Hepatic ischemia-reperfusion injury (IRI) is a multifactorial phenomenon which has been associated with adverse clinical outcomes. IRI related tissue damage is characterized by various chronological events depending on the experimental model or clinical setting. Despite the fact that IRI research has been in the spotlight of scientific interest for over three decades with a significant and continuous increase in publication activity over the years and the large number of pharmacological and surgical therapeutic attempts introduced, not many of these strategies have made their way into everyday clinical practice. Furthermore, the pathomechanism of hepatic IRI has not been fully elucidated yet. In the complex process of the IRI, flow properties of blood are not neglectable. Hemorheological factors play an important role in determining tissue perfusion and orchestrating mechanical shear stress-dependent endothelial functions. Antioxidant and anti-inflammatory agents, ischemic conditioning protocols, dynamic organ preservation techniques may improve rheological properties of the post-reperfusion hepatic blood flow and target endothelial cells, exerting a potent protection against hepatic IRI. In this review paper we give a comprehensive overview of microcirculatory, rheological and molecular–pathophysiological aspects of hepatic circulation in the context of IRI and hepatoprotective approaches.

PURPOSE:The failure of small-caliber vascular grafts still means a serious problem. Concerning the early postoperative complications we aimed to investigate the hemostaseological and hemorheological aspects of this issue in a canine model. METHODS:In the Control group only anesthesia was induced. In the Grafted group under general anesthesia a 3.5-cm segment was resected unilaterally from the femoral artery and replaced with a PTFE graft (diameter: 3 mm). On the 1 st -3 rd -5 th -7 th and 14 th postoperative days the skin temperature of both hind limbs was measured, and blood sampling occurred for hematological, hemostaseological and hemorheological tests. RESULTS:The skin temperature of the operated versus intact limbs did not differ. In the Grafted group leukocyte count was elevated by the 1 st postoperative day, while platelet count increased over the entire follow-up period. Fibrinogen concentration rose on the 1 st -5 th days, activated partial thromboplastin time increased on the 3 rd -7 th days. Erythrocyte aggregation was enhanced significantly on the 1 st -5 th days. In specimens taken on the 14 th day, histologically we found matured thrombus narrowing the graft lumen. CONCLUSIONS:Small-caliber PTFE graft implantation into the femoral artery caused significant changes in several hemostaseological and hemorheological parameters. However, better clarifying the factors leading to early thrombosis of these grafts needs further studies.Key words: Vascular Grafting. Graft Occlusion, Vascular. Erythrocyte Aggregation. Blood Coagulation. Models, Animal. Dogs. Early postoperative changes in hematological, erythrocyte aggregation and blood coagulation parameters after unilateral implantation of polytetrafluoroethylene vascular graft in the femoral artery of beagle dogs

Previously we have investigated the cerulein-induced acute pancreatitis and provided data on its micro-rheological impact in the rat. We hypothesized that non-steroid anti-inflammatory agent flunixin, the xanthine-derivate pentoxifylline and the low molecular weight heparin enoxaparin may have various beneficial effects improving microcirculatory and rheological parameters. In female rats, under general anesthesia, 10 g/kg cerulein s.c. was administered and 2 hours afterwards microcirculation was tested by laser Doppler flowmetry on the tongue and after performing laparotomy on the small intestine, liver and pancreas prior to terminal blood sampling. From blood samples hematological parameters, blood pH, lactate concentration, erythrocyte deformability, osmoscan parameters and erythrocyte aggregation were tested. Compared to normal control in acute pancreatitis group we found severe deterioration in tissue microcirculation together with impaired erythrocyte deformability and enhanced aggregation, accompanied by acidic pH and increasing lactate concentration. Improvement was found when using flunixin (s.c.), pentoxifylline (i.p.) or enoxaparin (s.c.). These drugs could partly improve the blood flux on the surface of the investigated organs, and the flunixin had the most expressed improving effects on micro-rheological parameters. Surprisingly, the improving effect of pentoxifylline on micro-rheological parameters was not obvious (red blood cell deformability did not improved better than in the other treated groups), however, microcirculatory parameters improved.

PURPOSE:To examine how the ischemia-reperfusion injury of latissimus dorsi-cutaneous maximus (LDCM) musculocutaneous flap affects the microcirculatory (flap's skin surface) and hemorheological parameters, and whether an intraoperative deterioration would predictively suggest flap failure in the postoperative period. METHODS:Ten healthy male rats were subjected to the study. In Group I the left flap was sutured back after 2-hour, while the contralateral side was right after its elevation. In Group II the same technique was applied, but the pedicle of the left flap was atraumatically clamped for 2-hour. The contralateral side was left intact. On the flap skin surface laser Doppler tissue flowmetry measurements were done before and after and during the protocols applied in the groups. Microcirculatory and hemorheological examinations were done postoperatively. RESULTS:The microcirculatory parameters significantly decreased during immobilization and ischemia. Afterwards, all the regions showed normalization. In the retrospective analysis there was a prominent difference between the microcirculatory parameters of necrotic and survived flap during the early postoperative days (1-3) in Group II. Erythrocyte aggregation and deformability showed only slight differences.CONCLUSIONS: Two-hour ischemia and reperfusion caused deterioration in latissimus dorsi-cutaneous maximus flap microcirculation.Predicting the possible postoperative complication, the intraoperative laser Doppler measurement can be informative.

No abstract