1. 3D Printing of Human Anatomy:11
3D Printing of Human Anatomy:
The Production of Realistic Airway Models for Cricothyroidotomy Simulation
Michelle L. Smith [1], Tiarnan Byrne [1], Conan McCaul [2,3], Peter J. McMahon [4],
Tomas Breslin [5], James F.X. Jones [1]
[1] Discipline of Anatomy, School of Medicine , University College Dublin, Ireland [2] The Department of Anaesthetics, Mater Misericordiae University Hospital, Dublin, Ireland [3] The Rotunda Hospital, Dublin, Ireland [4] The Department of Radiology, Mater Misericordiae University Hospital, Dublin, Ireland [5] The Accident and Emergency Department, Mater Misericordiae University Hospital, Dublin, Ireland
Background
Emergency airway management algorithms recommend creation of a surgical airway (e.g. cricothyroidotomy) as a last resort in life-threatening situations. As this technique is rarely required it is often unsuccessful. The high failure rate is in part due to difficulty in identifying the relevant anatomical landmarks and also a result of limited training opportunities. The most important step in establishing a surgical airway is to identify the surface markings of the thyroid cartilage. After that, the skin and the cricothyroid membrane can be incised allowing ventilation and subsequent re-oxygenation.
Objectives
There are a number of low-fidelity plastic models available for training in surgical airway techniques. Although useful, these models lack relevant or realistic anatomical characteristics. The common artistic renditions are usually modelled using dimensions taken from an average male thyroid cartilage.
3D printing is not a new technology; however in the past decade, it has demonstrated a role in medical research and specifically pre-operative surgical planning. Our aim was to 3D print patient specific anatomically accurate upper airways. . 1 1
Figure 1. The degrees of placental invasion
Materials and Methods
We utilised an open-source database of human anatomy to make our initial prototype. The ‘lifesciencesdb’ website has a catalogue of anatomical structures in stereolithographic (STL) file format. STL files encode the instructions for the 3D printing software. We modified the anatomical STLs using Meshlab, a free and open-source software, to generate a range of models based on individual structures.
To confer realistic biomechanical properties to the model we printed the airway with novel porous materials (e.g. the Porolay™ filament series). This material is deposited in solid form and its properties modified by immersion into liquid. The overlying adipose tissues and skin were replicated using silicone of varying Shore hardness.
Processing: Z Edit Pro (3D Systems, Rock Hill, South Carolina, U.S.) a proprietary 3D printing preparation software package was used for mesh editing. The model was subsequently scaled to fit the available print volume. This was then printed using a Z Print 250 binder jetting printer. Post processing of the model involved oven curing to improve model strength before an infusion system (Cyanoacrylate) was applied to allow intensive model manipulation without fear of breakage.
Anatomical 3D file database
Meshmixer file processing
Outer casing printed using Zprint250 printer, post processing complete
3D printing airway with Ultimaker using Layfoam 40
Results/Conclusions
We created a haptic modular 3D printed model of the larynx and trachea which includes the cricothyroid membrane and associated structures. Our future work will focus on the generation of models which represent male and female thyroid cartilage as well as the difficult airway.
Novel Layfoam 40 airway model pre-, during and post immersion in deionised water
Ethical Approval
Ethical exemption was granted by the Human Research Ethics Committee in University College Dublin.
Complete 3D printed cricothyroidotomy model
Incised cricothyroidotomy model