Rhonchi

I recently posted a piece on my own blog about the use of home made ventilators during the polio epidemic of the late 1940s and early 1950s. Here is the link.

Home made Polio Epidemic Ventilators

The need for ventilators was greater than the supply, and it appeared that many people especially children would die as a result. Some of the original inventors and developers of ventilators including Drinker, produced designs for ventilators that could be built from easily obtainable components and constructed by craftsmen. These home built ventilators were used to save the lives of people who could not obtain a commercial ventilator to use in this emergency. There are pictures and assembly drawings of these ventilators.

The Pandemic Ventilator Project

I have the first design for the Pandemic Ventilator up on my blog at Pandemic Ventilator Project
www.panvent.blogspot.com

This is a design for a ventilator you can build yourself from readily available parts such a pipe, tubing electrically operated valves, a Programable Logic Controller (PLC) and a regular computer (PC) if a pandemic arrives. The software to drive the equipment and operate all of the alarm systems will be available as free and open source. Please click on the Digg icon and send this URL to your friends if you think that this is a worthwhile project and that I should keep working on it.

Here is another piece I wrote dealing with the ventilator shortage problem.

In 1984 the Canadian Red Cross publicly informed hemophiliacs that the blood products it distributed were safe, even though not all sources of blood were tested. Spokesmen for the Red Cross also referred to the need to look at the cost benefit ratio in treating hemophiliacs. It was later found that more than 800 of Canada’s 2500 hemophiliacs had contracted AIDS from using the untested blood. About 95% of them contracted Hepatitis C. Even two years after it was known that untested and untreated blood was dangerous to use, the Canadian Red Cross was still distributing its older untested stocks.

This incident was a blot on the integrity of public health care organizations in Canada. Many people asked afterwards, “How could this happen?”, “They knew the dangers”. The answer of course was that they placed fiscal accountability and efficiency above the needs of the people that placed their trust in them. The Canadian Red Cross was not the only group that fell short of their responsibility. This same pattern was repeated by other organizations in other countries of the world as well.

We all tend to place a great deal of trust in organizations such as the Red Cross. Such groups we trust are the FDA, the CDC, HHS. In Canada we have The Ontario ministry of Health and Long Term Care, Health Canada and The Public Health Agency of Canada. These groups have developed plans to deal with a pandemic. They all acknowledge that there will be a severe shortage of ventilators. The plans they have to increase the availability of ventilators fall far short of even their own predictions. Again they know the dangers, but are not doing enough to solve the problem. They have to be fiscally accountable and efficient you know. That old cost benefit ratio.

They have a plan to deal with it though; it involves rationing. They will pick who lives and dies. You can find lots of these plans on the web. Just Google Pandemic Ventilator Plan Ration. Now Ontario, Canada where I live, has 1,096 ventilator support beds in ICUs in the province. The total demand for ventilators in a pandemic could easily be twice this amount. There are also 1,400 chronic ventilator patients on other ventilators. The published triage plans are not very specific on whether it will involve taking ventilators away from sicker chronic patients to give to the pandemic patients. I hope we can trust them.

for more information you can see my blog at
http://panvent.blogspot.com/

Some of the current plans for dealing with the expected shortage of available ventilators in a pandemic crisis depend on stockpiling manual ventilators (ambu-bags). They would arrange for teams of friends and family members operate the ambu-bags during the crisis. There is some disagreement as to whether this is a viable option. Some experts dismiss this as being totally unworkable in a mass casualty situation as there are three basic problems with this plan:

1. The physical effort of squeezing a bag continuously is too exhausting for a person to manage very long.
2. Infection control issues related to having many volunteers man the bags in an ICU full of contagious flu victims. The number of deaths due to additional infections generated by such a plan could actually be greater than the number of people saved with the manual ventilators.
3. Lack of monitoring combined with minimally trained volunteers will probably result in a very high morbidity and mortality for the patients.

Now of course it is possible for a team of trained experts to keep someone alive on a manual ventilator for an extended time. In 1955, as a result of a polio epidemic, the demand for negative pressure ventilators exceeded the availability of negative pressure ventilators. There was such a shortage in Sweden that medical students, working in shifts, manually ventilated patients to keep them alive. Now a polio epidemic may sound bad, but the number of patients requiring mechanical ventilation in a flu pandemic will probably be many times higher.

Now instead of throwing our hands in the air in a panic and crying doom, suppose we looked for a way to solve these three problems. Number 1 is easy to solve. Just take an electric motor with some gear reduction and a cam arrangement, to make a pair of mechanical hands to squeeze the bag. The operator can now just turn a control knob to speed up or slow down the rate, or press a button for each cycle if you wanted to have some sort of assist mode going. If you solve problem #1, you also solve problem #2 because you do not need that large group of volunteers.

Solving problem #3 is a little harder. You would need a pressure sensor and an electronic controller to analyze the pressure conditions in the ventilator circuit to determine when alarms such a low rate, high pressure and disconnection occur and sound an alarm. A rudimentary but functional device could be constructed from any standard instrumentation pressure sensor and basic industrial programmable logic controller. If someone worked out a good program ahead of time that was well tested, this could be freely shared to run thousands of devices across the country.

Incidentally, if you were fortunate enough to have stockpiled a quantity of pressure driven transport ventilators ahead of time, you do not get problems #1 and #2. The same monitoring system could be used to enhance safety of these devices for unattended operation.

Clarence Graansma
For more information you can visit my Pandemic ventilator Project blog at http://www.panvent.blogspot.com/