Anesthetic gas consumption with target-controlled administration a semi-closed circle system with automatic end-tidal concentration control in an artificial lung model.

The use of volatile anesthetics as sedatives in the intensive care unit is relevant to the patient's outcome. We compared anesthetic gas consumption of the conventional semi-closed Aisys CS with the MIRUS system, which is the first anesthetic gas reflector system that can administer desflurane in addition to isoflurane and sevoflurane. We connected an artificial lung model to either a MIRUS system and a Puritan Bennett 840 ventilator or an Aisys CS anesthesia machine. We found that consumption of 0.5% isoflurane, which corresponds to the target concentration 0.5 MAC, was averaged to 2 mL/h in the MIRUS system, which is identical to the Aisys CS at a fresh gas flow (FGF) of 1.0 L/min. MIRUS consumption of 1% sevoflurane was averaged to 10 mL/h, which corresponds to 8.4 mL/h at FGF 2.5 L/min. The MIRUS system consumed 3% or 4% desflurane at an average of 13.0 mL/h or 21.3 mL/h, which is between the consumption at 1.0 L/min and 2.5 L/min FGF. Thus, the MIRUS system can effectively deliver volatile anesthetics in clinically relevant concentrations in a similar rate as a conventional circular breathing system at FGFs between 1.0 L/min and 2.5 L/min.