The Pressure in an Iron Lung

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

The Pressure in an Iron Lung

Before today’s respirators, patients with several breathing problems relied on a machine called an iron lung. Unlike the modern respirators that use positive pressure (greater than 1 atmosphere) that force air into the lungs, the iron lung was a negative pressure ventilator. The machine surrounded the person and the sealed cavity’s pressure was reduced to induce inhalation by the patient and then the pressure was increased to 1 atmosphere (15 psi or 750 mmHg). While all but obsolete today, these types of machines were extensively used when patients with polio were treated because of loss of muscle control that extended to their ability to breath. Thankfully, Dr. Jonas Salk discovered a vaccine to prevent polio (in 1953) and subsequent vaccines have eliminated polio as a health problem and today positive respirators using microelectromechanical systems (MEMS) pressure sensors can be so small that they are portable.

Iron Lung

The pressure gauge in this iron lung has been replace in modern respirators by MEMS pressure sensors. Source: Pittsburgh Post-Gazette website.

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