TissueDB/Simulators/Cricothyrotomy Simulator (Calvo)

The Cricothyrotomy Simulator (Calvo) is a low-cost airway trainer — a 3D-printed trachea covered with pork belly — for training emergency surgical cricothyrotomy in a "can't intubate, can't oxygenate" situation.^[1] A learner palpates the laryngeal landmarks through the pork-belly skin, then incises over the cricothyroid membrane to reach the airway; the model lets air escape when the membrane is pierced and bleeds at the incision. It is a modification of the REAL CRIC Trainer (Kei et al. 2019) and can also be scanned with ultrasound to identify the laryngeal landmarks.

1. Print the 3D trachea from the published REAL CRIC STL file (https://airwaycollaboration.org/3d-cric-trainer-1/) because Calvo et al. 2021 reproduce the original REAL CRIC trachea from this file; the print material, printer, and slicing parameters are not specified in the paper and must be selected locally.
2. Seal the distal exit of the printed trachea with paper tape so that pump-driven air escapes at the cricothyroid-membrane puncture rather than the open distal end (Calvo et al. 2021, Fig 1D).
3. Fasten and secure the 3D-printed trachea with foam adhesive tape (Calvo et al. 2021, Fig 1E).

1. Place an endotracheal tube inside the 3D-printed trachea because Calvo et al. route the air supply through an ETT seated in the model (Calvo et al. 2021, Fig 1B–C).
2. Connect the foot-operated air pump to the ETT because, in the modified model, the original Ambu bag is replaced by an air pump the instructor operates by foot away from the participant; this releases air at the cricothyroid membrane when the membrane is pierced (Calvo et al. 2021, Fig 1F).

1. Stain a 1 L bag of saline red with food dye because Calvo et al. use red-stained saline as the simulated blood (Calvo et al. 2021).
2. Mount the saline bag in an IV pressuriser because, in the modified model, the hand-squeezed bag of the original RCT is replaced by a pressuriser that delivers a greater, constant pressure and frees the instructor's hands (Calvo et al. 2021, Fig 1J).
3. Connect the IV infusion set to the bag because the set carries the simulated blood to the tunnelled outlet in the pork belly (Calvo et al. 2021, Fig 1J).

1. Obtain a pork-belly slab with the skin intact, sized to cover the 3D-printed trachea, because the pork belly provides the skin and subcutaneous layers the learner incises; specific dimensions are not given by Calvo et al. and follow the original REAL CRIC specification (Kei et al. 2019).^[2]
2. Infiltrate the subcutaneous tissue of the pork belly with the simulated blood because the saturated tissue produces visible bleeding when the skin is incised (Calvo et al. 2021, Fig 1G).
3. Tunnel the distal end of the IV infusion set through the subcutaneous layer using the protective plastic sleeve of a spinal-block needle, advancing the tunnel beyond the planned incision line, because in the original RCT tissue resistance at a shallow tunnel could exceed the blood pressure and block the outlet; the longer tunnel lowers resistance so blood reaches the incision (Calvo et al. 2021, Fig 1H–I).

1. Place the prepared pork belly over the 3D-printed trachea, skin surface outward, with the trachea centred beneath the tissue because this reproduces the skin–soft-tissue–airway relationship the learner palpates and incises (Calvo et al. 2021).
2. Connect the tunnelled IV outlet in the pork belly to the pressurised saline bag (Calvo et al. 2021, Fig 1J).
3. Attach the assembled phantom to a high-fidelity simulator's neck for the multidisciplinary scenario because Calvo et al. integrate the model on a high-fidelity simulator neck for the CICO simulation (Calvo et al. 2021).
4. Palpate through the pork belly to confirm the build — the thyroid cartilage and cricoid cartilage landmarks on the 3D-printed model must be identifiable through the overlying tissue; then, with the blood pressuriser charged and the instructor operating the foot air pump, confirm that blood reaches the incision and air escapes at the cricothyroid membrane on entry.

Build reference: Figures 1A–1K in Calvo et al. (2021) show the assembly sequence (3D trachea; ETT placement; sealing the distal exit with paper tape; fastening with foam adhesive tape; air-pump connection; pork-belly blood infiltration; tunnelling with the spinal-block needle protector; IV-set placement; and the final phantom). The figures are published under CC BY-NC-ND 4.0 and are not reproduced here; see the open-access article for the figure plate.

1. Replace the pork-belly slab when its skin is compromised by prior incisions because the pork belly is a consumable layer; Calvo et al. do not state a reuse count.
2. Refill the simulated-blood bag and re-tunnel the IV outlet for each fresh pork-belly slab (operational step; Calvo et al. do not describe a reset protocol).
3. Inspect the reusable 3D-printed trachea and re-seal its distal exit with paper tape if the seal is broken (operational step; not specified by Calvo et al.).

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