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The Iron Lung

Around 1500 words

Published: 14 October 2018

Large, cumbersome and very expensive, in its time the iron lung was the state of the art in high-tech life support.

The cabinet respirator, better known as the iron lung, kept a patient breathing when their lungs stopped working. The first iron lung was used to save the life of an eight-year-old girl with polio in 1928. 

What was it for?

The iron lung helped patients to breathe when their lungs failed. It was first developed for the polio epidemics of the 20th century.

Around the beginning of the 20th century incidents of poliomyelitis (polio) began to rise to epidemic proportions across Europe and North America, reaching their peak in the United States in 1952, with 57,628 cases in one year.

One of the worst symptoms of acute polio was paralysis. If paralysis affected the chest muscles, the patient could no longer breathe unaided and usually died. Doctors looked to technology for a way to keep these patients alive.

child with infantile paralysis in splints and walking frame Wellcome Collection, CC-BY





Find out more about poliomyelitis.

The solution came from a team of researchers at Harvard University and machine was originally developed to treat coal gas poisoning. The 'iron lung' as it was nicknamed, was a huge metal box attached to bellows in which the patient was encased. The suction from the bellows made the patient breathe.

It soon became a defining feature of the polio epidemics of the mid-20th century. By 1939, around a thousand iron lungs were in use in the USA, and whole wards were created for the intensive care required to maintain and care for the people inside them.

Who made it?

Philip Drinker and Louis Agassiz Shaw invented the first iron lung at Harvard School of Public Health. It consisted of a huge metal box with a set of bellows attached at one end to pump air in and out. The whole body was enclosed in an air tight chamber, apart from the head. A tight rubber seal supported the neck and ensured that air did not escape.

Mechanical breathing apparatus were not a new idea, but the huge scale of the polio epidemics motivated researchers to come up with a device. But development of the iron lung was not without controversy.

In 1931, John Haven Emerson improved on the design so that the bed could slide in and out of the cabinet and portholes on the sides allowed access to the patient without loss of air pressure. But Drinker and Harvard University sued Emerson for infringing on their patents. In court, Emerson's lawyers demonstrated that all the technologies used by Drinker already existed and so could not be patented. Emerson won the case and the patents were declared invalid. The judge also agreed with Emerson that a technology that saved lives should not be shared by everyone.

Another version of the iron lung born of necessity was the Both Respirator. When a polio epidemic broke out in Australia in 1937, the cost of buying and transporting Drinker Respirators was so high that the South Australian Health Department asked biomedical engineer Edward Both to come up with a cheaper alternative.

The Both respirator was made of plywood. It was not only cheaper, it was easier to construct and transport. In some cases, it was in use within one hour of production. A year later, in London, Lord Nuffield was so impressed with the Both design that he had around 1700 machines built at his car manufacturing plant and donated them to hospitals around the world.

How did it work?

For each breath, the bellows would expand. sucking air out of the sealed cabinet and causing the air pressure in the cabinet to fall below atmospheric levels. This made the patient’s lungs expand automatically and draw in fresh air. When the bellows deflated, the air pressure returned to atmospheric levels and the patient's lungs passively deflated, making the patient breathe out. This method of artificial respiration was called External Negative Pressure Ventilation (ENPV).

What was it like for the patient?

Most polio patients would spend around two weeks in the machine, but those left permanently paralysed by the disease faced a lifetime of confinement. Going into an iron lung was a bewildering process for patients, many of whom were delirious and in extreme pain.

Life in an iron lung was difficult for both patient and carers. The numerous tasks involved in treating the patient included:

  • blood transfusions
  • intravenous glucose feeds
  • inserting and replacing catheters
  • and endless adjustments to the body and equipment.

In addition to medical care, itches were scratched, noses blown, hair combed, bodies washed, and bedpans inserted and removed, all through the portholes as far as possible.

When the portholes were inadequate, tasks such as physical therapy had to be completed in the few minutes that a patient could breathe on their own outside the iron lung. Physical therapy in the form of ice packs, heat packs and massage were necessary to stop unused muscles from atrophying.

Boy in an iron lung, his smiling face is seen in a mirror attached to the machine, 1930s-1950s. AP / Steve & Mary DeGenaro / Boston Children’s Hospital Archive / AARC’s Virtual Museum Image source
Polio patient, United States, 1930s-1950s.

One of the biggest problems for patients was boredom. A mirror could be attached above the patient’s head, so they could see what was happening around them. They could also read books suspended in front of their faces if someone turned the pages for them.

In larger iron lung wards they had other patients nearby to provide companionship and psychological support, but visiting hours for family were limited. Polio particularly affected young children, and it was especially difficult for them to understand what was happening to them. 

Lord Mayor Treloar Hospital in Hampshire specialised in the treatment of children affected by tuberculosis and polio. They used dolls to explain what would happen to them during treatment.

How long did you have to stay in an iron lung?

Most patients were weaned from the iron lung after a few weeks or months depending on the severity of the polio attack. Therapists used several techniques to help patients regain strength in their chest muscles. By slowly extending the time outside the cabinet the patient could gradually build up the muscles to the point where they could spend most of the day outside the iron lung, returning to it at night to give tired chest muscles time to rest.

The technique sounds straightforward, but in practice learning to breathe again was a difficult and frightening process, as one patient, Kenneth Kingery recalled:

I’d have to strain my every fibre for a breath of air. And there was always a helpless terror – wondering whether they’d close the tank in time.

As muscle strength returned some patients were transferred to rocking beds, which used gravity to help with breathing. As the head of the bed tilted upwards, gravity pulled the internal organs downwards, drawing air into the lungs. When it tilted the other way, gravity pushed the internal organs up on to the diaphragm, pushing air out of the lungs.

Overslung rocking bed for aiding respiration, by the Cape Engineering Co. Ltd., Warwick, 1973.
Science Museum Group Collection More information

The process of rehabilitation could be long and difficult. Polio damaged muscles could take up to two years to recover maximum functionality, during which time the patient had to continue a rigorous regime of physical therapy and exercise.

Is it still used today?

Once an effective polio vaccine was developed in the 1950s, there was no longer a need for iron lung wards and only a very few machines were kept for those patients dependent on them for the rest of their lives.

Modern ventilators are used now in intensive care units and emergency wards. They have the advantage of allowing full access to the patient and they can also monitor breathing and other vital signs.

Ventilators are also used in surgery thanks to John Haven Emerson, who went on to develop a mechanical assistor for anaesthesia in 1949. Surgeons began to use drugs during operations to relax the muscles and make surgery easier, but since the drugs also paralysed the respiratory muscles, a ventilator was needed to make sure the patient didn't stop breathing. It's the job of the anaesthetist to make sure that the patient stays unconscious during the operation but keeps breathing.

Barnet Mark III ventilator and anaesthetic apparatus, England, 1950-1970.
Science Museum Group Collection More information

Modern ventilators, tend to use Positive Pressure Ventilation Systems (PPVS), in which air is pushed into into the patient's lungs via intubation of the airway. But even the modern device has a connection to the iron lung: the first PPVS device was developed in 1952 for an outbreak in Copenhagan, Denmark.

Suggested further research

Iron lung patients:

More about poliomyelitis:

More about ventilators: