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Monday, August 31, 2009

The Crisis is Near Now

A High Frequency Oscillatory Ventilator Design

Some of the news items I have been reading say that there will be a particular shortage of high frequency oscillatory ventilators. Many ICU units do not have any or may only have one. This type of ventilator is required to care for patients with the most damaged lungs.

I found a design for such a device in the IEEE transactions on Biomedical Engineering publication. Here is the drawing.

The link to the PDF is located at this link.
The PDF essentially gives instructions on how to build this ventilator.

This device is much more complex than the basic ventilators I have built, but it seems that it would possible to build such a ventilator from common valves, sensors and control systems substituting for some of the components that are listed. The diaphragm actuator for example could be a large bass (subwoofer) type speaker.

It would be great if someone could build one of these unists and get back to me about how feasible it is and how well it works in testing.

Next week an idea for using ECMO.
Don't know what ECMO is?
Have a look.

Now My Rant
Many of the recent reports that I have read indicate that there is a high likelihood that the current H1N1 pandemic will result in very busy ICU units and shortages of ventilators this fall in Canada. Doctors that work in ICU units that have had to treat H1N1 patients with Acute Respiratory Distress Syndrome (ARDS) say that the patients may have to be on a ventilator for a longer time period than they have seen with patients that got lung function complications in normal seasonal flu.

Here is a link to one such news item from CP.
Intensive care units likely to be main battlegrounds in the war against H1N1
There have been many stories like it originating from hospitals in Canada, the US, India, Australia, UK, Brazil, etc.

When I first proposed the Pandemic Ventilator Project two years ago as a means to alleviate some of the needs for ventilators in a pandemic, I expected it might be used for the H5N1 Avian flu. It seemed like a good insurance plan for a pandemic that, if we were lucky, might not even happen. Things have changed a lot since then. Now it is H1N1, people have actualy died from it, and this pandemic might return stronger this fall and winter, killing even more people. The risk of ventilator shortages has gone from a remote possibility to more likely. A lot has changed in the last six months.

Unfortunately, something that has not changed is the development status of the Pandemic Ventilator Project. As I have said several times before, the project has largely reached the limits of what I can do on my own to develop it. I need people with more ideas, more technical knowledge, more clinical expertise and better management and organizational skills than I possess on my own to carry the project further than I have. It would be a shame if we reach the stage where we really could use a ventilator from he pandemic ventilator project, but no one worked on it beforehand to get it ready in time.


  1. I know several technical and medical types who could contribute but everyone wants to know what the end goal really is?
    Would someone, somewhere be expected to crank out high volumes of this latest design or would it remain a DIY project?
    The reality is that patients will die on this machine (like all ventilators) and someone will be taken to court about it (at least in the US of A). Be clear about the goals and you may find qualified people to stand up and help. Like many solutions in medical technology, the show-stopper is the "L" word. As in Legal, Law, Lawyer and Liability.
    That's your biggest issue!

  2. The idea is to develop a workable design that is tested and proven by the developers using simulated runs and test equipment. The design is then published along with a list of materials that are required to build a unit. Smaller groups would assemble the units for local use as needed. Calibration and initial setup and end user instructions would also have to be provided. Some published pandemic plans recommend that certain liability provisions be suspended during a pandemic crisis. Some of the exceptions that I have read about have been for staff that are not specifically licensed to work in that state, country or that specific specialty, vaccine suppliers, and triage persons responsible for selecting which person gets access to equipment and treatment. The trick will be to get the liability exempted triage personnel to make the decision to use the non certified equipment. I have not heard of any specific exemptions for the use of uncertified equipment, older equipment that may not have been recently maintained or the use of equipment with fewer alarms than what is commonly used in an ICU environment such as transport ventilators. Some places have stockpiled ventilators with fewer alarms, and many places have been keeping their old equipment in storage in case it may be needed. In any case all of these pandemic plans are only recommendations. They have no force in law until they are passed by a government.

    I think what you say about the liability issue is very true. I do not know how to solve it. My favorite example when asked about the liability question is this: You have probably seen the inflatable floating toys that children play with. The all have a warning printed on them “NOT TO BE USED AS A LIFE PRESERVER”. This makes sense, these devices can leak and they are not designed for that purpose. Nobody should buy these things to serve as the safety devices required in boats pools or docks. Now if you were near the water and you saw a person drowning, you would look for a life preserver to throw to them. If all you could find nearby was one of these children’s toys with the warning on it, would you throw that to them or would you refuse because of the liability risk? The ventilator designs I am proposing are only to be used as a final option when the only alternative for that person is certain death.

  3. Sadly, there is no real perfect solution to this problem.. Nobody in a position of power is prepared to stick their neck out in this period of calm. When the SHTF, everybody will wring their hands in dispair. The only 'solution' I can see, and this is not a good solution, is for designs to be created, and prototyped, and the knowledge dispersed to as many competent, interested engineering types as possible, so that when the crisis happens, an amount of additional devices can be constructed at short notice. At the correct time, nobody will care about the number of medals it has won for design.
    I am a bit late in this discussion :) but the problem hasnt changed.
    I wonder if garden watering solenoid valves would work as air valves? They are very cheap.


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