RESUMEN
Liver oxygenation was studied with hemorrhagic hypotension and corrected using whole blood, a synthetic colloid (hydroxyethyl starch or hetastarch, HES; mol. wt. 120,000), or a crystalloid solution. Measurements were performed directly by recording pig liver tissue oxygen tension with an implanted silicone elastomer (Silastic) tube, and indirectly by calculating blood oxygen contributions. The direct method seems fairly reliable and accurately reflects different levels of bleeding and shock and their correction. Liver tissue oxygen tension (PlO2) may thus be used as an indicator of central organ response to shock management. PlO2 decreased during bleeding from 33.5 +/- 0.5 to 16.0 +/- 0.5 torr, and normalized rapidly after retransfusion. The baseline values were significantly exceeded after hetastarch infusion but were never reached with Ringer's solution. The correction of liver oxygen consumption was less complete after crystalloid infusion as well. On the other hand, the difference in liver oxygenation was less marked after crystalloid infusion and retransfusion, which restored perfusion to the baseline. The total amount of Ringer's solution needed to keep the animals hemodynamically stable during the 2-h follow-up period was four times higher than with hetastarch and some five times the blood volume shed. The cause of defective correction of liver oxygenation seems to be the poor response of liver blood flow to refilling in the Ringer group, in addition to apparent tissue edema after crystalloid infusion. According to our study, hemorrhagic hypotension related to liver oxygenation is more promptly and completely corrected with the colloid hydroxyethyl starch than with a crystalloid solution in the early phase of treatment.