| Objective To investigate the effect of different degree acute normovolemic hemodilution with 6% HES on the serum level of S-100B proteinum and cerebral oxygen metabolism under common temperature in rabbits.Methods Twenty-four major rabbits were randomly assigned to four groups (n=6): Group A was control group; HCT in Group B, C and D were targeted with 24%, 18% and 12% respectively. All animals were anaesthetized with intravenous 20% ethyl carbamate 5ml.kg-1 and mechanically ventilated(Vt =15ml kg-1, f=30 bpm) with body temperature maintained on 37oC. Left jugular artery and vein were cannulated for BP, blood gas analysis and blood sample collection, Right jugular vein was for CVP monitoring, Left femoral artery and vein were cannulated for hemodilution. Blood withdrawn from femoral artery was simultaneously replaced by intravenous infusion of equal volume of 6% HES until achieving targeted HCT. Blood gas, CERO2 and serum levels of S-100B proteinum were analyzed at 2 hours, 4 hours and 8 hours after hemodilution. Brain water content was examined using the"dry-wet weighing technique".Results There were no obvious difference in the serum level of S-100B proteinum, CERO2 and PHjv between Group A and B (P>0.05). Levels of S-100B proteinum and CERO2 raised while PHjv decreased significantly at 8 hours after hemodilution in group C (P<0.05); In group D, the levels of S-100B proteinum and CERO2 stepped up from 2 hours (T1) to 8 hours (T3) after hemodilution with lower PHjv (P<0.05). There were no significant difference in brain water content between all groups (P>0.05).Conclusion When targeted HCT with 24%, ANH do not disturb cerebral oxygen metabolism. If the targeted HCT is 18%, ANH can disturb cerebral oxygen metabolism at 8 hours after hemodilution. When the hemodilution for 12% target HCT is performed, all of the compensation mechanism can not sustain cerebral oxygen metabolism on common temperature and brain will be impaired. |
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