Novel Cost-effective D.I.Y. Gelatin Model for Endobronchial Ultrasound-guided Transbronchial Needle Aspiration Simulation Training

As Henri Colt has often said, "Patients should not bear the burden of procedure-related training." In the era of heightened awareness regarding patient safety, the traditional apprenticeship model of training is far from ideal. Studies have shown that, despite direct attending supervision, bronchoscopies performed by pulmonary fellows take longer, with a trend toward a higher risk of complications.1 Early guidelines from national and international societies recommend numbers of at least 40 to 50 endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) procedures for initial acquisition of competence, mostly based on expert opinion.2–5 Subsequent studies have shown that the performance of 50 cases does not necessarily ensure mastery of this procedure.2,6 In other fields, such as aviation and surgery, simulation training has long been the cornerstone of training before direct application.6 The few studies in the world of pulmonary medicine show that simulation-based training not only shortens the learning curve, but is equally effective in achieving competency in trainees compared with wet laboratory training and performing actual procedures on patients.7,8 Indeed, training on a virtual bronchoscopy simulator machine was found to be superior in the beginning of the learning curve for EBUS-TBNA6,9,10 and the skills acquired were proven to be transferrable to a clinical setting.10 However, this benefit implies an investment from the training department. Currently, the most accurate high-fidelity simulation experience is provided by a 3D simulator which is cost-prohibitive for most training programs. Even the more widely utilized commercial gel model may not be affordable for some programs, especially given the need for replacement after multiple uses. We propose a cost-effective alternative to the low-fidelity commercial gel model. This "Do It Yourself" (D.I.Y.) recipe for constructing an inexpensive gelatin model of airways can be easily adopted by most fellowship programs for <$10 each with remarkable advantages and very few disadvantages (Table 1). Ironically, we have found that the image resolution is far more crisp than what is offered by the commercial gel model. Finally, our model is superior to the latter because it is transparent and provides a unique "triple-view" perspective which allows the learner to have a better understanding of the anatomic relationship of the lymph node and the angle of needle entry, as seen through a camera view, an ultrasound view, and an aerial view from above (Fig. 1; Supplemental Digital Content, Video 1, https://links.lww.com/LBR/A209). TABLE 1 - Pros and Cons of the Endobronchial Ultrasound-guided Transbronchial Needle Aspiration (EBUS-TBNA) Gelatin Model Simulation Trainer Pros EBUS-TBNA Simulation Trainer Cons EBUS-TBNA Simulation Trainer Low production cost. The average cost of a model is <$10 Needs preparation time (average 45-60 mintes) and 4 h refrigeration Wide availability of materials Needle tracks form after each use Portability (although it is highly recommended to keep the model refrigerated or in ice to maintain the consistency) Shelf life of 1-3 wk High fidelity ultrasound images Breaks with excessive pressure "Triple-view" perspective for optimal trainee understanding Creation of any airway anatomy shape and the possibility to create different mediastinal lymph node stations with a large scanning surface Once used, the model can be disposed of safely as it does not contain any biohazard material FIGURE 1: Compilation of the 3 views during and fine-needle aspiration (FNA) biopsy to a target. Panel A, Bronchoscopic view; panel B, ultrasound view; panel C, direct operator view.Specifically, this homemade see-through model provides a view of: The position of the EBUS-TBNA bronchoscope in relationship to the lymph node as the needle is advanced. Direct bronchoscopic view of the needle puncturing the target behind the gelatin wall. High-resolution ultrasound image of needle aspiration at an angle originating from the cephalad direction. This model also allows for repeated practice of the entire workflow of EBUS-TBNA sampling, starting with the dexterity needed to manipulate the bronchoscope through the airways, identifying the target lymph node and completing a needle aspiration using real-life equipment. Our EBUS-TBNA simulator model is created using a food container, unflavored gelatin, vinyl tubing, isopropyl alcohol, glue sticks, water and firm green grapes (Fig. 2, panel A). Among multiple targets tested, green grapes showed the echotexture on ultrasound which was most similar to a lymph node.FIGURE 2: Panel A, Material used to create the Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) Simulation Model. A, Food container. B, Vinyl tubing. C, Isopropyl alcohol. D, Unflavored gelatin. E, Glue gun/sticks. F, Grapes. Panel B, EBUS-TBNA Simulation Model construction. G, Food container with 6 holes drilled and a vinyl tube to create the airway, secured at the ends with glue to prevent spilling (arrow pointing at glue); H, Three airways with glue and targets held in place by tubing. I and J, Finished model after 4 hours of refrigeration and extraction of the vinyl tubes.Steps to create the EBUS-TBNA simulator model (Fig. 2, panel B): Drill a hole on both sides of the food container with the desired diameter of the tubing that will create the airway. In this model we used a 3/8" outer diameter vinyl tubing, which in our experience provided the optimal contact surface between the bronchoscope, allowing the best ultrasound image acquisition. Pass the vinyl tubing through the holes created and cover the entrance and exit of the tubing with glue using a glue gun to avoid spilling of the liquid gelatin. After placing the tubes, we recommend coating with a bit of cooking oil to facilitate the future removal of the tubes. Place the green grapes in between the tubing so that they are held in place by the tubing. These will represent the lymph nodes/tumors. Prepare the gelatin mixture depending on the size of the food container used. The proportions should be as follows: 250 mL (~1 cup) of water, 21 g of unflavored gelatin (~1/8 cup) and 15 mL (~1/16 cup) of 70% isopropyl alcohol. Heat the water in a pot until boiling and add the isopropyl alcohol. With the water at a boil, add the gelatin slowly while whisking continuously until completely dissolved. This process takes ~3 to 5 minutes. This mixture is poured into the container selected. The model should be placed in the refrigerator for at least 4 hours before use. Remove the glue and slide the vinyl tube out of the model to create the airway lumen. In summary, simulation models have been validated to expedite the learning curve for EBUS-TBNA but have not been widely adopted by most training programs due to availability and cost constraints. We present a recipe for a unique homemade, inexpensive gelatin model with high-resolution images. Our model is transparent and allows for triple-view teaching of the anatomic relationships of the scope relative to the target as well as the angle of needle entry. This model can be made for <$10 each and provides a realistic venue for unlimited practice of all the steps to performing EBUS-TBNA before performing the procedure in live patients.