The REAL CRIC Trainer
Background:
Surgical cricothyrotomy is a rare procedure, but must be mastered by any physician who is involved in advanced airway management. Lack of experience and practice, the high stress nature of a "can't intubate, can't oxygenate" emergency, and the unavailability of realistic simulators, all contribute to physician hesitance and inaptitude while employing cricothyrotomy during difficult and failed airways. The REAL CRIC Trainer was created to alleviate some of the barriers surrounding a surgical airway. It is designed to provide the user an affordable, easy to replicate, reusable and extremely realistic experience in cricothyrotomy, in order to prepare for this rare event.
The REAL CRIC Trainer uses a three dimensional printed tracheal model that is covered with pork belly with skin, replicating human neck tissue. Red dyed normal saline is connected to the pork belly using intravenous tubing to simulate bleeding as an incision is made into the porcine skin. A bag-valve-mask connected to an endotracheal tube and to the trachea model will simulate breathing and replicate the puff of air experienced as the cricothyroid membrane is pierced with a scalpel. This simulator is cost effective and easy to replicate. Detailed step-by-step instructions are provided, so that physicians working in any specialty involved in advanced airway management can easily recreate this trainer.
Supplies:
1. 3D printed model of a trachea, printed from the following STL file: https://www.airwaycollaboration.org/3d-cric-trainer-1/ ($0-50, depending on where you print it).
2. 15 cm piece of corrugated ventilator tubing
3. Duct tape
4. Roll of 3M Microfoam surgical tape
5. 8-0 endotracheal tube and bag valve mask
6. Mannequin head ($15 online)
7. Pork Belly with skin still attached, about a 15 x 15 cm piece that is 3 cm thick ($5 from grocery store or local meat market)
8. IV tubing and 1 liter bag of normal saline
9. Bottle of red food coloring
10. Blue sterile drapes
11. Plastic storage container to hold supplies and lid for base of trainer (or you may use some other plastic tray as the base to secure the trainer down and collect the fake blood).
12. Cricothyrotomy supplies: #10 scalpel, 6-0 endotracheal tube, and a bougie.
Instructions:
1. Print or order a filament or resin 3D trachea (filament is cheaper but more brittle while the more expensive resin will last for >100 cricothyrotomy practice sessions). Attach a piece of corrugated tubing (ventilator plastic tubing) to the distal/inferior opening with duct tape. Then seal the open end of the tubing with duct tape; this will serve as the carina. Puncture two air vents in the tubing by making two small holes with a scalpel; these holes must be smaller than the diameter of a bougie.
2. Place an 8-0 endotracheal tube (ETT) into the trachea model from the superior opening. Be sure that the ETT is not pushed too far down. The bevel of the ETT should be pointing up and not visible from the cricothyroid opening. The ETT should then be connected to an BVM which will allow for a puff of air to be created when the cricothyroid membrane is pierced by the participant with a scalpel (Figure 1A).
3. Using a piece of 3M microfoam surgical tape, secure the trachea set-up to a fluid collection tray (for example: lid of a plastic storage container/cookie tray/oil drip pan). The microfoam tape will also serve as the cricothyroid membrane (if microfoam tape is not available, duct tape or 3M Tegaderm can be used as a substitute).
4. Above the trachea, a mannequin head is placed to create a more realistic experience. Velcro can be used to secure the head to the tray. Place this trachea set up aside (Figure 1B).
5. Take a piece of fresh pork belly with skin still attached, measuring about 15 x15 cm and about 3 cm thick. In the center of this piece of meat, subcutaneously inject 30 ml of fake blood with an 18 gauge needle; the fake blood can be made by injecting 10 ml of red food coloring dye into a liter bag of normal saline. Create a midline weal just under the skin in a linear vertical fashion that is about 5 cm in length. This subcutaneous fluid will mimic immediate bleeding as a scalpel cuts through the first few layers of dermis (Figure 2A). Be sure create this weal just before the simulator is to be used.
6. Using a #10 scalpel, create a tunneled incision that is parallel to the skin surface and about 0.5 cm beneath it. This incision should start at the inferior portion of the pork belly, directly midline and end half way up the piece of meat, stopping just under the weal you created (Figure 2B).
7. With your IV tubing starter kit, cut the tubing with scissors distally, just above the first injection port, removing all of the roller clamps and slide clamps. What should be remaining is the bag spike, drip chamber and a long piece of plastic tubing with no other plastic hardware. Spike a liter bag of normal saline mixed with 10 ml of red food coloring dye. Slide the intravenous tubing into the pork belly incision you just created (Figure 2C). The faculty member running the simulator can replicate copious bleeding and control the amount of bleeding during the procedure by simply squeezing the bag of normal saline.
8. Finally, place this prepared piece of pork belly over the trachea model with the IV tubing side facing inferiorly (Figure 3A). Blue surgical drapes can be placed around the model for a more realistic appearance (Figure 3B). Your REAL CRIC Trainer is now ready for use.
Each trainer will need to be supervised by a faculty member. The faculty member can control the amount of bleeding by squeezing the IV bag with fake blood and they can also create a flash of air by squeezing the BVM as the participant cuts through the cricothyroid membrane.
Figures 1A and 1B.
Figures 2A, 2B, and 2C.
Figures 3A and 3B.
YouTube Instructional Video
The REAL CRIC Publication in the Journal of Emergency Medicine, Kei and Mebust, April, 2019.
Link to Dr. Laura Duggan's Free Downloadable 3-D Printed Trachea STL File