More than 5% of hospitalized patients with COVID-19 are healthcare providers, according to a recent report by the Centers for Disease Control and Prevention (CDC)[1]. The COVID-19 pandemic has made it strikingly clear that we are poorly equipped when it comes to protecting frontline workers from aerosols and droplet exposure during procedures such as endotracheal intubation. With the airway management market growing at a vertiginous pace, scientists and investors are working together to fill the gap and make intubation a safer procedure for clinicians. Amongst widespread chaos at the beginning of the pandemic, on May 1st 2020 the FDA issued an Emergency Use Authorization for a new device – the aerosol box – and its derivatives (known as protective barrier enclosures), in the hope that these devices could provide “an extra layer of barrier protection in addition to personal protective equipment (PPE) when caring for or performing medical procedures on patients who are known or suspected to have COVID-19”[2].

The original aerosol box was designed by the Taiwanese anesthesiologist, Dr. Lai Hsien-yung, in an effort to protect medical staff from aerosol and droplet exposure during endotracheal intubation. Its straightforward design consists of a transparent acrylic or polycarbonate box that is placed over the patient’s head, with holes for the healthcare provider’s arms that enable the procedure to take place. Variations on the original design incorporate extra holes to provide oxygen and suction, and surgical gloves to seal the arm holes[3]. The concept behind the aerosol box is simple: isolating the patient should, in theory, protect medical staff from exposure, while the armholes provide access to the patient’s airway. Dr. Hsien-yung shared the original design via Google Sites in March 2020, and his efforts met with quick public acclaim and diffusion over social media[4]. However, more rigorous studies in preclinical models have cast serious doubts on the efficacy and safety of protective barrier enclosures, leading to the FDA withdrawing its Emergency Use Authorization on August 20th, 2020.

“There is no doubt that genuine fear is motivating distribution and use of these devices, especially in systems with critical PPE shortages,” reflect Begley et al[5] in their article which recommends caution when using the aerosol box, pointing out several weak aspects of the design which could potentially harm not only clinicians but also their patients. In their experimental study, time to intubation was significantly higher in both first-generation and evolved aerosol boxes, which in a clinical setting could set patients at risk for hypoxia (a finding also observed in other studies[6]). Also, various breaches of personal protective equipment were observed when using the aerosol box, exposing healthcare workers to the very risk they seek to avoid: contact with aerosols and droplets. Another study[7] found that combining the aerosol box with a drape leads to aerosols escaping once the drape is lifted to manipulate the airway, thus provoking increased risk of exposure.

But not only does the use of aerosol boxes pose a potential risk to personal protective equipment and lead to increased intubation times; whether protective barrier enclosures meet their primary objective of creating an effective barrier for aerosols and droplets is uncertain. In their prospective, non-blinded in-situ simulation study, Simpson et al[8] observed that – contrary to popular belief – the aerosol box did not reduce exposure to aerosols, and in fact increased exposure especially in cough simulations. This finding contrasts somewhat with the conclusions reached by Fidler et al in their experimental review published in Anesthesiology[9]. Although vapor experiments in manikins showed leakage at armholes, the aerosol box reduced aerosol exposure at the operator’s mouth 20-fold when compared to no barrier. Other protective barrier enclosures such as the ‘interlocking box’ (a variant of the original aerosol box) were less successful, with results comparable to no barrier observed. However, none of the tested barrier devices provided full protection against aerosol exposure, leading to the authors’ suggestion that a more appropriate name would be ‘droplet box’, leaving the name ‘aerosol boxes’ for fully enclosed devices. The authors caution that “even with fully closed devices, aerosol counts outside the barrier device were reduced but still statistically significantly elevated above baseline, highlighting the importance of personal protective equipment”. It remains to be seen whether future studies will provide conclusive evidence on the now highly-questioned safety and efficacy of the aerosol box.

In the FDA’s original Emergency Use Authorization, one of the main reasons behind approving this kind of device without existing preclinical or clinical trials was the absence of other “adequate, approved, and available alternative(s) to the emergency use of these protective barrier enclosures”[10]. Airway ShieldTM is an innovative device which seeks to fill this gap. With robust preclinical studies already conducted in experimental scenarios, and clinical trials planned for early 2021, we hope to provide adequate protection for clinicians while facilitating airway management, making our technology a safe and efficient solution for both healthcare providers and their patients. Clearly, to solve the current problem of protecting frontline workers from aerosol exposure in the COVID-19 pandemic, investigators must ‘think outside the box’.

[1]Kambhampati, A. K., O’Halloran, A. C., Whitaker, M., Magill, S. S., Chea, N., Chai, S. J., … & Yousey-Hindes, K. (2020). COVID-19–Associated Hospitalizations Among Health Care Personnel—COVID-NET, 13 States, March 1–May 31, 2020. Morbidity and Mortality Weekly Report, 69(43), 1576.

[2] U.S. Food and Drug Administration. Emergency Use Authorization for Protective Barrier Enclosures. Accessed December 5, 2020.

[3] Maniar, A., & Jagannathan, B. (2020). The aerosol box. Journal of Anaesthesiology, Clinical Pharmacology, 36(Suppl 1), S141.

[4] Mariano, E. R., Kou, A., Stiegler, M. A., & Matava, C. (2020). The rise and fall of the COVID-19 aerosol box through the lens of Twitter. Journal of Clinical Anesthesia.

[5] Begley, J. L., Lavery, K. E., Nickson, C. P., & Brewster, D. J. (2020). The aerosol box for intubation in COVID‐19 patients: an in‐situ simulation crossover study. Anaesthesia.

[6] Canelli, R., Connor, C. W., Gonzalez, M., Nozari, A., & Ortega, R. (2020). Barrier enclosure during endotracheal intubation. New England Journal of Medicine, 382(20), 1957-1958.

[7] Fidler, R. L., Niedek, C. R., Teng, J. J., Sturgeon, M. E., Zhang, Q., Robinowitz, D. L., & Hirsch, J. (2020). Aerosol Retention Characteristics of Barrier Devices. Anesthesiology.

[8] Simpson, J. P., Wong, D. N., Verco, L., Carter, R., Dzidowski, M., & Chan, P. Y. (2020). Measurement of airborne particle exposure during simulated tracheal intubation using various proposed aerosol containment devices during the COVID‐19 pandemic. Anaesthesia, 75(12), 1587-1595.

[9] Fidler, R. L., Niedek, C. R., Teng, J. J., Sturgeon, M. E., Zhang, Q., Robinowitz, D. L., & Hirsch, J. (2020). Aerosol Retention Characteristics of Barrier Devices. Anesthesiology.

[10] U.S. Food and Drug Administration. Emergency Use Authorization for Protective Barrier Enclosures. Accessed December 5, 2020.



Leave a Reply

This website uses cookies so that you have the best user experience. If you continue browsing, you are giving your consent for the acceptance of the aforementioned cookies and the acceptance of our cookie policy, click the link for more information.

Aviso de cookies