Letter to Editor

Dear editor,

Since March 2020, after China, Europe and the rest of the world are facing the COVID-19 pandemic, caused by the SARS-COV-2 virus [1]. This health crisis has led to oxygen shortages in developing countries but also in nursing homes because of the limited capacity of oxy-concentrators, when present, to provide an adequate oxygen flow [2-4].

The Double-Trunk-Mask (DTM) is a device designed to increase the fraction of inspired oxygen in adult patients who receive oxygen by a nasal cannula (Figure 1). The mask was developed by Duprez et al in 2001 [5]. The DTM is composed of a regular aerosol mask with corrugated tubing (ISO 22 - 15 cm length) inserted into two lateral holes. The tubing collects oxygen that is wasted from the nasal cannula during expiration or because of mouth breathing. During the next inspiration, the subject inhales the enriched oxygen gas mixture sequestered in the tubing instead of room air. Therefore, the DTM acts as a FiO₂ booster.

When the DTM is placed above low-flow or high-flow nasal cannula and the oxygen output is not modified; the PaO₂ increases without clinical impact on the PaCO₂ in patients hospitalized in intensive care [6,7]. In the same vein, a recent publication also showed that, for an identical oxygen saturation, the DTM can be used to reduce de oxygen output by 50% on average in COVID-19 patients hospitalized in COVID-19 wards [8] (Table 1).

Other practical issues are associated with the use of the DTM. First, this patent-free system is easy to assemble and inexpensive since all disposables are readily found in various clinical settings. Second, if required, performing a nebulization is facilitated because a regular aerosol mask composes the whole mask. Third, if the patient removes the DTM, he conserves at least a source of oxygen through the nasal cannulas. In view of the above considerations, in Belgium, the use of the DTM has been integrated in a stepby-step algorithm for oxygenation of hospitalized patients with COVID-19 by the Federal Agency for Medicines and Health Products [9]. This health crisis has highlighted the lack of and the need for oxygen, so we believe that this mask may be a part of the solutions to these problems.

References

1. Cucinotta D, Vanelli M (2020) WHO Declares COVID-19 a Pandemic. Acta Bio Medica Atenei Parmensis 91: 157-160.
2. Fraser B (2020) COVID-19 strains remote regions of Peru. The Lancet 395: 1684.
3. Thornton J (2020) Covid-19: Care homes in Belgium and Spain had “Alarming living conditions,” says MSF report. BMJ m3271.
4. World Health Organization (2020) Oxygen sources and distribution for COVID-19 treatment centres: interim guidance.
5. Duprez F, Laghmiche A, Trimpont FV, Gatera E, Bodur G (2001) Clinical Evaluation of New Ways of Administration of Oxygen: Tusk Mask II and Double Trunk Mask. Prehospital and Disaster Medicine 16: S23-S23.
6. Duprez F, Cocu S, Legrand A, Brimioulle S, Mashayekhi S, et al. (2020) Improvement of arterial oxygenation using the double trunk mask above low flow nasal cannula: a pilot study. Journal of Clinical Monitoring and Computing.
7. Duprez F, Bruyneel A, Machayekhi S, Droguet M, Bouckaert Y, et al. (2019) The Double-Trunk Mask Improves Oxygenation During High-Flow Nasal Cannula Therapy for Acute Hypoxemic Respiratory Failure. Respiratory Care 64: 908-914.
8. Poncin W, Baudet L, Reychler G, Duprez F, Liistro G, et al. (2020) Impact of an Improvised System on Preserving Oxygen Supplies in Patients with COVID-19. Archivos de Bronconeumología, S0300289620302544.
9. Agence fédérale des médicaments et des produits de santé (2020) Prise en charge et traitement respiratoires pour les patients COVID-19 hospitalisé