La influencia de la administración de solución de lactato de Ringer o HES 130 / 0,4 en la integridad de la mucosa del intestino delgado en un modelo porcino de hemorragia controlada

Résumé

Perioperative and/or intraoperative hypovolaemia occur frequently in both human and veterinary critical care medicine and may lead to intestinal hypoperfusion. Intestinal hypoperfusion, in its turn, is associated with increased morbidity. Little is known about the effects of different intravenous solutions that may be used in the attempt to restore the volaemia and tissue perfusion, on the integrity of the intestinal mucosa in this clinical situation and whether some with would be associated with decreased damage of the intestinal mucosa. This study analysed the effect of two physiological solutions, Ringer’s lactate and hydroxyethyl starch (HES) 130/0.4, on the small intestinal mucosa in pigs under general anaesthesia submitted to severe acute bleeding. Twenty-eight healthy Large White pigs, with three months of age, were submitted to severe acute bleeding (30 ml/kg) under total intravenous anaesthesia with propofol and remifentanil. Pigs were randomly allocated in three groups: Group 1 (n=11) received Ringer Lactate solution (25ml/kg) after bleeding; Group 2 (n=11) received HES 130/0.4 solution (20ml/kg) after bleeding; animals in Group 3 (n=6) did not undergo bleeding or volume replacement. All pigs were euthanised with intravenous KCl after the study and the small intestine was collected for histopathological analysis. Small intestinal oedema, congestion, hyperaemia, haemorrhage, inflammatory infiltration, cellular degeneration, necrosis, and epithelial detachment were evaluated and classified. Mucosal loss percentage (%ML) and crypt:interstitium ratio (C:I) were also analysed. In addition, apoptotic events were investigated by performing immunohistochemistry using Cytochrome c antibody, TUNEL method and M30Cytodeath immunofluorescence assay. The results of this study suggest that, in a situation of controlled haemorrhage, HES 130/0.4 can minimize the percentage of mucosal loss on the small intestine, when compared with Ringer Lactate solution, when used for volume replacement. Data in our study also suggest that the duodenum may be the small intestine segment most sensitive to hypovolaemia caused by severe bleeding. Hyperaemia in the small intestine was significantly higher with HES 130/0.4 compared to Ringer Lactate; this suggests that HES130/0.4 administration may more efficiently restore intestinal perfusion and therefore be associated with decreased %ML. Despite the very significant differences in histopathology for the %ML, the immunohistochemical methods used to evaluate apoptotic events in the small intestine epithelium (cytochrome c antibody, TUNEL method and M30Cytodeath immunofluorescence assays, revealed no significant differences in the percentage of apoptosis between groups.