Fig. 1
From: Laryngeal mask versus facemask in the respiratory management during catheter ablation
a and b Representative capnography waveforms obtained from an enrolled patient in this study. The expiratory phase was divided into 0, I, II, and III phases. The respiratory interval is defined by the distance between adjacent points of end-tidal CO2 (ETCO2). The interval between adjacent ETCO2 values is defined as respiratory interval. c: Representative capnography waveforms (blue lines) and their differential CO2 curves (magenta lines) obtained from an enrolled patient in this study. The differential CO2 curve was constructed, and the local maximum and minimum values were calculated where the respiratory intervals, and expiratory and inspiratory durations could be easily identified and calculated