There is currently a shortage of ventilators to help patients with severe respiratory distress due to COVID-19.
Many DIY designs are thus popping up on the Internet showing how mechanisms to pump a bag valve mask (BVM, AKA by the proprietary name “Ambu bag”) could be used as a makeshift ventilator.
Unfortunately, these can do a lot more harm than good. I would like to point anyone thinking about constructing such mechanism to first watch the following video:
In the US, even under these emergency circumstances, these quickly-built “Ventilators for Emergency Mass Use” (VEMU) or “Emergency Use Ventilators” (EUV) MUST receive authorization by FDA before they can be used to ventilate patients.
FDA has issued an Emergency Use Authorization (“EUA”) that allows certain ventilators – as well as anesthesia gas machines modified for use as ventilators, positive pressure breathing devices modified for use as ventilators, ventilator tubing connectors and ventilator accessories – to be distributed in the U.S., notwithstanding the fact that the devices have not obtained the FDA marketing authorizations that would otherwise be required prior to marketing the products.
To be authorized under the EUA, a device must meet certain requirements, and must be added by FDA to a list of authorized products . Detailed information about the EUA, including regarding the criteria that must be satisfied for a product to be authorized was issued by FDA on March 24, 2020 and is available here.
In this letter you will see that the requirements are not simple at all, and that the vast majority of DIY designs that simply pump an ambu bag don’t even start to scratch the surface of what would be needed to fulfill even the most basic requirements for safety and performance set by FDA under this emergency.
AAMI published a DRAFT Emergency Use Ventilator (EUV) Design Guidance which describes the minimum requirements of ISO 80601-2-80 that must be fulfilled by an EUV.
If you are considering the design of a VEMU, please start by learning about the requirements for safety and performance rather than by building yet another contraption that can do much more harm than good in this emergency.