Fig. 1

Mainstream monitoring using the novel method. An illustration of the NPPV cap ONE mask ® used in this study. The capnometer was calibrated in terms of the P_ETCO₂ reading before each use of the NKV 330 ventilator (Nihon Kohden Tokyo, Japan). In addition, the mainstream P_ETCO₂ sensor has a special anti-fog film on the specimen window, which guarantees accurate measurements for 72 h