Fig. 2. Effects of hypoxia (F_IO2=fraction of oxygen in the inspired air) on acid—base status before and after reducing haematocrit (filled and unfilled circles, respectively). (A) Arterial pH (pHa); (B) plasma bicarbonate concentration; (C) arterial carbon dioxide tension (Pa_CO2; 1 mm Hg=133.3 Pa) and (D) Davenport diagram. In the Davenport diagram, an in vitro buffer line previously determined by Andersen et al. (2001) is shown as a dotted line, and isobars for carbon dioxide tension have been added (grey lines). Significant effects of hypoxia within each of the two groups (normal and low haematocrit, respectively) are marked with an asterisk, and significant differences between the groups are marked with a dagger. Data are presented as means ± 1 S.E.M. (N=6).