The value of simulation training in bronchoscopy education is well established, and use of simulation in training programs is recommended by multiple specialist societies.1 However, high fidelity simulation equipment is expensive,2 and the availability of simulation models to interventional pulmonology trainees remains limited.
We describe development of an airway model using 3-dimensional (3D) printer technology for bronchoscopy simulation, and we present imaging demonstrating the high anatomic fidelity of the model.
B.M. underwent diagnostic computed tomography (CT) chest for assessment of a solitary pulmonary nodule. Following written consent, Digital Imaging and Communication in Medicine images from this diagnostic study, acquired with 1 mm slice thickness every 0.8 mm were used to create a virtual 3D airway model. The CT chest was performed for planning of electromagnetic navigation bronchoscopy using parameters previously described.3
To achieve isolation of the airways, Digital Imaging and Communication in Medicine data were processed in 3DSlicer (Fig. 1A), a free, open source tool jointly developed by the Surgical Planning Laboratory at the Brigham and Women’s Hospital and the MIT Artificial Intelligence Laboratory in 1998 (http://www.slicer.org/). The airway segmentation plugin was used to create a surface tessellation language (.stl) file of the internal surface of the tracheobronchial tree.
This .stl file was then imported into Tinkercad (Fig. 1B) (Autodesk Inc, San Rafael, CA)—a free, open access online computer-assisted design (CAD) program, and incorporated into a 3-block structure (https://www.tinkercad.com/).
Using these .stl files, a rigid material model was created on a Flashforge Creator Pro X printer (Flashforge, Jinhua, China) using acronitrile butadiene styrene (ABS) plastic filament for the model itself, and high-impact polystyrene (HIPS) as soluble support material. The blocks were then immersed for several days in d-limonene to dissolve the HIPS, leaving a hollow lumen through which a bronchoscope could be passed. The 3 blocks were then articulated together to create a complete airway model (Fig. 2).
The model was then examined using a bronchoscope (Olympus MP160, Tokyo Japan) and images compared with images from Virtual Bronchoscopy (Supplementary Video file 1, Supplemental Digital Content 1, http://links.lww.com/LBR/A131) derived from the diagnostic CT.
The 3 components were easily assembled (Fig. 2). A high degree of anatomic fidelity was identified in the model. Multiple experienced bronchoscopists noted qualitatively that bronchoscope handling was highly consistent with that experienced during clinical bronchoscopy.
Bronchoscope navigation (Supplementary Video file, Supplemental Digital Content 1, http://links.lww.com/LBR/A131) demonstrated high fidelity when compared with virtual bronchoscopy imaging.
Three-dimensional printing is rapidly becoming cheaper and more readily available. There is an ever-increasing number of reports of novel applications for 3D-printed products, including domestic, medical,4 and even construction.
Previous interventional pulmonology training programs and guidelines emphasized a clinical volume-based approach to procedural competency.5 However, there are significant difficulties with this approach.1,5 Many trainees will not reach the specified number, as a consequence of increased trainee numbers, increased complexity, and number of advanced bronchoscopic techniques. Validated competency assessment tools have identified that the number of procedures required to achieve competency varies widely.1,5
Bronchoscopy training programs emphasize that competency in bronchoscopy requires mastery in several domains including cognitive and dexterity skills as well as in knowledge of bronchial anatomy. Simulation enhances training in each of these domains, with a systematic review concluding significant improvements in bronchoscopy procedure time, process, technique, and trainee satisfaction.6 Interestingly, the review also notes that plastic part-task models may be superior to more costly virtual-reality simulators.6 Such low-cost models are frequently nonanatomic, however, our model aids acquisition of lobar and segmental bronchial anatomy knowledge, in addition to bronchoscopy technique and dexterity. Simulation models may also serve as a model for assessment of competency metrics should this become a requirement of certification in future.7,8 Our model used a combined total of approximately 500 g of ABS ($AUD 70/kg) and HIPS ($AUD 90/kg) filament. The resulting cost of approximately $AUD 40 per unit is well within reach of even small respiratory services, and may improve uptake of simulation training.
The apprenticeship model for bronchoscopic education is problematic, with previous studies indicating a higher likelihood of complications, as well as greater patient discomfort and sedation requirements in procedures performed by trainees.9 Skills gained during simulation training appear comparable to those obtained by clinical bronchoscopy practice,10 illustrating the potential of simulation to minimize the burden of procedural learning on patients.
Our model comprises airways distal to the larynx, therefore, no experience in navigation of the upper airway is obtained. Pharyngeal and laryngeal anatomy is likely to be harder to replicate, being more dynamic than lower airway anatomy, therefore an ABS model for simulation of passage of the bronchoscope through the upper airway is likely to be of limited value. This could be overcome by use of an upper airway mannequin. However, we believe that important skills in bronchoscopy are addressed by an infraglottic model, including anatomic knowledge, scope steering, and dexterity.
Further modification to the model could allow development of devices for training in more advanced bronchoscopic procedures, such as transbronchial needle aspiration.
The optimal role for such a model in bronchoscopic training remains to be defined in future studies. The nature of 3D-printed models means that trainees could have practically unlimited exposure for training purposes, unlike more expensive simulators where exposure is limited to the duration of a training course. Whether extended unstructured exposure achieves greater benefit than a structured teaching program remains to be established. Limited studies have suggested that procedural dexterity gained through simulation training is not matched by improvement in “cognitive” skills,2 hence the role of simulation within a bronchoscopy training program remains to be defined.
We have presented a 3D anatomic bronchial model suitable for low-cost, high anatomic fidelity bronchoscopy simulation. This model can be reproduced easily using a standard DICOM image set and freely available image processing software. The model demonstrates high fidelity compared with virtual bronchoscopy findings, and replicates accurately the haptics of clinical bronchoscopy making it potentially useful for both training in, and assessment of, bronchoscopic skills.
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