Fig. 1

Changes in end-tidal CO₂, arterial and peripheral venous pH and PCO₂ (kPa, mmHg) in response to hyper- (a, b) and hypoventilation (c, d). Changes in end-tidal CO₂ (EtCO₂; black), arterial (red) and peripheral venous (blue) pH and PCO₂ plotted as a change from baseline (∆) in response to hyperventilation (a & b) and hypoventilation (c & d). Data presented as mean ± SD. Error bars (only one side shown) represent SD at that time point. Dotted black horizontal lines represent the widest LoAs of the variability at baseline in the arterial and peripheral venous blood for pH (a & c) and PCO₂ (b & d) in the respective graphs. *statistically significant with P < 0.05 when compared to baseline using a repeated measures ANOVA followed by a post-hoc test with Bonferroni’s correction