TissueDB/Simulators/Cricothyrotomy Simulator (Calvo)

The Cricothyrotomy Simulator (Calvo) is a low-cost airway trainer for emergency surgical cricothyrotomy in a "can't intubate, can't oxygenate" situation. A learner palpates the laryngeal landmarks through a pork-belly skin layer, then makes a skin incision over the cricothyroid membrane to reach the airway of a 3D-printed trachea. An instructor-controlled air pump releases air when the membrane is pierced, and a pressurised circuit produces bleeding at the incision. The model is a modification of the REAL CRIC Trainer (Kei et al. 2019) and also supports ultrasound identification of the laryngeal landmarks.^[1]

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.^[1]
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).^[1]
3. Fasten and secure the 3D-printed trachea with foam adhesive tape (Calvo et al. 2021, Fig 1E).^[1]

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).^[1]
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]

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).^[1]
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).^[1]
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]

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).^[1][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).^[1]
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]

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).^[1]
2. Connect the tunnelled IV outlet in the pork belly to the pressurised saline bag (Calvo et al. 2021, Fig 1J).^[1]
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).^[1]
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.^[1]

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.^[1]
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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