3D printed airway simulators: Adding a dimension to bronchoscopy training.

Abstract

The last decade has witnessed significant changes in the field of interventional pulmonology. With advances in technology, the bronchoscopist's toolkit has expanded beyond flexible bronchoscopy to include an array of advanced diagnostic and therapeutic procedures including endobronchial ultrasound, peripheral cryobiopsy, trans-parenchymal sampling methods, bronchial thermoplasty, endobronchial valve placement and a variety of ablative therapies. In parallel, there has been a shift of credentialing bodies away from solely volume-based certification to knowledge- and skills-based recognition of competency.1 In this context, there is a need to re-examine the conventional approach to bronchoscopy training, which has largely relied on an apprenticeship-based ‘see one, do one, teach one’ method. While there are clear advantages to learning by performing procedures on live patients, these must be weighed against the risk of harm to patients from inexperienced operators. Although flexible bronchoscopy complications are rare, trainee participation has been shown to increase procedural duration, amount of sedation required and complication rates.2 In addition, there is variability in terms of supervisor style and exposure to sufficient numbers of complex procedures in some centres, making standardization of teaching and objective evaluation of skill acquisition challenging. This is particularly pertinent in the initial steep portion of the learning curve of a bronchoscopic procedure. Simulation is a validated mode of delivering bronchoscopy education in a zero-risk environment, and its incorporation in training programmes is recommended.1 Bronchoscopy simulation training currently exists in two forms: high-fidelity virtual simulators and low-fidelity physical models.3 While the latter offers significant advantages in terms of cost and ease of development, a key limitation has been the degree of anatomical fidelity to the clinical reality. With the advent of three-dimensional (3D) printing technology, low-fidelity simulators can now be designed to a high degree of anatomical realism with enhanced interactivity. This technology has already been shown to be of value in surgical simulation. However, its application in medical specialties, and more specifically bronchoscopy training, is largely unexplored. Since the first report of a 3D printed bronchoscopy simulator generated from patient imaging data in 2014,4 only a handful of studies have been published (Table 1). Observational Observational To provide accurate airway orientation and navigational skills, bronchoscopy simulators require a high degree of anatomical accuracy and fidelity. The strengths of 3D printed simulators in this regard are well established. In published studies, evaluation of face validity has typically been performed by collecting qualitative feedback from experienced bronchoscopists in respiratory medicine,5, 11 anaesthetics6 and thoracic surgery.4 Furthermore, in addition to normal anatomical variation, bespoke models have been designed to reflect a range of pathological anatomy.3, 11 Almost unanimously, models have been judged to provide an authentic endobronchial navigation experience with respect to orientation, airway branching and bronchoscope manipulation. Bronchoscopy skill assessment is generally performed with modified versions of validated pre-existing tools. Using these, procedural dexterity and precision has been shown to increase with 3D printed bronchoscopy simulator training, where the benefits are threefold. First, a brief period of training using 3D printed models has been shown to result in significant improvements in novices' standards of task performance when compared to no training. In a pilot study, DeBoer et al. measured the median number of lung markers (6 in total) which were correctly identified in a 10-min period. This increased from 1 versus 1 (simulator vs control group) pre-study to 6 versus 1.5 post-study, reflecting an effect size of 1.8 (P < 0.001).9 Second, 3D printed simulators have discriminatory ability when combined with a validated assessment tool. Steinfort et al. evaluated the success rates of three participant groups with high, intermediate and no bronchoscopy experience, in navigating and entering the superior segment of the right upper lobe and anterior segment of the left lower lobe.12 Within a 60-s timeframe, 100%, 64% and 32% of the target bronchial segments were successfully entered by each group, respectively. Finally, the benefits of a short unstructured simulator training session on bronchoscopy skill quality can be retained. In a study conducted by Feng et al., novices retained bronchoscopic manipulation skills 8 weeks after completing a simulation session with a 3D printed model.13 The implication of this is that learners can use 3D printed bronchoscopy simulators to track their improvements in skill over time. Furthermore, procedure completion time has also been observed to improve after training with 3D printed bronchoscopy simulators.7, 9, 10 The cost of producing 3D printed bronchoscopy models is a distinct advantage over high-fidelity and commercially available low-fidelity simulators. 3D model production costs vary depending on the design complexity, materials used and printing methods. Semi-flexible simulators have been reported to range from $1 to $150, while most rigid models cost less than $100 to produce.5, 7 Using a paediatric bronchoscopy model, DeBoer et al. estimated a 40% annualized training cost reduction per trainee when comparing their model to the nearest priced commercially available simulator, suggesting that 3D printed bronchoscopy simulators represent an economically viable method for training.9 As the field of bronchoscopy and interventional pulmonology evolves, so too must the training in these techniques. With increased sensitivity of radiological imaging and frequency of computed tomography (CT) scanning through lung cancer screening programmes, the incidence of pulmonary anomalies requiring bronchoscopic tissue sampling will also rise. Furthermore, bronchoscopic techniques are becoming increasingly complex with a focus on precision sampling in real time. To develop expertise, there is a concentration of such techniques at specific institutions, resulting in less opportunity for hands-on training at other centres. In a post coronavirus disease 2019 (COVID-19) setting, the risk to patient and proceduralist is increased in aerosol-generating-procedures, and pressures on trainees attaining competency will increase as they will often be excluded from elective procedures. As 3D printing technology becomes more easily accessible, it offers the possibility of access to bronchoscopic simulation training by lowering the cost and increasing availability. In addition, the versatility of 3D printing has potential to design patient-specific pathological models, thereby allowing plan and practise complex procedures before performing them in clinical practice. Collaboration between bronchoscopists, 3D printing and endoscopic companies will be essential to develop simulators that maintain high standards of training.