Isquemia e reperfusão hepática total em condições de normalidade e sob estado de choque hemorrágico controlado: efeitos no sequestro de neutrófilos no rim do rato

Unfeasible experimental model of normothermic hepatic ischemia and reperfusion in rats using the Pringle maneuver

BACKGROUND

The negative result of a research does not always indicate failure, and when the data do not permit a proper conclusion, or are contrary to the initial project, should not simply be discarded and archived.

AIM

To report failure after performing experimental model of liver ischemia and reperfusion normothermic, continuous or intermittent, in small animals aiming at the study of biochemical and histological parameters after postoperative recovery.

METHODS

Fifteen Wistar rats were divided into three groups of five animals each; all underwent surgery, the abdomen was sutured after the proposed procedures for each group and the animals were observed for 6 h or until they died, and then were reoperated. In Group 1, control (sham-operated): dissection of the hepatic hilum was performed; in Group 2: clamping of the hepatic hilum for 30 m; in Group 3: clamping of the hepatic hilum for 15 m, reperfusion for 5 m and another 15 m of clamping. Data from Groups 2 and 3 were compared with Student's t test.

RESULTS

All animals of Group 1 survived for 6 h. Two animals in Group 2 died before the 6 h needed to validate the experiment; two did not recover from anesthesia and one survived until the end. In Group 3, four animals died before the 6 h established and one of them survived the required time. Only one animal in Group 2 and one in Group 3 survived and were able to accomplish the study. There was no statistical significance when the results of Groups 2 and 3 were compared (p>0.05).

CONCLUSION

The death of six animals before the necessary period of observation turned the initial proposal of the experiment unfeasible.

Animal models for trauma research: what are the options?

Even if trauma patients initially avoid death after trauma (due to massive blood volume loss, primary severe brain injury), they are still at risk for multiple organ failure. Thus, it is crucial to elucidate the underlying pathophysiological mechanisms of trauma/hemorrhagic shock and the immune response involved. As of now, many hemorrhagic shock/trauma studies have used various types of animal models. Despite a large number of results from these efforts, some authors have argued that animal model results are difficult to translate directly into the clinical scenario. This review summarizes the advantages and the disadvantages of using animal models in trauma/hemorrhagic shock studies and discusses the relevance of various animal studies to the clinical scenario.

Total hepatic ischemia and reperfusion after state controlled hemorrhagic shock, with used of different solutions: effects of neutrophils sequestration in kidney of rats

PURPOSE: To evaluate and compare neutrophils sequestration in the renal cortex of rats, result of total hepatic ischemia and reperfusion after controlled hemorrhagic shock, with use of different electrolytic solutions. METHODS: Used 18 rats Wistar, males, adult, divided into three groups as the solution used to reanimation: Group PSS: physiologic saline solution; Group HSS: hypertonic saline hypertonic (7,5%) followed by lactated ringer's solution; Group LRS: lactated ringer's solution. All the animals were submitted to the bleeding controlled until mean arterial pressure (MAP) 40 mmHg, for 20 minutes. Performed volemic replacement until PAM=80 mmHg with the solution according the studied group, followed by laparotomy and Pringle's Maneuver for 15 minutes. The animals were accompanied until for two hours. To statistical comparisons between mean of neutrophils sequestration, in interstitium of the renal cortex, were made the tests One-way ANOVA and covariance analysis, adjusting itself for time of supervened. The hemodynamic parameters evaluated were: MAP, heat rate, cardiac index, vascular resistance system index. The analyzed metabolic variables were: pH, bicarbonate, base deficit and lactato, besides electrolytes. RESULTS: The mean values of supervened, in minutes, for group were: Group PSS 79,0±12,0; Group LRS 97,0±11,0; Group HSS 67,0±10. The mean values of neutrophils/field in the renal cortex were: Group PSS 0,55±0,68; Group LRS 1,68±0,53; Group HSS 1,33±0,43. When adjusted for time of supervened: Group PSS 0,55; Group LRS 1,62; Group HSS 1,39. There was statistically significant difference in neutrophils sequestration, between Group PSS regarding the others groups, using itself or not the adjustment by time of supervened (p=0,016 and p=0,0128). CONCLUSION: Both critical situations in this model, controlled hemorrhagic shock followed by Pringle's maneuver, promoted neutrophils sequestration in the interstitium renal of rat, and the physiologic saline solution demonstrated minor mean, differentiating statistically of the others solutions.