Blood gas analyses
The pH level was maintained above 7.35 in the HbV and RBC/PPP groups via
respiratory compensation throughout the experiment, whereas the pH level
in the HES group was significantly decreased below 7.35 at 45 and 60 min
owing to a lack of haemoglobin (p <0.01) (Figure 3C).
There were no significant differences in the base excess levels, the
values of PaO2 and PaCO2 among all
groups throughout the experiment, indicating that the respiratory
function of the animals was well-preserved throughout the experiment
(Figure 3D, Figure S2A, B). During the initial 30 min, the
CtO2 (i.e. the sum of oxygen bound to haemoglobin)
decreased to approximately 6.5 vol% in all the three groups. RBC
transfusion or HbV infusion restored the CtO2 to 7.0-8.0
vol% in the RBC/PPP and HbV groups. In contrast, the
CtO2 decreased to unmeasurable values at 60 min in the
HES group (Figure 3E). Hence, lactate levels were maintained at
approximately 3.0 mmol/L throughout the experiment in the HbV and
RBC/PPP groups, whereas the lactate level in the HES group critically
increased to 6 mmol/L at 60 min, which was significantly higher than
that in the other groups (p <0.05) (Figure 3F). At the
end of the experiment, the HCO3- level
was higher in RBC/PPP group than in the other groups
(p <0.05) (Figure S2C).