hirudin and Shock--Septic

Incidence of deep vein thrombosis in critically ill patients depends on the underlying disease but may be as high as 60%. The Surviving Sepsis Campaign clearly recommends administering anticoagulation in the absence of specific contraindications in patients with severe sepsis or septic shock. The article discusses risk factor for thromboembolic events in critical illness as well as means of non-pharmacologic and pharmacologic thrombosis prophylaxis. Peripheral vasoconstriction, edema, shock, and administration of catecholamines may reduce the bioavailability and efficacy of subcutaneous administration of low molecular weight heparin. This article further elaborates on the problem and pathophysiology of heparin resistance. Continuous intravenous administration of new anticoagulants may be a promising alternative to indirect anticoagulants. Severity of illness and SAPS II-score determine dosing of the direct thrombin inhibitor argatroban which needs to be about 10-times lower than in patients without critical illness.

Topics: Anticoagulants; Arginine; Biological Availability; Chromosome Breakage; Chromosome Disorders; Critical Care; Dose-Response Relationship, Drug; Drug Resistance; Heparin; Heparin, Low-Molecular-Weight; Hirudins; Humans; Infusions, Intravenous; Injections, Subcutaneous; Pipecolic Acids; Recombinant Proteins; Risk Factors; Sepsis; Severity of Illness Index; Shock, Septic; Sulfonamides; Thrombin; Thrombocytopenia; Venous Thrombosis

We evaluated the endothelin-1 (ET-1) and thrombin involvement in cardiovascular and respiratory dysfunction during endotoxic shock in 18 anaesthetized, mechanically ventilated pigs, divided into three groups. Group 1 was pre-treated only with lipopolysaccharide (LPS), group 2 was treated with lepirudin, a thrombin inhibitor, group 3 was pre-treated with bosentan, a dual inhibitor of ET-1 receptors. Results show that LPS caused systemic hypotension, pulmonary biphasic hypertension, increase in lung resistances (R(L)) and decrease in compliance (C(L)). Lepirudin partially reduced the LPS-dependent pulmonary hypertension, without affecting the changes in C(L) and R(L). On the contrary, bosentan completely abolished the pulmonary hypertension and the changes inC(L) and R(L), and worsened the LPS-dependent systemic hypotension. Our results show that ET-1 is largely responsible for pulmonary derangement due to endotoxic shock; at bronchial level, the ET-1 release seems due only to LPS, while, at pulmonary vascular level, it results also from LPS-dependent thrombin activation.

Topics: Animals; Antihypertensive Agents; Bosentan; Cardiovascular System; Endothelin-1; Female; Fibrinolytic Agents; Hemodynamics; Hirudins; Lipopolysaccharides; Lung; Male; Recombinant Proteins; Respiratory System; Shock, Septic; Sulfonamides; Swine; Thrombin; Time Factors

Previous work has shown that pre-treatment with the thrombin inhibitor recombinant desulfato-hirudin prevented fibrin formation and respiratory dysfunction in porcine lipopolysaccharide shock. We examined the effects of delayed administration of recombinant desulfato-hirudin in bacterial lipopolysaccharide shock. Miniature pigs were studied under anaesthesia and ventilation, and received a bacterial lipopolysaccharide infusion (2 microg/kg/h) for 7 h; recombinant desulfato-hirudin was started 1 h after bacterial lipopolysaccharide in 10 animals (bolus 12.9 nmol/kg; continuous infusion 6.5 nmol/ kg/h); 10 randomised control animals received saline instead of recombinant desulfato-hirudin. Fibrin and thrombin-antithrombin complex levels in plasma were significantly lower in bacterial lipopolysaccharide+recombinant desulfato-hirudin animals than in controls. Both groups displayed a similar rise in pulmonary vascular resistance and other parameters of lung dysfunction; only lung tissue wet/dry ratio was lower in recombinant desulfato-hirudin-treated than in control animals. Both groups had similar circulatory alterations. Recombinant desulfato-hirudin interrupted coagulation activation during ongoing bacterial lipopolysaccharide-induced shock in pigs even when administered with a delay of one hour after start of the bacterial lipopolysaccharide infusion. A protective effect of delayed recombinant desulfato-hirudin administration on bacterial lipopolysaccharide-induced acute lung injury and alterations in the systemic circulation could not be demonstrated in this experiment.

Topics: Animals; Ascites; Cardiovascular System; Fibrin; Fibrinolytic Agents; Hirudin Therapy; Hirudins; Kidney; Lipopolysaccharides; Lung; Peritoneal Cavity; Recombinant Proteins; Shock, Septic; Swine; Swine, Miniature; Time Factors

Hirulog is a thrombin catalytic site inhibitor which exhibits specificity for the anionic binding exosite of alpha thrombin. Here, we have evaluated the effect of Hirulog (1, 5 and 10 mg/kg, 30 min pretreatment) in a rat model of endotoxemia. Intravenous injection of lipopolysaccharide from E. coli (25 mg/kg; serotype 0127:B8) caused decreases in blood pressure which were significantly reduced (about 60%) in animals pretreated with Hirulog. Rat survival to endotoxin was significantly increased in Hirulog pretreated group (5 and 10 mg/kg) up to 24 hours. Hirulog at the dose of 10 mg/kg inhibited both endotoxin-induced leukopenia at 30 and 60 minute points and thrombocytopenia at 30 minute point but not at 90 and 120 minute points. Fibrinogen levels were significantly reduced after 2 hours following endotoxin administration. Pretreatment with Hirulog (5-10 mg/kg i.v.) 30 min prior to administration of endotoxin prevented changes in fibrinogen plasma levels. These results demonstrate that Hirulog-induced inhibition of thrombin is effective in reducing toxic and lethal effects of endotoxin.

Topics: Animals; Antithrombins; Evaluation Studies as Topic; Fibrinogen; Hirudins; Hypotension; Leukopenia; Lipopolysaccharides; Male; Peptide Fragments; Rats; Rats, Wistar; Recombinant Proteins; Shock, Septic; Thrombin; Thrombocytopenia; Toxemia

1. Hypotension and vascular hyporesponsiveness to vasoconstrictors are observed during endotoxic shock, and are associated with increased production of nitric oxide in the vascular wall. Disseminated intravascular coagulation is another feature of septicaemia. We hypothesized that thrombin generated during disseminated intravascular coagulation might modulate the changes in vascular tone induced by endotoxin. 2. Incubation of rat aortic rings for 4 h with alpha-thrombin (0.003-3.0 NIH units/ml) did not change their reactivity to noradrenaline. Incubation for 4 h with lipopolysaccharide increased the EC50 for noradrenaline, whereas co-incubation of thrombin (0.5 NIH units/ml) with lipopolysaccharide did not alter this hyporeactivity to noradrenaline. 3. In vivo in rats, lipopolysaccharide caused early (1 h) and late (4-6 h) hyporeactivity to noradrenaline. In rats infused with lipopolysaccharide and heparin (1 U min-1 kg-1, 0.4 ml/h) or hirudin (2.2 mg ml-1 kg-1, 0.8 ml/h), vasopressor responses to noradrenaline were not different from those after infusion of lipopolysaccharide alone. Aortic rings taken from rats receiving both anticoagulant treatment and lipopolysaccharide had the same sensitivity to noradrenaline as those obtained from rats receiving lipopolysaccharide alone. 4. Our results suggest that, in vivo, disseminated intravascular coagulation does not modify the early and late effects of lipopolysaccharide on arterial pressure and that, in vitro, thrombin neither induces hyporeactivity to noradrenaline nor modifies lipopolysaccharide-induced hyporeactivity. We propose that thrombin generated during disseminated intravascular coagulation in rats does not play a major role in the alterations of vascular tone observed during endotoxic shock.

Topics: Animals; Aorta; Disseminated Intravascular Coagulation; Heparin; Hirudins; In Vitro Techniques; Lipopolysaccharides; Male; Norepinephrine; Rats; Rats, Wistar; Shock, Septic; Thrombin; Vascular Resistance; Vasoconstriction

Reproducible disseminated intravascular coagulation in rabbits was provoked by two intravenous injections 24 hours apart of endotoxin from Salmonella enteritidis. There were mild symptoms of DIC before the second injection which considerably increased thereafter. In detail there was a sharp drop of the platelet count and a considerable diminution of Antithrombin III, of Protein C, Plasminogen and Antiplasmin as well as an appearance of fibrin monomer complexes and an increase of the aPTT. When PEG-hirudin in a single dose of 1 mg/kg BW was given simultaneously with the second injection of endotoxin the following alterations were observed: The drop of the platelet count and of the activities of Antithrombin III, Protein C, Plasminogen and Antiplasmin was significantly less pronounced. The fibrin monomer complexes were lower and the aPTT was less prolonged. The thrombin time, however, as a sign of a direct action of hirudin on thrombin was considerably more prolonged than in the controls. The combined effect of these alterations strongly points in the direction of a favourable influence of PEG-hirudin on the course of DIC. It is of special interest that 6 h after the intravenous injection of PEG-hirudin its full effect on the thrombin time was still detectable. This is apparently due to a longer half-life in circulation of PEG-hirudin than of natural hirudin.

Topics: Animals; Bacterial Toxins; Blood Coagulation Factors; Delayed-Action Preparations; Disseminated Intravascular Coagulation; Endotoxins; Half-Life; Hirudin Therapy; Hirudins; Lipopolysaccharides; Male; Microcirculation; Polyethylene Glycols; Rabbits; Recombinant Proteins; Shock, Septic

Endotoxin shock and contact system activation were used to study effects of hirudin, antithrombin III, eglin C, aprotinin, and [Arg15]-aprotinin in anesthetized pigs. Alterations in the systemic and pulmonary circulation were in part prevented by administration of the inhibitors.

Topics: Animals; Aprotinin; Dextran Sulfate; Hirudin Therapy; Hirudins; Lipopolysaccharides; Protease Inhibitors; Proteins; Recombinant Proteins; Serine Proteinase Inhibitors; Serpins; Shock, Septic; Swine; Swine, Miniature

An enzyme-linked immunosorbent assay (ELISA) was developed for the determination of the thrombin-hirudin complex (TH) in plasma. The test is based on the sandwich principle and uses appropriate antibodies which selectively bind the corresponding moieties of the complex. The assay was calibrated by adding performed TH to normal human citrated plasma. The detection limit of the assay was 1.2 ng/ml. Mean coefficients of variation of 6.0% (intra-assay) and 6.4% (inter-assay) were found. The presence of TH was demonstrated in normal human plasma that was spiked with hirudin and subsequently activated in vitro by calcium-thromboplastin to generate thrombin. This complex was also found in plasma samples from pigs which had been treated with hirudin during experimentally induced septicaemia.

Topics: Animals; Antithrombin III; Enzyme-Linked Immunosorbent Assay; Hirudin Therapy; Hirudins; Humans; Peptide Hydrolases; Shock, Septic; Swine; Thrombin