Design and characterization of a measurement system for monitoring pressure exerted by bronchial blockers: In vitro trials

Diagnostic Value of Virtual Bronchoscopic Navigation in the Bronchial Tuberculosis Induced Central Airway Stenosis

Introduction

Electronic bronchoscopy is invasive and may cause pain. This study aimed to explore the clinical value of virtual bronchoscopic navigation (VBN) in the diagnosis of benign central airway stenosis (CAS) secondary to tracheobronchial tuberculosis (TBT).

Methods

Sixty-eight patients with benign CAS caused by TBT were recruited between July 2015 and December 2017. The location, length and diameter of stenoses were independently determined by VBN and electronic bronchoscopy (EOB), and the sensitivity and specificity of VBN in identifying stenosis were assessed with EOB as the gold standard.

Results

In 68 patients with TBT, the overall coincidence between EOB and VBN in the identification of stenosis was 100%. A total of 188 sites were selected from the central airway, and the stenosis was graded into 0%, ≤ 25%, 26–50%, 51–75%, 76–90% and > 90%. The sensitivity of VBN in determining the degree of stenosis was 98.45%, 100.00%, 100.00%, 100.00%, 84.62% and 0.00%, respectively; the specificity was 91.53%, 96.07%, 97.09%, 97.08%, 97.14% and 97.30%, respectively; the accuracy rate was 96.28%, 96.28%, 97.34%, 97.34%, 96.28% and 95.7%, respectively. The length of airway stenosis on EOB was divided into < 10 mm, 10–30 mm, 30–50 mm and > 50 mm. There was no significant difference in the length of airway stenosis between VBN and EOB (t = 0.083, P = 0.936; t = 1.340, P = 0.199; t = 1.297, P = 0.216; t = 2.186, P = 0.081). In three patients who received stent placement, VBN was able to accurately assess the postoperative expansion.

Conclusion

VBN is helpful for the diagnosis of TBT-induced CBS and may provide important information on the location, length, diameter and cross-sectional area of stenosis for further EOB examination and interventional therapy. VBN is recommended for patients with TBT and those with contradictions to bronchoscopy, as well as for regular follow-up of stable TBT, because it reduces the incidence of injury, avoids repeat operations and shortens treatment time.

Ex vivo animal-model assessment of a non-invasive system for loss of resistance detection during epidural blockade

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.