A Novel 3-Dimensional Printing Fabrication Approach for the Production of Pediatric Airway Models

Abstract

Background: Pediatric airway models currently available for use in education or simulation do not replicate anatomy or tissue responses to procedures. Emphasis on mass production with sturdy but homogeneous materials and low-fidelity casting techniques diminishes these models' abilities to realistically represent the unique characteristics of the pediatric airway, particularly in the infant and younger age ranges. Newer fabrication technologies, including 3-dimensional (3D) printing and castable tissue-like silicones, open new approaches to the simulation of pediatric airways with greater anatomical fidelity and utility for procedure training.

Methods: After ethics approval, available/archived computerized tomography data sets of patients under the age of 2 years were reviewed to identify those suitable for designing new models. A single 21-month-old subject was selected for 3D reconstruction. Manual thresholding was then performed to produce 3D models of selected regions and tissue types within the dataset, which were either directly 3D-printed or later cast in 3D-printed molds with a variety of tissue-like silicones. A series of testing mannequins derived using this multimodal approach were then further refined following direct clinician feedback to develop a series of pediatric airway model prototypes.

Results: The initial prototype consisted of separate skeletal (skull, mandible, vertebrae) and soft-tissue (nasal mucosa, pharynx, larynx, gingivae, tongue, functional temporomandibular joint [TMJ] "sleeve," skin) modules. The first iterations of these modules were generated using both single-material and multimaterial 3D printing techniques to achieve the haptic properties of real human tissues. After direct clinical feedback, subsequent prototypes relied on a combination of 3D printing for osseous elements and casting of soft-tissue components from 3D-printed molds, which refined the haptic properties of the nasal, oropharyngeal, laryngeal, and airway tissues, and improved the range of movement required for airway management procedures. This approach of modification based on clinical feedback resulted in superior functional performance.

Conclusions: Our hybrid manufacturing approach, merging 3D-printed components and 3D-printed molds for silicone casting, allows a more accurate representation of both the anatomy and functional characteristics of the pediatric airway for model production. Further, it allows for the direct translation of anatomy derived from real patient medical imaging into a functional airway management simulator, and our modular design allows for modification of individual elements to easily vary anatomical configurations, haptic qualities of components or exchange components to replicate pathology.

Figure 1.

Examples of simulator components developed for prototype 1. A, Two-part 3D-printed mold (Z650 powder print) for casting the vertebral column insert with Ecoflex 00-30 alongside an anterior oblique view of the cast silicone insert with individual 3D-printed (Z650 powder print) vertebrae; (B) superior oblique view of the cast cervical fascia and muscle module in Ecoflex 00-10; (C) superior oblique and superior view screenshots and 3D-printed (Z650 powder print) mandible with T-pin anchor points for attaching silicone cast oral cavity and tongue components; (D) anterior oblique screenshot and cast silicone tongue module in Ecoflex 00-10 with reciprocal pin recesses for the mandible anchor points; (E) anterior oblique screenshots and 3D-printed (Connex 350 multi-material) combined upper airway, gingivae, and oral mucosa in Tango Black material with embedded tracheal cartilages. Scale bars = 1 cm. 3D indicates 3-dimensional.

Figure 2.

Examples of simulator components developed or adapted for prototype 2. A, Anterior oblique screenshots and cast silicone tongue module in Ecoflex 00-10 with redesigned mortise-and-tenon for joining the posterior aspect with the pharyngeal component, and a T-shaped groove for joining the mandible; (B) anterior oblique screenshot and cast silicone oral mucosal module in Ecoflex 00-10; (C) inferior oblique view of the cast silicone temporomandibular sleeves in Ecoflex 00-10 affixed to the 3D-printed (Z650 powder print) skull with and without the 3D-printed (Z650 powder print) mandible in position; (D) anterior oblique screenshot and view of the 3D-printed (Connex 350 multi-material) revised nasopharyngeal model in Tango Clear material with tenon for tongue articulation and embedded tracheal cartilages; (E) lateral and anterior view of the assembled prototype 2 simulator (without overlying skin or oral mucosa modules) to demonstrate the fit of skeletal, muscular, TMJ, and nasopharyngeal components. Scale bars = 1 cm. 3D indicates 3-dimensional; TMJ, temporomandibular joint.

Figure 3.

Examples of simulator components developed or adapted for prototype 3. A, Superior view of the cast silicone Ecoflex 00-10 tongue, mandibular gingivae, and Ecoflex 00-30 temporomandibular sleeves in articulation with the 3D-printed (Form 2 SLA White resin) mandible; (B) lateral view of the cast silicone Ecoflex 00-30 nasopharyngeal module with midsagittal section demonstrating the reproduction of internal anatomical structures from the conchae and auditory tube meatus to the mucosal folds of the epiglottis and larynx; (C) lateral and anterior view of the assembled prototype 3 simulator with the cast silicone nasopharynx module, gingivae, tongue, and temporomandibular sleeves with the 3D-printed (Form 2 SLA White resin) skull, mandible, and vertebral column modules; (D), lateral and anterior views of the fully assembled prototype 3 with cast Ecoflex 00-30 skin and superficial fascia. Scale bars = 1 cm. 3D indicates 3-dimensional; SLA, stereolithography.