The iron lung is a medical device that once supported individuals unable to breathe independently. This specialized ventilator provided artificial respiration, allowing patients to survive conditions that would otherwise be fatal. Its development offered a lifeline to many throughout the 20th century.
How the Iron Lung Works
The iron lung operates on the principle of negative pressure ventilation, a method distinct from many modern breathing aids. A patient lies inside a sealed, horizontal cylinder, with only their head exposed to the outside air. An airtight seal is created around the patient’s neck, separating the body within the chamber from the external environment.
An electric motor and pump system inside the machine periodically reduce air pressure within the chamber, creating a vacuum around the patient’s chest. This negative pressure causes the chest wall to expand, drawing air into the lungs through the nose and mouth. When the pressure is then released, the chest naturally recoils, pushing air out of the lungs in a simulated exhalation. This rhythmic cycle of pressure changes mimics normal breathing.
Historical Use for Polio
The iron lung became widely known for its extensive use during the polio epidemics, particularly from the 1930s to the 1950s. Poliovirus could attack motor neurons in the brainstem, leading to a severe form of the disease known as bulbar polio. Patients afflicted with bulbar polio often experienced paralysis of the muscles necessary for breathing, including the diaphragm and intercostal muscles. Without mechanical assistance, these individuals would quickly succumb to respiratory failure.
Hospitals established specialized wards filled with rows of these large, cylindrical machines to accommodate the surge of patients. The iron lung provided the continuous respiratory support these patients needed to survive the acute phase of the illness. Many remained in the devices for weeks, months, or even years, depending on the severity and permanence of their paralysis. The widespread deployment of the iron lung improved survival rates for those with respiratory compromise due to polio.
Modern Respiratory Support and Current Use
The widespread use of the iron lung began to decline sharply following the development and mass implementation of the polio vaccine in the mid-1950s. The vaccine effectively prevented new cases of paralytic polio, significantly reducing the demand for extensive respiratory support. Another factor contributing to its obsolescence was the advent of positive pressure ventilators.
Modern positive pressure ventilators push air directly into the lungs through a tube inserted into the trachea, offering a more compact and versatile solution. These devices are smaller, more portable, and allow for greater patient mobility. While the iron lung is rarely used today, a small number of individuals, primarily long-term polio survivors, continue to rely on them. These individuals have adapted to the specific mechanics of the iron lung over decades and find it provides comfortable and effective support for their unique respiratory needs.