# How the Iron Lung Artificial Respirator Works

> A 1933 patent for a mechanical respirator that uses external air pressure changes to force a patient's lungs to expand and contract.

- **Patent:** US 1906844
- **Original title:** Artificial respirator
- **Owner:** Individual
- **Granted:** 1933
- **Status:** Public domain (expired)
- **Times cited:** 7
- **Field:** biotech, mechanical

## What it does

The device, commonly known as an iron lung, creates a sealed environment around a patient's body, leaving only the head exposed. By using a pump to rhythmically lower and raise the air pressure inside the chamber, the device forces the patient's chest to expand and deflate. This mechanical action mimics the natural process of breathing for individuals who have lost the ability to control their own diaphragm muscles.

## What it does NOT cover

- Does not cover positive-pressure ventilators that push air directly into the lungs through a tube.
- Does not cover portable or wearable breathing assistance devices.
- Does not cover electronic sensors or automated feedback loops for monitoring blood oxygen levels.

## The clever bit

The invention cleverly uses external negative pressure to manipulate the chest wall, avoiding the need for invasive procedures or direct intubation of the patient's airway.

## Real-world examples

1. The Drinker Respirator
2. Historical polio ward iron lung machines

## Why it matters

This invention was critical during the mid-20th century polio epidemics, providing life-saving support for patients suffering from respiratory paralysis. It represents a foundational moment in intensive care medicine, proving that mechanical intervention could sustain life during prolonged respiratory failure.

## Frequently asked questions

### What does How the Iron Lung Artificial Respirator Works cover?

A 1933 patent for a mechanical respirator that uses external air pressure changes to force a patient's lungs to expand and contract.

### Who owns patent US 1906844?

Individual owns this patent, granted in 1933.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 1906844 cited by?

This patent has been cited by 7 later patents that build on its ideas.

### What problem does this patent solve?

This invention was critical during the mid-20th century polio epidemics, providing life-saving support for patients suffering from respiratory paralysis. It represents a foundational moment in intensive care medicine, proving that mechanical intervention could sustain life during prolonged respiratory failure.

### What does this patent NOT cover?

Does not cover positive-pressure ventilators that push air directly into the lungs through a tube.

**Full plain-English explainer:** https://patentbrief.org/patent/us/1906844/iron-lung-respirator-drinker

**Original patent:** https://patents.google.com/patent/US1906844

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How Dr. Forrest Bird's Mechanical Respirator Controls Patient Breathing](https://patentbrief.org/patent/us/3191596/bird-respirator-ventilator) — A 1965 patent describing a mechanical ventilator that automatically switches between inhaling and exhaling based on pressure levels in a patient's airway.
- [How the First Heart-Lung Machine Oxygenated Blood](https://patentbrief.org/patent/us/2702035/heart-lung-machine-gibbon) — A 1955 invention that allowed surgeons to oxygenate a patient's blood outside the body, enabling the first successful open-heart surgeries.
- [How the Aqua-Lung Scuba Regulator Works](https://patentbrief.org/patent/us/2485039/aqualung-scuba-cousteau-gagnan) — The foundational 1947 patent by Jacques Cousteau and Emile Gagnan for the automatic demand regulator that allows divers to breathe compressed air underwater.
- [Leonarde Keeler's Early Mechanical Blood Pressure Recorder](https://patentbrief.org/patent/us/1788434/polygraph-lie-detector-keeler) — A 1925 invention by Leonarde Keeler designed to mechanically record a patient's arterial blood pressure over time.
- [How CPAP Machines Gradually Increase Air Pressure for Sleeping Patients](https://patentbrief.org/patent/us/5199424/cpap-sleep-apnea-sullivan) — A 1993 patent describing a CPAP machine that lets patients choose how slowly the air pressure ramps up to their therapeutic level, making it easier to fall asleep.