The iron lung, a large mechanical respirator, supported individuals unable to breathe on their own. This cylindrical device, often associated with mid-20th-century health crises, was a pioneering form of life support. While its prominence has waned, its legacy in advancing respiratory care remains notable.
The Medical Challenge It Addressed
The iron lung emerged as a response to the impact of poliomyelitis, commonly known as polio. This viral disease primarily affected children, with severe cases leading to paralysis, including the muscles essential for breathing. When the poliovirus attacked the nervous system, especially nerves controlling the diaphragm and chest muscles, patients could lose the ability to inhale and exhale independently, leading to respiratory failure. An estimated 5-10% of those paralyzed by polio died when their breathing muscles became immobilized. The need for a device that could mechanically assist breathing became clear during widespread polio epidemics.
The Mechanics of Negative Pressure Ventilation
The iron lung operated on the principle of negative pressure ventilation, mimicking natural breathing. A patient’s body, from the neck down, was enclosed within an airtight, horizontal metal cylinder, with their head remaining outside. A rubber seal around the neck ensured no air escaped, creating a sealed chamber.
Inside this sealed environment, a motor-driven pump or bellows altered the air pressure. When the pump created negative pressure by drawing air out of the chamber, the patient’s chest cavity expanded due to the pressure difference, pulling air into the lungs through their mouth and nose. This replicated the diaphragm’s natural contraction.
When pressure equalized or slightly increased, the patient’s chest and abdomen would relax and partially collapse. This passive exhalation pushed air out of the lungs. This rhythmic pressure cycling ensured continuous artificial respiration for patients with compromised breathing muscles. Early models like the Drinker respirator, invented in 1928, used air pumps from vacuum cleaners to achieve these changes, while later versions, such as the Emerson respirator, introduced improvements for patient access and quieter operation.
Life Inside the Iron Lung
Life within an iron lung presented challenges for patients and their caregivers. Patients lay on a sliding bed that could be pulled out of the cylinder for limited care access. Daily tasks like feeding, hygiene, and medical procedures were performed through portholes or by temporarily sliding the patient out.
Confinement was extensive, with some patients spending weeks, months, or even decades inside the machine. Communication was aided by mirrors above the patient’s head, allowing them to see their surroundings and interact with others. Despite restrictions, many engaged with the world, reading books suspended overhead or pursuing education and careers using mouth-manipulated tools. The machine’s constant rhythmic sound became a familiar part of their existence.
From Iron Lung to Modern Respiratory Support
The widespread use of the iron lung declined with the advent of the polio vaccine in the mid-1950s. The vaccine reduced new cases of poliomyelitis, diminishing its need. This breakthrough largely eradicated polio, making the iron lung increasingly obsolete.
Concurrently, medical advancements led to more versatile, less restrictive respiratory support methods. Positive pressure ventilation, which pushes air directly into the lungs through tubes inserted into the airway, emerged as a common approach. These modern ventilators offer greater mobility and easier access for medical staff, marking an evolution in respiratory care. While the iron lung is now largely a historical artifact, its role as a life-saving innovation during an important period of public health and its pioneering mechanical ventilation laid groundwork for today’s sophisticated respiratory technologies.