Chronic Obstructive Pulmonary Disease (COPD) is quite rightly recognised to be a major cause of lung disease throughout the world, and on November 17th the Global Initiative for Chronic Obstructive Lung Disease (GOLD) will hold their 19th annual World COPD Day.
This exovent article (a) draws attention to the importance of prevention of COPD, (b) talks about the use of conventional ventilation methods in some patients with this condition, and then (c) goes on to introduce what we hope will be a future supportive breathing therapy, using the Exovent. This a modern version of a decades-old technology in which we hope a NEGATIVE PRESSURE ventilator support device will help certain groups of patients with COPD. It is being developed by a charity consisting of a team of engineers, doctors and nurses, and other enablers who hope to see it add to the treatments available to clinical teams to help these patients across the world.
Prevention of COPD
The emphasis in this year’s World COPD Day is highlighting prevention, discouraging cigarette smoking, reducing air pollution generally and legislating to minimise industrial exposure, and encouraging physical activity …
“Healthy Lungs: Never More Important”
Coming immediately after the world Cop26 talks on climate change, with its huge emphasis on improving the environment and reducing air pollution, it could not be more timely. And there can be no argument that prevention is better than cure.
Also, the COVID pandemic has made it abundantly clear that viruses wreak their greatest devastation in people with chronic illnesses, especially lung diseases, such as COPD.
However, all of these changes take a long time to bite, and meanwhile patients across the world are faced not only with chronic ill health from COPD, but also by serious episodes of often severe deterioration – acute exacerbations – which require effective therapies. Sometimes usual treatments such as increasing or adding in extra medications, skilled nursing care, and extra oxygen is not enough, and patients may go on to require specialist support for their breathing via some form of ventilation.
When patients require ventilator support
Ventilation, or mechanical breathing with a machine, can be lifesaving in patients with acute worsening episodes of their COPD where all of the normal treatments have not helped them enough with their breathing. Sometimes this is provided by actually taking over a patient’s breathing with a ventilator that helps remove carbon-dioxide and add oxygen to the blood by blowing a mixture of air and oxygen down a tube that goes through the larynx (voice box) and into the trachea (the main windpipe). Because the air and oxygen is being blown into the lungs, it is called positive-pressure ventilation.
Doctors try to limit the amount of time that patients are ventilated for a lot of reasons. First, it usually requires them to be kept deeply sedated. Second, having the tube through their larynx and trachea risks traumatising them, as well as risking being an entry point for more germs. Third, the way that ventilators deliver positive-pressure to the lung tissue can actually cause damage, or can cause them to spring a leak into the chest which needs treating (pneumothorax).
For these reasons, other types of positive-pressure support has been developed over recent years which have used sealed face masks or nasal prongs instead of a tube into the airway. These have been used both to ventilate patients, and to apply a continuous positive airway pressure (CPAP) which helps by keeping the lungs expanded better. Each of these advances has helped many people, but many of the disadvantages of this type of support remain a problem.
Negative pressure breathing
The Exovent team has been working to produce an modern lightweight device that will help patients with COPD during acute exacerbations by delivering negative-pressure support. Negative-pressure breathing goes back millions of years – it is the way that we all breathe naturally by our chests expanding and gently drawing air into our lungs. It is the way our lungs are meant to work!
You may be familiar with the very old-fashioned negative-pressure ventilators called ‘iron lungs’ which saved tens of thousands of lives during a previous viral pandemic when polio struck about 80 years ago. They were effective, but literally weighed hundreds of kilograms and were very awkward to operate, so went out of use when small lightweight positive-pressure ventilators became available. Compared to those, the Exovent is a modern, lightweight device which is many-times more efficient, despite just sitting over the patient’s torso, and it can provide a negative-pressure equivalent of CPAP, and can deliver sophisticated ventilation. And it does all this by producing natural breathing, which is gentle but effective.
How does it differ from conventional positive-pressure treatments?
The Exovent is used in fully awake patients – there is no need for them to have tubes fitted or to be sedated, so they can eat and drink, and talk to the doctors and nurses, and of course to their loved ones. We have tested it out on members of the Exovent development team. All of them found it very relaxing to have their breathing done for them on full ventilation mode – one even found it so restful that they dozed off to sleep whilst ‘testing it out’. None of them even noticed when they were being treated with the Exovent equivalent of CPAP, even though the tests showed that it powerfully increased their lung expansion, which is a very different experience from having positive-pressure CPAP.
As well as being more pleasant, negative-pressure ventilation has been shown to be better at removing carbon-dioxide and delivering oxygen than conventional devices. Also, they are far less likely to produce the long-term lung damage that may be seen with positive-pressure therapy, and do not cause pneumothorax lung-leaks.
Finally, negative-pressure ventilation does not reduce the output of the heart in the way that positive-pressure treatments do. This is important because many patients with COPD also have heart complications of their condition which can be worsened during conventional ventilation.
Past experience of negative-pressure treatments for COPD
Although the ‘iron lungs’ were phased out in general after about 1960, a modernised version was used during the 1970s to 1990s in Italy, and were used by Professor Antonio Corrado’s group to ventilate well over 2,000 people with acute respiratory failure due to acute worsening of their COPD. His device was still a large ‘iron lung’, but by then also had sophisticated control systems, and were shown to be very effective in helping patients with COPD. He also showed that his devices could deliver the equivalent of COPD comfortably, and that this produced a highly effective treatment. Despite providing superior treatment, Prof Corrado’s device was eventually abandoned because of its awkward size and inconvenience to use.
The future
We very much hope that the Exovent will prove to add a modern version of negative-pressure breathing support for patients whose COPD becomes severe enough to require extra therapy, alongside the proven treatments already available. Unlike its predecessors, it is a modern device that is simple and convenient to use. We anticipate Exovent being used outside of intensive-care units due to their relative simplicity, and because the patients can be treated without deep sedation.
As well as being more comfortable and less invasive than other therapies, Exovent will be considerably cheaper to produce than standard positive-pressure ventilators. The Exovent charity is working with colleagues in low and middle-income countries who are aiming to build extremely inexpensive local versions for this world-wide problem.
Further information on COPD can be found at:
Chronic obstructive pulmonary disease (COPD) (who.int)
COPD (chronic obstructive pulmonary disease) | BLF
Chronic obstructive pulmonary disease (COPD) – NHS (www.nhs.uk)
COPD: Symptoms, Diagnosis, and Treatment (cdc.gov)
