Abstract The first anesthetic machines appeared following their public demonstration by Morton in 1846. These initial devices were simple inhalers based on the evaporation of the anesthetic agent. Their main problem was the loss of effectiveness with cooling. More complex inhalers were subsequently developed, in which the main difference was the possibility to provide more than one agent. Moreover, the concentration of the inhaled anesthetic was regulated for greater efficiency. At the beginning of the twentieth century, gas machines emerged, allowing the application of an anesthetic flow independent of the patient’s inspiratory effort. These machines incorporated technological advances such as flow meters, carbon dioxide absorption systems and fine adjustment vaporizers. In this period, in the field of thoracic surgery, intraoperative artificial ventilation began to be employed, which helped overcome the problem of pneumothorax associated with open pleura by applying positive pressure. From the 1930s, the gas machines were fitted with a ventilator, and by the 1950s this had become a basic component of the anesthesia system. Later still, in the 1980s, alarm and monitoring systems were incorporated, giving rise to the current generation of workstations.

The aim of mechanical ventilation is to substitute physiological respiratory function. The boom of mechanical ventilation came during the XVIII century with the development of Reanimation Societies in Europe, who promoted the use of positive pressure ventilation modes. This type of ventilation caused new complications due to excessive positive pressure in the airway. Therefore, during the XIX century negative pressure ventilation predominated, which became essential during the second half of the 19th century and first half of the 20th century. Positive pressure ventilation was relegated to operating rooms until 1952, when it was imposed over negative pressure ventilation during the Copenhagen polio epidemic. Björn Ibsen contributed significantly to this change of ventilation paradigm, which led to the latest ventilation strategies and the development of the actual intensive care units.