Feasibility and Safety Properties of Metabolic Flow Anesthesia Driven by Automated Gas Control in Pediatric Patients

Low flow anesthesia was considered to be causing rebreathing, hypoxia and hypercarbia in the past. However, developing technologies made anesthesia ventilators safer. Low flow anesthesia is proved to be safe and cost-effective for almost a decade, and newer anesthetic machines with automated gas flow and metabolic flow anesthesia (<0.3 L/min gas flow) features are now becoming prominent.

The literature still lacks of pediatric data regarding the cost analysis and safety profile of low flow and especially in metabolic flow anesthesia. In this study, it is aimed to observe inhaled agent expenditure of automated gas flow anesthesia which reaches metabolic flow limits in pediatric patients. For that, automated gas flow will be set to provide a desired end-tidal sevoflurane concentration during general anesthesia. Accordingly, inspired fraction of oxygen and air values will be recorded in 15-minute intervals. Primary outcome will be the inhaled agent (sevoflurane) amount wasted in milliliters for both inhaled agent maintenance speed (8-fast and 4-slow). Secondarily, delta value of set and detected inspired fraction of oxygen (DeltaFiO2=DetectedFiO2-SetFiO2) will be analyzed. DeltaFiO2 higher than 5 units will be accepted as "unsafe" gas mixture, and the incidence will be evaluated. Secondary outcomes will also include duration of emergence from anesthesia including both extubation and obeying verbal commands.