Positive Pressure (Air Control)
Introduction
Mechanical ventilation is a therapeutic strategy that consists of mechanically assisting spontaneous pulmonary ventilation when it is non-existent or ineffective for life. To carry out mechanical ventilation, you can use a mechanical ventilator (or artificial respirator) or a person manually pumping the air by compressing an air bag or bellows.[1].
Spontaneous pulmonary ventilation
The exchange of gases between the lungs and the atmosphere is called pulmonary ventilation. Its purpose is to allow oxygenation of the blood and the elimination of carbon dioxide.
In spontaneous ventilation, during inspiration, an individual generates negative intrathoracic pressures by increasing thoracic volume thanks to the respiratory muscles (mainly the diaphragm). The pressure inside the thorax becomes lower than atmospheric pressure, thus generating a pressure gradient that causes air to enter the lungs to balance this difference.
expiration (breathing out air) is normally a passive process.
During spontaneous ventilation, a regular volume of air called tidal volume, approximately ½ liter, is introduced and expelled at a certain respiratory rate (12-20 breaths per minute).
History of mechanical ventilation
Practices that are very common today for any nurse, such as intubating and connecting a patient to an assisted ventilation system") are, without a doubt, the result of centuries of history that are not usually even suspected by ordinary people and even by many doctors.
To the surprise of many who might think that mechanical ventilation is a very recent practice, it has its roots in 1543 with the first experimental application of mechanical ventilation thanks to the doctor Andrés Vesalio. The experiment consisted of supporting the breathing of a canine thanks to a system of bellows connected directly to its trachea and was the first perfectly documented experiment in the history of medicine on this topic, but it was not valued at its time. In fact, it was not until 1776 that the Scottish doctor John Hunter, based on Vesalius's experiment, used a double bellows system.