"...exovent became a registered charity 2 days later on 11 June"


March 2020 - An initial thought gathered pace!

In early March Dave McKeown was considering the looming COVID-19 pandemic and thinking about what his family would need if things got worse and the NHS became overwhelmed. He concluded that they would need oxygen and ventilators. He found examples of low-cost positive pressure ventilators (PPV), but he also found a lot of negative information about the effects of PPV and this led him to investigate Negative Pressure Ventilation (NPV). These devices, previously referred to as iron lungs, were first built in the 1930’s and Dave thought that, if it had been possible to build them then, it should be possible to build one at home now. He did some preliminary design work which suggested that it would be possible to make a cheap, simple NPV device in large quantities quickly. He spoke to a family friend Nigel Speight who's feedback was encouraging and who linked Dave to Malcolm Coulthard. Dave, Malcolm and Nigel put together a proposal to build 5000 units in 7 days and emailed it to the Department of Business, Energy and Industrial Strategy (BEIS) on 19 March. BEIS forwarded it to the Cabinet Office. Neither replied, then or since. But, later that day, someone, who has never been identified, posted Dave’s email on a Facebook group for GPs called GPComms where it was seen by a number of medics who started to contact Dave to get involved.

As a result, an enlarged group consisting of Dave McKeown, Dr Malcolm Coulthard, Professor David Howard, Dr Colin Speight, Professor Neil Downie, Dr Nick Ryan, Jon Harris, Heather Lambert, and Dr Diane Downie had a group call on 20 March and formed a taskforce with the aim of developing an NPV device.

Sir John Burn, a professor at Newcastle university additionally contacted Dave McKeown and offered his medical physics labs for testing. The group started to build prototypes, developing enclosures with pumps and valves. The group decided from the start that the device would need to leave as much of the body accessible as possible to allow for patient care and so set about developing seals for the neck and hips from equipment they had at home. They also used their networks to bring others into the team including Lucy Hawking, several senior anaesthetists, Anil Patel, Peter Young, Jim Roberts), a critical care nurse Emily Hodges and a PR company (Kate Miller and Claire Davidson at DRD).


The pace of work was intense with daily calls, driven by the potential need for the device in a very short timescale. There was no hierarchy and the team all enjoyed the opportunity to work with other disciplines. After a week or so, the team moved from phone calls to Zoom, allowing them to see each other for the first time which helped to build the relationships further.

Dr Malcolm Coulthard began researching the history of NPV which had last been widely used in the 1950s to treat polio patients. NPV had faded from use because the inaccessibility of the patient was very restrictive and the units were large and cumbersome compared to the new PPV devices. Many medics were sceptical about the use of NPV for patients with Acute Respiratory Distress Syndrome (ARDS), which is a symptom of COVID-19, rather than polio.  In the past when NPV was used to treat polio patients, the lungs were undamaged but the muscles were paralysed so the NPV just acted to move the healthy lungs. With ARDS the lungs are full of mucus and may also be damaged and the medics were unsure if NPV would be able to ‘unstick’ them. Malcolm was very encouraged when his research uncovered the work of Antonio Corrado, an Italian doctor who had done a lot of work on NPV devices and used them to treat patients with pneumonia and smoking related illnesses. The many benefits that Dr Corrado had found for NPV over PPV, especially CPAP, made Malcolm think that rather than just being a quick, cheap emergency alternative to PPV it could become the ventilation method of choice for a range of respiratory conditions. Benefits Dr Corrado had found included:

  • The patient was conscious and could eat, drink and talk etc.
  • NPV did not reduce cardiac function like PPV
  • It was much more comfortable for patients than CPAP which many patients found intolerable.
  • It did not force mucus further into the lungs
  • It could potentially be used at home or in care homes
  • The skill level to operate it was much lower
  • The patient could leave the machine for periods of time
  • Some physio could be done on the patient while in the machine
  • It could be used to rebuild muscle strength after prolonged PP ventilation
  • It was less invasive, avoiding the damage to vocal cords and throat sometime seen with PPV
  • Removing the patient from the device could easily be reversed if they struggled whereas extubation from a ventilator is usually a one-way process.

When compared to the old iron lung the proposed exovent design had the following advantages:

  • The hip level seal rather than a whole body enclosure overcame many of the nursing concerns with iron lungs
  • The smaller volume resulting from the hip seal made it very efficient and negative pressure could be achieved with a small pump e.g. a vacuum cleaner rather than the large mechanical diaphragm mechanism that had been used in the past.

On 26 March the name exovent was agreed.