SummaryWe systematically reviewed peripheral nerve blockade guided by ultrasound versus electrical stimulation. We included 26 comparisons in 23 randomised controlled trials of 2125 participants. Ultrasound reduced the rate of pain during the procedure, relative risk (95% CI) 0.60 (0.41-0.89), p = 0.01. Ultrasound with or without electrical stimulation reduced the rate of analgesic or anaesthetic rescue versus electrical stimulation alone, relative risk (95% CI) 0.40 (0.29-0.54) and 0.29 (0.16-0.52), respectively, p < 0.0001 for both. The rate of rescue was unaffected by the addition of electrical stimulation to ultrasound, relative risk (95% CI) 1.07 (0.54-2.10), p = 0.85. Ultrasound, with or without electrical stimulation, reduced the pooled rate of vascular puncture, relative risk (95% CI) 0.23 (0.15-0.37), p < 0.0001. There was no difference in the rate of postoperative neurological side-effects, relative risk (95% CI) 0.76 (0.53-1.09), p = 0.13.

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.

No abstract

SummaryUltrasound 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).

Citation for published version (APA):Munimara, S., Zeally, K., Schwab, A., Columb, M., Corner, G. A., Eisma, R., & McLeod, G. A. (2016). Trainee anaesthetist diagnosis of intraneural injection. A study comparing B-Mode ultrasound with the fusion of B-Mode and elastography in the soft embalmed Thiel cadaver model. British Journal of Anaesthesia, 117(6), 792-800. DOI: 10.1093/bja/aew337General rights Copyright and moral rights for the publications made accessible in Discovery Research Portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from Discovery Research Portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain.• You may freely distribute the URL identifying the publication in the public portal. Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Running head Elastography diagnosis of intraneural injectionPage 2 of 26 British Journal of Anaesthesia 3 ABSTRACT 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 hypothesised 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 BMode ultrasound onto a single image. Conclusions: Fusion elastography improved the accuracy, reliability and confidence of trainee anaesthetist diagnosis of intraneural injection. Methods