Illustrative case: Imagine a 5-year-old girl who, on a summer morning, wakes up with fever and muscle pain. Within a few days, her legs stop responding and, shortly after, breathing begins to fail. The doctors place her inside a large metal cylinder, which then breathes for her. The scene is fictional, but it summarises what happened to thousands of real children during the poliomyelitis epidemics of the 20th century.

What is the iron lung

The iron lung is a negative pressure ventilator. It was created in 1927 by Philip Drinker and Louis Agassiz Shaw at Harvard University, and further refined a few years later by John Haven Emerson.

Its operation differs from what most people imagine when they think of a "breathing apparatus". The patient lies inside a hermetic metal cylinder, with only the head outside, secured by a rubber ring that seals the neck. A system of pumps varies the pressure inside the cylinder. When pressure drops, the thorax expands and air enters the lungs. When pressure rises, the thorax retracts and air exits. In other words, the machine does not push air into the patient. It recreates, from outside to inside, the natural movement of breathing.

Why this was the choice: which diseases required this need

The iron lung did not treat the disease itself. It sustained breathing whilst the muscles responsible for this movement were paralysed. The condition most associated with the apparatus is poliomyelitis, a viral infection that can attack motor neurones in the spinal cord and compromise the diaphragm and thoracic muscles.

But poliomyelitis was not the only indication. Any condition capable of weakening respiratory muscles without directly damaging the lungs could lead to this need, including:

  • Guillain-Barré syndrome, an autoimmune disease that can cause progressive muscle weakness and affect about a quarter of patients to the point of requiring ventilatory support
  • Myasthenia gravis, which compromises transmission between nerve and muscle
  • Botulism, an intoxication that blocks nerve signals to the muscles
  • Spinal cord injuries, especially the highest ones, close to the neck
  • Tetanus, which can generate spasms and compromise breathing

In all these cases, the lungs themselves function normally. The problem lies in the "pump" that moves the air, that is, in the muscles and the nerves that control them.

What was the routine like for those dependent on the apparatus

During the polio epidemics of the 1930s to 1950s, hospitals had entire rooms full of iron lungs, and many patients spent weeks or months inside them until they recovered enough strength to breathe on their own. However, some never recovered this strength and became permanently dependent on the machine, sleeping inside it every night for the rest of their lives.

Why the iron lung fell out of use

Two developments changed this scenario. The first was the poliomyelitis vaccine, made available from 1955 onwards, which drastically reduced the number of new cases and, with that, the main cause that led to the use of the apparatus. The second was the development of modern mechanical ventilators, which operate on the opposite principle: instead of varying pressure around the body, they push air directly into the lungs through a tube in the trachea. These devices are smaller, more precise and allow for the care of patients with varying degrees of severity, which made them the standard in intensive medicine from the second half of the 20th century onwards.

The end of an era

In 2026, the iron lung ceased to have any known user. Paul Alexander, who had been dependent on the apparatus since the 1950s because of polio, died in March 2024. Martha Lillard, who contracted the disease at age 5, in 1953, and spent more than seven decades using the machine, died on 26 June 2026, aged 78, as a result of complications from post-polio syndrome and long covid. With her death, the chapter on continuous use of the iron lung in the United States effectively ended, and there is no record of equivalent use in other countries at present.

Is negative pressure ventilation still used today?

Very limited use. There are simplified and portable versions of the same principle, such as cuirass ventilators (a kind of rigid "shell" that covers only the thorax) and jacket ventilators. They appear occasionally in medical literature for home treatment of chronic respiratory insufficiency, especially in neuromuscular diseases, but their use today is considered experimental and restricted to very specific situations, without the same volume of scientific evidence accumulated by the methods that replaced them.

What science recommends today

For people with respiratory insufficiency of neuromuscular cause, similar to what previously required the iron lung, current guidelines prioritise non-invasive positive pressure ventilation, delivered by facial or nasal mask connected to an external device, without the need for a tube or surgery. This approach is supported by various studies, is more comfortable, allows the patient to speak, eat and sleep more naturally, and for this reason is usually the first choice whenever the clinical condition permits. When non-invasive ventilation is insufficient or the patient cannot tolerate it, the alternative is invasive ventilation via tracheostomy, indicated more judiciously as it carries greater risk of infection and secretion accumulation.

Thus, although the iron lung was decisive in its time and holds a symbolic place in the history of respiratory medicine, today's clinical practice is supported by safer technologies and much more robust evidence than that available a century ago.

This content is informational in nature and does not replace consultation, diagnosis or treatment by a healthcare professional. In case of doubts about respiratory symptoms or neuromuscular diseases, seek medical guidance.

Dr Rebeca Soares Andrade CRM - GO 39335