A Look at the Ventilators Used During the Coronavirus Pandemic

14-04-2020 |   |  By Liam Critchey

There's a wide range of electronic devices that are being used in the fight against the recent coronavirus (COVID-19-, SARS-CoV-2) outbreak which is causing disruption on a global scale. These same electronics have been used in many other outbreaks, from SARS to bird flu and even polio, and it is likely that they will continue to be used in any future outbreaks.

The electronics in question are temperature sensors, biosensors and ventilation machines. While the two sensors are needed to determine if someone has got the disease, ventilators are crucial for keeping people alive once they have contracted the virus, and in the cases where they are not enough to keep people alive, they provide some assisted comfort to the patient when they have severe breathing problems. Despite being limited in number in some regions the world, ventilators have been crucial during this outbreak, as they have in other outbreaks, and here we look at which of these useful machines are being used in the fight against the coronavirus.

How Ventilators were used in the Past

Medical science is always advancing, and so is the equipment that is used to treat an ailment. Naturally, there were predecessors to the modern-day ventilators, but their development was important as they served the population during the worldwide polio crisis, and it has meant that we now have the advanced ventilation capabilities required to tackle the current coronavirus pandemic, as well as any new pandemics that may occur in the future.

The older style ventilators worked on a process known as negative pressure ventilation and required the use of a thoracic cage (one notable example being the iron lung) where the patient had to be situated inside the cage. These ventilators worked by lowering the pressure in the thoracic cage, this, in turn, created a pressure of less than one atmosphere. The low atmospheric pressure caused the chest wall to expand, inflating the lungs. Exhaling was performed by the recoil of the chest wall. Despite them not being used much these days, their development gave rise to the non-invasive ventilators that are being used in the current pandemic.

Non-invasive Ventilators

Non-invasive ventilators are used for a range of clinical cases, from less severe where some assisted breathing is required, to more severe cases where more assistance is required – however, mechanical ventilators are in place for the most severe of cases. Modern-day non-invasive ventilators now work by creating a positive airway pressure. This means that the air pressure outside of the lungs is greater than the pressure inside the lungs, creating a pressure gradient between the body and the ventilator. This pressure difference then forces air into the lungs, down the pressure gradient, making it easier for the patient to breathe as not as much work is required by the lungs. Forcing air into the lungs this way also helps to keep the chest and lungs expanded, as enough air remains in the lungs to keep them expanded after the patient has exhaled.

non-invasive ventilators

BiPAP using a ventilator 

James Heilman, MD / CC BY-SA

As this is a non-invasive process, the patient typically wears a mask where the air (i.e. oxygen) is delivered at either a constant or a variable pressure, depending on what the patient needs at the time, so they are used on patients with relative ease and with low risk.

Mechanical Ventilators

Of the two ventilators used, mechanical ventilators are the more complex of the two. They are used when a patient has a more severe respiratory issue and are seen as a type of life support machine because it is essentially a machine that provides assisted breathing when a patient is too unwell to breathe on their own. These are highly invasive systems that require the patient to be intubated by the clinical staff in the hospital, so the use of mechanical ventilators is not taken likely as there is a lot more risk involved. These are the ventilators which have been in short supply, yet are crucial during the coronavirus pandemic, as they have been used for the severe cases where the risk of respiratory failure is high.

Because they are used to keep a patient alive and breathing without the patient needing to do any of the work themselves, the process and the breathing mechanism is a lot more complex than just air being forced into the lungs. Because the ventilator takes over the breathing process, as well as feeding in oxygen via one tube, they also remove the carbon dioxide that is present in the lungs during a normal exhale. It should be noted that only one tube (endotracheal) goes into the patient via the nose or mouth and into the windpipe, but both the oxygen and carbon dioxide tubes are connected to the single endotracheal tube outside of the patient.

Both the addition and removal of gases is controlled using a ventilator unit which maintains the air pressure throughout and controls any changes needed. In addition to this unit, the inlet oxygen tube is also regulated by a humidifier unit so that the air temperature going into the body matches the body temperature, and any moisture can be added to the air supply if required. Regulating the pressure is vital for these ventilators to work, as this stops the lung from collapsing. In some cases, other tubes are needed if the patient is using the ventilator for a long time period or if their trachea is blocked.

While these ventilators need close monitoring from trained staff, they are vital for monitoring critical patients during the current outbreak and will be vital for many more years to come. These ventilators typically monitor the pressure, heart rate, respiratory rate, blood pressure, and oxygen saturation of a patient and adjust accordingly. Mechanical ventilators are complex pieces of machinery that are vital for giving a patient’s body time to fight off the virus naturally without the body expending energy on breathing (as the body will expend more energy than normal breathing if the lungs are struggling). In short, the survival rate of patients during this coronavirus outbreak and other outbreaks is significantly better thanks to ventilators.

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By Liam Critchey

Liam is a science writer who specialises in chemistry and nanotechnology, and reports on the extensive amount of areas which cross-over with these disciplines. As a writer, Liam has worked with companies, media sites and associations around the world and has published over 600 articles to date. Liam is also a member of the advisory board for the National Graphene Association and the Nanotechnology World Association and is a member of the board of Trustees for the charity GlamSci. Before becoming a writer, Liam obtained two masters degrees in Chemistry with Nanotechnology and Chemical Engineering.

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