Iron lung

The Iron Lung, also known as a negative pressure ventilator, is a medical device used to mechanically assist or replace the function of respiration in patients with respiratory failure or difficulty. It derives its name from the large, bulky metallic exterior that encases the patient's body, leaving only their head exposed.

Iron lung with dome and patient

Historical Context

The Iron Lung was developed in the early 20th century, with the first practical model invented by American industrial hygienist Philip Drinker and physicist Louis Agassiz Shaw in 1927. The device was primarily used for patients suffering from poliomyelitis, a viral disease that can cause paralysis and difficulty in breathing. Iron lungs were particularly prominent during the mid-20th century polio epidemics before the introduction of the polio vaccine in the 1950s.

Operation and Use

The Iron Lung functions by creating a vacuum to draw air into the lungs and then releasing the vacuum to allow the lungs to deflate. The patient is placed inside the chamber, which is sealed around their neck. The pressure inside the chamber is alternately reduced and then increased, simulating the negative pressure environment of the chest cavity during normal breathing. This alternating pressure causes the patient's chest and abdomen to rise and fall, pulling air into the lungs and then pushing it out.

Limitations and Alternatives

Despite its historic importance, the use of the Iron Lung has significantly decreased in recent decades. The device is bulky, restrictive, and requires continuous power to operate. It also does not permit many activities such as eating, speaking, or moving around. Modern mechanical ventilators, which provide positive pressure ventilation by delivering air directly into the airway through a tube, have largely replaced the Iron Lung. These devices are more portable, flexible, and allow patients to interact more freely with their environment.

See Also

• Mechanical Ventilation
• Respiratory Therapy
• Poliomyelitis
• Respiratory Failure

External links

• A Short History of the Negative Pressure Ventilator

References

• John F. Bach, "History of Polio and Iron Lungs," Respiratory Care, vol. 58, no. 6, pp. 1012–1018, 2013.
• Daniel J. Wilson, "Living with Polio in the Epidemic Years, 1949-1954: I Remember the Iron Lung," The Pennsylvania Magazine of History and Biography, vol. 136, no. 4, pp. 361–383, 2012.

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