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. 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. 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. Consistent spread to lumbar nerve roots was achieved using the transmuscular approach through the quadratus lumborum.

Background There is heterogeneity in the names and anatomical descriptions of regional anesthetic techniques. This may have adverse consequences on education, research, and implementation into clinical practice. We aimed to produce standardized nomenclature for abdominal wall, paraspinal, and chest wall regional anesthetic techniques. Methods We conducted an international consensus study involving experts using a three-round Delphi method to produce a list of names and corresponding descriptions of anatomical targets. After long-list formulation by a Steering Committee, the first and second rounds involved anonymous electronic voting and commenting, with the third round involving a virtual round table discussion aiming to achieve consensus on items that had yet to achieve it. Novel names were presented where required for anatomical clarity and harmonization. Strong consensus was defined as ≥75% agreement and weak consensus as 50% to 74% agreement. Results Sixty expert Collaborators participated in this study. After three rounds and clarification, harmonization, and introduction of novel nomenclature, strong consensus was achieved for the names of 16 block names and weak consensus for four names. For anatomical descriptions, strong consensus was achieved for 19 blocks and weak consensus was achieved for one approach. Several areas requiring further research were identified. Conclusions Harmonization and standardization of nomenclature may improve education, research, and ultimately patient care. We present the first international consensus on nomenclature and anatomical descriptions of blocks of the abdominal wall, chest wall, and paraspinal blocks. We recommend using the consensus results in academic and clinical practice.

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 mg ml^–1 provides a predictable spread but to high thoracic levels. In contrast, dextrose concentrations between 8 and 30 mg 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°C before embarking on clinical studies. Methods. Density (mg 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°C on 10 plain solutions of bupivacaine (2.5, 5, and 7.5 mg ml^–1) levobupivacaine (2.5, 5, and 7.5 mg ml^–1) and ropivacaine (2, 5, 7.5, and 10 mg ml^–1). Following this, 750 density measurements were taken at 23 and 37°C on the 5 mg ml^–1 solutions of bupivacaine, levobupivacaine, and ropivacaine with added dextrose (10, 20, 30, 50, and 80 mg ml^–1). Results. There was a linear relationship between density and dextrose concentration for all three local anaesthetics (R²=0.99) at 23 and 37°C. The mean density of levobupivacaine 5 mg ml^–1 was significantly greater than the densities of bupivacaine 5 mg ml^–1 and ropivacaine 5 mg ml^–1 after adjusting for dextrose concentration using analysis of covariance. This difference existed both at 23 and 37°C. The mean (sd) density of levobupivacaine 7.5 mg ml^–1 was 1.00056 (0.00003) mg ml^–1, the lower 0.5% percentile (1.00047 mg 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 mg ml^–1 has a significantly higher density compared with bupivacaine 5 mg ml^–1 and ropivacaine 5 mg ml^–1 at 23 and 37°C both with and without dextrose. Levobupivacaine 7.5 mg ml^–1 is an isobaric solution within all patient groups at 37°C. Br J Anaesth 2004; 92: 547–51

Summary: 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.

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. 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. 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. 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.