selective peripheral nerve blockade provides alternative analgesia to interscalene blockade.•Operative pathways should integrate preoperative patient education, intraoperative regional anaesthesia, and multimodal postoperative analgesia. By reading this article you should be able to:•Plan the intraoperative conduct of shoulder surgery with the patient either awake, sedated, or using general anaesthesia.•Describe the steps required to safely perform interscalene brachial plexus blockade for shoulder surgery.•Describe the complications and adverse effects of interscalene nerve block.•Discuss the differences between regional anaesthetic techniques performed for anaesthesia to facilitate awake surgery and techniques used to provide postoperative analgesia. The shoulder receives sensory innervation from the cervical (C3,4) and brachial plexuses (C5,6). The major motor and sensory innervation to the shoulder is from the suprascapular nerve (upper trunk of the brachial plexus) and axillary nerve (posterior cord of the brachial plexus). Minor sensory innervation is from the lateral pectoral, musculocutaneous, and subscapular nerves. The cutaneous supply to the cape of the shoulder, upper thoracic region and also a sensory contribution to the acromioclavicular and sternoclavicular joints is from the supraclavicular nerves (descending branches of the cervical plexus; C3,4). The cutaneous supply distal to the glenohumeral joint is from the superior lateral cutaneous nerve of the arm (from the axillary nerve), the medial cutaneous nerve of the arm (from the medial cord of the brachial plexus), and the lateral cutaneous branch of the second intercostal nerve. The prevalence of shoulder pain in the population is 7% overall, increasing to 26% in those aged >70 yrs.1Linsell L. Dawson J. Zondervan K. et al.Prevalence and incidence of adults consulting for shoulder conditions in UK primary care; patterns of diagnosis and referral.Rheumatology. 2006; 45: 215-221Crossref PubMed Scopus (231) Google Scholar Acromioplasty (sub-acromial decompression), stabilisation, adhesiolysis (release of frozen shoulder) and rotator cuff repair are the most common procedures undertaken, and these are usually performed arthroscopically. Open procedures include arthroplasty of the glenohumeral joint, which can be performed as a total or partial joint replacement, open stabilisation (e.g. Latarjet–Bristow procedures), open rotator cuff repair, and most trauma procedures. Total joint replacements are divided into anatomical or reverse procedures. In the latter, the ball-and-socket arrangement of the joint is reversed prosthetically in the presence of a deficient rotator cuff to provide a mechanical advantage to the remaining deltoid muscle. Shoulder arthroscopy is conducted via two or three ports, the position of which depends on the surgery being conducted. Typically, a posterior port is sited inferior and medial to the posterior-lateral aspect of the acromion and serves as a primary viewing portal, with anterior port, lateral port, or both (whose position is variable depending on the proposed surgery) gaining access to the joint for instrumentation. The standard approach for shoulder arthroplasty is an anterior skin incision running from the coracoid process along the deltopectoral line towards the deltoid tuberosity of the humerus. The beach chair position improves surgical access and reduces intraoperative venous pressure and associated bleeding. The lateral position allows the application of traction to the arm to improve surgical access. Both arthroscopic (particularly rotator cuff repair and stabilisation) and open shoulder surgery are associated with moderate to severe postoperative pain; surgery to the shoulder is one of the most painful procedures undertaken as a day case. Patients attending for shoulder surgery range from young adults with sporting injuries to older patients presenting with arthritic complications and trauma. Patients with diabetes mellitus have a higher incidence of frozen shoulder compared with the general population. Consistent preoperative verbal and written communication outlining the expected anaesthetic technique should be provided. Patients can be counselled about the regional anaesthetic; undergoing surgery while conscious; the anticipated postoperative recovery period and plan for pain management. Given that shoulder surgery generally results in significant postoperative pain requiring opioids, regional anaesthesia forms an important part of the anaesthetic technique by improving patient experience and increasing the success of day case pathways. Regional anaesthesia reduces operating theatre time, allows earlier discharge from (or bypassing of) the postanaesthesia care unit, and reduces postoperative complications such as pain, sedation, nausea, and vomiting, and the need for overnight stay.2Hadzic A. Williams B.A. Karaca P.E. et al.For outpatient rotator cuff surgery, nerve block anesthesia provides superior same-day recovery over general anesthesia.Anesthesiology. 2005; 102: 1001-1007Crossref PubMed Scopus (230) Google Scholar Regional anaesthesia can be used as a sole anaesthetic technique or it can be combined with general anaesthesia. At the authors' institutions, arthroscopic cases are performed routinely under regional blockade in conscious or sedated patients, whereas open surgery is usually performed using regional blockade supplemented with general anaesthesia. Undertaking shoulder surgery in conscious patients offers several advantages, summarised in Box 1.Box 1Potential advantages of conducting shoulder surgery in conscious patients.Tabled 1Avoidance of potential airway, respiratory, and cardiovascular complications of general anaesthesia (including reduction of hypotension in the 'beach-chair' position)Reduced postoperative nausea and vomitingFaster return to normal diet and medications in the postoperative periodEfficiency savings in time to institute and conduct general anaesthesia safelyIncreased engagement of patient in their care (patients able to see their pathology and observe their treatment on the monitor in real time) Open table in a new tab Tabled 1Avoidance of potential airway, respiratory, and cardiovascular complications of general anaesthesia (including reduction of hypotension in the 'beach-chair' position)Reduced postoperative nausea and vomitingFaster return to normal diet and medications in the postoperative periodEfficiency savings in time to institute and conduct general anaesthesia safelyIncreased engagement of patient in their care (patients able to see their pathology and observe their treatment on the monitor in real time) Open table in a new tab Despite the paucity of evidence to support the safety of performing nerve blocks in conscious compared with anaesthetised patients, nerve blocks for shoulder surgery at our institutions are performed with the patient awake, unless factors related to the patient render this inadvisable (e.g. a movement disorder). Anxiety is effectively allayed by preoperative education and communication from the anaesthetist during block performance. Midazolam 1–2 mg i.v. also exerts a useful anxiolytic effect while preserving the ability of the patient to communicate warning signs of impending nerve injury or local anaesthetic toxicity. Blockade of the brachial plexus at the interscalene groove has evolved substantially since Winnie's original landmark description and subsequent modifications (which were designed to reduce the risk of neuraxial injury and improve ease of catheter insertion). Elicited paraesthesiae and nerve stimulation are now rarely used as sole methods of localising nerves, having been superseded by visualisation of the relevant anatomy, needle-tip position and local anaesthetic spread using ultrasound. Peripheral nerve stimulation with or without pressure monitoring may be combined with ultrasound, but there is no direct evidence that any single or combined technique reduces the risk of peripheral nerve injury after regional anaesthesia.3Hewson D.W. Bedforth N.M. Hardman J.G. Peripheral nerve injury arising in anaesthesia practice.Anaesthesia. 2018; 73: 51-60Crossref PubMed Scopus (53) Google Scholar Ultrasound does, however, allow fewer needle passes, lower volumes of local anaesthetic, and better postoperative analgesia compared with nerve stimulation.4McNaught A. Shastri U. Carmichael N. et al.Ultrasound reduces the minimum effective local anaesthetic volume compared with peripheral nerve stimulation for interscalene block.Br J Anaesth. 2011; 106: 124-130Abstract Full Text Full Text PDF PubMed Scopus (118) Google Scholar Interscalene brachial plexus blockade (ISB) is typically conducted in an awake patient after verbal consent, institution of routine monitoring, and contralateral peripheral i.v. access. With the patient positioned 30° supine and the head slightly turned to the opposite side, expose the ipsilateral neck and perform skin asepsis. The anaesthetist, patient, and ultrasound machine should be ergonomically arranged to facilitate scanning and needling (Fig. 1). A high-frequency (e.g. 15–6 MHz) linear array ultrasound transducer is ideally suited to identify the superficial interscalene groove and relevant anatomy as it is rare that the structures of interest lie deeper than 4 cm. First, identify the subclavian artery lying in the supraclavicular fossa and obtain a short-axis view of the trunks of the brachial plexus lying posterior and superficial to the artery. Then scan superiorly to trace the plexus between the anterior and middle scalene muscles deep to the prevertebral fascia. The sternocleidomastoid muscle lies superficially, and the phrenic nerve may be seen passing over the anterior scalene muscle away from the C5 root scanning superior to inferior. More medial scanning reveals the internal jugular vein, carotid artery, thyroid gland, and trachea. Scanning superiorly from the subclavian artery, the upper and middle trunks of the plexus give way to the roots which appear as hypoechoic round structures, with the superficial C5 nerve root overlying the typically bifid C6 nerve root, and the C7 root passing onto its characteristic transverse process (Fig. 2). The vertebral artery can be identified anterior to the C7 transverse process using colour Doppler. The dorsal scapular nerve arises from the C5 nerve root and can often be seen as a hyperechoic structure traversing through the middle scalene muscle (Fig. 2), sometimes accompanied by the long thoracic nerve. Both must be avoided when needling. The characteristic ultrasound shapes of the cervical transverse processes can be successively demonstrated by scanning inferiorly to superiorly (Supplementary Figs S1a-g). Our preference is an in-plane posterior-lateral to anterior-medial approach using a 50 mm echogenic short-bevel needle, positioning the tip initially deep to the C6 nerve root or upper trunk and seeking spread of local anaesthetic anterior and posterior to the nerves within the interscalene groove. Re-positioning of the needle superficial to the C5 nerve root or upper trunk is often required to obtain satisfactory spread of local anaesthetic. We do not routinely needle between C5 and C6 (and certainly not between the bifid heads of C6) unless muscular bridges are preventing adequate spread. The ability to observe in real time the spread of local anaesthetic around the roots or upper trunk is a clear advantage of ultrasound guidance. After the injection of local anaesthetic (ropivacaine 0.75% 10–15 ml produces surgical anaesthesia in approximately 20 min) in the interscalene groove, the needle is withdrawn and passed superficial to the pre-vertebral fascia overlying the scalene muscles into the superficial cervical fascia deep to the sternocleidomastoid muscle. The supraclavicular nerve trunk can be traced superiorly to inferiorly from the C4 root, passing superficially and posteriorly over the middle scalene muscle, through the pre-vertebral fascia, before dividing into terminal branches within the superficial cervical fascia deep to the sternocleidomastoid muscle (Fig. 2).5Maybin J. Townsley P. Bedforth N. Allan A. Ultrasound guided supraclavicular nerve blockade: first technical description and the relevance for shoulder surgery under regional anaesthesia.Anaesthesia. 2011; 66: 1053-1055Crossref PubMed Scopus (19) Google Scholar A further injection of 2–3 ml local anaesthetic (without need to make a second skin puncture) targeting these nerves provides cutaneous anaesthesia and blocks their sensory contribution to the acromioclavicular joint for surgery.Fig 2Interscalene groove including dorsal scapular nerve in middle scalene muscle (MS) and supraclavicular nerve before division.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The phrenic nerve lies on the superficial surface of the anterior scalene muscle, close to the brachial plexus at the level of C5/6 before moving away from the plexus over the muscle surface inferiorly in the neck. Consequently, it is often blocked during the performance of an ISB. The duration is related to the type and mass of local anaesthetic administered. The incidence is reported as 100% with a traditional landmark based approach using volumes greater than 20 ml.6Urmey W.F. Talts K.H. Sharrock N.E. One hundred percent incidence of hemidiaphragmatic paresis associated with interscalene brachial plexus anesthesia as diagnosed by ultrasonography.Anesth Analg. 1991; 72: 498-503Crossref PubMed Scopus (426) Google Scholar Even with local anaesthetic dose reduction, the incidence of phrenic nerve palsy is approximately 25–50%.7Riazi S. Carmichael N. Awad I. Holtby R.M. McCartney C.J.L. Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block.Br J Anaesth. 2008; 101: 549-556Abstract Full Text Full Text PDF PubMed Scopus (280) Google Scholar Most healthy individuals remain asymptomatic and compensate for the unilateral reduction in diaphragmatic activity by using their intercostal and accessory muscles to maintain tidal volume. Forced expiratory volume in 1 s (FEV1) may be reduced by up to 40%, however, and patients with comorbidities, particularly obesity and respiratory disease, may develop troublesome dyspnoea. In rare cases some degree of ventilatory support may be needed. Physiological compensation means that pulse oximetry is not a sensitive test for identifying phrenic nerve dysfunction. Diaphragmatic ultrasound scanning, performed 15–30 min after the block, is a relatively simple bedside test that is more accurate.8El-Boghdadly K. Alberto Goffi M. Chan V. Point of care diaphragmatic ultrasonography made easy.Can J Anesth. 2017; 64: 327-328Google Scholar Identification of patients at high risk of deterioration from phrenic nerve palsy is essential. These patients are often the same group who would benefit from the avoidance of perioperative opioids and general anaesthesia. Although phrenic nerve palsy can be reduced by modifying the ISB technique, plans for possible postoperative respiratory support in a high dependency unit should be made for high risk patients. Intraoperative continuous positive pressure ventilation (CPAP) or high flow nasal oxygenation can be beneficial, and the authors have had success with these modalities prophylactically in patients with poor respiratory function and in the treatment of symptomatic dyspnoea. Persistent phrenic nerve dysfunction has been reported with a suggested incidence of approximately 1:2000.9Hogan Q.H. Phrenic nerve function after interscalene block revisited. now, the long view.Anesthesiol. 2013; 119: 250-252Crossref PubMed Scopus (25) Google Scholar The most likely pathophysiology is considered to be compressive neuropathy, and this may be amenable to surgical decompression.10Kaufman M. Elkwood A. Rose M. et al.Surgical treatment of permanent diaphragm paralysis after interscalene nerve block for shoulder surgery.Anesthesiol. 2013; 119: 484-487Crossref PubMed Scopus (39) Google Scholar ISB has previously been reported to be associated with a higher incidence of neurological dysfunction than many other peripheral blocks, with an incidence of temporary dysfunction up to 14% at 10 days in some series.11Borgeat A. Ekatodramis G. Kalberer F. Benz C. Acute and nonacute complications associated with interscalene block and shoulder surgery: a prospective study.Anesthesiol. 2001; 95: 875-880Crossref PubMed Scopus (398) Google Scholar In addition to peripheral nerve injury, neurological injury from cervical cord trauma has been described after landmark ISB was performed in an anaesthetised patient.12Benumof J. Permanent loss of cervical spinal cord function associated with interscalene block performed under general anesthesia.Anesthesiol. 2000; 93: 1541-1544Crossref PubMed Scopus (237) Google Scholar Although ultrasound guidance may mitigate this risk, the performance of ISBs in deeply sedated or anaesthetised patients should only be performed after an individual patient risk/benefit assessment. The spread of local anaesthetic to surrounding structures will produce predictable adverse effects such as transient Horner's syndrome (in approximately 50% of patients) and recurrent laryngeal nerve blockade. Although these are usually minor, they may be distressing to patients and it is prudent to mention them during the consent process. Horner's syndrome is common and produces ipsilateral ptosis, miosis, nasal congestion, and anhydrosis. Spontaneous resolution occurs after a few hours, and reassurance is all that is required. Recurrent laryngeal nerve blockade, caused by local anaesthetic spread over the anterior scalene muscle, results in a hoarse voice that is usually of no significant clinical consequence. Systemic local anaesthetic toxicity cause by absorption is rare, but the presence of vessels including the vertebral artery near to the roots of the plexus means that toxicity from intravascular injection is a possibility. The rapid delivery of local anaesthetic from the vertebral artery to the brain means that the presenting features are CNS adverse effects and convulsions. Careful needle visualisation (maintaining a superficial trajectory in relation to the C7 nerve root), aspiration before injection, incremental injection, and direct visualisation of local anaesthetic spread within tissues, all help prevent this complication. The incidence of hypotensive and bradycardic events is up to 20% during shoulder surgery.13Song S. Roh W. Hypotensive bradycardic events during shoulder arthroscopic surgery under interscalene brachial plexus blocks.Korean J Anesthesiol. 2012; 62: 209-219Crossref PubMed Scopus (25) Google Scholar These typically occur in the sitting position around 30 min after the placement of an ISB. The origin is multifactorial and may be a vasovagal response but the Bezold–Jarisch reflex is often implicated; high circulating concentrations of catecholamines and an underfilled, hypercontractile ventricle (induced by venous pooling in the sitting position) stimulates intramyocardial mechanoreceptors, resulting in an abrupt reduction in sympathetic tone together with increased vagal tone. Prompt treatment with an antimuscarinic (ideally atropine because of its rapid onset) with or without sympathomimetic drugs is indicated. Although ISB is the most commonly used regional anaesthetic technique for shoulder surgery, a number of other approaches have been investigated in an attempt to avoid unwanted adverse effects such as phrenic nerve blockade. The C5 and C6 nerve roots may be tracked distally in the interscalene groove, where they fuse to form the superior trunk. As the course of the suprascapular and transverse cervical arteries is highly variable, these vessels should be sought and their position noted before needling. Using a posterior-lateral to anterior-medial in-plane approach and a hydrodissection technique, the superior trunk may be surrounded with 10–15 ml local anaesthetic. This will effectively block the major nervous innervation to the shoulder joint. The suprascapular nerve originates from the superior trunk and moves laterally deep to omohyoid muscle (Fig. 3); the block is therefore performed proximal to this point. Although case reports indicate effective analgesia and absence of phrenic nerve blockade (because of the more distal approach), there are no prospectively randomised data to support this technique. We will often perform a superior trunk block if this provides a superior view (e.g. in a patient with a short neck). The supraclavicular brachial plexus block has also produced shoulder anaesthesia with similar analgesic effect to that of ISB, with a reduced incidence of adverse effects such as Horner's syndrome.14Ryu T. Kil B.T. Kim J.H. Comparison between ultrasound-guided supraclavicular and interscalene brachial plexus blocks in patients undergoing arthroscopic shoulder surgery: a prospective, randomized, parallel study.Medicine (Baltimore). 2015; 94: e1726Crossref PubMed Scopus (31) Google Scholar However, the risk of phrenic nerve block is not appreciably different to that of ISB, limiting its benefits in clinical practice.15Guo C.W. Ma J.X. Ma X.L. et al.Supraclavicular block versus interscalene brachial plexus block for shoulder surgery: a meta-analysis of clinical control trials.Int J Surg. 2017; 45: 85-91Crossref PubMed Scopus (15) Google Scholar In addition, a supraclavicular brachial plexus block risks missing the more proximally departing suprascapular nerve. Having placed an ISB, efficacy can easily be assessed by verifying motor weakness in the deltoid and biceps muscles (C5/6). Loss of sensation over the cape of the shoulder will confirm blockade of the supraclavicular nerves. Patients may then self-position on the operating table in either beach chair or in the lateral position with traction applied to the arm. We favour the beach chair position as it provides superior patient comfort during awake surgery. The drapes should be supported so that they do not lie on the patient's face, providing an option to view the surgical monitor during awake surgery. A pillow positioned under the knees also reduces stretch on the hamstrings and increases comfort in awake patients (Fig. 4). A proportion of patients' supraclavicular nerve distribution will not cover the posterior port site, so subcutaneous infiltration of long-acting local anaesthetic should be placed before starting surgery. Once started, the anaesthetist or surgeon can engage and inform the patient by describing the surgery. A proportion (in our experience, 10–20%) of patients will experience intraoperative pain at some point. Having discussed this with patients before operation, a dose of alfentanil i.v. will allow surgery to continue in virtually all patients by providing analgesia without disinhibition. Bradycardia and hypotension (described above) must be managed rapidly to prevent severe bradycardia, syncope secondary to decreased cerebral perfusion, or both. For those patients requesting sedation, the authors prefer to use midazolam boluses and propofol via target-controlled infusion with supplemental oxygen and monitoring of exhaled CO2. At the end of surgery, awake patients can reposition (with support) onto the bed. If general anaesthesia is planned in the beach chair position, care should be taken to pad and support the heels and arms. The head is placed and secured in a specific support with the neck optimally positioned. One benefit of the beach chair position is that airway management with a supraglottic airway is often sufficient (the authors prefer second-generation devices); these also have the advantage of being less stimulating during head movement that occurs during surgical traction on the arm. Spontaneous respiration or pressure-support ventilation decreases the reduction of venous return and resulting hypotension associated with the beach chair position and mandatory positive pressure ventilation. The head-up nature of the beach chair position has been implicated in producing cerebral ischaemia secondary to hypotension or thromboembolic events;16Pohl A. Cullen D. Cerebral ischemia during shoulder surgery in the upright position: a case series.J Clin Anesth. 2005; 17: 463-469Crossref PubMed Scopus (240) Google Scholar therefore, the authors prefer to maintain blood pressure during general anaesthesia close to baseline values, appreciating the vertical distance of the head above the heart. A vasopressor infusion may be used to achieve this. Careful surgical dissection is also vital to avoid air embolus. In addition to standard monitoring, titration of anaesthetic depth using depth of anaesthesia monitoring may be advantageous to reduce hypotension secondary to deep anaesthesia. Although it is not part of our routine practice, cerebral oxygen saturation monitoring has also been used in the beach chair position to try and ensure adequate cerebral blood flow during surgery. Most patients who have undergone arthroscopic shoulder surgery can be discharged home on the day of surgery. After shoulder surgery, most patients will be discharged with their arm in an adjustable supporting sling. All patients should be instructed to protect the insensate limb from accidental damage until the ISB has worn off. Despite the excellent immediate postoperative analgesia provided by a regional anaesthetic technique, one fifth of patients report their postoperative pain after shoulder surgery as 'the worst pain imaginable' once the block has worn off.17Wilson A.T. Nicholson E. Burton L. Wild C. Analgesia for day-case shoulder surgery.Br J Anaesth. 2004; 92: 414-415Abstract Full Text Full Text PDF PubMed Scopus (77) Google Scholar It is therefore vital to ensure that patients begin a multimodal oral analgesic regimen before the block has worn off. Paracetamol and a non-steroidal anti-inflammatory agent (unless contraindicated) should be provided. Strong opioids are often required in the first 48 h after block resolution, and the majority of patients cope well with titrating immediate release oral morphine at home. Major shoulder procedures such as arthroplasty are associated with moderate to severe postoperative pain which outlasts the typical 12–24 h of analgesia provided by single injection ISB. Postoperative continuous infusion of local anaesthetic into the interscalene groove via a perineural catheter reduces both rest and dynamic shoulder pain and opioid consumption compared with single injection ISB and is associated with higher patient satisfaction.18Vorobeichik L. Brull R. Bowry R. Laffey J.G. Abdallah F.W. Should continuous rather than single-injection interscalene block be routinely offered for major shoulder surgery? A meta-analysis of the analgesic and side-effects profiles.Br J Anaesth. 2018; 120: 679-692Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar Catheter insertion may be performed either in-plane or out-of-plane according to operator preference. Although overall complication rates are low, the consequences of interscalene catheter malposition or dislodgement may be significant.19Yanovski B. Gaitini L. Volodarski D. Ben-David B. Catastrophic complication of an interscalene catheter for continuous peripheral nerve block analgesia.Anaesthesia. 2012; 67: 1166-1169Crossref PubMed Scopus (35) Google Scholar For this reason, the catheter tip position should be verified with ultrasound and a test bolus of local anaesthetic with or without adrenaline administered while the patient is still in a monitored environment. If the catheter and tip is difficult to visualise, small 'pulses' of fluid can be detected using Doppler-mode ultrasound. Injection of a tiny volume of air or manual 'wiggling' of the catheter can also help confirm position. Secure fixation is essential and a number of methods including skin glue, specialist anchor dressings, and tunneling have all been described to prevent dislodgement. Skin glue is additionally helpful in preventing leakage of local anaesthetic from the skin puncture site. Interscalene catheter placement is an advanced technique requiring skilled operators for block placement and the infrastructure to monitor and troubleshoot the infusion after surgery. Pharmacological adjuncts such as dexamethasone can prolong analgesia following single injection ISB to 20–24 h, and for many anaesthetists this offers an acceptable compromise between extended duration and ease of technique. This can be performed by the surgeon at the end of the procedure, either as a single injection of 20–40 ml local anaesthetic or accompanied by placement of a catheter. Such techniques are of marginal, if any, clinical benefit however and carry a risk of iatrogenic chondrolysis. Blockade of the suprascapular nerve provides an alternative to ISB for postoperative analgesia in patients who receive general anaesthesia for surgery. The early postoperative analgesia provided by suprascapular nerve blockade is inferior to that of ISB but superior to intra-articular infiltration.20Singelyn F.J. Lhotel L. Fabre B. Pain relief after arthroscopic shoulder surgery: a comparison of intraarticular analgesia, suprascapular nerve block, and interscalene brachial plexus block.Anesth Analg. 2004; : 589-592Google Scholar The suprascapular nerve may be blocked posteriorly in the supraspinatus fossa or anteriorly as it exits the upper trunk of the plexus and moves laterally deep to the omohyoid muscle (Fig. 3). Combining selective suprascapular nerve with axillary nerve block21Price D. The shoulder block: a new alternative to interscalene brachial plexus blockade for the control of postoperative shoulder pain.Anaesth Intensive Care. 2007; 35: 575PubMed Google Scholar provides superior analgesia to suprascapular nerve block alone.22Lee J.J. Kim D.-Y. Hwang J.-T. et al.Effect of ultrasonographically guided axillary nerve block combined with suprascapular nerve block in arthroscopic rotator cuff repair: a randomized controlled trial.Arthrosc J Arthrosc Relat Surg. 2014; 30: 906-914Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar As all nerves innervating the shoulder are not blocked, this technique is unsuitable for awake surgery but is reserved as an analgesic alternative to ISB. The axillary nerve may be blocked by imaging the posterior surface of the humerus just distal to the humeral head. The posterior circumflex humeral artery and axillary nerve may be seen at this point, and local anaesthetic is injected deep to the deltoid muscle. A volume of 5–7 ml may be sufficient to travel proximally through the quadrilateral space to block the axillary articular supply to the shoulder.23Price D. How I do it: ultrasound-guided combined suprascapular and axillary nerve block.Am Soc Reg Anesth Pain Med News. 2013; 13: 22-25Google Scholar The axillary nerve may alternatively be targeted by an infraclavicular approach also aiming to block the subscapular, musculocutaneous, and lateral pectoral nerves and thus achieve fairly complete shoulder analgesia with a low incidence of phrenic nerve palsy. At present evidence is limited to case reports,24Casanova M.G. Choi S. McHardy P.G. Ultrasound-guided posterior cord and selective suprascapular block for shoulder surgery.Br J Anaesth. 2016; 117: 835Abstract Full Text Full Text PDF PubMed Scopus (3) Google Scholar, 25Vagh F. Baker E. Arndt C. Billstrand M.M. Anterior approach to the suprascapular nerve.Reg Anesth Pain Med. 2017; 42: 680Google Scholar and further larger-scale studies are warranted to establish effectiveness compared with ISB. Up to 40% of patients may fail to demonstrate either sensory or motor block after combined suprascapular and axillary nerve block, and in our experience this limits its role compared with the very reliable and reproducible ISB. The authors declare that they have no conflicts of interest. The associated MCQs (to support CME/CPD activity) will be accessible at www.bjaed.org/cme/home by subscribers to BJA Education. The following are the Supplementary data to this article: Supplementary Fig 1 Characteristic ultrasound appearance of respective cervical transverse processes. (Figs S1a and S1 b) C7 transverse process acoustic shadow with posterior tubercle and absent anterior tubercle. Note the C5, C6, and C7 nerve roots superficial to the transverse process. (Figs S1c and S1d) Colour Doppler applied to the C7 transverse process demonstrating the proximity of the vertebral artery. (Figs S1e and S1f) C6 transverse process acoustic shadow with less prominent posterior tubercle (PT) and more prominent anterior tubercle (AT); also known as Chassaignac's tubercle. Note the C5 and C6 nerve roots superficial to the transverse process. (Figs S1g and S1h) C5 transverse process acoustic shadow with prominent posterior tubercle (PT) and less prominent anterior tubercle (AT). Note the C5 nerve root superficial to the transverse process.https://www.bjaed.org/cms/asset/0894dcd2-bdb5-459d-91bc-b56da033adf7/mmc1.mp4Loading ... Download .mp4 (6.83 MB) Help with .mp4 files Video 1Interscalene brachial plexus block prescan. Prescan for interscalene brachial plexus block. Scan the plexus from inferior to superior, observing the formation of the trunks, the superficial supraclavicular nerves coalescing, and the nerves passing through the middle scalene muscle. If reading the pdf online, click on the image to view the videohttps://www.bjaed.org/cms/asset/9cc0d9dd-2c1a-42c4-a248-fbed98827a81/mmc2.mp4Loading ... Download .mp4 (3.66 MB) Help with .mp4 files Video 2Supraclavicular trunk and divisions prescan. Prescan for the supraclavicular trunk and divisions. Scan from superior to inferior starting superior to the C5 nerve root. The supraclavicular nerve is seen passing superficially and posteriorly before dividing into terminal branches within the superficial cervical fascia. If reading the pdf online, click on the image to view the video.eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiIzNDY5MjhhYWM2ZmNiMzc3NGFkZDNjODY1MGRhYTJhZCIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc5NDEzODMzfQ.dEBktawztvfURnA1aweU8wakyoD3g69L0UyvPEBPYbc1yTJbqKjXkVl-111Qn42vHM6d1KnhwkTO3qlDCwONPCwH5tDNukQvFQrfW7Ypwz4xynOT9HEtydkj0_ZlqsyIT0Jg8AiGxTA3JiN-LCd8ZNdp1Nzl9MQ2J7aTRP_9k4X2Ukb4jqU2xvn-cn6hBYah9O4hPBSj-iR1DxrRnhBs9BvygUsTTyMG3-F840bsHbRKNyk2XPJFCpzUVrZ0PK8hjZAFzM0N-QAnitwywObaYbkfYU8LIxtcC6iFYJ2OhwqmXTnKYQVLJkmJ8T82kZg8A4rWSM9FHjWwgV8K1fJvXA Download .mp4 (5.19 MB) Help with .mp4 files Video 3Suprascapular nerve prescan. Prescan to observe the suprascapular nerve departing posteriorly from the upper trunk. Scan inferiorly from the upper trunk to observe the suprascapular nerve departing posteriorly underneath the omohyoid muscle. If reading the pdf online, click on the image to view the video.https://www.bjaed.org/cms/asset/545c5491-a2c8-4742-9fb7-cc16b8ee4b38/mmc4.mp4Loading ... Download .mp4 (9.9 MB) Help with .mp4 files Video 4Interscalene brachial plexus block placement 1. Short axis (view of the nerves), in-plane (needle with respect to the transducer) needle insertion technique. Local is placed deep to C6 root. If reading the pdf online, click on the image to view the video.eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiI3M2I5ZjFlODc0NWJjYzRmNjgzNWJlZGFmODY3M2YxNiIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc5NDEzODMzfQ.dhbJF_H195wIffeo7NXlU0YTgJphHeM9lX1ouc1fF4jVlhvxNccV7o2fc2ucMZf8sArV308JBt2YLiTuHCMb6LDk35Ve01qiR9c8yHXPX_lHVgLxvpjfYXKUdfVzH76NhEmoUuwfF9DysdTxFsw9_Yi8LdH8_AWbcr3auYn8JS8QOTbbrl1hkDpxMHgJWrk1lhgwrbWTSaV3Qd3QmTpynWWOTYGH7ZtZS381C_HWKN6Sl6DJURImJTGPUWHLT2Vby96KndsDJRgKufJkZ-1ZrgrAmscyMEzrb7qbIzjTa6OVsXsGK5nzKTfZFW818V_h2ptEgNIW4SQLyxs0b4ln6A Download .mp4 (9.07 MB) Help with .mp4 files Video 5Interscalene brachial plexus block placement 2. Local anaesthetic is placed around C5 nerve root. If reading the pdf online, click on the image to view the video.eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJhYmY0ZWUyZjBkZjhmYjhkZWViOTY1ODJiODNlNDkwNiIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc5NDEzODMzfQ.eh-GHZUvoy8wNCfTrlZhpv2QuHCfgsyugUK35Mc7I0MxmOvaFw29bEZUt2b-F3eThSwX47JStOn6iC1symiM2buCcoYZnVtZePbb35GyF-ZlyOFUxlKkFA0zYCgJDxiW0XciTrzC9DJ7bvqiFIC31EpCBSo5LlH19uCw07W3CI0SAAPiGiVJZXPJXti2aK1m36sa6c0Ks14xhcQHBxXjFZdQoOfjTaPWYnwepmoBhiEdAFVa8yauWk5_vcvKZe0OqSM6toch6nDA4Yl0hek6flq-I4umus6lPUMXyLPyw13bmxqy6hFvKtgxQWM74xc4gViUPxPT9WccrNZZtU5Z1Q Download .mp4 (9.76 MB) Help with .mp4 files Video 6Interscalene brachial plexus block placement 3. Local anaesthetic is placed around the supraclavicular nerve branches within the superficial cervical fascia. If reading the pdf online, click on the image to view the video.Fig. S1BView Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. S1CView Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. S1DView Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. S1EView Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. S1FView Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. S1GView Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig. S1HView Large Image Figure ViewerDownload Hi-res image Download (PPT) David Hewson BSc (Hons) PGCert FHEA FRCA is a consultant anaesthetist and honorary assistant professor in Nottingham with clinical and research interests in regional anaesthesia, sedation practice, and patient experience. He is a current NIHR Investigator undertaking research into sedation with propofol. Matt Oldman FRCA PGCert EDRA is a consultant anaesthetist in Plymouth who has clinical interests in orthopaedic and regional anaesthesia. He is a former secretary of Regional Anaesthesia UK and a current examiner for the European Diploma in regional anaesthesia. He teaches ultrasound-guided regional anaesthesia in the UK and internationally. Nigel Bedforth BMedSci FRCA a consultant anaesthetist and honorary associate professor in Nottingham whose clinical interests include regional and orthopaedic anaesthesia. His research interests include training in regional anaesthesia and patient experiences during regional anaesthesia. He is a current NIHR Principal Investigator.

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.

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.

Editor, Interscalene brachial plexus block (ISBPB) provides excellent anaesthesia for arthroscopic shoulder surgery; allowing surgery to be performed awake and avoiding the risks of general anaesthesia. ISBPB can be associated with dyspnoea and hypoxaemia due to hemidiaphragmatic paresis caused by transient phrenic nerve blockade (PnB).1 Although these changes are usually well tolerated in healthy individuals, obese patients are at increased risk from the deleterious respiratory effects of PnB.2 Continuous positive airway pressure (CPAP) is a mode of noninvasive ventilation used to manage obstructive sleep apnoea, acute hypoxaemic respiratory failure and cardiogenic pulmonary oedema. In healthy volunteers, CPAP has been shown to increase tidal volume, and alter diaphragmatic kinetics and breathing patterns.3 The effect of CPAP on respiratory dynamics in the context of ISBPB is unknown. Our hypothesis in this proof-of-concept study was that the use of CPAP in obese patients undergoing awake shoulder surgery under ISBPB would result in measurable changes in peri-operative respiratory parameters, ipsilateral diaphragm displacement and subjective markers of dyspnoea. Ethics Ethical approval for this study was provided by the NHS West of Scotland Research Ethics Committee (Reference: 18/WS/0033) of West Glasgow Ambulatory Care Hospital, Glasgow, Scotland (Chairperson Dr Ken James) on 5 March 2018. The study was registered at The Research Registry (Ref: 3073). Method Written informed consent was obtained from all patients. Adults at least 18 years old with a BMI more than 30 kg m−2, scheduled for awake shoulder arthroscopy under ISBPB were eligible to participate. Exclusion criteria were contraindication to use of ISBPB, requirement for supplementation of ISBPB with general anaesthesia or contraindication to the use of a CPAP device. A convenience sample of 10 sequential patients meeting the inclusion criteria was agreed to demonstrate proof-of-concept. After routine monitoring and intravenous access were established, a baseline assessment of respiratory rate, arterial oxygen saturation, subjective dyspnoea (using the Borg Dyspnoea Scale)4 and diaphragmatic excursion was made. All diaphragm assessments were performed by the same member of the study team (TF) using a subcostal approach in a 45° semirecumbent position using a 5 to 2 MHz curvilinear transducer (Sonosite SII; SonoSite Inc., Bothwell, Washington, USA), in B-mode and M-mode, applied in a longitudinal parasagittal orientation in the anterior axillary line.5 After ultrasound-guided, in-plane needle insertion with respect to the ultrasound transducer, ISBPB was then performed using a 15 to 6 MHz linear array transducer (Sonosite SII; SonoSite Inc.) and a 50-mm echogenic short-bevelled needle (Stimuplex Ultra; B.Braun Melsungen AG, Melsungen, Germany). All patients received between 15 and 20 ml of local anaesthetic as part of their ISBPB, consisting of either a mixture of 10 ml of 2% lidocaine and 10 ml of 0.5% levobupivacaine, or 15 to 20 ml of 0.75% ropivacaine (according to the anaesthetists’ preference), aiming to deposit local anaesthetic around the C5 to C6 nerve roots. Following demonstration of ISBPB efficacy (loss of ability to abduct the shoulder and cutaneous sensation over the shoulder), respiratory assessments were repeated. CPAP (Flow-Safe II; Mercury Medical, Clearwater, Florida, USA) was then started to provide positive airway pressure of 8 to 9 cmH2O. Once the device had been established for 5 min, a third set of assessments was made. Surgery was then conducted with patients awake or lightly sedated in the deckchair position. Results The study began on 23 April 2018 and by 1 August 2018, 10 patients had been recruited. Baseline ipsilateral hemidiaphragmatic movement was demonstrated on M-mode ultrasound scanning to be normal in all patients prior to ISBPB (Fig. 1a). Following the ISBPB, all patients demonstrated ipsilateral hemidiaphragmatic paresis (Fig. 1b), which improved following the application of CPAP (Fig. 1c). Quantification of results is shown in Table 1. All patients underwent surgery awake in the deckchair position with no adverse events detected.Fig. 1: M-mode ultrasound image of ipsilateral hemidiaphragm (visualised as hyperechoic line) during deep breathing. (a) Prior to performance of interscalene brachial plexus block. (b) After interscalene brachial plexus block before application of continuous positive airway pressure. (c) After interscalene brachial plexus block and after application of continuous positive airway pressure.Table 1: Effect of interscalene brachial plexus block without and with continuous positive airway pressure on hemidiaphragmatic movement and respiratory variablesDiscussion To our knowledge, this is the first report describing this clinical application of a CPAP device. Several advantages of this single-use CPAP system became apparent during our study. The device can be attached to the auxiliary oxygen flowmeter of anaesthesia machines, provides an in-line manometer to facilitate precise CPAP titration and can accompany patients from the operating theatre to the postanaesthesia care unit if further ventilatory support is required. Other noninvasive ventilatory strategies such as Bilevel positive airway pressure and nasal high-flow oxygen are available; however, these are comparatively more expensive, requiring additional equipment and training. A number of ‘phrenic-sparing’ ISBPB techniques have been described.6,7 Although such modifications are useful in reducing PnB, our experience is that they reduce the efficacy of the ISBPB in providing surgical anaesthesia for awake shoulder surgery. It is our experience that patients with respiratory comorbidity or obesity are most likely to suffer from the adverse effects of PnB but also benefit most from avoiding a general anaesthetic technique. The authors acknowledge that the current study is subject to several limitations in design. This was a single-centre proof-of-concept study of a single-use CPAP device. We did not attempt to generate comparison with a control group, and patient and outcome assessors were not blinded. As with many disposable CPAP systems, the device used in this study is unable to deliver precise fractional inspired oxygen (FIO2) concentrations. The manufacturers estimate that when set to generate a positive pressure of 8 to 9 cmH2O, the device delivers an FIO2 of approximately 0.6 (personal correspondence). This relatively high FIO2 may, in itself, account for the improvement in subjective dyspnoea scores and arterial oxygen saturations during the study period. High FIO2 does not account, however, for the improvement in diaphragmatic excursion after CPAP was applied. We believe that future work is warranted to compare the effects of intra-operative CPAP against a group receiving standard clinical care in the form of supplemental oxygen delivered by variable performance facemask to determine comparative effects on subjective and objective markers of respiratory function. Acknowledgements relating to this article Assistance with the study: none. Financial support and sponsorship: this study was supported by departmental funding. Conflicts of interest: none.

Editor, Many patients experience anxiety when undergoing awake procedures.1 Procedural anxiety is an intrinsically negative experience and is associated with deleterious surgical outcomes such as postoperative pain.2 Target-controlled infusion of propofol is a popular choice for intra-operative sedation because of the drug's favourable pharmacokinetic profile. However, anaesthetists have been shown to be inaccurate in judging patients’ pre-operative anxiety.3 This could result in insufficient or excessive dosing of sedation in relation to the actual anxiolytic requirements of individual patients. One possibility for overcoming this is allowing patients to exert control over the depth of their sedation. The aim of this study was to examine the ability of patients to sedate themselves using effect-site targeted (Cet), patient-maintained propofol sedation (PMPS) under the supervision of an anaesthetist in lower limb orthopaedic surgery performed under spinal anaesthesia. Ethical approval for this study was provided by NHS Research Ethics Committee Wales 6 (Reference: 16/WA/0080) on 17 March 2016. The study was registered on Research Registry (Reference: 2521). We obtained written consent from all individuals. Reviews of previously published studies suggested that a convenience sample of 25 patients would provide useful data regarding the technique. Inclusion criteria were age more than 18 years presenting for elective lower limb orthopaedic surgery, expressing a pre-operative preference for surgery to be performed under regional anaesthesia with sedation. Exclusion criteria were inability to use a hand-held button, need for surgery to be conducted under general anaesthesia, contraindication to the use of propofol and inability to communicate in English. After establishing routine monitoring and intravenous access, a spinal anaesthetic using 12 to 15 mg of hyperbaric bupivacaine was performed. After confirming sensory block to T10, we commenced a Cet PMPS regimen using Schnider modelling4 (Alaris PK; Carefusion, Basingstoke, UK). We gave patients a hand-held button indicating a request for deepening of sedation. We asked individuals to ‘press the button if you feel anxious or want to be more sleepy’. On hearing a beep indicating a button-press, a study investigator adjusted the Cet according to a standardised protocol. We commenced the Cet at 0.5 μg ml−1 and incremented this by 0.2 μg ml−1 up to a maximum of 2.0 μg ml−1. We ignored repeat button-presses until the calculated effect-site concentration was equal to the target. If patients did not press the button for 6 min, we reduced the Cet by 0.1 μg ml−1. At the end of surgery, we discontinued the sedation and transferred patients to the postanaesthetic care unit, recording the time taken to achieve a modified Aldrete Score at least 9. We administered a postoperative questionnaire seeking feedback on the use of the sedation system and general narrative responses. Twenty-six patients received PMPS between 26 May 2016 and 22 March 2017. There were no instances of adverse physiological disturbance (>20% deviation from baseline before spinal anaesthesia), airway compromise or apnoea during the sedation. The median (interquartile range, IQR [range]) modified Wilson sedation score during surgery for all patients was 2 (1 [1 to 4]). The mean (SD) calculated effect-site concentration during surgery for all patients was 0.73 (0.32) μg ml−1, and the mean (SD) maximum calculated effect-site concentration was 0.89 (0.48) μg ml−1. Fourteen patients used the button a median (IQR [range]) of 6 (6 [1 to 29]) times; the remaining 12 patients chose not to press the button. Median (IQR [range]) time to Aldrete Score at least 9 was 6 (14 [1 to 58]) min. Figure 1 shows patients were able to alter their depth of sedation according to personal preference. There was a positive correlation (ρ = 0.76) between calculated effect-site concentration of propofol and depth of sedation measured using the modified Wilson Sedation Scale.Fig. 1: Calculated effect-site concentration of propofol during sedation for four patients. Patient 1 (dotted line), patient 2 (solid line), patient 3 (dashed line), patient 4 (double line).Patient 1 appeared anxious pre-operatively and chose to achieve a deep level of sedation as soon as the button was provided. Patient 2 initially chose not to press the button, but when surgery commenced, with associated noise, decided to deepen the sedation. Patient 3 used the button intermittently throughout the procedure and maintained a steady depth of sedation. Patient 4 appeared relaxed for most of surgery and did not press the button until the noisy siting of the knee prosthesis, at which point the sedation was deepened. Narrative responses on the sedation regime included ‘it was comforting to know that you could do it if you wanted to’ and ‘although I didn’t use the button I liked knowing that I could have if I had wanted to’. There were no negative narrative responses. When asked whether they felt they were sedated to the right level, 25 out of 26 patients recorded: ‘I felt I was sedated at the right level’. One patient recorded: ‘I cannot remember’. Median (IQR [range]) 10-point numeric rating scale response was 10 (1.4 [5 to 10]) for satisfaction with sedation. When asked if they would use the same sedation technique again, 25 out of 26 patients responded with ‘very likely’ or ‘likely’, one patient responded ‘unsure’. By applying PMPS in the setting of spinal anaesthesia, we have shown that the technique is useful wherein the hypnotic-anxiolytic properties of propofol can be tailored to the anxiety of individual patients in a procedure associated with no intra-operative pain. Our study suggests that an upper limit of 2.0 μg ml−1 in nonpainful procedures is sufficient for the purposes of anxiolysis. Our study replicates the previous findings of high levels of satisfaction with PMPS.5,6 The narrative responses from patients also suggest a degree of empowerment felt by holding a control button. Further studies should address the extent to which this feeling of empowerment translates into reduced procedural anxiety. Conclusions drawn from data arising from observational trials on the safety and utility of anaesthetic techniques must be interpreted carefully.7 Although our work reports no incidences of physiological compromise, a much larger sample size is required to provide evidence regarding the safety of this technique. We have, however, demonstrated that PMPS can deliver individualised procedural sedation for patients presenting for elective lower-limb orthopaedic surgery under spinal anaesthesia with a high degree of patient satisfaction. Future research should develop and obtain regulatory approvals for the investigation of fully automated systems capable of patient-maintained propofol sedation. Acknowledgements relating to this article Assistance with the study: we are grateful to the Research Nurses of the Department of Research and Education (Critical Care, Acute Medicine and Emergency Department), Nottingham University Hospitals NHS Trust, for their efforts during data collection. Financial support: this study was supported by a research grant from B.Braun Melsungen AG. B. Braun Mesungen AG has no role in the study design, data collection, data analysis, decision to publish or preparation of the manuscript. Conflicts of interest: none.