In 1953, doctors Holger Hesse and Henning Ruben developed the concept of the world's first manual device for artificial ventilation. According to their idea, it should have been a bag-pump, containing in a plastic case with the medical valve systems and a flexible face mask.
The bag created by them - or a breathing AMBU bag - is a device for emergency ventilation of the lungs in conditions of inaccessibility of resuscitation equipment. This bag has a compact size and the independence from the power source.
An AMBU bag consists of seven parts: a mask, a main ventilation and backup bags, medical valve systems and a nipple. Compared with artificial mouth-to-mouth breathing, it is more hygienic, simple and effective.
When the ventilation bag is squeezed, the air enters the lungs of the patient, while the nonreversible breathing valve prevents backfiring of the exhaled air. Then the AMBU self-dispenses by sucking air from the valve from its back side. An ambient air can be used as a "fuel", or an oxygen cylinder can be connected. In the latter case, it is possible to connect a tank to collect an excess oxygen, which was not used by the patient.
A distinctive feature of the AMBU breathing bag is a non-reversible medical valve system with input and output ports. In the process of inhalation one of them opens letting the respiratory mixture to the patient. Through the exhalation port the exhaust gas is released into the atmosphere.
Thanks to the peculiarities of the structure, even when the safety medical valve system is closed, oxygen does not exceed the peak values of internal pressure and patient's lungs are reliably protected from barotrauma.
The design of this equipment is constantly evolving, resulting in the device becoming safer and easier to use. The latest models of breathing bags are characterized by improved design and functionality, allowing the exact volume of the incoming mixture to be accurately metered through medical valve systems, depending on the condition and age of the patient.
Nearly seventy years are passed since the creation of the first bag of Ambu. On the peak of the achievements in this field of manual lungs ventilation is mini Ambu bags - special medical devices capable of compact folding and occupying almost 5 times smaller volume - at a weight of 500 grams, the dimensions of the plastic case are only 13.5 x 7.2 centimeters. Such bags are enclosed in a shockproof case, placed in the field first aid kit. Like many other inventions, they were developed for the army and then find itselves in more peaceful areas.
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