[Anesthesia ventilators]

New technology has led to improved performance in the latest generation of ventilators for anesthesia. However, the wide variety of designs by different manufacturers means that there are significant differences in how the ventilators work. First, two radically different concepts dominate the market. One is that of anesthesia ventilator, which fits in as a module within an anesthesia system or a workstation. Another concept is that of ventilator adapted for anesthesia, which constitutes in and of itself the anesthesia machine. Second, the differences extend to the systems for generating pressure used by different manufacturers of each model, to the algorithms employed in the software, or the "solutions" proposed by each to compensate for certain deficiencies inherent to the design. Lack of uniformity prevents the anesthesiologist from meeting the ideal objective of working on a daily basis with systems that are sufficiently well understood and that perform predictably, with knowledge following from the study of the functional features of each model before clinical use starts. To this lack of knowledge, we must add the scarcity of information from studies to analyze the performance of each model in the various possible clinical situations involving anesthesia. The present paper aims to develop a systematic classification of anesthesia ventilators and to describe the main parameters that determine the performance of all ventilators.