Solving the Ventilator shortage - The Correct Strategy

Covid-19 has companies around the world rushing to help the situation, and since Ventilator access is the biggest hurdle in our fight to keep death rates low, the real race against time is to get enough Ventilators out there.

Most companies are taking the approach of redesigning ventilators, in order to simplify manufacturing and ramp up production. Here's what I have came across till now:

1. MIT based team tried to simply motorise the squeezing action of a Ambulance air Bag

Not intended to be a complete solution, but a way to give the emergency staff or paramedics some help while the patient is waiting for a Ventilator.

Very similar to this design is Virgin rocket company announcing something a few days ago:

2. Italian engineers turn snorkel masks to ease respirator overload

In the worst-case infections, patients have to be hooked up to respirators in intensive-care units. The snorkelling mask solution could be a stop-gap measure for patients on the brink of intensive-care treatment but for whom no beds nor respirators are available. Hospital masks for the less-intensive BiPAP (bilevel positive airway pressure) machines are also lacking.

3. Doctors try to use single ventilator for multiple patients 

This multiple-patient approach is highly risky for a host of reasons and could be disastrous in certain scenarios.

The issue is- these approaches have the best intentions but will not get us ready in the time frame Corona has forced upon us. 

Why do I say that? Because I had the same initial idea of simplifying the Ventilator design. I spent 100s of hours recently attempting a redesign, only to realize it is not as straightforward and will not be figured out as quickly as we need to ramp up Ventilator access. 

When I started work on Rotimatic, I had a similar sense of naivety which led us to underestimate the complexity of designing a such machinery. Rotimatic sits at the intersection of various frontiers- from technology to human elements to environmental variances in particle behaviour to manufacturing limitations. The devil is in the details and it us took 8 years of R&D to get to the other side.

Ventilators also sit at the edges of multiple branches of science, from human biology to fluid mechanics, to thermodynamics, to control systems. 

Ventilator Design: An Engineer’s Analysis 

Covid-19 causes ARDS (acute respiratory distress syndrome) in severe cases

In effect, ARDS impairs the lungs' ability to exchange oxygen and carbon dioxide. Diagnosis is based on a PaO2/FiO2 ratio (ratio of partial pressure arterial oxygen and fraction of inspired oxygen) of less than 300 mm Hg despite a positive end-expiratory pressure(PEEP) of more than 5 cm H2O. Heart related pulmonary edema, as the cause, must be excluded.

The primary treatment involves mechanical ventilation together with treatments directed at the underlying cause. Ventilation strategies include using low volumes and low pressures.If oxygenation remains insufficient, lung recruitment manoeuvres and neuromuscular blockers may be used. If this is insufficient, extracorporeal membrane oxygenation (ECMO) may be an option. The syndrome is associated with a death rate between 35 and 50 %.

So in such a case, a Ventilator for oxygenation and ventilation (both is needed). It is also called as Respirator and ICU respirator.

There are two ways of delivering the solution to the patient:

Invasive - Usually a plastic tube is inserted through the nose or mouth into the windpipe (trachea). If people need mechanical ventilation for more than a few days, doctors may insert the tube directly into the trachea through a small incision in the front of the neck (tracheostomy). A tracheostomy is safer and more comfortable for long-term ventilation. The tube is then attached to the ventilator. 

Non Invasive - Some people do not require complete support of their breathing. These people may be treated with a tight-fitting mask placed over the nose or nose and mouth. A mixture of oxygen and air is delivered under pressure through the mask. The pressure assists the person’s own breathing efforts and prevents fatigue of the respiratory muscles. 

In about half of the people with respiratory failure, this technique (called bilevel positive airway pressure [BiPAP], or continuous positive airway pressure [CPAP]) can help people avoid the need for a tracheostomy. Use of bilevel positive airway pressure at night can help people whose respiratory failure is caused by muscle weakness, because after resting at night, the respiratory muscles are able to function more effectively during the day.

BUT in the cases of ARDS caused by COVID-19 - Patients who need a Ventilator, are administered this via a breathing tube inserted via the throat to the lungs - Endo tracheal tube (ETtube) https://www.nytimes.com/article/ventilator-coronavirus.html

Non invasive airtight masks are dangerous as aerosolization of virus can result in spread of infection and put everyone at risk, including the medical staff. https://err.ersjournals.com/content/23/134/427

Technical challenges to be figured out to redesign a Ventilator 

Some of the sketches from the redesigns I was exploring:

Not an overnight effort with such a long list of challenges & objectives:

1. Mechanical challenge in selection of Valves at various locations depending on functionality and pressure and flow rate requirements.
2. Tubing that would allow Oxygen to mix in the right adjustable ratio with clean air and be delivered in the right direction to the patient during inhale phase, and then remove Carbon Dioxide and release it out during exhale, both while maintaining right set pressures (PEEP and PS over PEEP), and making sure the two tubings are isolated, and not affecting air pressures to be affected, is not a simple task.
3. Air tight delivery of the system is crucial to maintain the pressures as mentioned above. Which is why ET tube is the invasive method used to ventilate a patient.
4. Electronics challenge in selection of ICs or sensors for pressure sensing with the right specifications as to sensitivity, reliability etc
5. Designing for a ventilation system that will work in extreme conditions, long term use, reliability of the system, parts and the control, these are highly test dependent.
6. Quality of the system is not very easy to achieve in such a crunch timeline - we are talking about a live use of the system on a patient’s lung - highly sensitive and risky.
7. Software control and mechanical safety cut off design is crucial. A lot of testing would be needed to make sure we get this right.
8. Certification bodies are meant to keep the final market launch ready products in check. And these take time, even if done with an emergency mindset.
9. In a medical product, field trials, along with these certifications are necessary for prudence and right sensibility.

Recommendations to save time in this race against Corona

If time is of essence- making new ground-up complete ventilators is not feasible given the safety, accuracy of the functionality and reliability that is needed for Ventilators.

In my personal opinion this is the time for collaboration - between existing ventilator manufacturers and localised OEM/ODM businesses. And solve for funding and shortage issues at their end - for example raw material storage etc. This is where governments should step in. This is what Tesla is doing for example (I believe) - they are licensing the design from Resmed (makers of Ventilators) and starting a line in their Giga factory manufacturing of Ventilators. This in my view is the absolute best strategy and where I would urge the respective people to put their focus on.

The work by other players like Dyson or Virgin or Ford and GM should continue happening in the background too. https://edition.cnn.com/2020/03/30/business/ford-ge-healthcare-ventilators/index.html

Sometimes the simplest solution is the best one, sometimes the proven solution is the best bet. We need to quickly double down on the latter if we are to win this race against Corona. Big companies in this moment are placed to do amazing work if they licence designs from existing Healthcare equipment manufacturers and ramp up manufacturing.