The effect of Sulphated cellulose on System of Haemostasis

Experimental studies and analyses of new compounds with different mechanisms of action on systemic haemostasis are relevant for the identification and development of potential pharmacological preparations. The modified sulphated polysaccharides with anticoagulant and antithrombin activity were studied for haemostasis. Platelet-rich plasma was obtained by centrifugation at 200g for 10 minutes. The remaining citrate blood was further centrifuged at 1500g for 10 min to obtain platelet-poor plasma. The antithrombin activity of the compounds was evaluated In vitro by their effect on the recalcification time, thrombin and prothrombin time of rabbit and human blood plasma stabilized with a 3.8% sodium citrate solution in the ratio 9:1. The results showed that the anticoagulant activity of the studied sulphates increased with an increasing degree of sulphation. Sulphated polysaccharides showed strong anticoagulant activity In vitro. The experimental results showed a significant increase in the coagulation time of blood plasma in tests for prothrombin and thrombin time. These properties of these components are of particular interest, and further detailed studies of the physicochemical characteristics and mechanisms of action of these molecules should be performed, which will eventually allow them to be used as heparin-like drugs.

Off Target: Case Report of Heparin Resistance in a Neurosurgical Intensive Care Unit Patient

Introduction Heparin resistance was discovered in a patient in the surgical intensive care unit who underwent emergency endovascular coiling and later an anterior communicating artery clipping procedure to treat subarachnoid hemorrhage due to rupture of an anterior communicating artery aneurysm. Clinical Findings On intensive care unit day 17/postoperative day 3, the patient experienced shortness of breath, persistent tachycardia, and hypoxia. Bilateral pulmonary emboli, a saddle embolus, and lower-extremity and upper-extremity deep vein thrombi were diagnosed. The patient received high-dose unfractionated heparin (>35 000 U/24 h), and activated partial thromboplastin times remained subtherapeutic over the next 72 hours. Diagnosis Factor VIII activity, fibrinogen, antithrombin activity, antithrombin antigen, and platelet factor 4 were measured. The results demonstrated an increase in factor VIII activity to 342% (reference range, 50%-200%), elevated fibrinogen level of 441 mg/dL (reference range, 200-400 mg/dL), antithrombin antigen level of 92% (reference range, 80%-130%), elevated antithrombin activity of 108% (reference range, 80%-100%), and negative platelet factor 4 result, indicating that the patient did not have heparin-induced thrombocytopenia and confirming the diagnosis of heparin resistance. Conclusions Risk factors for heparin resistance include antithrombin deficiency, elevation of factor VIII or fibrinogen level, elevation in heparin-binding proteins, increased heparin clearance, sepsis, trauma, and burns. The astute critical care nurse may be the first to recognize this condition in a patient, preventing a potentially fatal complication.

Decreased antithrombin activity and inflammation in cats

Objectives The objective of this study was to determine if inflammatory markers are associated with antithrombin activity in cats. Methods For a retrospective population of 231 cats admitted to a referral hospital, antithrombin activity was classified as decreased (n = 77), intermediate (n = 97) or in the upper quartile (n = 57). Odds ratios (ORs) were calculated for an association between decreased or upper quartile activity and hypoalbuminemia, hyperfibrinogenemia, band neutrophilia and toxic change. Multiple logistic regression was performed to determine if an association between band neutrophilia and decreased antithrombin activity was independent of decreased hepatic synthesis, consumptive coagulopathy or protein loss. Results Cats with decreased antithrombin activity were more likely than cats with intermediate-to-upper quartile activity to have band neutrophilia (OR 2.85; P = 0.0050), hypoalbuminemia (OR 12.1, P <0.0001) or toxic neutrophils (OR 4.47, P <0.0001). Cats with antithrombin activity in the upper quartile were less likely than those with intermediate-to-low activity to have hypoalbuminemia (OR 0.31, P = 0.0023) or toxic neutrophils (OR 0.44, P = 0.033). In a regression model that included other mechanisms for decreased antithrombin, band neutrophilia remained associated with decreased antithrombin activity (adjusted OR 2.62, P = 0.013). Conclusions and relevance Contrary to previous studies suggesting antithrombin is a feline positive acute phase protein, this study demonstrates an association between decreased antithrombin activity and inflammation. Further studies are needed to determine the mechanistic basis of this association.

Effect of antithrombin in fresh frozen plasma on hemostasis after cardiopulmonary bypass surgery

Introduction: Supplementation of fresh frozen plasma immediately after cardiopulmonary bypass is an effective method to enhance clotting ability as coagulation factors are consumed in the extracorporeal circuit during cardiopulmonary bypass. On the other hand, the anticoagulation factors in fresh frozen plasma can also deter the clotting ability. This study investigated the effect of fresh frozen plasma administration on the comprehensive clotting ability following cardiopulmonary bypass. Methods: This prospective observational study included 22 patients scheduled for cardiac surgery. Clotting times and maximum clot firmness were evaluated using the types of rotational thromboelastometry, intrinsic rotational thromboelastometry, and heparinase thromboelastography preoperatively, immediately after cardiopulmonary bypass, and 1 hour after cardiopulmonary bypass. Activated clotting time, antithrombin activity, and heparin concentration were also measured at these time-points. Results: Antithrombin activity (62.9 ± 7.2% vs. 51.1 ± 7.4%, p < 0.0001) and activated clotting time (132.6 ± 9.6% vs. 120.0 ± 9.0%, p < 0.001) were significantly higher 1 hour after cardiopulmonary bypass compared to measurements taken immediately after cardiopulmonary bypass. Heparin concentration 1 hour after cardiopulmonary bypass was significantly decreased compared to that immediately after cardiopulmonary bypass. On the other hand, maximum clot firmness determined via intrinsic rotational thromboelastometry was significantly greater 1 hour after cardiopulmonary bypass (53.8 ± 4.8 mm) than that immediately after cardiopulmonary bypass (49.5 ± 4.8 mm). Clotting time determined via intrinsic rotational thromboelastometry and heparinase thromboelastography was also significantly shorter 1 hour after cardiopulmonary bypass than that immediately after cardiopulmonary bypass. Conclusion: Fresh frozen plasma administration increased antithrombin activity and caused activated clotting time prolongation, but then increased clotting ability. Thus, testing by rotational thromboelastometry after cardiopulmonary bypass could be valuable in the detection of comprehensive clotting ability.

The Effect of Direct Oral Anticoagulants on Antithrombin Activity Testing Is Abolished by DOAC-Stop in Venous Thromboembolism Patients

Context.— Direct oral anticoagulants (DOACs) may cause false negative results of antithrombin (AT) deficiency screening. Objective.— To evaluate the impact of DOAC-Stop, an agent reversing in vitro effects of DOACs, on AT testing in anticoagulated patients. Design.— We assessed 130 venous thromboembolism patients aged 46.7 ± 13.5 years. Blood samples were collected 2 to 27 hours after DOAC intake from 49 patients on rivaroxaban, 54 on apixaban, and 27 on dabigatran. Antithrombin activity was assessed using the activated factor X (FXa)–based and the activated factor II (FIIa)–based method twice, before and after DOAC-Stop treatment, together with plasma DOAC levels using coagulometric assays. Results.— The use of DOAC-Stop did not influence AT activity measured using the FIIa-based assay, whereas there was a marked decrease in AT activity determined using the FXa-based assay (ΔAT = 16.9%; 95% CI, 12.9%–19.1%). The AT-FIIa assay revealed decreased AT level (&lt;79%) in all 10 (7.7%) genetically confirmed AT-deficient patients treated with rivaroxaban or apixaban (n = 5 each), whereas the AT-FXa assay showed decreased AT activity (&lt;83%) in 2 subjects on rivaroxaban and 1 on apixaban with low plasma DOAC concentrations (&lt;90 ng/mL). After DOAC-Stop median AT-FXa activity lowered from 83.5% (interquartile range, 66%–143%) to 65.5% (interquartile range, 57%–75%; P = .005; ΔAT = 18%) in AT-deficient patients, without any false negative results. The ΔAT in the FXa-based assay correlated with rivaroxaban and apixaban concentrations in the AT-deficient patients (r = 0.99, P &lt; .001). Conclusions.— Application of DOAC-Stop enables reliable evaluation of AT deficiency screening in patients taking rivaroxaban or apixaban and tested using the FXa-based method.

Plasmapheresis for the Treatment of Iatrogenic Antithrombin Excess as a Result of Spuriously Low Antithrombin Activity Measurements

We report an intensive care patient who was given excessive amounts of antithrombin concentrate in response to spuriously low antithrombin activity measurements and was then treated with plasmapheresis (therapeutic plasma exchange or TPE) to remove the excess.