Ventilators. A device few had heard of before the pandemic.

This life saving machine is desperately sought after by hospitals around the world. COVID patients with the most severe symptoms require ventilator support to survive and recover. But what is this machine? And what does it actually do?

THE BASICS

Breathing is a simple task, one that we do not think about. When we breathe our chest expands, and air is pulled into our lungs. Here oxygen is exchanged into the blood and transported by the pumping heart throughout the body. In our cells the oxygen is used to release energy from our food, and drive every process and reaction that keeps us alive and functioning.

COVID-19 is a respiratory disease caused by the coronavirus. Its symptoms include a dry cough, fever, feeling tired and more. In most patients the disease is mild. However some suffer from severe disease, causing havoc in their lungs. It can cause viral pneumonia in both of the patients lungs, which reduces the amount of lung able to bring in oxygen to the lung. The patient’s respiratory rate increases, as they struggle to draw in oxygen.

If a person is struggling to breathe on room air doctors can provide them extra oxygen. This is given through a mask they wear on their face. Normal air only has 21% oxygen, but in hospitals it is possible to give air that is 100% oxygen. This means more oxygen reaches the blood, and the patient has to put in less effort to breathe to get the same amount of oxygen to their cells.

In severe cases it can cause widespread inflammation in the lungs, causing fluid to build up and making breathing harder and more laborious. The patient can become tired having to breathe quicker and harder, and this is when doctors look to intensive care specialists and ventilator support.

VENTILATION

If a person is unable to breathe for themselves, it is possible to do this manually or mechanically. Specialists can insert a tube into the mouth of an unconscious patient that enters their windpipe. A bag pump can be attached to this, which a doctor can squeeze to push air into the patient’s lungs. But a person cannot continuously squeeze this bag to keep ventilating someone, as this is time consuming and tiring.

Ventilators are composed of a compressible reservoir or turbine that can push air into the patients lungs. Unlike regular pumps that continuously push air or water, ventilators have to mimic how we breathe. We inspire air in, then expire air out. Ventilators achieve this by pushing in air for a few seconds, inflating the lungs, then releasing the pressure. The natural elasticity of the patients ribs and lungs squeezes the excess air out, mimicking exhalation.

Modern ventilators are very smart, and have many configurable settings. They can be set to deliver defined quantities of air, change the rate of breathing and other advanced settings.

Hospitals regularly use ventilators for patients who are struggling to breathe, patients who are in a coma and have lost the ability to breathe, and also for anaesthetised patients in operating theatres. During the pandemic hospitals are cancelling unnecessary or non-emergency operations, redistributing these ventilators to be used for COVID patients instead.

MAKE MORE VENTS

It is estimated that up to 30% of patients that are admitted to hospital require ventilators. Most hospitals across the world do not have enough ventilators because they have never needed to ventilate so many patients. Governments have recruited the help of manufacturing companies to ramp up production of ventilators. In the UK F1 teams, military aircraft constructors and hoover manufacturers have all taken up the challenge and repurposed their factories.

There have also been innovations to create new ventilator designs that are cheap and easy to produce. This often involves off-the-shelf equipment that is already present in hospitals, and 3D printed parts. Such machines often do not require electricity or circuit board electronics, and can even be powered by the high pressure oxygen flowing from gas canisters or hospital walls.

- University College Dublin: https://techcrunch.com/2020/03/19/open-source-project-spins-up-3d-printed-ventilator-validation-prototype-in-just-one-week/

- University of Oxford: http://www.ox.ac.uk/news/2020-03-31-ventilator-project-oxvent-gets-green-light-uk-government-proceed-next-stage-testing

NEVER A SIMPLE SOLUTION

But as always its not always this simple. Ventilators are complex machines requiring specialist training to function and maintain, as ventilation and respiratory physiology is quite complicated. Ventilators will be of limited use if hospitals do not have enough staff trained to use them safely.

Ventilators are not without risk either. Because they push air into the lung, continuous use, excessive pressures and improper use can cause some damage to the delicate anatomy inside the lung, causing problems in itself. The plastic tube can also be a source of infection. Some hospitals that have had a sharp increase in ventilated patients have encountered problems supplying all their patients with pressurised oxygen. The patient load is overwhelming their infrastructure.

Unfortunately like most things in medicine, ventilators are not a magic cure. Due to the shortage of ventilators not everyone who needs one is able to get it. Most patients who end up needing ventilation are severely ill. The longer a person is on a ventilator the less likely they are to survive. This means that current mortality is rather high.

As more ventilators become available this treatment may become available to those with less severe symptoms, who are more likely to survive especially with this extra help. It is difficult to make these predictions because so many different variables can have an effect. For now we will have to wait and see.

WHAT DOES IT MEAN FOR ME?

The best way to help in these situations is by not catching the virus. This is especially true for those who are elderly, have diabetes, cardiovascular issues or lung diseases. These high-risk patients are more likely to have more serious symptoms, requiring hospitalization. This is why so many countries have enforced lockdown measures. The fewer that are infected, the fewer that need ventilation.

If you do need to leave the house, always follow the following procedures:

- Wash your hands regularly for 20 seconds with soap or alcohol

- Wear a mask outside: This is now official WHO policy

- If you need to cough or sneeze do so into your arm or a tissue

- Only leave the house for essential activities, shopping or to visit the doctor.

Dr Rajan Choudhary, Chief Product Officer & President, Second Medic UK

www.secondmedic.com