Novel co-axial, disposable, low-cost 3D printed videolaryngoscopes for patients with COVID-19: a manikin study

Abstract

Background: COVID-19 continues to present challenges to both patient management and the protection of the airway management team involved, in particular in resource-constrained low-income countries. Among the most concerning complications in affected patients is rapid hypoxemic respiratory failure requiring tracheal intubation and mechanical ventilation. Videolaryngoscopy without peri-intubation oxygenation is the recommended approach in COVID-19 patients. However, the absence of peri-intubation oxygenation during intubation attempts can lead to hypoxia, and result in life-threatening complications in already critically ill patients.

Objective: To develop low-cost disposable 3D printed videolaryngoscope designs with integrated channels for oxygen, suction, WIFI-enabled camera and tracheal tube channels, as well as a flexible transparent barrier anchor to offer optional additional protection to the user and airway management team.

Design: A manikin study.

Setting and participants: Three experienced consultant anaesthetists in the Mater Misericordiae University Hospital, Dublin, Ireland.

Main outcome measures: To generate novel co-axial videolaryngoscopes that meet International Standards, ISO7376 : 2020 standards for anaesthetic and respiratory equipment (laryngoscopes for tracheal intubation), and to demonstrate successful tracheal intubation of a manikin trainer in a range of configurations ('easy' to 'difficult') in accordance with the Cormack-Lehane grading of laryngeal view.

Results: Final design prototypes met the minimum criteria for strength and rigidity according to ISO7376 : 2020, including blade tip displacement under load (65 N and 150 N). Preliminary validation has demonstrated successful tracheal intubation of a manikin trainer in all configurations including 'difficult' (Cormack-Lehane Grade 3 view).

Conclusions: This low-cost, rapid in-house manufacture could offer a mitigation of supply chain disruptions that can arise during global pandemics. Furthermore, it could offer a low-cost solution in low-income countries where there is an infection risk caused by re-using most current videolaryngoscopes requiring sterilisation before re-use, as well as limitations in the availability of personal protective equipment.

Fig. 1

Rear, front (blade tip) and side views of a digital video-laryngoscope design inspired by the English-type Macintosh, E-MAC (size 3) in Fusion 360™. REAR VIEW; rear routed WIFI camera cable channel^ and tracheal tube guide^∗. FRONT VIEW: blade tip featuring (from left to right) a tracheal tube guide^∗, WIFI camera channel^ with a flexible clip to pin the camera in place once inserted and a co-axial oxygen+ and suction- channel. SIDE VIEW: magnified view of the co-axial oxygen+ and suction- channel ports and an anchor point for an optional barrier envelope (push down to fit).

Fig. 2

Final printed designs featuring ergonomic grip (E-MAC sizes 3 and 4), tracheal tube channel^∗, central WIFI camera channel^ to accommodate a maximum 3.9 mm lens diameter and co-axial tube enabling separate suction- and oxygen+ delivery. The AVL (in green) features a tracheal tube channel^∗ measuring 13.5 mm in width and accommodates a tracheal tube size up to 7.0 mm internal diameter. Circled is a magnified view of the channel openings at the distal (blade tip) end of the AVL.

Fig. 3

Finite element analysis (FEA) of each laryngoscope blade -- English-type Macintosh (E-MAC) and channelled adult videolaryngoscope (AVL) incorporating internal oxygen, suction and camera channels -- to assess structural performance under a static 150 N load.

Fig. 4

Test setup schematic (left) and final laboratory setup (right). Each video laryngoscope was secured to the test instrument (Lloyd LR30K Plus Materials Testing Machine) via a steel mounting pin, and rotational movement prevented via a steel pin.

Fig. 5

(a) Intubation and visualisation of the vocal cords of a manikin using the E-MAC size 4 and a WIFI camera connected to the operator's mobile phone. (b) An example of the AVL in use without the optional protective barrier sheet in place. (c) Intubation of a manikin with the protective barrier sheet attached to the barrier anchor point built into the videolaryngoscope handle. (d) View of the passage of a size 6.0 mm tracheal tube beyond the vocal cords during manikin testing with a protective barrier sheet in place.