Cardiorespiratory function after replacement of blood loss with hydroxyethyl starch 120, dextran-70, and Ringerʼs acetate in pigs

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Abstract
The small intestines of 20 anesthetized pigs weighing 12 to 17 kg were exteriorized in a saline-moistened gauze in order to simulate an intra-abdominal operation. During a 2-h period, 4% of the animals'' body weight was bled through an arterial cannula in six increments and replaced immediately with one of the following fluids: a) a new medium-MW hydroxyethyl starch (HES 120), b) dextran-70 (DEX), or c) Ringer''s acetate (RA). The amount of fluid infused was equal to the amount of blood withdrawn in the plasma substitute groups, but was increased four-fold in the RA group. Five nonbled pigs served as controls. No statistically significant changes occurred within the control group in any of the variables measured. One animal died of hypovolemic shock 3 h after RA administration. Bleeding and fluid infusion caused a 41% and 44% reduction in Hgb in the HES and DEX groups, respectively, while RA caused only a 25% reduction. A prompt increase in cardiac output was detected in animals receiving colloids (52% with HES), and cardiac output was maintained above initial values during the entire 5-h follow-up period. In the RA group, no increase in cardiac output occurred during fluid administration; during the follow-up period, cardiac output decreased consistently. Similarly, stroke volume and arterial pressures were best maintained with HES, but decreased after RA. Oxygen consumption and delivery were highest after HES and lowest in the RA group, where arteriovenous oxygen difference increased throughout the study. We conclude that both colloid solutions were superior to RA, which did not prevent hypovolemia or maintain adequate oxygen transport.