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Mechanisms of hemostasis. Effect on intracerebral hemorrhage.

Aspects of the mechanisms of hemostasis are reviewed with particular emphasis on the assembly of enzyme complexes on the membranes of cells. The way this membrane fixation of reactions accelerates coagulation, inhibition, and fibrinolytic systems is discussed. The complex nature of the hemostatic system and the multiple complications of its abnormalities present a difficult problem for the neurologist and neurosurgeon managing the patient with intracerebral hemorrhage. This is a situation in which close consultation and collaboration among the neurological and hematologic specialists are imperative to achieve the most favorable outcome for the patient with this life-threatening situation.

Anticoagulants↗

[The infrared contact coagulator for hemostasis in the renal parenchyma (author's transl)].

Investigations on hemostasis with the infrared contact coagulator (ICC) after renal pole resections in dogs with and without clamping of the renal vessels are reported. Clamping the renal vessels led to less bleeding, but the coagulation time was distinctly prolonged. In addition the use of ICC in renal pole amputations in humans is described in two cases of urogenital tuberculosis. In both cases we were able to stop the bleeding quickly and satisfactorily without clamping the renal vessels. The results of animal experiments and the significance of using the ICC in man are discussed.

Animals↗

Heparin coating of an extracorporeal circuit partly improves hemostasis after cardiopulmonary bypass.

Heparin coating of an extracorporeal circuit for cardiopulmonary bypass improves the hemocompatibility of the circuit and reduces the inflammatory response of the body. It has not been established, however, that heparin coating also improves postoperative hemostasis. We therefore performed a study in 30 patients who underwent a routine coronary artery bypass graft operation subjected to cardiopulmonary bypass with an uncoated (control) or a heparin-coated extracorporeal circuit (Duraflo II). We found significantly higher plasma levels of heparin in the Duraflo II group. However, we found no significant differences between the two groups with regard to other parameters of activation of the fibrinolytic and coagulation systems and to activation of platelets. Postoperative blood loss and donor blood transfusions were reduced in the Duraflo II group but not to a statistically significant extent. We conclude that heparin coating of an extracorporeal circuit improves anticoagulation but does not significantly reduce platelet activation, fibrinolysis, postoperative blood loss, and donor blood transfusions in routine coronary bypass operations.

Blood Loss, Surgical↗

Understanding thrombin and hemostasis.

Unlike other factors in blood coagulation and fibrinolysis, thrombin has several functions in hemostasis from injury to recovery. Because of continual consumption, thrombin generation controls prethrombotic thrombin functions and may be prevented by inactivation of its precursors or by inhibition of thrombin-mediated amplification steps. The direct activation product of prothrombin, alpha-thrombin, not only converts fibrinogen into clottable fibrin but also is actively incorporated into the forming thrombus, where it is protected and transformed into other or inactive forms with thrombus maturation. Larger protein inhibitors, such as antithrombin III, cannot penetrate the thrombus, whereas hirudin and small thrombin inhibitors can. Unique structural features of thrombin allow the design and synthesis of a variety of small inhibitors. Such small inhibitors may prevent rethrombosis upon lysis of immature thrombi. On the other hand, such intervention must be used with caution, because low levels of thrombin appear to promote wound healing. In this regard, the scars of healing are but manifestations of the many functions of thrombin.

Amino Acid Sequence↗

Analysis of hemostasis in horses with colic.

Eight tests of hemostasis were measured in 233 horses with colic. Blood samples were obtained at admission and for 4 consecutive days of hospitalization. Data were analyzed retrospectively by outcome, by broad-category diagnosis group, by small intestinal disorder, and by smaller categories for comparing specific diseases. Nonsurviving horses and horses with the most severe forms of intestinal ischemia had changes interpreted as hypercoagulative, the intensity of which was increased on the first and second mornings (sample times 2 and 3) after admission, when most significant differences for results of specific tests were detected. Nonsurvivors had decreased antithrombin III activity and prolonged prothrombin and activated partial thromboplastin times; those with strangulating obstructions also had decreased protein C and plasminogen activities. During hospitalization and with survival, these changes tended to reverse. In most horses, regardless of diagnosis or outcome, concentration of fibrin degradation products and fibrinogen, and alpha 2-antiplasmin activity increased over time. Whether these changes reflected specific effects of colic or of the acute-phase response was not determined. In comparisons of small intestinal disorders (proximal enteritis, strangulations, and impactions), diagnostically distinguishing features were not found. Likewise, in comparisons of specific diseases (small vs large intestinal impaction, proximal enteritis vs colitis, small vs large intestinal obstruction), diagnostically distinguishing features were not found.

Animals↗

Kinetic characterization of hemostasis in thermal injury.

Hemostasis has been characterized by kinetic measurements in 12 patients with severe burns. Survival and turnover of 51Cr-platelets, 131I-fibrinogen, and 125I-plasminogen were simultaneously measured in 10 patients within 24 hours of injury; the disappearance times were shortened in concert to approximately 20% of normal values, and platelet and fibrinogen turnover were increased to more than three times normal. Serial studies in five of these patients 3 and 5 weeks later showed progressive improvement in kinetic measurements ,but normal values were not achieved. Two additional patients with similar rates of consumption demonstrated localization of radiolabeled platelets and fibrinogen in the burn wound. Heparin therapy did not modify consumption significantly. Enhanced fibrinolysis was reflected by marked reduction in 125I-plasminogen survival, depletion of the plasma plasminogen levels, and elevated levels of fibrin degradation products. Initial low levels of platelets and fibrinogen were followed by compensatory elevations; factor V and prothrombin complex factors were depressed during the first five days, but factor VIII levels were not reduced. Thermal injury is characterized by marked and prolonged consumption within the wound of platelets, fibrinogen, and plasminogen that is not reversible by heparin. This process depletes hemostatic components and causes bleeding when the burn is massive or complications are severe.

Adolescent↗

[Markers of hemostasis and myocardial infarction in persons under 40 years of age].

Coronary disease before the age of 40 has special clinical and pathogenic features. The authors sought evidence of the existence of abnormalities of hemostasis markers in 39 patients aged under 40, several weeks after a myocardial infarction (MI). Blood samples were drawn a mean of 8 months after the MI. These laboratory studies included assay of C and S proteins, fibrinogen, clotting factors VII and VIII and antithrombin III, as well as detection of any possible circulating anticoagulant. Plasma levels of platelet factor 4 (PT4) and of beta-thromboglobulin (BTG) were measured in the same sample, enabling determination of the BTG/PF4 ratio. Only fibrinogen and plasma levels of platelet proteins were abnormal, revealing a significant difference between patients with multi-vessel disease and those with single vessel disease or free of severe angiographic lesions. Platelet activation appeared to persist some time after the MI, chiefly in patients with multi-vessel disease, and showing no relation to either age or treatment. Conclusions require prudence in view of difficulties in interpreting plasma assays of PF4 and of BTG.

Adult↗

Function and regulation of the beta 3 integrins in hemostasis and vascular biology.

The beta 3 integrins, alpha IIb beta 3 and alpha V beta 3, are prominently expressed on the surfaces of platelets and endothelial cells, respectively. This vascular localization places them in a strategic position to perform adhesive functions necessary for hemostasis, wound healing and angiogenesis. In addition, these integrins are now known to serve a signaling function, whereby environmental cues on either side of the plasma membrane can be transmitted across the membrane to the other side. Indeed, preliminary studies indicate that these dual function receptors are wired to other signaling pathways within platelets and endothelial cells, thus helping to explain how integrin-mediated cell anchorage can affect cytoskeletal organization and cell motility as well as endothelial cell growth, differentiation and apoptosis.

Animals↗

Hemostasis: a practical review of conservative and operative care.

Progress in the treatment of persons with hemophilia has improved quality of life and made surgical intervention in these patients possible. Optimum management should include a facility equipped with a special coagulation laboratory, a hematologist proficient in the management of coagulation disorders, a surgeon with experience operating on persons with a clotting disorder, and a blood bank with experienced personnel. Persons with inhibitors should undergo elective procedures only after consultation between surgeon and hematologist. Replacement of deficient factor protein by the intravenous infusion of factor concentrates allows normal hemostasis. The manufacture of factor concentrates includes purification and viral attenuation procedures to limit exposure to other proteins and decrease the risk of transmission of viral infection. These concentrates may be delivered by bolus intravenous infusion or as a continuous intravenous infusion which allows for less total units of factor to be administered. In patients with mild hemophilia A, intravenous or intranasal desmopressin acetate may be used to increase the Factor VIII: coagulant level and eliminate exposure to blood products. With careful perioperative management, patients with hemophilia may undergo surgery safely without excessive bleeding. In the future because of prophylactic therapy, the need for orthopaedic procedures may be decreased substantially.

Blood Coagulation Factors↗

[Heart surgery, cardiopulmonary bypass and inflammatory response. I. Changes in hemostasis and complement].

The use of cardiopulmonary bypass for surgical cardiac procedures is characterized by a whole-body inflammatory reaction due to the contact of blood through nonendothelialized surfaces; this stimulates the organism to recognize the cardiopulmonary bypass system as "nonself" and to activate specific (immune) and nonspecific (inflammatory) responses. These responses are then related with postoperative damage to many body systems, like pulmonary, renal or brain dysfunction, excessive bleeding and postoperative sepsis. In this paper, present knowledge on untoward responses of the patient to the use of cardiopulmonary bypass in cardiac surgery is reviewed and discussed, particularly focusing on the perturbation of the hemostasis and of the complement activation system.

Blood Coagulation↗

[Effect of age on hemostasis and plasma level of TXB2 and 6-keto-PGF1 alpha].

UNLABELLED: Hemostasis (HS) in 134 healthy subjects of over 20 years old was investigated. The cases with HS symptom were 45.5%, which increased with age. TXB2, 6-keto-PGF1 alpha and T/K ratio were measured by radioimmuno assay (RIA). RESULTS: elevation of TXB2 was more significant in the middle age and old age than in the young group (P < 0.01). But the level of 6-keto-PGF1 alpha in various age group didn't changed significantly; while the ratio between TXB2 and 6-keto-PGF1 alpha was more significant in the aged than in the young person (P < 0.01). The results revealed that there was hypercoagulable tendency with the increase of age, and it was correlated with TXB2 and 6-keto-PGF1 alpha. It is significant in theory and practice to prevent and cure the cardiovascular and cerebrovascular disease as well as HS with the traditional Chinese medicine.

6-Ketoprostaglandin F1 alpha↗

[Effectiveness of using gelatin sponge for hemostasis during treatment of acute iliofemoral venous thrombosis].

Patients with acute thrombosis of profound large veins of the lower limbs and pelvis (83) were administered anticoagulants of indirect action, heparin and thrombolytic drugs (fibrinolysin or thrombolytin), as a result of it all patients showed marked hypocoagulemia, contributing to increased blood loss during the operation and the development of hemorrhagic complications postoperatively. With the purpose of hemostasis gelatin sponge was employed in 47 operative interventions. The number of hemorrhagic complications, while using the sponge, was reliably decreased as compared with the group of patients (57) in whom the sponge was not employed.

Acute Disease↗

Activity alterations of chosen parameters of cord blood hemostasis in newborns from complicated pregnancies with premature ablation of placenta.

The study was carried out on 20 newborns with diagnosed premature ablation of placenta of 0,I,II clinical degree. In comparison to healthy newborns (n = 30) statistically significant differences were proved in: ATIII activity-48% (65%), plasminogen concentration-50% (63%), alpha 2antyplasmin activity 53% (67%); euglobulin clot fibrinolysis time 70 (95) min., and fibrinogen concentration 1.4 (1.8) g/l. The presented differences prove increased coagulation system activation in newborns from mothers with symptoms of premature ablation of placenta. Activity changes of hemostasis system in cases of premature ablation of placenta have the features of disorders accompanying intrauterine fetal anoxia.

Abruptio Placentae↗

[Hemostasis disorders after resection of liver and approaches to their prevention and correction].

Second- or third-degree dysfunction of hepatocytes was the most frequent (47.9%) disorder in the hemostasis system on the first-second days after extensive resection of the liver, whereas after economic resection this disorder was observed in only 5.5% patients. Intraoperative blood loss of more than 3 liters is fraught with hemorrhages and hepatorenal insufficiency in the postoperative period. Such blood loss is complicated by coagulopathic states presenting as 1) hepatocyte dysfunction of the second-third degree, 2) hypoxia and decreased production of blood clotting factors, and 3) variants of the DIC syndrome. Study of the genesis of postoperative coagulopathies after resection of the liver and development of pathogenetically-based methods of drug correction, together with introduction of novel instrumental methods affecting the intensity of local and total hemostatic reaction, helped reduce 2.5 to 3 times the total blood loss.

Adolescent↗

Altered hemostasis: considerations for dental care.

Patients with altered hemostatic ability present unique challenges for the provision of dental treatment. In this article, a review of normal hemostatic mechanisms is presented, as well as the pathophysiological processes underlying the more common abnormalities associated with altered hemostasis. The products available for managing these problems are reviewed, with a focus on how dental professionals can interact with their medical colleagues to prepare the patient for safe provision of all phases of dental therapy.

Blood Coagulation↗

[The therapeutic correction of disorders in thrombocyte-vascular hemostasis and of changes in the rheological properties of the blood in patients with arterial hypertension].

158 patients with essential hypertension received beta-adrenoblockers and were exposed to travelling impulse magnetic field, magnetolaser radiation. The study of platelet-vessel hemostasis and blood rheology revealed a relation of good clinical response and increased exercise tolerance with initial platelet dysfunction and rheological disorders which underwent positive changes in the course of treatment.

Adrenergic beta-Antagonists↗

Comprehensive study on platelet function, hemostasis, fibrinolysis, peripheral serotonergic system and serum lipids in nephrotic syndrome.

A comprehensive study on platelet aggregation, hemostasis, fibrinolysis and serum lipids in relation to peripheral serotonergic system has been performed on 41 nephrotic patients. Enhanced platelet aggregatory responses in both whole blood and in platelet rich plasma (PRP) were found upon stimulation with different agonists when compared to healthy volunteers. Increased levels of fibrinogen, fibrin monomers, and protein C activity were observed in nephrotic patients. Euglobulin clot lysis time was significantly prolonged in nephrotic patients. Activity of tissue plasminogen activator (tPA) inhibitor was higher in nephrotic syndrome, whereas tPA activity was significantly lower in these patients when compared to controls. Urokinase concentration, lipoprotein (a), cholesterol, LDL and VLDL levels were significantly higher in nephrotic patients over controls. Whole blood serotonin was significantly lower, whereas plasma serotonin was significantly higher in nephrotic patients relative to controls. Serotonin uptake and its release from platelets were markedly diminished in patients with nephrotic syndrome. Disequilibrium in the coagulolytic system, platelet hyperactivity, hyperfibrinogenemia, disturbances in peripheral serotonergic system together with lipid abnormalities may contribute to the progression and development of atherosclerosis and an enhanced risk of thromboembolic complications in nephrotic syndrome.

Adenosine Diphosphate↗

Hemostasis in aortic and cardiothoracic surgery.

Hemostasis abnormalities in cardiovascular and aortic surgery remain a major source of morbidity and mortality in patients undergoing such complex procedures. The need for frequent transfusions of red cell and other blood products increases risks and costs to patients and institutions providing patient care. Specifically in cardiovascular and aortic surgery, the nature of the surgery is, at best, semi-elective, and careful preparation to preserve the hemostatic mechanisms of the body is essential. Contact of blood with the extracorporeal circuit induces a hemorrhagic diathesis through a variety of different mechanisms. Dilution of the patient's blood volume by the extracorporeal circuit prime causes depletion of platelets and coagulation factor levels. Aorto intimal disease initiates fibrinolysis by the release of tissue plasminogen activator. Due to the numerous etiologies of bleeding, a combination of blood conservation strategies is suggested. The ideal combination of interventions has yet to be determined and is currently dependent on patient variables, physician and institutional practices, and economic pressures.

Aminocaproic Acid↗