Bench testing of noninvasive ventilation masks with viral filters for the protection from inhalation of infectious respirable particles

Figures & data

Figure 1. Non-vented NIV mask in combination with a viral-proof filter as indicated by the black arrows.

Figure 2. Mannequin head. Nasal and mouth openings of the mannequin connect to a tube/outlet that exits the head on the backside (A–D). This outlet connects to a filter outside the measuring box (E). A soft wound dressing simulates the elastic properties of facial skin (D).

Figure 3. Airtight transparent measuring box connected to a dual test lung; see the Materials and Method section for details.

Figure 4. Workflow of the experiment.

Figure 5. Part A shows the scintigraphic image of the radioactive items shown in part B. The table shows the radioactive counts for the respective items.

Figure 6. Surgical masks and respirators that were tested on the mannequin head during simulation of spontaneous breathing as described in the Materials and Method section (A: Vlies mouth protector Typ 3 R,Wiros GmbH Willich, Germany; B: OP Mask 657000, Mölnlycke Health Care GmbH, Düsseldorf, Germany; C: FFP 3 mask P-3900, Ampri GmbH, Winsen/Luhe, Germany; D: SH 2950 respirator N95, San Huei United CO. LTD, Taipei, Taiwan).

Figure 7. Tested NIV masks (A: AcuCare, ResMed, San Diego, USA; B: JOYCEclinic FF Loewenstein, Bad Ems, Germany; C: Mirage Quattro FX, ResMed, San Diego, USA) and a woven scarf (D, Passigatti, Neu-Ulm, German, 65% polyester, and 35% viscose) which were tested on the mannequin head during simulation of spontaneous breathing as described in the method section. The simulated protection factor of the different masks on the mannequin head is being determined by the filtration efficiency of the tested device and the leakage around the device on the dummy head. In order to determine the performance of a surgical mask without leakage, we clamped a surgical mask over a plastic cup which was connected instead of the mannequin head (E).

Figure 8. Simulated protection factors of the tested devices.

Table 1. Differences of the simulated protection factor between the tested devices.

	ResMed AcuCare	ResMed Mirage Quattro FX	Loewenstein JOYCEclinic FF	Surgical mask rubber band	Surgical mask ribbon	FFP3	N95	Scarf	Mask cloth
ResMed AcuCare		p < 0.001	p = 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001	p < 0.001
ResMed Mirage Quattro FX	CI 8 to 16.2		p = 0.001	NS	NS	NS	NS	NS	p = 0.032
Loewenstein JOYCEclinic FF	CI 1.9 to 10.2	CI −10.2 to −1.9		p < 0.001	p < 0.001	p < 0.001	p = 0.001	p < 0.001	NS
Surgical mask rubber band	CI 9.5 to 17.8	CI −2.6 to 5.7	CI 3.4 to 11.7		NS	NS	NS	NS	p = 0.002
Surgical mask ribbon	CI 8.8 to 17.1	CI −3.3 to 5	CI 2.7 to 11	CI −4.9 to 3.4		NS	NS	NS	p = 0.006
FFP3	CI 9.1 to 17.4	CI −3 to 5.3	CI 3 to 11.3	CI −4.5 to 3.7	CI −3.8 to 4.5		NS	NS	p = 0.003
N95	CI 7.8 to 16.1	CI −4.3 to 4	CI 1.8 to 10.1	CI −5.8 to 2.5	CI −5.1 to 3.2	CI −5.4 to 2.9		NS	p =0.04
Scarf	CI 9.7 to 18	CI −2.4 to 5.9	CI 3.6 to 12	CI −3.9 to 4.4	CI −3.2 to 5.1	CI −3.5 to 4.7	CI −2.3 to 6		p = 0.001
Mask cloth	CI 3.6 to 11.9	CI −8.5 to 0.2	CI −2.5 to 5.8	CI −10 to −1.7	CI −9.3 to −1	CI −9.6 to −1.3	CI −8.4 to −0.1	CI −10.2 to −2

p values of pairwise comparisons are shown in the white upper part of the table and 95% confidence intervals (CI) for the same comparisons in the gray-colored lower part of the table.

Figure 9. Increased radioactivity is seen around the upper edge of the respirator indicating leak flow in this area (A: scintigraphic image of the mounted mask (B)).