## 4 Discussion
In contrast, when a needle is inserted into the muscle, the tip orifice may lie partially on collagenous fibres, such as the epimysium (surrounding the muscle), or partially within the perimysium. This information highlights the complexity of needle insertion and injection techniques and emphasises the importance of considering the physical properties of different tissues when performing medical procedures. Based on the results obtained, we have formulated a hypothesis that a continuous infusion technique is more effective in identifying the subcircumneural spaces with a less force as compared to the standard bolus technique. Our hypothesis is supported by some evidence as well. In particular, researchers using an epidural needle-based system that relies on computerised injection pump technology (Compuflo, Livingston, NJ, USA) reported higher injection accuracy with fewer dural punctures [22]. The system employs a constant infusion rate of approximately 3 mL/min and measures the changes in injection pressure at 4 Hz. Furthermore, an ex vivo study has suggested that this system is more accurate than the B-Smart (BS) in-line manometer and could be used for peripheral nerve blocking procedures [23]. In our study of isolated nerves, we followed the same fundamental principles as in previous research. However, in our study, we infused saline at a rate of 1.8 mL per minute and measured the pressure and force at a frequency of 10 Hz. Our primary focus was examining the initial interaction between the needle and the nerve and the hypothetical separation of the circumneurium. At this stage, we cannot comment on the clinical applications of this technique, as further research is needed to investigate the subsequent dosing and other aspects. In order to gain a more detailed understanding of the changes at the epineurium and the subcircumneural compartments, we plan to conduct future studies using microultrasound on cadaver models. The research findings presented a comprehensive understanding of needle-tissue interaction dynamics, directly impacting clinical practices in regional anaesthesia. Specifically, our study explains the biomechanical factors influencing tissue trauma and injection precision. By integrating these insights into clinical protocols, practitioners can tailor their approaches to minimise tissue trauma and optimise injection precision. This involves careful consideration of needle insertion angles and infusion techniques to reduce the force exertion on tissues during needle insertion. Additionally, the findings of the result underscore the significance of real-time visualization technologies in guiding needle placement with heightened accuracy and safety. Moreover, this study assesses the stage for future research to refine the existing techniques and develop creative technologies to enhance the efficacy and safety of ultrasound-guided regional anaesthesia procedures. This study we conducted has two main impacts that are worth highlighting. Firstly, force is a physical entity used in bioengineering to identify and measure the interaction of trocars, needles and sutures with soft tissue. However, it has yet to be widely applied to regional anaesthesia procedures [24]. Our research findings suggest that the forces generated during regional anaesthesia administration can be significant, but are rarely appreciated because they are not measured. We have performed ongoing work showing that forceful interaction with tissues is a crucial aspect of regional anaesthesia administration, which deserves further exploration. Secondly, using a liquid as a lubricant could potentially improve the ease and efficiency of medical procedures. Our study results can inform the understanding of the forces encountered during needle-based procedures in soft tissue. These findings have significant implications in the medical field as they may lead to the development of more effective techniques for carrying out procedures like anaesthesia- and other needle-based procedures.