Figure 2.

P_ETCO₂ increases obtained with the modeling of end-tidal CO₂ samples. The group mean±SE change is displayed over representative traces of the four different manipulations. Left to right: PC and FI on the top, and BH and HV on the bottom. In each plot, the gray oscillating trace represents the continuous sampling of CO₂, and the black trace the model fitted to the P_ETCO₂ points. The horizontal dotted lines correspond to the spontaneously arising resting P_ETCO₂ in this subject. In the gas methods, the dashed traces connect the minimum of tidal PCO₂ points, indicating the inspired gas concentration.