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Ultrasound guidance is now common in regional anaesthesia practice, but remains limited by poor visibility of the needle tip and poor quantification of local anaesthetic spread. Sonoelastography based on tissue compression is a technique depicting tissue strain. Hitherto used largely for tumour diagnosis, we used it in both Thiel embalmed cadavers and two patients receiving interscalene and femoral blocks to observe changes in tissue strain during local anaesthetic injection. The primary aim of our study was to measure the area under the curve (weighted for time) of the strain pattern in Thiel perineural tissue when using a range of volumes of embalming fluid (0.25, 0.5, 1, 2.5, 5 and 7.5 ml) for interscalene and femoral blocks using sonoelastography. Our secondary aims were to evaluate static images of anatomy and videos of needle insertion and perineural injection using combined B-Mode ultrasound and sonoelastography. Independent raters assessed the anatomy and spread using a 7-point Likert scale, ranked from extremely poor to extremely good. We performed 83 blocks in cadavers. Concordance between both raters was good, with weighted Kappa (95% CI) 0.66 (0.61-0.71). The characteristics of spread were similar with both interscalene and femoral block; spread increased with injectate volume up to 1 ml. Analysis of variance showed differences in spread between injection volumes (p = 0.009), but not between regional blocks (p = 0.05). Post-hoc analysis showed greater spread with 1 and 2.5 ml volumes compared with 0.25 ml. In patients, visibility of strain during injection was better with sonoelastography than with B-Mode ultrasound and showed a dose response from 1 to 5 ml volumes of local anaesthetic. Colour strain recognition using sonoelastography offers the ability to differentiate between nerve and surrounding tissue during local anaesthetic injection by improving visibility of spread (p = 0.04). [ABSTRACT FROM AUTHOR]

Background: We investigated the intraneural spread of injected fluid in brachial plexus nerve roots, examining the potential for intrafascicular spread and identifying influencing factors., Methods: Twelve deliberate ultrasound-guided intraneural injections were performed at the ventral rami of the brachial plexus nerve roots at their exits from the neuroforamina in six fresh, unembalmed, cryopreserved human cadavers. A 22-G, 30-degree bevel echogenic regional anaesthesia needle was used. Each injection contained 1 ml of heparinised erythrocytes as a marker. Nerve swelling observed on ultrasound images confirmed intraneural injection., Results: Intraneural spread was observed in 12 ventral rami of the six brachial plexi: C5 (1), C6 (3), C7 (5), C8 (2), and T1 (1). Among these, intrafascicular spread was detected in eight cases, six in monofascicular roots and two in bifascicular roots, though none in roots with three or more fascicles. The fascicle diameters in these cases (2.1-3.8 mm) were at least twice the diameter of the needle orifice, measured at 0.9 mm, which was entirely inside the fascicles. In the four cases with intraneural but without intrafascicular spread, the fascicle diameters were about two times the diameter of the needle orifice in three instances, but the entire needle orifice was not always inside a fascicle., Conclusions: In contrast with multifascicular peripheral nerves, intrafascicular spread was possible after deliberate intraneural injections near the neuroforaminal canal exit of the brachial plexus nerve roots in several monofascicular or bifascicular ventral rami if the fascicle diameter was more than twice the needle opening length and the entire opening was inside the fascicle., Competing Interests: Declaration of interest The authors declare no conflicts of interest., (Copyright © 2024 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Study Objectives: Seizures are rare in rapid eye movement (REM) sleep. However, seizures sometimes occur in REM sleep, and a small number of focal epilepsy patients display their maximum rate of interictal epileptiform discharges in REM sleep. We sought to systematically identify and characterize seizures in REM sleep., Methods: We reviewed all admissions to the epilepsy monitoring unit at the Winnipeg Health Sciences Center over 12 months in 2014-2015. American Academy of Sleep Medicine sleep-stage scoring was initially applied in the standard 30-second epochs. Then, to capture sudden changes in sleep-wake state on shorter timescales that are associated with seizure formation and propagation, we rescored ictal and peri-ictal electroencephalography epochs every 1 second. Patients found to have seizures in REM sleep were subject to chart review spanning 3 years pre- and postadmission., Results: REM sleep seizures occurred in 3 of 63 patients admitted to the epilepsy monitoring unit. Notably, 1 patient exhibited continuous epileptiform activity, consistent with focal nonconvulsive electrographic status epilepticus, throughout REM sleep cycles for each night of her admission. Otherwise, discrete REM sleep seizures constituted a small fraction of the other patients' total seizures (range 5.0-8.3%), occurred shortly after REM sleep onset from stage N2 sleep, and were manifest as minor epileptic arousals., Conclusions: Our results confirm that REM sleep seizures are rare, while highlighting outliers who widen the known spectrum of heterogeneous sleep effects on seizures/epilepsy. We also report, to our knowledge, the first case of paradoxical status epilepticus in REM sleep., Citation: McLeod GA, Szelemej PA, Toutant D, McKenzie MB, Ng MC. Dreams interrupted: characteristics of REM sleep-associated seizures and status epilepticus. J Clin Sleep Med. 2025;21(1):23-32., (© 2025 American Academy of Sleep Medicine.)

Background: Chronic pain management is challenging. Those with chronic pain present to health professionals, including osteopaths., Methods: Secondary analysis of a cross-sectional survey of the Osteopathy Research Connect - New Zealand (ORC-NZ), a practice-based research network (PBRN). Demographic, practice, and treatment characteristics of osteopaths who 'often' and 'not often' treat chronic pain patients were collected., Results: Two hundred and seventy-seven (277) NZ osteopaths responded and just over half (50.7% N  = 138) reported 'often' treating chronic pain patients. This group, who have a similar male-to-female ratio, often use a diagnostic screening questionnaire (aOR 3.78), and often treat patients with non-musculoskeletal complaints (aOR 3.12) and tendinopathies (aOR 3.41)., Conclusions: This study highlights practice and clinical management characteristics of NZ osteopaths who manage chronic pain patients.

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., Competing Interests: Competing interests: EA: grants from Swiss Academy for Anesthesia Research, Bbraun, Swiss National Science Foundation. Honoraria from Bbraun and Sintetica. JG: consulting fees from Pacira Biosciences and Pajunk Medical. AP: honoraria from FuijiFilm Sonosite. MW: advisory Board for Sintetica, Honoraria from Wisonic and Medovate. SA: Advisory Panel for DATAR innovations. JA: moderator of the Working Group Regional Anaesthesia Switzerland, Honoraria from Medtronic and Sintetica. AMRA: honoraria form AllerganSébastien Bloc—Consulting fees from BBraun—GE Medical Systems—Pajunk—Pfizer SAS. JB: Consulting fees from Intelligent Ultrasound. BC: jonoraria from Bbraun and Rivanna, Consulting from Stryker and Flat Medical, Research funding from Pacira, Share Options from Flat Medical. AC: speaking honoraria from GE Healthcare, royalties from textbook Oxford University Press. SC: consulting fees from MSD, Bbraun Medical, Wisonic, research grants from BARA (Belgian association of Regional anesthesia), ESRA and BeSARP (Belgian anesthesia society) HE-Consulting/Advisory Board Neuronoff, SPR, GateScience, NeuronoffBenjamin Fox—Speaking fees from Medovate and Sintetica. SG: consulting and speaking fees from MSD Switzerland. PH: royalties from Bestek Products. NH: Honoraria from Butterfly Network. RMGH- Honoraria from GE Healthcare. MH: consulting fees from Pacira Biosciences, Honoraria from Parcira Biosciences and Pajunk Medical. BMI: research funding to institution from SPR Therapeutics, Infutronix, Epimed International. AM: Consultant fees from Intelligent Ultrasound. CM: consultant fees from Masimo Corporation. SGM: Owner SGM Consulting, Partner Parvizi Surgical Innovations, Patent for Multicatheter infusion system. AN: Research support from SPR Therapeutics. SLO: Royalties from book Wolters-Kluwer. APawa: Honoraria from GE Healthcare, Consulting fees from Pacira Biosciences. PP: equipment support from Sonosiite Fujifilm Canada. MPS: Medovate speaking but no honoraria paid. SKS- Cofounder of Gate Science (developing a catheter for performing nerve blocks) JS: consulting fees from Sintetica. RT: Consulting fees from Clarius Mobile Health. VU: Associate Editor of the Canadian Journal of Anesthesia and Regional Anesthesia & Pain Medicine journals. TV: honoraria from CSL Behring, Pajunk., (© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Health professionals develop their own approach to patient care based on education, experience and philosophical stance. Literature suggests that this practice approach informs patient care, and clinical outcomes. The Osteopaths' Therapeutic Approaches Questionnaire (Osteo-TAQ) is a novel 36-item instrument developed from qualitative grounded theory research with osteopaths in the United Kingdom. The aim of the study was to develop evidence for the structural and construct validity of the Osteo-TAQ in the Australian osteopathic profession and provide initial descriptive data about the therapeutic approaches of osteopaths in Australia., Methods: A cross-sectional study design was used to collect data from registered osteopaths in Australia using the Osteo-TAQ and analysed with Exploratory Factor Analysis (EFA). The EFA utilised parallel analysis to determine the number of factors to extract and McDonald's omega calculated as the reliability estimation statistic., Results: 691 Australian osteopaths provided data for the study, representing 25% of the Australian osteopathic profession. Empirically the number of factors to extract based on the parallel analysis was seven. Two- and three-factor solutions were evaluated given the underpinning theory identifying two conceptions of practice and three interrelated therapeutic approaches. Both the two- and three-factor solutions were consistent with the underpinning theory with acceptable reliability estimations for each factor. Descriptive data suggested the most common element of the therapeutic approach of Australian osteopaths was establishing rapport, while the least common was 'only talking' with their patients., Conclusions: This study provides evidence for the structural, content and construct validity of the Osteo-TAQ in an Australian osteopathic practitioner population. The results support both a two- and three-factor structure for the Osteo-TAQ in an Australian osteopathic population, with each factor demonstrating acceptable reliability estimations supporting the items comprising each factor as measuring a single construct. From a theoretical and empirical perspective, it can be inferred that the Osteo-TAQ tool encapsulates an osteopaths' conception of practice (professional artistry and technical rational) and three main therapeutic approaches to patient care: Educator, Communicator and Treater. Further research is required to explore each of these therapeutic approaches to better understand how they relate to an individual osteopath's conception of practice, and their associations with other measures of practice including clinical outcomes., (© 2024. The Author(s).)

Postmortem histology and in vivo, animal-based ultra-high-definition microultrasound demonstrate a complex array of non-communicating adipose tissue compartments enclosed by fascia. Classic nerve block mechanisms and histology do not consider this tissue. Injected local anesthetic agents can occupy any of these adipose compartments, which may explain the significant differences in outcomes such as success rates, onset time, block density, duration of nerve block, and secondary continuous block failure. Furthermore, these adipose tissue compartments may influence injection pressures, making conclusions about needle tip location unreliable. This educational review will explain the neural anatomy associated with these fatty compartments in detail and suggest how they may affect block outcomes., Competing Interests: Competing interests: AB invented perineural catheters (StimuCath, TheraCath, and UltraCath) for which he received royalties from Arrow International and later, after 2007, from TeleFlex Medical for their sales for the duration of the patents, which have now expired. All other authors declare no conflict of interest., (© American Society of Regional Anesthesia & Pain Medicine 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Study Objective: We previously designed and validated a virtual reality-based simulator to help train novices in ultrasound-guided needling skills necessary for safe and competent ultrasound-guided regional anaesthesia. This study was designed to compare the performance and error rates of novices trained by a human faculty aided with the assistance of this virtual reality simulator (virtual reality-assisted training), versus novices trained wholly by humans (conventional training)., Design, Setting, and Participants: In this single centre, randomised controlled study, we used a standardised teaching protocol, rigorous blinding, iterative training of assessors, and validated global rating scale and composite error score checklists to assess skills learning of novice participants., Main Results: We recruited 45 novices and scored 270 assessments of performance and error rates. Inter-rater correlation coefficient of reliability of scoring between assessors for the global rating scale was 0.84 (95%CI 0.68-0.92) and for the composite error score checklist was 0.87 (95%CI 0.73-0.93). After adjustment for age, sex, Depression, Anxiety and Stress-21, and baseline score, there was no statistical difference for virtual reality-assisted training compared to conventional training in final global rating score (average treatment effect -3.30 (95%CI-13.07-6.48), p = 0.51) or in the final composite error score (average treatment effect 1.14 (95%CI -0.60-2.88), p = 0.20). Realism in the virtual reality simulator was similar to real-life when measured by the Presence Questionnaire, all components p > 0.79; and task workload assessed by the NASA-Task Load Index was not statistically different between groups, average treatment effect 5.02 (95%CI -3.51-13.54), p = 0.25. Results were achieved in the virtual reality-assisted group with half the human faculty involvement., Conclusion: Novices trained using a hybrid, virtual reality-assisted teaching program showed no superiority to novices trained using a conventional teaching program, but with less burden on teaching resources., Competing Interests: Declaration of competing interest None., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Fluid injection pressure measurement is promoted as a marker of needle tip position that discriminates between tissue layers. However, clinical ultrasound has insufficient resolution to identify the exact position of the needle tip. Our primary objective was to use 40 MHz ultrasound in anesthetized pigs in order to precisely locate the tip of the needle and measure opening injection pressure in muscle, at epineurium and in subepineurium., Methods: We surgically exposed the axillae of four anesthetized pigs. Two operators placed a 40 MHz ultrasound transducer over the pectoral muscle and imaged axillary, median and radial nerves. Injections (0.5 mL) were randomized to in-plane and out-of-plane needle trajectories and flow rates of 1, 6 and 12 mL/min., Results: We identified 541 fascicles in 23 nerves. The ratio of fascicle area to nerve area remained constant at ~0.30 for all nerves. Axillary nerves were smaller than median and radial nerves, difference in diameter (95% CI) 1.61 (0.87 to 2.36) mm, p<0.001 and 1.59 (0.82 to 2.36) mm, p=0.001, respectively. Axillary nerves had less fascicles per nerve than median nerves, difference 7.63 (2.43 to 12.83) and radial nerves, difference 9.02 (3.64 to 14.40). We visualized the circumneurium and injection within the subcircumneural compartment. Intraneural injection increased nerve area (SD) from 5.7 (2.2) mm 2 to 13.7 (5.5) mm 2 , difference 8.0 (5.4-10.6) mm 2 , p<0.001. Mean injection pressure was greater in subepineurium compared with muscle, geometric ratio 2.29 (1.30 to 4.10), p<0.001; and greater on epineurium compared with muscle, geometric ratio 1.73 (1.03 to 3.00), p=0.01. Twenty-two out of 23 injections in muscle, 14 out of 23 injections at epineurium and 11 out of 22 injections in subepineurium were <138 kPa (20 psi)., Conclusion: Needle tip position was not discernible using pressure monitoring. The circumneurium and subcircumneural injection compartment were observed but not intrafascicular injection., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Various neurologic manifestations have been reported in patients with COVID-19, mostly in retrospective studies of patients admitted to hospital, but there are few data on patients with mild COVID-19. We examined the frequency and persistence of neurologic/neuropsychiatric symptoms in patients with mild COVID-19 in a 1-year prospective cohort study, as well as assessment of use of health care services and patient-reported outcomes., Methods: Participants in the Alberta HOPE COVID-19 trial (hydroxychloroquine v. placebo for 5 d), managed as outpatients, were prospectively assessed 3 months and 1 year after their positive test result. They completed detailed neurologic/neuropsychiatric symptom questionnaires, the telephone version of the Montreal Cognitive Assessment (T-MoCA), the Kessler Psychological Distress Scale (K10) and the EuroQol EQ-5D-3L (measure of quality of life). Close informants completed the Mild Behavioural Impairment Checklist (MBI-C) and the Informant Questionnaire on Cognitive Decline in the Elderly. We also tracked use of health care services and neurologic investigations., Results: The cohort consisted of 198 participants (87 female [43.9%] median age 45 yr, interquartile range 37-54 yr). Of the 179 participants with symptom assessments, 139 (77.6%) reported at least 1 neurologic symptom, the most common being anosmia/dysgeusia (99 [55.3%]), myalgia (76 [42.5%]) and headache (75 [41.9%]). Forty patients (22.3%) reported persistent symptoms at 1 year, including confusion (20 [50.0%]), headache (21 [52.5%]), insomnia (16 [40.0%]) and depression (14 [35.0%]); 27/179 (15.1%) reported no improvement. Body mass index (BMI), a history of asthma and lack of full-time employment were associated with the presence and persistence of neurologic/neuropsychiatric symptoms; female sex was independently associated with both (presence: odds ratio [OR] adjusted for age, race, BMI, history of asthma and neuropsychiatric history 5.04, 95% confidence interval [CI] 1.58 to 16.10). Compared to participants without persistent symptoms, those with persistent symptoms had more hospital admissions and family physician visits, and worse MBI-C scores and less frequent independence for instrumental activities at 1 year (83.8% v. 97.8%, p = 0.005). Patients with any or persistent neurologic symptoms had worse psychologic distress (K10 score ≥ 20: adjusted OR 12.1, 95% CI 1.4 to 97.2) and quality of life (median EQ-5D-3L visual analogue scale rating 75 v. 90, p < 0.001); 42/84 (50.0%) had a T-MoCA score less than 18 at 3 months, as did 36 (42.9%) at 1 year. Participants who reported memory loss were more likely than those who did not report such symptoms to have informant-reported cognitive-behavioural decline (1-yr MBI-C score ≥ 6.5: adjusted OR 15.0, 95% CI 2.42 to 92.60)., Interpretation: Neurologic/neuropsychiatric symptoms were commonly reported in survivors of mild COVID-19, and they persisted in 1 in 5 patients 1 year later. Symptoms were associated with worse participant- and informant-reported outcomes. Trial registration: ClinicalTrials.gov, no. NCT04329611., Competing Interests: Competing interests: Aravind Ganesh reports membership on the editorial boards of Neurology, Stroke and Neurology Clinical Practice; consulting fees and honoraria from Atheneum, MD Analytics, Figure 1, MyMedicalPanel, Creative Research Designs, CTC Communications Corp, Alexion and Biogen; research support from Alberta Innovates, Campus Alberta Neuroscience, the Canadian Cardiovascular Society, the University of Calgary (Hotchkiss Brain Institute), the Sunnybrook Research Institute INOVAIT program and the Canadian Institutes of Health Research (CIHR), outside the submitted work; and stock/stock options from SnapDx and Let’s Get Proof. He has a patent application (US 17/317,771) for a system for prehospital patient monitoring/assessment and delivery of remote ischemic conditioning or other cuff-based therapies. Ryan Rosentreter reports the same patent application (US 17/317,771). Luanne Metz reports grant funding from the MS Society of Canada, outside the submitted work. Eric Smith reports grant funding from the CIHR, Brain Canada and the Weston Brain Institute, outside the submitted work; consulting fees from Bayer, Biogen and Javelin Technologies; royalties from UpToDate; and payment from the American Heart Association for work as associate editor of Stroke. Michael Hill is a director of the Canadian Neurological Sciences Federation and the Canadian Stroke Consortium. He reports consulting fees from BrainsGate; industry grant support to the University of Calgary from NoNO, Biogen, Medtronic and Boehringer-Ingelheim Canada; and public grant support to the University of Calgary from Alberta Innovates, CIHR, the Heart & Stroke Foundation of Canada, and the National Institute of Neurological Disorders and Stroke. He reports a patent to US Patent office (US 62/086,077) issued and licensed. He owns stock in PureWeb. No other competing interests were declared., (© 2023 CMA Impact Inc. or its licensors.)

Background and Aims: Bystanders should be protected against aerosols, droplets, saliva, blood and vomitus during resuscitation after cardiac arrest The SARUS (safer - airway - resuscitation) CPR airway hood™ is a clear plastic cover and integrated mask that envelopes the head and torso. Our objectives were to test leakage using saline aerosol generation tests, then assess the performance of the hood during mock cardio-pulmonary resuscitation on a manikin., Methods: A checklist was validated by comparing the performance of 10 novices against 10 experts during mock resuscitation. Thereafter, 15 novices were tested with and without the hood, in a randomised cross-over study, one week apart., Results: Laboratory analysis showed a > 99% reduction of saline particles detected 5 cm, 75 cm and 165 cm above volunteers wearing the hood. On manikins, experts scored better compared to novices, 8.5 (0.7) vs 7.6 (1.2), difference (95%CI) 0.9 (0.4-1.3), P = 0.0004. Novice performance was equivalent using the hood and standard equipment, 7.3 (1.4) vs 7.3 (1.1) respectively, difference (90%CI) 0.0 (-0.3 - 0.3), P = 0.90., Conclusion: Aerosol transmission reduced in the breathing zone. Simulated resuscitation by novices was equivalent with and without the hood.

Introduction: Shear wave elastography (SWE) presents nerves in colour, but the dimensions of its colour maps have not been validated with paired B-Mode nerve images. Our primary objective was to define the bias and limits of agreement of SWE with B-Mode nerve diameter. Our secondary objectives were to compare nerve area and shape, and provide a clinical standard for future application of new colour imaging technologies such as artificial intelligence., Materials and Methods: Eleven combined ultrasound-guided regional nerve blocks were conducted using a dual-mode transducer. Two raters outlined nerve margins on 110 paired B-Mode and SWE images every second for 20 s before and during injection. Bias and limits of agreement were plotted on Bland-Altman plots. We hypothesized that the bias of nerve diameter would be <2.5% and that the percent limits of agreement would lie ±0.67% (2 SD) of the bias., Results: There was no difference in the bias (95% confidence interval (CI) limits of agreement) of nerve diameter measurement, 0.01 (-0.14 to 0.16) cm, P = 0.85, equivalent to a 1.4% (-56.6% to 59.5) % difference. The bias and limits of agreement were 0.03 (-0.08 to 0.15) cm 2 , P = 0.54 for cross-sectional nerve area; and 0.02 (-0.03 to 0.07), P = 0.45 for shape. Reliability (ICC) between raters was 0.96 (0.94-0.98) for B-Mode nerve area and 0.91 (0.83-0.95) for SWE nerve area., Conclusions: Nerve diameter measurement from B-Mode and SWE images fell within a priori measures of bias and limits of agreement., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2022.)

Despite advances in needle positioning techniques, nerve damage still occurs after regional anesthesia. Recognized causes include local anesthetic toxicity, subperineural injection, high subepineural fluid injection pressures and subepineural hematoma after forceful needle--nerve contact.We hypothesize that subperineural injection is still possible, but less likely to be the cause of nerve damage because needle penetration of fascicles and mechanical damage is difficult to achieve. High-resolution (75 µm) 40 MHz micro-ultrasound images of pig axillae show short-bevelled 22 g, 0.7 mm wide block needles that are three times larger than the average fascicle. Fascicular bundles are extremely difficult to puncture because they spin away on needle contact. Histology from fresh cadavers after supposed intrafascicular injection shows fluid spread within perineurium and intrafascicular perineural septae, but no breach of endoneurium or axons.We propose that mechanotransduction, the cellular changes that occur in response to force, contributes to nerve damage. Piezo ion channel proteins transduce force into electrical activity by rapid entry of cations into cells. Excessive Ca 2+ influx into cells has the potential to inhibit nerve regeneration. Cellular changes include regulation of gene expression. The forces associated with purposeful needle insertion are generally unknown. Our experiments in the soft embalmed Thiel cadaver showed a lognormal range of forces between 0.6 N and 16.8 N on epineural penetration.We hypothesize that forceful needle injury may cause nerve damage by activation of Piezo receptors and release of intracellular Ca 2 ., Competing Interests: Competing interests: None declared., (© American Society of Regional Anesthesia & Pain Medicine 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Study Objectives: To compare estimated epileptic source localizations from 5 sleep-wake states (SWS): wakefulness (W), rapid eye movement sleep (REM), and non-REM 1-3., Methods: Electrical source localization (sLORETA) of interictal spikes from different SWS on surface EEG from the epilepsy monitoring unit at spike peak and take-off, with results mapped to individual brain models for 75% of patients. Concordance was defined as source localization voxels shared between 2 and 5 SWS, and discordance as those unique to 1 SWS against 1-4 other SWS., Results: 563 spikes from 16 prospectively recruited focal epilepsy patients across 161 day-nights. SWS exerted significant differences at spike peak but not take-off. Source localization size did not vary between SWS. REM localizations were smaller in multifocal than unifocal patients (28.8% vs. 54.4%, p = .0091). All five SWS contributed about 45% of their localizations to converge onto 17.0 ± 15.5% voxels. Against any one other SWS, REM was least concordant (54.4% vs. 66.9%, p = .0006) and most discordant (39.3% vs. 29.6%, p = .0008). REM also yielded the most unique localizations (20.0% vs. 8.6%, p = .0059)., Conclusions: REM was best suited to identify candidate epileptic sources. sLORETA proposes a model in which an "omni-concordant core" of source localizations shared by all five SWS is surrounded by a "penumbra" of source localizations shared by some but not all SWS. Uniquely, REM spares this core to "move" source voxels from the penumbra to unique cortex not localized by other SWS. This may reflect differential intra-spike propagation in REM, which may account for its reported superior localizing abilities., (© The Author(s) 2022. Published by Oxford University Press on behalf of Sleep Research Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

In this study, we measured the performance of medical students and anaesthetists using a new tracker needle during simulated sciatic nerve block on soft embalmed cadavers. The tracker needle incorporates a piezo element near its tip that generates an electrical signal in response to insonation. A circle, superimposed on the ultrasound image surrounding the needle tip, changes size and colour according to the position of the piezo element within the ultrasound beam. Our primary objective was to compare sciatic block performance with the tracker switched on and off. Our secondary objectives were to record psychometrics, procedure efficiency, participant self-regulation and focused attention using eye-tracking technology. Our primary outcome measures were the number of steps successfully performed and the number of errors committed during each block. Videos were scored by trained experts using validated checklists. Sequential tracker activation and deactivation was randomised equally within subjects. With needle activation, steps improved in 10 (25%) subjects and errors reduced in six (15%) subjects. The most important steps were: needle tip identification before injection, OR (95%CI) 2.12 (1.61-2.80; p < 0.001); and needle tip identification before advance of the needle, 1.80 (1.36-2.39; p < 0.001). The most important errors were: failure to identify the needle tip before injection, 2.40 (1.78-3.24; p < 0.001); and failure to quickly regain needle tip position when tip visibility was lost, 2.03 (1.5-2.75; p < 0.001). In conclusion, needle-tracking technology improved performance in a quarter of subjects., (© 2020 Association of Anaesthetists.)

The current fourth industrial revolution is a distinct technological era characterised by the blurring of physics, computing and biology. The driver of change is data, powered by artificial intelligence. The UK National Health Service Topol Report embraced this digital revolution and emphasised the importance of artificial intelligence to the health service. Application of artificial intelligence within regional anaesthesia, however, remains limited. An example of the use of a convoluted neural network applied to visual detection of nerves on ultrasound images is described. New technologies that may impact on regional anaesthesia include robotics and artificial sensing. Robotics in anaesthesia falls into three categories. The first, used commonly, is pharmaceutical, typified by target-controlled anaesthesia using electroencephalography within a feedback loop. Other types include mechanical robots that provide precision and dexterity better than humans, and cognitive robots that act as decision support systems. It is likely that the latter technology will expand considerably over the next decades and provide an autopilot for anaesthesia. Technical robotics will focus on the development of accurate sensors for training that incorporate visual and motion metrics. These will be incorporated into augmented reality and visual reality environments that will provide training at home or the office on life-like simulators. Real-time feedback will be offered that stimulates and rewards performance. In discussing the scope, applications, limitations and barriers to adoption of these technologies, we aimed to stimulate discussion towards a framework for the optimal application of current and emerging technologies in regional anaesthesia., (© 2021 Association of Anaesthetists.)

The accuracy and reliability of ultrasound are still insufficient to guarantee complete and safe nerve block for all patients. Injection of local anaesthetic close to, but not touching, the nerve is key to outcomes, but the exact relationship between the needle tip and nerve epineurium is difficult to evaluate, even with ultrasound. Ultrasound has insufficient resolution, tissues are difficult to discern due to acoustic impedance and needles are more difficult to see with increased angulation. The limitations of ultrasound have shifted the focus of innovation towards bio-markers that help detect needle tip position by utilising the physical properties of tissues, (e.g. pressure, electrical, optics, acoustic and elastic). Although most are at the laboratory stage and results are as yet only available from phantom or cadaver studies, clinical trials are imminent. For example, fine optical fibres placed within the lumen of block needles can measure needle tip pressure. Electrical impedance differentiates between intraneural and perineural needle tip placement. A new tip tracker needle has a piezo element embedded at its distal end that tracks the needle tip in-plane and out-of-plane as a blue/red or green circle depending on its relative location within the beam. Micro-ultrasound at the tip of the needle is in development. Early images using 40MHz in anaesthetised pigs reveal muscle striation, distinct epineurium and 30-40 fascicles > 75 micron in diameter. The next few years will see a technological revolution in tip-tracking technology that has the potential to improve patient safety and, in doing so, change practice., (© 2021 Association of Anaesthetists.)

Epilepsy is a common and debilitating neurological disease. When medication cannot control seizures in up to 40% of cases, surgical resection of epileptogenic tissue is a clinically and cost- effective therapy to achieve seizure freedom. To simultaneously resect minimal yet sufficient cortex, exquisite localization of the epileptogenic zone (EZ) is crucial. However, localization is not straightforward, given relative difficulty of capturing seizures, constraints of the inverse problem in source localization, and possible disparate locations of symptomatogenic vs. epileptogenic regions. Thus, attention has been paid to which state of vigilance best localizes the EZ, in the hopes that one or another sleep-wake state may hold the key to improved accuracy of localization. Studies investigating this topic have employed diverse methodologies and produced diverse results. Nonetheless, rapid eye movement sleep (REM) has emerged as a promising sleep-wake state, as epileptic phenomena captured in REM may spatially correspond more closely to the EZ. Cortical neuronal asynchrony in REM may spatially constrain epileptic phenomena to reduce propagation away from the source generator, rendering them of high localizing value. However, some recent work demonstrates best localization in sleep-wake states other than REM, and there are reports of REM providing clearly false localization. Moreover, synchronistic properties and basic mechanisms of human REM remain to be fully characterized. Amidst these uncertainties, there is an urgent need for recording and analytical techniques to improve accuracy of localization. Here we present a systematic review and quantitative analysis of pertinent literature on whether and how REM may help localize epileptogenic foci. To help streamline and accelerate future work on the intriguing anti-epileptic properties of REM, we also introduce a simple, conceptually clear set-theoretic framework to conveniently and rigorously describe the spatial properties of epileptic phenomena in the brain., (Copyright © 2020 McLeod, Ghassemi and Ng.)

Despite growing use of critical care electroencephalography (ccEEG) to detect seizures and status epilepticus in the intensive care unit (ICU), integrating ccEEG findings with traditionally described benign EEG variants (BEVs) is a relatively new concept. BEV-like waveforms are now increasingly encountered in the ICU, and have also been explicitly included in proposed definitions of brief potentially ictal rhythmic discharges (BIRDs) in the ICU, bringing to the fore the question of if and which EEG patterns in critically ill patients can be safely deemed "benign". Though well-characterized as benign in healthy outpatients at low pre-test risk for neurologic disease, the significance of BEVs in the ICU remains largely unknown. Simultaneously, there has been mounting evidence to suggest that certain BEVs can arise from heterogeneous intracranial sources, including some pathologic generators. We conducted an extensive literature review on all known BEVs to assess what is known of BEVs in the ICU. Here we discuss critically ill BEVs and how to interpret them., Competing Interests: Declaration of Competing Interest None of the authors have potential conflicts of interest to be disclosed., (Copyright © 2020 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.)

Visibility of the needle tip is difficult to maintain during ultrasound-guided nerve block. A new needle has been developed that incorporates a piezo element 2-2.3 mm from the tip, activated by ultrasound. The electrical signal manifests as a coloured circle surrounding the needle tip, and allows real-time tracking. We hypothesised that novice regional anaesthetists would perform nerve block better with the tracker turned on rather than off. Our primary objective was to evaluate the new needle by measuring the performance of novice anaesthetists conducting simulated sciatic block on the soft embalmed Thiel cadaver. Training consisted of a lecture, scanning in volunteers and practice on cadavers. Testing entailed scanning the sciatic nerve of a cadaver and conducting 20 in-plane sciatic blocks in the mid-to-upper thigh region. Subjects were randomised equally, in groups of five, according to the sequence: tracker on/off/on/off; or tracker off/on/off/on. Video recordings were assessed by six raters for steps performed correctly and errors committed. Eight subjects were recruited and 160 videos were analysed. Using the tracking needle, five correct steps improved and one error reduced. The benefits included: better identification of the needle tip before advancing the needle, OR (95%CI) 3.4 (1.6-7.7; p < 0.001); better alignment of the needle to the transducer, 3.1 (1.3-8.7; p = 0.009); and better visibility of the needle tip 3.0 (1.4-7.3; p = 0.005). In conclusion, use of the tracker needle improved the sciatic block performance of novices on the soft embalmed cadaver., (© 2019 Association of Anaesthetists.)

Background: There is limited literature that explores the experiences of osteopaths injured while engaging in clinical practice. Evidence from other similar health professions has described the numerous effects of work-related musculoskeletal injuries (WRMI). Work-related musculoskeletal injury refers to trauma to joints, ligaments, muscles and tendons resulting from injury sustained while undertaking work duties. This research aimed to gain a contextualised understanding of the experiences of osteopaths who have sustained a work-related musculoskeletal injury while performing clinical practice., Method: This research used a descriptive qualitative design. Participants were recruited as part of a larger cross-sectional study. Thirteen Australian osteopaths who had sustained a work-related musculoskeletal injury consented to participate in semi-structured interviews during May and June 2016. Thematic analysis was used to elicit important themes from the interview transcripts that had been recorded and transcribed verbatim. The qualitative accounts provided by the participants were coded for the impacts of their injuries on work, home life and leisure activities., Results: The participants provided detailed, contextual information about their injuries, including the contributing factors and the experience of living with a WRMI. The findings indicate that injured osteopaths often continue working because of financial commitments and their dedication to patient care. The participants offered insights into the challenges they faced due to the injury and the management strategies they used to deal with the impact on their work and personal life. The injuries were mostly unreported, the burden being carried by the participants and their families., Conclusion: This is the first research that explores the experiences of osteopaths who have sustained a WRMI. We anticipate that this research will encourage a broad and constructive discussion within the profession of the issues associated with WRMIs, including risk minimisation and injury prevention. Further research is warranted to understand the relationship between osteopaths training in ergonomics and injury prevention. This would lead to the development of guidelines and educational curricula addressing safe work for osteopaths.

Background: The incidence of intraneural injection during trainee anaesthetist ultrasound guided nerve block varies between 16% in experts and up to 35% in trainees. We hypothesized that elastography, an ultrasound-based technology that presents colour images of tissue strain, had the potential to improve trainee diagnosis of intraneural injection during UGRA, when integrated with B-Mode ultrasound onto a single image., Methods: We recorded 40 median nerve blocks randomly allocated to 0.25 ml, 0.5 ml, 1 ml volumes to five sites, on both arms of two soft embalmed cadavers, using a dedicated B-Mode ultrasound and elastography transducer. We wrote software to fuse elastogram and B-Mode videos, then asked 20 trainee anaesthetists whether injection was intraneural or extraneural when seeing B-Mode videos, adjacent B-Mode and elastogram videos, fusion elastography videos or repeated B-Mode ultrasound videos., Results: Fusion elastography improved the diagnosis of intraneural injection compared with B-Mode ultrasound, Diagnostic Odds Ratio (DOR) (95%CI) 21.7 (14.5 - 33.3) vs DOR 7.4 (5.2 - 10.6), P < 0.001. Compared with extraneural injection, intraneural injection was identified on fusion elastography as a distinct, brighter translucent image, geometric ratio 0.33 (95%CI: 0.16 - 0.49) P < 0.001. Fusion elastography was associated with greater trainee diagnostic confidence, OR (95%CI) 1.89 (1.69 - 2.11), P < 0.001, and an improvement in reliability, Kappa 0.60 (0.55 - 0.66)., Conclusions: Fusion elastography improved the accuracy, reliability and confidence of trainee anaesthetist diagnosis of intraneural injection., (© The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Posterior variants of abdominal wall block include the quadratus lumborum type I, quadratus lumborum type II and quadratus lumborum transmuscular blocks. Our objectives were to compare the spread of injectate and nerve involvement, after conducting blocks using ultrasound guidance in soft embalmed cadavers., Methods: After randomization, an experienced anaesthetist conducted three quadratus lumborum 1, three quadratus lumborum 2 and four transmuscular blocks on the left or right sides of five cadavers. All cadavers were placed in the lateral position and the quadratus lumborum muscle seen using a 3-9 MHz ultrasound probe placed in the flank. For each block, a 20 ml mixture of 17.75 ml water, 2 mls latex and 0.25 ml India ink was injected. The lumbar region and abdominal flank were dissected 72 h later., Results: We conducted 10 blocks. Two quadratus lumborum 1 and two quadratus lumborum 2 blocks were associated with spread of dye within the TAP plane. One quadratus lumborum 1 block spread to the deep muscles of the back and one quadratus lumborum 2 block dispersed within the subcutaneous tissue surrounding the abdominal flank. All transmuscular quadratus lumborum blocks spread consistently to L1 and L3 nerve roots and within psoas major and quadratus lumborum muscles., Conclusions: Consistent spread to lumbar nerve roots was achieved using the transmuscular approach through the quadratus lumborum., (© The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: We evaluated the physical properties and functional alignment of the soft-embalmed Thiel cadaver as follows: by assessing tissue visibility; by measuring its acoustic, mechanical and elastic properties; by evaluating its durability in response to repeated injection; and by aligning images with humans., Methods: In four soft-embalmed Thiel cadavers, we conducted three independent studies. We assessed the following factors: (i) soft tissue visibility in a single cadaver for 28 weeks after embalming; (ii) the displacement of tissues in response to 1 and 5 ml interscalene and femoral nerve blocks in a single cadaver; and (iii) the stiffness of nerves and perineural tissue in two cadavers. We aligned our findings with ultrasound images from three patients and one volunteer. Durability was qualified by assessing B-mode images from repetitive injections during supervised training., Results: There was no difference in visibility of nerves between 2 and 28 weeks after embalming {geometric mean ratio 1.13 [95% confidence interval (CI): 0.75-1.68], P=1.0}. Mean tissue displacement was similar for cadaver femoral and interscalene blocks [geometric mean ratio 1.02 (95% CI: 0.59-1.78), P=0.86], and for 1 and 5 ml injection volumes [geometric mean ratio 0.84 (95% CI: 0.70-1.01), P=0.19]. Cadavers had higher intraneural than extraneural stiffness [Young's modulus; geometric mean ratio 3.05 (95% CI: 2.98-3.12), P<0.001] and minimal distortion of anatomy when conducting 934 left-sided interscalene blocks on the same cadaver throughout a 10 day period., Conclusions: The soft-embalmed Thiel cadaver is a highly durable simulator that has excellent physical and functional properties that allow repeated injection for intensive ultrasound-guided regional anaesthesia training., (© The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

We compared the McGrath MAC(®) videolaryngoscope when used as both a direct and an indirect laryngoscope with a standard Macintosh laryngoscope in patients without predictors of a difficult tracheal intubation. We found higher median Intubation Difficulty Scores with the McGrath MAC as a direct laryngoscope, 1 (0-3 [0-5]) than when using it as an indirect videolaryngoscope, 0 (0-1 [0-5]) or when using the Macintosh laryngoscope, 0 (0-1 [0-5]), p = 0.04. This was mirrored in the subjective user reporting, scored out of 10, of difficulty for each method 3.0 (2.0-3.4 [0.5-80]); 2.0 (1.0-3.9 [0-70]) and 2.0 (1.0-3.3 [0-70]), respectively (p = 0.01). This difficulty is in part explained by the poorer laryngeal views recorded using the Cormack and Lehane classification system (p < 0.001) and reflected in the higher than normal operator force required (25%, 4%, 8% for each method, respectively, p < 0.001) and the increased use of rigid intubation aids (21%, 6%, 2%, respectively, p < 0.001). There was no difference between the groups in time taken to intubate or incidence of complications. There was no statistical difference in the performances as measured between the McGrath MAC used as an indirect videolaryngoscope and the Macintosh laryngoscope. We cannot recommend that the McGrath videolaryngoscope be used as a direct laryngscopic device in place of the Macintosh., (© 2015 The Association of Anaesthetists of Great Britain and Ireland.)

The authors describe a case of a 26-year-old female military veteran who presented with low back pain that she attributed to a recent foot injury. The patient reported a history of lumbar pain while in the military that had been treated successfully with high-velocity, low-amplitude osteopathic manipulative treatment. The patient's current pain was improved with osteopathic manipulative treatment and gait correction. Several weeks after her initial presentation, the patient reported that she had had a herniated disk diagnosed 2 years earlier by means of magnetic resonance imaging. Updated magnetic resonance imaging was performed, the results of which revealed a large herniated disk that had caused severe stenosis. The patient was immediately referred to a neurosurgeon for consultation and subsequently underwent surgical treatment.

Intravenous cannulation is a commonly performed procedure. This study aimed to determine whether the success rate and pain of intravenous cannulation is affected by prior injection of intradermal lidocaine. Intravenous cannulation was performed twice in 45 healthy volunteers. Intradermal lidocaine was administered prior to one of these cannulations. The outcome measures were success or failure of cannulation, and pain of cannulation, measured with a 100 mm visual analogue pain scale. The success rate of intravenous cannulation with and without prior intradermal lidocaine was 54% and 76%, respectively. The difference was 22.0% (95% CI 1.5-27.8%; P = 0.03). Log-linear analysis for three-way interaction between the variables (outcome, vascular condition and use of lidocaine) showed a significant influence of vascular condition on outcome (G(2) 24.6, P < 0.001). The mean (SD) pain scores in the control and intervention group were 34.8 (21.0) and 13.6 (13.2) mm, respectively. The difference between the mean pain scores was 21.2 mm (95% CI 15.1-27.3 mm). In conclusion, the success rate of intravenous cannulation may be reduced with the use of intradermal lidocaine, but success rate is primarily dependent on vascular condition. Intradermal lidocaine achieves a clinically significant reduction in the pain of intravenous cannulation.

Background: Infusion of local anaesthetic through femoral and sciatic catheters is an accepted method of providing pain relief after knee arthroplasty. However, the minimum effective concentration of perineural local anaesthetics is not known., Methods: Twenty-four patients received femoral and sciatic perineural infusions of levobupivacaine in order to prevent pain relief after total knee arthroplasty. The primary endpoint of the study was patient request for analgesic rescue for anterior or posterior knee pain within the first 36 h of perineural infusion. Treatment was determined by the method of sequential allocation, with a dosing interval of 0.002% w/v., Results: Thirteen patients did not require rescue analgesia for anterior knee pain and 16 patients did not require rescue analgesia for posterior knee pain. Median duration of failed blocks until rescue analgesia was 25 h (24-27 h) for the femoral block and 27 h (24-29 h) for the sciatic block. The minimum concentration at which patients did not require rescue analgesia was 0.024% for the femoral nerve and 0.014% for the sciatic nerve. Comparison of EC(50) showed that local anaesthetic requirements were significantly (P=0.03) higher by a factor of 1.25 (95% CI 1.03-1.55) for the femoral compared with the sciatic nerve., Conclusions: The EC(50) for femoral perineural infusion is greater than the EC(50) for sciatic perineural infusion.

Bradykinin and substance P are involved in inflammation and act through Gq-protein-coupled receptors. Local anaesthetics inhibit the signalling of these receptors and have potent anti-inflammatory actions. The aim of this study was to investigate the effects of local anaesthetics on the cutaneous flare responses to bradykinin and substance P. Skin blood flow responses to intradermal injections of bradykinin and substance P were assessed in the absence and presence of anaesthetic and analgesic concentrations of lidocaine, levobupivacaine and ropivacaine. All local anaesthetics significantly attenuated the vascular responses to bradykinin (p = 0.001) and substance P (p < 0.001). There were no differences in this effect between the different agents, but anaesthetic concentrations had a greater attenuating effect than analgesic concentrations on the substance P response (p < 0.001). Local anaesthetics may therefore be useful in the suppression of inflammation and the prevention of postoperative hyperalgesia.

Background: Few studies have investigated efficacy and side effects of the combination of diclofenac and paracetamol used for pain relief after major surgery., Methods: After ethical approval, 78 patients, presenting for elective caesarean section, were recruited to this double-blind trial and randomised to receive one of three analgesic modalities: paracetamol, diclofenac, or diclofenac and paracetamol. Anaesthesia was standardised with 2.25-2.5 mL of spinal bupivacaine 5 mg/mL in dextrose 80 mg/mL and fentanyl 12.5 mug. Study drugs were given as a suppository at the end of surgery then orally for 24 h. The primary outcome was i.v. morphine use when administered as patient-controlled analgesia for the first 24 h after surgery. Secondary outcomes were visual analogue pain scores measured 2, 4, 6, 10 and 24 h after surgery and verbal rating pain scores and side effects measured 2-hourly for the first 12 h and 4-hourly thereafter., Results: Patients given the combination of diclofenac and paracetamol required less morphine than did patients given paracetamol alone (mean+/-SD: 33.8+/-23.9 mg versus 54.5+/-28.5 mg, P=0.02). Morphine use in patients given diclofenac alone (42.2+/-26.0 mg) was not significantly different from morphine use in the other two groups. Eight out of 26 patients receiving paracetamol alone were not satisfied with pain management; two required intravenous morphine injections., Conclusions: Patients given a combination of diclofenac and paracetamol used 38% less morphine compared to patients given paracetamol.

Background: Few data describe the pharmacological interactions between local anaesthetics and opioids. The aim of this study was to measure the median effective concentration (MEC) of diamorphine and levobupivacaine when given separately and as mixtures for epidural analgesia, and determine whether the combination is additive or synergistic., Methods: One hundred and twenty patients were enrolled in this prospective randomized, two-phase, double-blind study. In the first phase, 60 women were randomized to receive a fixed 20 ml volume of either levobupivacaine or diamorphine epidurally . Dosing was determined using up-down sequential allocation with testing intervals, respectively, of 0.01%w/v and 12.5 microg ml(-1). After estimations of the MEC of levobupivacaine and diamorphine, a further 60 patients were randomized in the second phase to one of the three mixtures: (a) diamorphine 70 microg ml(-1) (fixed) and levobupivacaine (testing interval 0.004%w/v, starting at 0.044%w/v); (b) levobupivacaine 0.044%w/v (fixed) and diamorphine (testing interval 7 microg ml(-1), starting at 70 microg ml(-1)); and (c) bivariate diamorphine and levobupivacaine (testing intervals of 7 microg ml(-1) and 0.004%w/v starting at 70 microg ml(-1) and 0.044% w/v respectively)., Results: The MEC estimates from the first phase were 143.8 microg ml(-1) (95% CI 122.2-165.3) for diamorphine and 0.083%w/v (95% CI 0.071-0.095) for levobupivacaine. In the second phase, the MEC and interaction index (gamma) of the three combinations were: diamorphine 65.5 microg ml(-1) (56.8-74.2), gamma = 0.99; levobupivacaine 0.041%w/v (0.037-0.049), gamma = 0.98; and for the fixed combination diamorphine 69.5 microg ml(-1) (60.5-78.5) and levobupivacaine 0.044%w/v (0.039-0.049), gamma = 1.02., Conclusion: The combination of diamorphine and levobupivacaine is additive and not synergistic when used for epidural analgesia in the first stage of labour.

The vasodilator properties of lidocaine are believed to be due mainly to the inhibition of action potentials via sodium channel blocking in vasoconstrictor sympathetic nerves. However, mechanisms involving the vascular endothelium may also play a role, and in this study we investigated the potential influences of nitric oxide release, the cyclo-oxygenase pathway and the beta-adrenoceptors of vascular smooth muscle. Laser Doppler imaging was used to measure microvascular blood flow responses to intradermal injection of lidocaine 2%, with or without the addition of preservatives, in eight healthy, male volunteers. Co-injection of the nitric-oxide-synthase inhibitor Nomega-nitro-L-arginine methyl ester caused a 60% reduction in the response after about 20 min, and this reduction was enhanced with the lidocaine solution containing the preservatives methylhydroxybenzoate and propylhydroxybenzoate. No reduction in response was seen after blocking the cyclo-oxygenase or beta-adrenoceptor pathways. Nitric oxide release contributes to the vasoactivity of lidocaine in human skin.

Background: Many years ago regular intermittent bolus administration of epidural local anaesthetic solution was recognized to produce more effective analgesia than continuous infusion, but only recently has the development of suitable pumps allowed the former technique's wider evaluation., Methods: In this randomized, double-blind trial, 40 primigravid patients had a lumbar epidural catheter inserted, and plain ropivacaine 0.2% 15-20 ml was titrated until analgesia and bilateral sensory block to T10 were produced (time zero). Patients were then given either an infusion of ropivacaine 2 mg ml(-1) with fentanyl 2 microg ml(-1) at 10 ml h(-1), or hourly boluses of 10 ml of the same solution. Pain, sensory block and motor block were measured frequently. If requested, additional 10 ml boluses of the study mixture were given for analgesia., Results: There were no differences between the two groups in patient characteristics, obstetric/neonatal outcome, or in sensory or motor block. A total of 12 (60%) patients in the continuous group required one or more additional boluses compared with 4 (20%) patients in the intermittent group (95% CI 9.6-61.7%, P=0.02). Therefore the intermittent group received a lower total drug dose than the infusion group (P=0.02). Duration of uninterrupted analgesia (time to first rescue bolus) was longer in the intermittent group (P<0.02)., Conclusions: The intermittent group required fewer supplementary injections and less drug to maintain similar pain scores, sensory and motor block compared with the continuous group. This represents a more efficacious mode of analgesia.

Background: In view of the wide variation in pain experience between patients, a clinical standard -- the time from the end of surgery to the first experience of pain -- was applied to 1359 consecutive patients in order to investigate whether the initial quality of epidural block has an effect on the overall quality of postoperative pain relief., Methods: Clinical data were recorded in 58,118 out of 72,412 h in 1359 patients, and transferred to a database. Data collected included pain scores on a four-point verbal rating scale; nausea and vomiting; motor block; sedation scores; systolic blood pressure <100 and <90 mm Hg; ventilatory frequency <10 and <8 bpm; and hourly epidural infusion rate., Results: As the time to first experience of pain increased from nil to >24 hours, the time from the first to last experience of pain shortened from 34 (19-50) h to 3 (1-12) h (p<0.001) and the proportion of patients receiving an epidural bolus decreased from 53 to 8% (p<0.001). Increases in the initial pain free time increased the proportion of patients with systolic BP<100 mmHg from 59 to 77%, (p<0.001) and increased the proportion of patients with respiratory rate <10 bpm from 13 to 26%, (p<0.001)., Conclusion: Extending pain relief for more than 12 h beyond the end of abdominal surgery significantly improves the overall quality of postoperative pain relief, but is associated with an increase in side-effects.

Background: Epinephrine is added to local anaesthetic preparations to prolong their action and reduce their systemic absorption. Bupivacaine and levobupivacaine cause vasodilatation at clinical doses, but lower doses appear to cause vasoconstriction. The aim of this study was to characterize fully the vasoactive effects of these anaesthetics, using an objective measure of blood flow, and to assess the influence of adding epinephrine., Methods: Laser Doppler imaging was used to measure the forearm skin blood flow responses to intradermal injection of eight doses of bupivacaine and levobupivacaine in 10 healthy male volunteers. The doses tested ranged from 0.008% to 0.75%, and the five highest doses were administered both with and without adjuvant epinephrine 2.5 microg ml(-1)., Results: The cumulative responses to the lower subclinical concentrations (0.008-0.0625%) of both anaesthetics were smaller than or similar to that produced by saline alone, indicating a net vasoconstrictive effect. Higher doses caused net vasodilatation, and the levobupivacaine responses were generally lower than the corresponding bupivacaine responses (P=0.022). Epinephrine 2.5 microg ml(-1) significantly reduced the responses to clinical doses of both drugs (P<0.001), producing net vasoconstriction., Conclusions: Bupivacaine and levobupivacaine have a biphasic vascular effect when injected intradermally, with subclinical doses causing net vasoconstriction. The addition of epinephrine 2.5 microg ml(-1) decreases these responses markedly.

Background: The physicochemical properties of diamorphine (3,6-diacetylmorphine) enhance its bioavailability compared with more lipid-soluble opioids when administered into the epidural space. However, the influence of concentration, volume or mass on the clinical efficacy of diamorphine is not known., Method: In this double-blind, randomized, prospective study, 62 women in active labour and

Background and Objectives: The recommended optimal concentration of adjuvant epinephrine for use with local infiltration anesthesia is usually 5 microg/mL. However, a lower dose might be as effective at prolonging the anesthetic effects, while limiting the risk of hazards associated with unintentional intravascular injection. The aim of our study was to determine the lowest effective vasoconstrictor concentration of epinephrine in human skin for a range of doses of bupivacaine and its less-vasodilatory S(-) isomer, levobupivacaine., Methods: We injected combinations of 0.125%, 0.25%, and 0.75% bupivacaine and levobupivacaine with 1.25, 2.5, and 5 microg/mL epinephrine into the forearm skin of 10 healthy volunteers and measured the resulting blood flow changes over 1 hour using laser Doppler imaging., Results: All 3 concentrations of epinephrine produced marked vasoconstriction, both alone and in combination with all 3 doses of the anesthetics ( P <.001 in all cases). There was almost no difference in effect between the 3 epinephrine concentrations., Conclusions: We conclude that 1.25 microg/mL epinephrine produces a comparable vasoconstrictor effect in human skin to that of higher concentrations when coinjected with clinical doses of bupivacaine and levobupivacaine and may be equally effective for infiltration anesthesia.

Background: Spread of intrathecal local anaesthetics is determined principally by baricity and position of the patient. Hypobaric solutions of bupivacaine are characterized by an unpredictable spread of sensory block whereas addition of dextrose 80 g ml(-1) provides a predictable spread but to high thoracic levels. In contrast, dextrose concentrations between 8 and 30 g ml(-1) have shown reliable and consistent spread for surgery. Hence, the aim of this study was to determine the density of bupivacaine, levobupivacaine, and ropivacaine with and without dextrose at both 23 and 37 degrees C before embarking on clinical studies., Methods: Density (g ml(-1)) was measured using the method of mechanical oscillation resonance, accurate to five decimal places on 1250 samples. 500 density measurements were performed in a randomized, blind fashion at 23 and 37 degrees C on 10 plain solutions of bupivacaine (2.5, 5, and 7.5 g ml(-1)) levobupivacaine (2.5, 5, and 7.5 g ml(-1)) and ropivacaine (2, 5, 7.5, and 10 g ml(-1)). Following this, 750 density measurements were taken at 23 and 37 degrees C on the 5 g ml(-1) solutions of bupivacaine, levobupivacaine, and ropivacaine with added dextrose (10, 20, 30, 50, and 80 g ml(-1))., Results: There was a linear relationship between density and dextrose concentration for all three local anaesthetics (R(2)=0.99) at 23 and 37 degrees C. The mean density of levobupivacaine 5 g ml(-1) was significantly greater than the densities of bupivacaine 5 g ml(-1) and ropivacaine 5 g ml(-1) after adjusting for dextrose concentration using analysis of covariance. This difference existed both at 23 and 37 degrees C. The mean (sd) density of levobupivacaine 7.5 g ml(-1) was 1.00056 (0.00003) g ml(-1), the lower 0.5% percentile (1.00047 g ml(-1)) lying above the upper limit of hypobaricity for all patient groups., Conclusions: The density of local anaesthetics decreases with increasing temperature and increases in a linear fashion with the addition of dextrose. Levobupivacaine 5 g ml(-1) has a significantly higher density compared with bupivacaine 5 g ml(-1) and ropivacaine 5 g ml(-1) at 23 and 37 degrees C both with and without dextrose. Levobupivacaine 7.5 g ml(-1) is an isobaric solution within all patient groups at 37 degrees C [corrected]