Introduction: Three dimensional printing can provide physiological models with internal complexity that is not possible using traditional subtractive manufacturing or injection moulding [1]. The intricacies of the passages of the upper airway are usually highlighted with CT or MRI and a soft sylgard model of the upper airway has been constructed using a negative dissolvable mold [2]. This model was ventilated with high nasal flow to study the effects of upper airway resistance and resistive work of breathing. At present there is a singular limitation when digital airway models are derived from radiological data sets. This pertains to the restrained posture of the patient when imaged in the confinements of a scanning machine. In this research we present a method for tuning the orientation of many complex anatomical parts in unison and with reference to defined anatomical planes. Methods: In order to manufacture the anatomical laryngopharynx, larynx and laryngeal cartilages, trachea and strap muscles of the neck, 3D digital files were downloaded from the open source BodyParts3D project (3) and assembled in Meshmixer as a model in a neutral position. Based on previously published papers describing the axial alignment of mouth, pharynx, and larynx obtained by flexion of the neck and extension of the head on the atlanto-occipital and upper cervical joint (4,5), axial planes were incorporated into the mesh. The resulting digital OBJ file was then exported into Blender as vertex groups in order to enable minute manipulation of the vertices or angular points of the individual anatomical parts. The angles of anatomic axes were adjusted in accordance with the values given in (4). The various angles between the axes were used as pivot points around which the rotation occurs and these were assigned using the Bounding Box Center or 3D Cursor functions within the software. Finally to test the physiological and anatomical accuracy of the bent model, the mesh was exported as an OBJ file into the slicer program Simplify3D and the individual components of the model assigned to different 3D printing filaments. A cross section of the model was saved as an STL file and printed using a Vivodeno T-Rex 3 independent dual extrusion 3D printer. Results: It was possible to generate multiple 3D prints with tuneable occipito-atlanto-axial extension (OAA) angles in the sniffing position relative to the neutral position. Conclusion: This method shows how a high fidelity 3D model with OAA extension in sniffing and simple head extension positions can be printed. Moreover, the use of soft and hard materials such as FilaFlex and polylactic acid (PLA) and experimental filaments of varying Shore hardness can be combined to produce a high fidelity, anthropomorphic training model for cricothyroidotomy or physiological models for studies of upper airway resistance.
Physiology 2019 (Aberdeen, UK) (2019) Proc Physiol Soc 43, PC053
Poster Communications: 3D printed upper airway models with tuneable postural orientation
L. Gorman1, T. Byrne1, T. Campbell1, J. F. Jones1, C. McCaul2
1. Anatomy, School of Medicine, Dublin, Ireland. 2. Rotunda Hospital Dublin, Dublin, Ireland.
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Where applicable, experiments conform with Society ethical requirements.