Manufacture of a Multi-Purpose Low-Cost Animal Bench-Model for Teaching Tracheostomy

The aim of this project is to describe every step of the manufacturing of a multipurpose, low-cost animal bench model used for teaching tracheostomy. The quality of the model has been tested by professional experts in the technique through the administration of a questionnaire after they executed the procedure. Tracheostomy is one of the most frequent procedures performed through various techniques in intensive care units and emergency situations.

In spite of this, there is a lack of training that affects this procedure's outcome, which is also dependent on operator's dexterity. This is why specific training and simulation should be taken into consideration. Clean the swine upper airways.

These are swine upper airways which are covered by muscles and fibrous tissue. The tongue is usually still attached to the larynx. With the help of a dissecting scalpel, Adson forceps, and Metzenbaum scissors, clean the trachea and larynx from excess surrounding tissues such as lateral muscles and excessive tongue by cutting and dissecting.

Remove tissue until the larynx cartilages are almost exposed and the tracheal rings are easy to palpate. Now remove the hyoid bone and surrounding soft tissues. Find the eminence of the greater horn and follow the horn with the blade.

Then, pass through the contralateral until the whole part is removed. This is the result. Cut the trachea at its distal side approximately 15 centimeters from the larynx using a dissecting knife.

The removed part composed of mediastinal organs will be used for the next step in the procedure. Here is the result. Prepare the thyroid.

Take the previously discarded mediastinal organs and search for the thymus. Adult pigs may have averagely small thymus which is usually located on the frontal portion of the mediastinum right over the right atrium. With dissecting forceps detach the thymus from surrounding tissue.

The just obtained pig thymus is then cut in a butterfly shape to recreate a simulated thyroid. With a dissecting knife, cut a flat slice of thymus 1.5 centimeters thick. With Metzenbaum scissors cut the slice in a butterfly shape with two lobes of three centimeters by two centimeters connected by a ismuth.

The overall dimensions of the thyroid should be three centimeter long, six centimeter large, and 1.5 centimeter thick. Suture the thyroid to the tracheal wall. For the next step, you need the previously prepared upper airways and the simulated thyroid.

Place the simulated thyroid between the first and third tracheal rings. Take a needle holder, some surgical forceps, and grab a two zero silk suture. Suture the thyroid with two lateral horizontal mattress stitches in each lobe to the lateral portion of the trachea.

The horizontal mattress stitch wraps more tissue than the normal stitch. This is important when suturing soft tissues that are easy to tear up, such as pig thymus. Try to pass the needle only in the superficial part of the trachea to prevent the possibility of seeing the thread in the tracheal lumen if performing fibroscopy.

As you can see, this is the result. Behind the trachea is the esophagus which is needed for the next step. And here is the epiglottis.

Prepare the esophagus. Use the esophagus, which is located on the back side of the trachea to simulate the neck fascia and muscles. Remove the esophagus from its larynx connection by cutting it with a scalpel or with surgical scissors.

Cut and open the esophagus on its length with surgical scissors. Hold the muscle and mucosa with tooth forceps to help the cutting procedure. The result of this operation will be a rectangle of muscle covered by esophagus mucosa.

Suture the esophagus to the trachea. Place the just obtained layer of muscles on top of the trachea and larynx with the mucous membrane face up. The aim is to cover the larynx from the thyroid cartilage summit to the last tracheal ring.

Suture the opened esophagus with at least six simple stitches. One on the proximal side of the model, on the summit of the thyroid cartilage. One on the distal side of the preparate on the frontal partition of the last tracheal ring.

Then place two simple stitches on each side of the trachea. This is what the sutured esophagus looks like. Mark a line on the esophagus mucosa with white India ink to simulate the linea alba.

To do so, use an insulin syringe. Withdraw some ink and then track a line on the simulated fascia by scratching it with the needle while spilling drops of ink. With a small swab, gently remove the excess ink.

Prepare the foam base for the model. Cut a square of foam of three by 10 by 15 centimeters. Shape a furrow 2.5 centimeters large and 10 centimeters long in the center of the foam.

To do this, fold the square of foam in half so that it creates a longitudinal hump on one side. Using scissors, cut one centimeter of the hump off all its length. Unfold the foam square and trim the just formed furrow smoothly.

Staple the model to the wooden tablet. Take a wooden tablet of the same dimensions of the foam. Place the foam square on the wooden tablet and insert the model in the foam furrow.

With a wood stapler place clips on the end of the trachea, on the remaining lateral muscles of the thyroid cartilage, and on the epiglottis. Prepare the skin. Take the pig skin collected from the butcher shop and cut it in a square shape big enough to cover the whole model.

Usually a square of 25 by 20 centimeters is sufficient. With a dissecting knife, cut the skin and cover the model with it. Staple the skin to the wooden tablet.

Take the stapler and fix the skin to the tablet with around 10 to 15 clips. Clips have to be placed on the side of the tablet. Now trim the excess skin on each side of the tablet with the help of a knife.

Kocher forceps can be used to firmly hold the skin to allow safer cutting. And this is the final result. 10 experts in the technique were enrolled.

The model scored an average of 3.45 on five for its anatomical realism. 4.75 on five for its usefulness as a training tool for simulation courses and assessments. The time necessary to build the model was 15 minutes and the cost amounted to 10 euros.

This animal bench model was considered a very useful simulator for tracheostomy training and assessment. Therefore, it could be used as a tool in medical courses and residencies. Thank you.