Experts from the Thomas Jefferson University Health Design Lab met with Emergency Medicine and Anesthesia physicians and local engineers A design was envisioned in which 3-D printed connectors could be created to add an additional HEPA Filter as shown in Figure 1 STL Files for the adapters were created based on standard HEPA filter diameters and 3-D printed The second HEPA filter was easily assembled by novice users using the adapters Ventilation adequacy using the double HEPA filter ambu-bag was similar to single HEPA filtered ambu-bag ventilation based on observed inflation of a test lun
