I became involved in the Exovent project back in March last year, just before the first national lockdown. We were already seeing rapidly increasing numbers of very unwell patients at the Covid Assessment Centre, most of whom were absolutely terrified. We had all been following the course of the initial outbreak in China, and then more recently in Italy, and all the front line medical staff were genuinely worried that the NHS would become overwhelmed. We had all heard terrifying reports of gross ventilator shortages in Northern Italy, and that in some hospitals anyone over the age of 50 who deteriorated was not even being considered for intubation and ventilation, and so were essentially just given palliative care. This is the kind of brutal healthcare rationing that doctors in wealthy countries just do not expect to have to deal with, and Italy has more critical care beds per capita than the UK. An Italian friend, working in one of the worst hit hospitals was incredulous at the lack of apparent meaningful action to try to slow the spread in the UK. Thousands of British tourists had been allowed to return from their skiing holidays in Northern Italy, without being advised to quarantine, even if they had symptoms, which is probably the most blatant example of the subsequently denied Westminster government policy of “herd immunity”.
My Dad forwarded me an email from the son-in-law of some very old family friends, a wonderful guy called Dave Mckeown. Dave, a Flood Prevention Engineer by trade down in Cornwall, was wondering if there might be a role for negative pressure ventilation in the response to the pandemic, given that it was predicted that conventional positive pressure ventilators were likely to be in short supply.
Like many doctors, my initial thought was: ‘If negative pressure ventilation worked well, surely it wouldn’t have been abandoned.’ My only knowledge of NPV at the time, was its historical use for patients who had been paralysed by polio, but I thought it might be worth exploring the idea, given how much simpler and how much cheaper the devices would undoubtedly be to mass produce, compared to conventional positive pressure ventilators.
My journey from open-minded sceptic to passionate proponent of NPV was actually rather rapid: I have always had a special interest in respiratory physiology, and the more I thought about it from basic physiological principles, the more enthusiastic I became.
Firstly, we already use CPAP (Continuous Positive Airway Pressure) widely in patients with Covid pneumonia, when they are deteriorating despite receiving oxygen (O2) therapy. The mechanism through which it improves oxygenation is largely by partially inflating the lungs, thereby opening up collapsed alveoli and improving exchange of both O2 and Carbon Dioxide (CO2). Applying a constant negative pressure to the outside of the thorax would intuitively have a similar effect, and so should work just as well, but would have the major advantage of being much more comfortable. In my experience, many patients are simply unable to tolerate the rather unpleasant feeling of a tight fitting CPAP mask blowing air up their nose, and so this is a common reason them needing to progress to sedation, intubation and ventilation.
Secondly, we know that negative pressure ventilation is perfectly capable of taking over the work of breathing entirely in patients who are completely paralysed, so intuitively NPV should easily be able to take over some or even all of the work of breathing in patients who are becoming exhausted, and hence starting to retain CO2. Taking over the work of breathing and increasing minute ventilation would help to address the CO2 retention, and also would reduce the patient’s oxygen requirements, given how hard the respiratory muscles have to work in patients with respiratory distress.
So I became convinced of the potential benefits of NPV based simply on basic physiological principles, but subsequently, all the papers that I have read on the subject, and all of the fascinating discussions I have had with the remarkable Exovent medical team, have only strengthened my belief that NPV will be hugely beneficial, not just for Covid, but for other types of acute pneumonia, and severe exacerbations of COPD/Asthma. I am confident that it has the potential to dramatically reduce the numbers of patients requiring intubation and PPV, therefore not only greatly reducing the incidence of positive pressure ventilator induced lung injury and pneumothoraces, but also providing a safe, low cost, therapeutic option in the many places in the world where ICU beds and ventilators are in short supply, or of course where they are simply not available. To describe the fact that the patients don’t require sedation, paralysis and intubation, and are able to eat, drink and talk, as an “advantage”, is really a bit of an understatement. I’m also sure that it will prove invaluable in helping to wean patients from invasive positive pressure ventilation.
I remember an early brainstorming session we had in April last year over WhatsApp, to try to come up with a name for our NPV device. I think Exovent was one of the ones that I had suggested, but it was only after it had been chosen by the wider team, and our logo had been designed accordingly, that I discovered following a brief internet search, that Exovent was a company of plumbers in Sweden. So I would like to take this opportunity to formally apologise for stealing their name. I really hope they don’t mind, but if you are ever in the Kungsbacka region of Sweden, and find yourself in need a plumber, then you know who to call!
I contacted some old Medecins sans Frontieres friends from my days working in HIV, to see if they might be by interested in helping us to trial the Exovent, as they were already involved in setting up Covid treatment centres, and I was passed up along the chain of command to MSF’s Director of Critical Care, Dr James Lee. He was very interested, and open minded about the potential benefits, but didn’t feel that MSF could become involved until we had completed a formal clinical trial demonstrating benefit, which I suppose was unsurprising. We have since completed a trial on healthy volunteers, which was published in Anaesthesia [Exovent: a study of a new negative‐pressure ventilatory support device in healthy adults – – 2021 – Anaesthesia – Wiley Online Library] and although we came tantalisingly close to holding a substantive clinical trial in Newcastle in the middle of last year, this fell through at the last hurdle, which was hugely frustrating. We are currently still looking for funding and awaiting formal MHRA approval, which is particularly frustrating, given the MHRA (Medicines & Healthcare products Regulatory Agency) “fast track” status that was given to positive pressure ventilator development and the large amount of money that was thrown in that direction. However, we are otherwise pretty much ready to start the first formal clinical trials on patients down in Southampton NHS Trust, which we are all very excited about.
Although I do have a special interest in respiratory physiology, and have worked extensively in the Covid assessment centre, I don’t really have any experience at all in anaesthesia or working in an adult ICU (Intensive Care Unit). Fortunately the medical team has Peter, Jim and Anil, the three most inspiring anaesthetists you could ever hope to meet, as well as Prof David Howard, a retired ENT surgeon, now the Exovent Chairman, who is true force of nature. Another core member of the medical team, Malcolm Coulthard, is actually a very old friend of my parents and I’ve known him since I was a kid, and is in fact the only member of the Exovent team who I knew previously. My first ever memory of him was when he was a junior paediatric registrar, and I was only five years old, and in a lot of pain following and appendicectomy, and I vividly remember the skill, care and compassion with which he cared for me. He is now a retired paediatric nephrologist, but has been busier and more productive in retirement that most doctors are in their entire career. He has invented and developed an infant dialysis machine, which is currently be trialed, and is currently in the process of completely revolutionising the way that children with shock in the context of Kwashiorkor are managed globally [Child Health Africa]. As well as leading the process of trial protocol development and paper writing, he has also studied pretty much every paper that has ever been written on negative pressure ventilatory support, and it is rare for someone to come away from talking to him to not be convinced of its benefits. Whoever it was that said “don’t meet your heroes” has clearly never met Malcolm.
Aside from the physiological and clinical aspects, I am also fascinated by the engineering side of things, and the whole design and development process. I am an amateur inventor, and hold a patent for a low cost approach to thermal solar power generation, which Nick Ryan, one of the lead Exovent engineers, very kindly gave me some invaluable advice on, regarding the next steps I need to take to get this developed. I also have various patents pending, including one for a new approach to tidal power generation, a bariatric medical device, a construction technique for retaining walls and a bolt-on downhill racing skateboard brake. The last one is probably the one that I am really most looking forward to getting someone to manufacture in the future, as although it will be undoubtedly be scoffed at and rejected by the purist elite athletes in the field, I suspect it will be embraced by the majority of enthusiasts, like myself, whose skill and ability do not quite match their passion and ambition. I hope it will prevent a lot of broken bones.
One thing this patent work has taught me, is that coming up with an idea is actually the easy bit: it is making something happen from that idea that is the really challenging job. This has given me the greatest of respect for Dave Mckeown, who not only came up with the concept of bringing back NPV, but has been the driving force, and has kept the team moving forwards all this time, with his infectious passion and enthusiasm on the weekly Tuesday evening Zoom calls that have continued without interruption since March last year. I am usually at work when these meetings occur, but have managed to join almost all of them, due to fact that my colleagues are genuinely interested in the progress of Exovent and have been very supportive of me sitting on a Zoom meeting, while they do all the work for an hour or so.
The team of engineers at Exovent are a great bunch, and are very patient with me, and although I am sure there is plenty of silent, but good natured eye-rolling every time I try to involve myself in the engineering side of things, very occasionally one of my suggestions captures their imagination, and gets taken forward. A simple mechanical open-loop approach to negative pressure control that I suggested, was subsequently adopted by one of the Exovent pioneer groups in Ghana as well as Prof Neil Downie, of “Saturday Science” fame [Erudition Saturday Science – Neil A. Downie – Erudition (eruditiondigital.co.uk)], for the Exovent he has built in his garage with his remarkable wife, Diane. I also recently came up with an approach for measuring tidal volume, and Neil and Di not only built and tested a prototype, but they posted me one, which then became the focus for what was without doubt, the best ever day of science/maths homeschooling for my two boys, during lockdown when their schools were closed. They had so much fun measuring and calculating each other’s average tidal and minute volumes, both at rest and following exertion, but when I told them how I came to have the meter in the first place, my youngest son’s response was: “So what you’re saying is, you emailed your Tony Stark friend with an idea, and he built it for you, and sent you one… for free?! I mean that’s all cool, but why couldn’t you have invented a jetpack, or a hover skateboard or something?!”
Back in February, the team received a bit of a boost, when the Exovent project had a great write up in the award winning book, ‘Intensive Care’, by my good friend Gavin Francis [http://www.gavinfrancis.com/]. Gavin is an old friend from my medical school days, and quite a remarkable guy: as well as being an award winning writer, he is a GP, naturalist, polar explorer, and has ridden round the world on his motorbike. He has also developed a bit of reputation as a heartthrob on the book festival circuit, and was described recently on Radio 4 as “the thinking woman’s Steve Backshall”!
In my youth I always hitch hiked wherever I travelled in the world, and the thing that I loved most about it, was that it always gave a very positively distorted impression of the people of every country I visited: all the unpleasant, self-centred people would, by definition, just drive on past, and I would be picked up a little later by a wonderful, warm-hearted, generous person. This is rather like the Exovent team. It’s just so refreshing to meet so many incredible people, working so hard and giving up so much of their time, with no interest at all in personal gain. They are such a wonderful and inspiring group to work with, and such a huge amount of energy and effort has been put into getting Exovent to where it is now.
I have great confidence that negative pressure ventilation is going to be widely available all over the world within the next few years, and that it will save a lot of lives. I feel very proud to have been able to contribute in some small way to this incredible humanitarian project.
Dr. Colin Speight