Welcome to a special COVID-19 edition of NHS Hot Topics. Here we dissect an issue that affects the NHS in the current COVID-19 pandemic. This week we are looking at ventilators.
Ventilators take over a person’s breathing when their lungs are failing to do so. It does this by forcing air into the lungs at certain intervals. There are 2 types of ventilation: mechanical and non-invasive.
Non-invasive ventilation involves a face mask fitted over the mouth and nose with no tube required to establish the airway. An example of the most basic ventilator is the bag valve mask; a mask is put over the patient’s mouth and nose and the bladder (looks kind of like an inflated balloon) is manually compressed, often by a first responder aiding the patient’s breathing.
When steady and controlled airflow is required, such as someone needing longer-term help with their breathing, a mechanical ventilator is required. A mechanical ventilator is connected to a tube that is inserted into the patient’s windpipe via their nose or mouth. A mechanical ventilator is much more sophisticated as it monitors and can control:
Another key advantage of a mechanical ventilator compared to an automated bag valve mask for example, is that it can provide positive end-expiratory pressure which prevents the alveoli collapsing.
There are many reasons why a patient may require a (mechanical) ventilator. Low oxygen saturation or severe shortness of breath due to an infection such as pneumonia is one of the most common reasons.
About one in six patients with COVID-19 become severely ill. If their oxygen saturation becomes low, they may require a ventilator. This happens because they struggle to breathe due to the damage the virus has done to their lungs.
The pneumonia – inflammation of the lungs – caused by COVID-19 is thought to affect the whole of the lungs so it is more severe than typical pneumonia, which normally only affects a small section of a lung.
Before this pandemic, there were thought to be roughly 8,000 ventilators in the NHS. The UK currently has between 10,000 and 12,000 ventilators, with Matt Hancock, the Health Secretary predicting the need for 18,000 ventilators at the peak of the virus. This is a big reduction from the original estimate of 30,000.
This is likely due to the impact of social distancing; a reduction in the number of daily cases of the virus which therefore means a decrease in the number of patients requiring a ventilator in intensive care.
This is a key part of ‘flattening the curve’; reducing the number of patients requiring hospital and intensive care treatment to ensure the NHS has capacity for all who require their care.
This is not a unique issue for the UK or NHS. As the COVID-19 pandemic badly affects many countries across the world, everywhere needs more ventilators than usual to meet predicted demand at the peak.
This means it is likely to be harder than usual to import ventilators from other countries as many may want to keep domestic supplies for their own country to ensure they have the capacity for everyone who requires ventilation at the peak of the outbreak.
Also, as mentioned above, mechanical ventilators are complex. They are not easy to design and must pass rigorous testing in order to be approved.
Unlike PPE, which many companies can more easily switch to manufacturing, ventilators are difficult to design and take much longer to produce.
Even if there is an increase in supply to provide a sufficient number of ventilators, each patient on a mechanical ventilator requires specially trained respiratory nurses and physicians.
This is an important factor to consider when thinking about caring for increased numbers of very unwell patients; if the number of ventilators increases, so must staff training to use them.
The government ordered a lot of ventilators in a bid to prepare for the peak of the virus. The Ventilator Challenge UK consortium, which includes companies such as Airbus and Rolls Royce are working to produce ventilators to increase capacity.
The government ordered 10,000 from them and it is hoped that by the start of May 1,500 will be produced a week. More ventilators have been ordered from a range of other companies, hoped to increase the UK’s total to 62,000 if all are approved and produced.
There is also scaling up of manufacture of non-invasive ventilators. UCL is teaming up with some Formula 1 teams to produce 10,000 CPAP devices – a type of non-invasive ventilator that uses mild pressure to keep the airways open.
However, there are a number of considerations that make mechanical ventilators difficult to design.
They must not over-inflate alveoli which can lead them to collapse of rupture, and simply forcing air in and out of a person’s lungs requires them to be heavily sedated.
Often the machine must monitor for a ‘trigger’ point to force the air into the person’s lungs. Over 30,000 ventilators ordered by the government are yet to be approved – they need to pass rigorous testing and regulations.
The UK government ordered hundreds of ventilators from China after many of the domestic designs did not meet NHS regulations.
Thankfully, it has been emerging that the NHS does have enough ventilators to meet demand, with the government increasingly confident in this capacity.
There are questions remaining about how well ventilators work for patients with severe cases of COVID-19.
A report at the beginning of April using available data from the UK (excluding Scotland) showed that of 2,249 patients admitted to critical care with coronavirus, only 15% had been discharged alive, about 15% had died and the remaining 70% were still in critical care.
Factors such as older age, obesity/ overweight and being male all, based on the information so far, are associated with increased mortality when admitted to critical care.
The road to recovery after just a few weeks on a ventilator can be very long. Many patients will need to learn to walk and talk again and the impacts can be wide-ranging and long-lasting. PTSD can also occur in patients who have spent time in intensive care.
Some data from China and New York suggest that it could be upwards of 80% of patients who are sick enough to require mechanical ventilation will not survive.
One reason for this may be that patients who have a certain type of lung damage that does not respond well to mechanical ventilation are being ventilated.
COVID-19 seems to have differences in typical acute respiratory distress syndrome that patients are often ventilated for.
Ventilators are certainly a useful tool for the sickest patients in the fight against COVID-19. However, this is a new disease with more remaining to learn, including how the most severe cases respond to ventilation.
Question to think about: What other shortages are affecting the NHS in the COVID-19 pandemic and how can some of these be reduced?
Words by: Safiya Zaloum
Accurate at the time of writing – 20/04/20
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