Functional characteristics of anesthesia machines with circle breathing system

SummaryPresently, the majority of anesthesia machines or workstations are ventilators that incorporate a classic circle system/circuit with a CO2 absorber that allows rebreathing of exhaled gases. The performance characteristics of these machines are related to the physical structure of the breathing circuit. Limitations related to the classical circle breathing circuit are progressively disappearing with the arrival on the market of modern anesthesia machines with modified circular circuits, which offer a series of advantages in relation to the classic circular circuit. The present review describes the basic functional characteristics common to any anesthesia machine and that determine their clinical performance. The knowledge of these characteristics is essential for the clinical use of anesthesia machines and for analyzing their evolution.