Platelet aggregation during abdominal surgery in an experimental pig model: The effects of presurgical antibiotic protocols and volume replacement with hydroxyethyl starch

The effect of presurgical antibiotic protocols in combination with hemodilu tion on platelet aggregation was studied. Thirty pigs were randomly assigne d to three groups. Group 1 received amoxicillin/clavulanic acid, group 2 me tronidazole+ cefuroxime, and group 3, as a control, sodium chloride. They u nderwent laparotomy, massive blood loss, and volume replacement with hydrox yethyl starch 200, followed by an anaphylactoid reaction. Platelet aggregat ion was measured by the turbidometric method. Neither antibiotic protocols had any effect on platelet aggregation as compared with the control group. In all three groups, aggregation to ADP and collagen was significantly redu ced after volume replacement with hydroxyethyl starch. In contrast, the sen sitivity to the aggregating effects of collagen was increased as assessed b y a higher frequency of responses to low concentrations of collagen and a s hortened latency of the aggregation response after collagen addition. Furth er in vitro studies revealed that dilution of plasma with hydroxyethyl star ch specifically induced the changes seen after in vivo volume replacement. The results suggest that the plasma substitute hydroxyethyl starch 200 incr eases the sensitivity to low doses of collagen, an effect never described b efore and considered of clinical relevance. (C) 2000 Elsevier Science Ltd. All rights reserved.