100 Patient Ventilator Concept for COVID-19 Ventilator Shortage

I have a relatively simple design based on commercially available parts that could ventilate as many as a hundred patients at one time while still allowing individual control of the breathing cycle and oxygen concentration for each patient.

Most current ventilator designs are aimed at a single patient. This is not the most efficient way to address this problem. If we are to provide long-term ventilation for the millions of people that will need it, the cost per person must be brought down dramatically. My Shared Manifold Ventilator design achieves this by connecting each patient to 3 different manifolds. The pressure in these manifolds is appropriate for either inspiration (oxygen and air) or expiration (maintaining a positive expiratory pressure is important for preventing lung collapse).

The shared manifold ventilator reduces cost by consolidating pressure regulation. There are three manifolds which can link to any patient in the shared ventilation ward. The pressure in those manifolds is carefully controlled. But the cost of this control per patient is dramatically less because one is controlling a manifold serving perhaps a hundred patients.

The simplest version of the shared manifold ventilator would have the two pressure supply manifolds, oxygen and air, set at a pressure which is appropriate for direct ventilation of patients, for example 20 centimeters of water head pressure. But local pressure control for each patient is also feasible using a relatively inexpensive local pressure accumulator for each patient.

This pressure accumulator would look like a relatively thick-walled elastomer balloon. In this scenario, the oxygen and air solenoid valves which connect each patient to the manifolds operate the same way as if they were delivering air directly to the patient but instead they deliver their air or oxygen to the pressure accumulator balloon, which allows for the inspiratory pressure to be lower than the manifold pressure.

It is possible to use polymer properties and balloon design to create something that will maintain a nearly constant but lower pressure than the pressure in the oxygen and air supply manifolds. In this case, it is still desirable to set the maximum pressure in the oxygen and air manifolds low enough so as not to cause damage to a patient’s lungs if there’s a failure of the control system. Making that pressure up to 40 centimeters water head pressure might be acceptable. Adding a pressure accumulator for each patient coupled with feedback controls does introduce more complexity and more possible points of failure. It is a trade-off.

It is also possible to introduce interactive intelligent design by providing sensors that the AI system can monitor. In particular, pulse oximeters for each patient can be deployed to provide real-time data on blood oxygenation and pulse rate. Ideally, a sensor for carbon dioxide concentration in the exhalation gas from each patient could be used in such a way that the carbon dioxide levels could be monitored. An oxygen sensor at the pressure accumulator would also be useful. These modifications could improve care but it should be borne in mind that complexity breeds breakdowns and that could kill somebody.

I am proposing to apply industrial-scale technology to this problem. By linking each patient to these 3 manifolds through 3 solenoid valves, it is possible to maintain a great deal of flexibility for optimizing the oxygen concentration and the breathing cycle for each patient.

Most serious COVID-19 infections will need oxygen, but after the disease has passed it is very important to reduce the oxygen concentration gradually. The software-controlled solenoid valves will allow that to occur quite simply.

The manifold ventilator can also allow for the adjustment of inspiratory pressure for each individual patient if the solenoid valves are proportional flow control valves and/or if each patient has a pressure monitoring sensor.

By using large-diameter manifolds one can have essentially a constant pressure manifold that goes throughout the entire hospital ward. The inspiratory pressure in the oxygen and air manifolds would have to be somewhere between 15 to 25 cm of water pressure (between 1.5–2.5% of normal atmospheric pressure) if the patients are directly linked to these supply manifolds via the solenoid valves.

There is evidence that if the pressure goes too high there’s permanent damage to the lungs in COVID-19 patients, which means it is safest to keep the manifold pressures below 25 centimeters of water.

I have written a detailed technical document describing this idea.

The most expensive components needed to make the simplest possible shared manifold ventilator that also allows individualized controls for each patient are the solenoid valves. I have invented a much less expensive type of solenoid valve that is applicable at the very low pressures needed for linking each patient to these manifolds. That work is patent pending but it is freely available for the COVID-19 crisis. The effect of lower cost solenoid valves is significant in terms of the overall cost per patient ventilated via the shared manifold ventilator.

I have also organized an open-source project to make a working prototype of the shared manifold ventilator through my startup company Rethink Respironics.

I have been working on a novel ventilator design for 2 years that I call the Conformal Vest Ventilator (CVV). Because I had been working for years on the CVV, I was well-prepared to see what was needed for emergency ventilation. The CVV is definitely not appropriate as an emergency ventilator except possibly on the battlefield or for saving somebody’s life after a car accident. That is why I came up with an alternative ventilator that could indeed save a lot of lives in this COVID-19 pandemic, the shared manifold ventilator.

AmericanInno recently wrote an article about my efforts as well.