When Edgar Pask took up his post as Reader the Department of Anaesthesia in Newcastle in 1947, he brought with him many progressive ideas. One of the most important was that his department must have a fully fitted workshop, staffed with highly able technicians. Pask’s inventive mind, combined with the skills of his chief technician Norman Burn, led to the design, construction and use of a great variety of anaesthetic equipment. Probably the most important devices, developed and used for over thirty years, were the Newcastle ventilators, initially known as respirators.

Pask's interest in resuscitation led onto the ventilation of the lungs during anaesthesia and for patients with respiratory failure. In 1948, using many war surplus parts, many from sources in the RAF, Pask (now a Professor of Anaesthetics – the second in the country) and Burn (an ex Flight Sergeant) set about building one of the first British positive pressure respirators , another being created by Blease.

"Mother"

Mercury switches (to avoid sparking in the days of ether) in the box on the top right controlled the electric motor. Via a spinning disc, which allowed speed variation, drive was transferred to a camshaft that in turn moved the four small bellows up and down to provide ventilation. This device was not used very often clinically, but was used for experimentation in the development of further devices. It no longer exists, as it was later scavenged for parts. The oxygen flush device (as used in Second World War German bombers) is in the Newcastle collection.

Following their initial success, ideas and cogs flew around the workshop. The demands made by Pask were not only for a ventilator that worked, but one that could be simply and cheaply constructed by any able technician. Polio was almost certainly the main incentive for this work. It is difficult for us in the Twenty First Century to appreciate the degree that post-war Europe was threatened by the poliomyelitis virus. The few "iron lungs" in Britain, mostly donated by Lord Nuffield, were wholly inadequate to deal with a full-blown epidemic. In 1946, there were under 1000 reported cases in England and Wales, but this soared to nearly 9,000 in the warm dry summer of 1947. Deaths from respiratory paralysis occurred in over 10% of cases. The Danish epidemic of 1952 is famous for the intervention of anaesthetists in the care of these patients, when tracheostomy and hand ventilation brought mortality in respiratory paralysis down from 90% to 30%. This experience lead to the famous Bang ventilator of 1953, versions of which were created elsewhere, such as the Clevedon of Bristol. Pask and Burn made their own interpretation of the Bang ventilator, still with Pask’s proviso that it must be cheap and easy to build quickly .

The Newcastle "Bang" ventilator

However, this device was still quite complex, with mercury switches and the need for frequent adjustment and maintenance. Therefore, two prototype "polio ventilators" were built, out of materials that were readily available in any workshop. They were powered by the "blow" side of a domestic vacuum cleaner, with the facility to power up to 10 ventilators from one Hoover! The device on the left, made of plywood, used a magnet to operate it’s main valve. Inflation pressure was varied by adding weights onto the hinged flap on top. Cycling was controlled by regulating the leak out of the

The two Newcastle "polio" ventilators

plastic bag under the flap. When the bag emptied, the magnet lowered and opened the main valve, allowing inspiration until the bag had filled enough to again lift the magnet from the valve, which would then shut until the bag was empty again.

The inspiratory and expiratory phases of the wooden polio ventilator

The device on the right in figure 3 had many similarities, but was constructed mainly from perspex. It used the "flick over" rocker from a light switch as a main switch which opened and closed a piece of Paul’s tubing to allow gas flow. Inflation pressure was varied by altering tension in springs rather than by using weights, while controlled gas leak was still used to control cycling. Both these devices therefore split the inlet air, from the vacuum cleaner, to both the patient and the control bag. The expansion of the bag triggered the main valve that stopped the flow of air and allowed expiration.

Luckily, mass production and use of these devices was not necessary in the North East. The two prototypes still exist in the anaesthetic collection at the Royal Victoria Infirmary in Newcastle upon Tyne, although not in working order. These early ventilators were followed by many more, for both adults and infants. "Home made" ventilators of all shaped and sizes persisted for another thirty years at the Royal Victoria Infirmary, and many have been saved and can be seen here in the museum.

I would like to thank Norman Burn for supplying invaluable information about his work with Professor Pask, and The University of Newcastle upon Tyne Audio Visual Department for the use of original photographs.

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