Figure 1

Schematic illustration for comparison of the automated ECO and AUTO mode. The figure illustrates the characteristics of the standardized ECO and AUTO mode during wash-in and maintenance, showing xenon injected flow, the resulting expiratory xenon concentration and the overall xenon usage. AUTO mode initially injects xenon at high flow (about 2 L/min) in order to reach fast the target concentration, while the ECO mode initially injects xenon at very low flow (about 0.5 L/min) to be economic. Accordingly during maintenance the AUTO mode repetitively injects xenon with frequent short pulses at low flow while the ECO mode only injects xenon each 10 to 20 minutes during maintenance.