Hubbry Logo
search
logo
2229376

Iron lung

logo
Community Hub0 Subscribers
Write something...
Be the first to start a discussion here.
Be the first to start a discussion here.
See all
Iron lung

An iron lung is a type of negative pressure ventilator, a mechanical respirator which encloses most of a person's body and varies the air pressure in the enclosed space to stimulate breathing. It assists breathing when muscle control is lost, or the work of breathing exceeds the person's ability. Need for this treatment may result from diseases including polio and botulism and certain poisons (for example, barbiturates and tubocurarine).

The use of iron lungs is largely obsolete in modern medicine as more modern breathing therapies have been developed and due to the eradication of polio in most of the world. In 2020, however, the COVID-19 pandemic revived some interest in them as a cheap, readily-producible substitute for positive-pressure ventilators, which were feared to be outnumbered by patients potentially needing temporary artificially assisted respiration.

The iron lung is a large horizontal cylinder designed to stimulate breathing in patients who have lost control of their respiratory muscles. The patient's head is exposed outside the cylinder, while the body is sealed inside. Air pressure inside the cylinder is cycled to facilitate inhalation and exhalation. Devices like the Drinker, Emerson, and Both respirators are examples of iron lungs, which can be manually or mechanically powered. Smaller versions, like the cuirass ventilator and jacket ventilator, enclose only the patient's torso. Breathing in humans occurs through negative pressure, where the rib cage expands and the diaphragm contracts, causing air to flow in and out of the lungs.

The concept of external negative pressure ventilation was introduced by John Mayow in 1670. The first widely used device was the iron lung, developed by Philip Drinker and Louis Shaw in 1928. Initially used for coal gas poisoning treatment, the iron lung gained fame for treating respiratory failure caused by polio in the mid-20th century. John Haven Emerson introduced an improved and more affordable version in 1931. The Both respirator, a cheaper and lighter alternative to the Drinker model, was invented in Australia in 1937. British philanthropist William Morris financed the production of the Both–Nuffield respirators, donating them to hospitals throughout Britain and the British Empire. During the polio outbreaks of the 1940s and 1950s, iron lungs filled hospital wards, assisting patients with paralyzed diaphragms in their recovery.

Polio vaccination programs and the development of modern ventilators have nearly eradicated the use of iron lungs in the developed world. Positive pressure ventilation systems, which blow air into the patient's lungs via intubation, have become more common than negative pressure systems like iron lungs. However, negative pressure ventilation is more similar to normal physiological breathing and may be preferable in rare conditions such as central hypoventilation syndrome. As of 2024, after the death of Paul Alexander, only one patient in the U.S., Martha Lillard, is still using an iron lung. In response to the COVID-19 pandemic and the shortage of modern ventilators, some enterprises developed prototypes of new, easily producible versions of the iron lung.

The iron lung is typically a large horizontal cylinder in which a person is laid, with their head protruding from a hole in the end of the cylinder, so that their full head (down to their voice box) is outside the cylinder, exposed to ambient air, and the rest of their body sealed inside the cylinder, where air pressure is continuously cycled up and down to stimulate breathing.

To cause the patient to inhale, air is pumped out of the cylinder, causing a slight vacuum, which causes the patient's chest and abdomen to expand (drawing air from outside the cylinder, through the patient's exposed nose or mouth, into their lungs). Then, for the patient to exhale, the air inside the cylinder is compressed slightly (or allowed to equalize to ambient room pressure), causing the patient's chest and abdomen to partially collapse, forcing air out of the lungs, as the patient exhales the breath through their exposed mouth and nose, outside the cylinder.

Examples of the device include the Drinker respirator, the Emerson respirator, and the Both respirator. Iron lungs can be either manually or mechanically powered, but are normally powered by an electric motor linked to a flexible pumping diaphragm (commonly opposite the end of the cylinder from the patient's head). Larger "room-sized" iron lungs were also developed, allowing for simultaneous ventilation of several patients (each with their heads protruding from sealed openings in the outer wall), with sufficient space inside for a nurse or a respiratory therapist to be inside the sealed room, attending the patients.

See all
User Avatar
No comments yet.