A cardiac anesthesiology fellow, and several engineers from the University of Minnesota and a local device company got together over the past few weeks and cobbled together a ventilator from some spare parts. Here’s a picture to give you an idea of what it looks like:
It uses a metal toolbox tray, an Ambu bag, and some other spare parts lying around one of the medical device labs at the university. Essentially, a servo motor intermittently squeezes the Ambu bag, and there are adjustments for how often (rate) and how deeply (volume) the bag is compressed. There is a pressure limiting device included in the system as well.
This project illustrates how we will need to think outside the (tool)box in the coming weeks, especially as the number of severe Coronavirus cases begins to tax our supply of ventilators. And obviously, this thing will not get FDA approval in your lifetime. But if a choice needs to be made between using something like this in a pinch vs letting someone asphyxiate, the answer is pretty clear.
The group has produced a short YouTube video as well (see below), but it is rather short on details. You get to see some partial views of it as it is being tested on pigs. But so far, the concept is promising.
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It’s unusual for me to post on a Saturday, but we are currently living in unusual times. This tidbit caught my attention and I wanted to get this interesting idea out there for all to think about.
Hopefully, it will never come to this. But there are reports from both Italy and New York City that ventilators are in short supply. This video illustrates the technique used in some research that was actually published way back in 2006. It demonstrated the efficacy of using one ventilator on four patients at once. It requires just a few connectors that are readily available.
But remember, this is off-label use and is not condoned by the FDA! And it probably violates every Department of Health and hospital policy written. But in a pinch, it is something to think about.
Obviously, there are lots of possible downsides. Four patients are essentially sharing one circuit. Even though the circuits are one-way, there is always an infectious cross-contamination risk. The paper shows that ventilation should be adequate on both pressure and volume control settings.
This type of thing is a very last resort, and hopefully no one will have to use it!
Reference: A single ventilator for multiple simulated patients to meet disaster surge. Acad Emerg Med 13(11):1246-9, 2006.
In my last post, I discussed the Passy-Muir valve, which allows patients who have a tracheostomy tube in place, and are not on a ventilator, to talk. But what about patients who are still vent dependent? It’s very frustrating for both patient and trauma professionals when we can’t communicate with each other.
Pulmodyne, Inc. makes the Blom tracheostomy tube system, which solves this problem. This device has a large fenestration in the back of the tube with a special bubble valve (see below), coupled with an inner cannula that has a 1-way flap valve. This allows controlled release of air into the pharynx, enabling speech while on the ventilator.
A multicenter study looked at voice production and intelligibility of speech in a group of 23 ventilated patients with a trach tube in place. Although not entirely clear in the paper, it appears that all were changed to Blom trach tubes for the study (2 had one in place at the beginning of the study). Overall, voice production and intelligibility were good. Most were able to begin audible speech within about 6 minutes of initial application. One deconditioned patient took longer. The video below shows an example of the speech that is achievable.
Bottom line: This novel product allows a subset of trauma patients to speak while still on the ventilator. It is most appropriate for those who do not have significant head injury, especially those with facial trauma requiring airway protection with a tracheostomy.