Assessing the characteristics of a 3D printed airway model forcricothyroidotomy simulation training in anaesthesia.
Dr Diana Munteanu, Dr Ian Chao, Dr Jeremy Young, Dr JasamineColes-Black, Dr Louise Ellard, Dr Timothy McIver, Mr Jason Chuen.
One of the emergencies feared by all airway specialists is the "cannotintubate, cannot oxygenate" (CICO) scenario. Albeit uncommon, this is life-threatening and can have catastrophic consequences if not managedappropriately. Cricothyroidotomy is the most commonly used means toachieve a surgical airway in this situation in order to re-establishoxygenation. Currently, surgical airway training relies on animal models orsynthetic commercial trainers. These have several limitations includingbiohazard and ethical implications, high cost and limited availability.
With the advances in 3D printing technology, our department haverecreated a plastic representation model of the human trachea, which haspreviously never been described in the literature.
In this study, our aim was to assess the penetrability of our 3D-printedhuman trachea model as compared to a porcine model and a syntheticcommercial model, in evaluating its potential use as a trainer for futureemergency airway simulation training.
Our team created a digital human trachea model from a de-identifiedCT scan using the open-source image segmentation program ‘3Dslicer’, and printed 20 identical copies via fusion deposition modellingtechnology using flexible flesh-coloured filament.
The force to puncture these models with a 14-gauge cannula at 45degrees and a size 10 round blade scalpel at 90 degrees wasmeasured with a hand-held force meter at three different locationsalong the trachea: the cricothyroid membrane, and two randomlychosen locations on the anterior trachea, below the cricoid cartilage.
These tests were subsequently also performed on 17 porcine airwaymodels, and 20 Frova Crico-trainers for comparison. Three differentoperators were involved in performing this experiment.
The results were analysed using a random-effects regression model toallow for heterogeneity within each group (type of model), adjusting fordifferent operators, location of puncture (cricothyroid membrane vslower trachea) and instrument used.
Table 1: Overall analysis for the force required to puncture the 3D model compared to the porcine trachea andthe FROVA Crico-trainer.
In total, 57 models were tested, and 341 force measurements taken.
The overall analysis showed a statistical difference in the force required topuncture the 3D models compared to porcine models, as well ascompared to the Frova Crico-Trainer, with p-values <0.001 (table 1).
At the cricothyroid membrane, the 3D model required a statistically higherforce than the porcine trachea (p <0.001), but there was no significantdifference between the Frova and the porcine trachea (p = 0.663; table 2).
Table 2: Difference in force required to puncture the 3D model and the FROVA at the cricothyroid membrane,compared to the porcine trachea, adjusting for operator and instrument effects.
A significantly higher force is required to puncture the 3D-printed tracheacompared to the porcine or Frova models, despite the mean difference onlybeing in the magnitude of 2.93N and 1.59N respectively.
This demonstrates that, at this stage, our 3D-printed model may not fullypossess the same properties as the porcine trachea, and further designrefinement is required to improve its tactile feel and realism.
Importantly, no statistically significant difference in puncture force wasfound between the commercial Frova trainer and the porcine model. Thissuggests that the Frova Crico-trainer may in fact be a realistic model forcricothyroidotomy simulation, which to our knowledge, has not beenpreviously demonstrated.
Figure 3: Force testing 3Dtrachea, size 10 scalpel 90º
Figure 4: Force testing 3D trachea, 14-gauge cannula at 45º.
Department of Anaesthesia, Austin Health & Eastern Health,with the support of 3D Lab at Austin Health, Victoria, Australia.
Figure 2: Two trachea models being printedwith the Flashforge 3D printer.
Figure 1: Frova Crico-trainer.