Carassiti M, Quarta R, Mattei A, Tesei M, Saccomandi P, Massaroni C, Setola R, Schena E
Annu Int Conf IEEE Eng Med Biol Soc. 2017 Jul;2017:759-762. doi: 10.1109/EMBC.2017.8036935.
During recent decades epidural analgesia has gained widespread recognition in many applications. In this complex procedure, anaesthetist uses a specific needle to inject anesthetic into the epidural space. It is crucial the appropriate insertion of the needle through inhomogeneous tissues placed between the skin and the epidural space to minimize anesthetic-related complications (e.g., nausea, headache, and dural puncture). Usually, anaesthetists perform the procedure without any supporting tools, and stop pushing the syringe when they sense a loss of resistance (LOR). This phenomenon is caused by the physical properties of the epidural space: the needle breaks the ligamentum flavum and reaches the epidural space, in this stage the anaesthetist perceives a LOR because the epidural space is much softer than the ligamentum flavum. To support the clinician in this maneuver we designed a non-invasive system able to detect the LOR by measuring the pressure exerted on the syringe plunger to push the needle up to the epidural space. In a previous work we described the system and its assessment during in vitro tests. This work aims at assessing the feasibility of the system for LOR detection on a more realistic model (ex vivo pig model). The system was assessed by analyzing: its ability to hold a constant value (saturation condition) during the insertion of the needle, and its ability to detect the entrance within the epidural space by a decrease of the system's output. Lastly, the anaesthetist was asked to assess how the ex vivo procedure mimics a clinical scenario. The system reached the saturation condition during the needle insertion; this feature is critical to avoid false positive during the procedure. However, it was not easy to detect the entrance within the epidural space due to its small volume in the animal model. Lastly, the practitioner found real the model, and performed the procedures in a conventional manner because the system did not influence his actions.
在最近几十年里，硬膜外镇痛在许多应用中得到了广泛认可。在这个复杂的操作过程中，麻醉师使用特定的针头将麻醉剂注入硬膜外间隙。至关重要的是，要将针头正确插入皮肤与硬膜外间隙之间的不均匀组织中，以尽量减少与麻醉相关的并发症（如恶心、头痛和硬膜穿刺）。通常，麻醉师在没有任何辅助工具的情况下进行该操作，当他们感觉到阻力消失（LOR）时就停止推注注射器。这种现象是由硬膜外间隙的物理特性引起的：针头穿过黄韧带到达硬膜外间隙，在这个阶段，麻醉师感觉到阻力消失，因为硬膜外间隙比黄韧带软得多。为了在这个操作中辅助临床医生，我们设计了一种非侵入性系统，该系统能够通过测量推注注射器活塞以将针头推进到硬膜外间隙时所施加的压力来检测阻力消失。在之前的一项工作中，我们描述了该系统及其在体外测试中的评估情况。这项工作旨在评估该系统在更真实的模型（离体猪模型）上检测阻力消失的可行性。通过分析该系统来进行评估：它在针头插入过程中保持恒定值（饱和状态）的能力，以及通过系统输出的降低来检测进入硬膜外间隙的能力。最后，要求麻醉师评估离体操作如何模拟临床场景。该系统在针头插入过程中达到了饱和状态；这一特性对于避免操作过程中的假阳性至关重要。然而，由于动物模型中硬膜外间隙体积较小，很难检测到进入硬膜外间隙的情况。最后，从业者认为该模型真实，并以传统方式进行操作，因为该系统没有影响他的操作。
