Comparison of three tracheal intubation methods for reducing droplet spread for use in COVID-19 patients

Editor—Tracheal intubation is a life-saving procedure for respiratory failure caused by coronavirus 2019 (COVID-19),¹ however it is a high-risk aerosol generating procedure.² Healthcare workers have been compelled to discover novel forms of physical barrier and develop specific techniques of tracheal intubation with the least risk of transmission.^{3 , 4} One such barrier method is an ‘intubation protection box’, a transparent box with openings for the hands that is placed over the patient's head to physically capture droplets and protect the laryngoscopist. Inspired by a previously described design,⁵ we created a similar model with some modifications (Supplementary File S1).

We compared three methods of tracheal intubation: direct laryngoscopy, videolaryngoscopy, and videolaryngoscopy with the protective intubation box (see online video and Supplementary File S2). In a simulated intubation, we measured the trajectory and amount of droplet spread. We used an airway mannequin with its airway connected to a laryngo-tracheal mucosal atomisation device (MADgic, Teleflex Medical, Ontario, Canada) to simulate a cough and aerosolisation of droplets, which was attached via a short connector tubing to a 10 ml syringe containing a red-dye solution. The first test with direct laryngoscopy showed a large amount of dye on the laryngoscopist's faceshield, gown, arms, glove, neck, and hair. The second test with the videolaryngoscopy technique showed a significantly lower amount of dye on the laryngoscopist in similar locations, visually less than half the quantity compared with direct laryngoscopy. The third test with videolaryngoscopy and the box showed dye only on the gloves and forearms within the box; no dye was visible on any part of the laryngoscopist located outside the box including gown, face shield, neck, and hair (Fig. 1 ).

Fig. 1.

Videolaryngoscopy with the protective intubation box.

Supplementary video related to this article can be found at https://doi.org/10.1016/j.bja.2020.04.083.

The following is the supplementary data related to this article:

Video

2

Our simulation method is one of the few simulations to show both large and small droplet trajectory. In the video, it is interesting to note that microdroplets lingered longer. Out of the three methods, videolaryngoscopy, as compared with direct laryngoscopy, was the preferred method of tracheal intubation given the significant decrease in the amount of aerosolised droplets on the laryngoscopist. The box offered an additional physical barrier as compared with videolaryngoscopy. However, we believe that with proper personal protection equipment, there is minimal additional benefit in terms of droplet protection. Our technique measured droplet spread primarily, and may be less sensitive to fine aerosols. A potential disadvantage of the box is the restriction to movement and adapting to a new way of intubation.⁶ In the event that the airway proves to be difficult, the box should be immediately abandoned.

Declaration of interests

The authors declare that they have no conflicts of interest.

Appendix A. Supplementary data

The following is the supplementary data to this article: