Hendrickx et al. [66] also showed similar results when studying the sevoflurane concentration installed in the evaporation flask in LFA 0.5 and 1 L / min to maintain Et sevoflurane in operation 1.3%. Their reuslts showed that sevoflurane in evaporation flask in group 0.5 L / min was significantly higher than that in group 1 L / min with p <0.05 (2.8% and 2%).