Closed-Circuit Anesthesia

Closed-circuit anesthesia is a technique that maintains a constant anesthetic state by adding gases and vapors to the breathing circuit at the same rate that the patient’s body redistributes (stores) or eliminates them. Some practitioners use liquid anesthetic injection at prescribed time intervals using the empiric square-root-of-time model; others monitor and maintain inspired or expired anesthetic tensions using a gas monitor that returns analyzed gas to the breathing circuit. Commercial almost–closed-circuit anesthesia machines are available in countries other than the United States.