Patient-specific and hyper-realistic phantom for an intubation simulator with a replaceable difficult airway of a toddler using 3D printing

Abstract

Difficult tracheal intubation is the third most common respiratory-related adverse co-morbid episode and can lead to death or brain damage. Since difficult tracheal intubation is less frequent, trainees have fewer opportunities to perform difficult tracheal intubation; this leads to the need to practice with a hyper-realistic intubation simulator. However, conventional simulators are expensive, relatively stiffer than the human airway, and have a lack of diversity in terms of disease variations and anatomic reproducibility. Therefore, we proposed the development of a patient-specific and hyper-realistic difficult tracheal intubation simulator using three-dimensional printing technology and silicone moulding and to test the feasibility of patient-specific and hyper-realistic difficult intubation simulation using 3D phantom for the trainee. This difficult tracheal intubation phantom can provide a realistic simulation experience of managing various difficult tracheal intubation cases to trainees, which could minimise unexpected tissue damage before anaesthesia. To achieve a more realistic simulation, a patient-specific phantom was fabricated to mimic human tissue with realistic mouth opening and accurate difficult airway shape. This has great potential for the medical education and training field.

Figure 1

A patient-specific and hyper-realistic phantom for difficult tracheal intubation simulator. (A) Assembly of the inner parts, including the back of the skull, cranio-maxilla, mandible, cervical-spine, airway, and tongue in the isometric view. (B) At state, (A) bottom view. (C) Final phantom with front and rear skins. (D) Intubation with Macintosh blades in the phantom with mouth opening.

Figure 2

Bland–Altman plots to evaluate the accuracies between the STL file and the three airway and tongue parts with different 3D-printing methods. (A) STL vs Objet J750 with agilus, (B) STL vs Form2 with elastic, and (C) STL vs X-fab with flexa 693. The lengths were measured at (a) the diameter of the airway, (b) width of the epiglottis, (c) length of at the epiglottis to the end of the airway, and (d) length of the tongue.

Figure 3

Box plot displaying measurements of Shore A hardness of printing methods including Objet j750 (blue), Form2 (red), and X-fab (green) with the number of Med6-6606 coatings. Specimens with 0, 1, 5, and 10 coatings. The box represents the middle 50% of the data and the quartile (IQ) range. The whiskers represent the maximum and minimum values less than 1.5 times the IQ range.

Figure 4

Bland–Altman plot to evaluate differences between the STL file and the phantom. (a) Measurements of STL and printed phantom at a 21 mm inter-incisor distance, (b) 32 mm inter-incisor distance, and (c) 47 mm inter-incisor distance.

Figure 5

Overall procedure of manufacturing a difficult tracheal intubation simulator of a toddler. FDM fused deposition modelling, CJP colour-jet printing, SLA stereolithography apparatus, C-spine cervical spine.

Figure 6

Visualisation of segmentation with various anatomic regions for designing the difficult tracheal intubation phantom in CT images of an 18-month-old patient with Crouzon syndrome. (A) Sagittal view, (B) axial view, and (C) 3D visualisation (cervical-spine, red; airway, dark blue; tongue, green; skull and mandible, yellow).

Figure 7

The airway and tongue were modelled based on CT images of a patient with Crouzon syndrome. (A) One part with the airway (blue) and tongue (green), and four measurements for evaluating fabrication accuracies, including (a) the inner diameter of the airway, (b) the width of the epiglottis, (c) the length between the epiglottis to the end of airway, and (d) the length of the tongue (connectors to a mandible and cranio-maxilla; yellow). (B) inner structure (brown) and the outer hole of the tongue to mimic the tactile sensing to press the tongue with Macintosh blades and holes at the isometric (upper) and front (lower) views.

Figure 8

The overall design of the mouth movement. (A) The cranio-maxilla with a trailed socket inserted by a circular shaped condyle of the mandible at the closed mouth in the cutting at trailed socket. (B) The cranio-maxilla with the slid and rotated mandible at the open mouth in the cutting view. (C) At state (B), the length of the mouth opening in the inter-incisor distance in 3D visualisation was measured (red line).

Figure 9

Assembly of a difficult tracheal intubation phantom with various anatomic parts including (A) the back of the skull, (B) the cranio-maxilla, (C) the cervical spine, (D) the airway and tongue, (E) the mandible, and (F) the assembly of the inner structures including (A)–(E), excluding the skins. With skins including (G) rear and (H) front parts, all parts are assembled in (I) which integrates (F)–(H). The blue parts of (I) were used as connectors of the rear and front skins into the skull.