Fig. 5. Representative data acquisition traces illustrating the lack of correspondence between changes in arterial P_CO2 (Pa_CO2; red trace, A), and those in ventilation, presented as the raw impedance trace (grey, B) overlain by the calculated ventilation amplitude (V_AMP) trace (black line, B). Rather, as the yellow area emphasizes, ventilation tracked changes in water P_CO2 (Pw_CO2; black line, B).