Monitoring of Low Molecular Weight Heparin Thromboprophylaxis with Alternative Methods to Anti-Factor Xa

Introduction: Initiating low molecular weight heparin (LMWH) thromboprophylaxis too early in patients with traumatic braininjury increases the risk of intracranial bleeding. Therefore, it is important to monitor LMWH and asses when it is safe to initiate.The aim of this research was to study alternative monitoring methods for LMWH than the standard method anti-factor Xa (antiFXa), and to investigate the peak anti-FXa level. We hoped to answer “How do rotational thromboelastometry (ROTEM) andSonoclot change at different LMWH concentrations added in vitro to blood from intensive care patients? How do point of careparameters change after subcutaneous LMWH administration on healthy volunteers with consecutive measurements to catch thepeak effect?”.Methods: Different concentrations of enoxaparin were added in vitro to citrated whole blood from fifteen intensive care patients.The first ten patients’ coagulation was analysed with ROTEM using the INTEM and NATEM assays, and the last five withSonoclot with a kaolin activator and ROTEM INTEM. Previously collected data was used from nine healthy volunteers that hadreceived subcutaneous enoxaparin. Citrated blood samples were collected before and after LMWH initiation and analysed withSonoclot kaolin and a chromogenic anti-FXa-assay. Friedman test, Dunn’s multiple comparison test and Spearman’s correlationtest were performed.Results: ROTEM INTEM CT, CFT, A10 and MCF were significantly affected with increasing in vitro enoxaparin from 0.4anti-FXa concentration. ROTEM NATEM CT was also prolonged at this LMWH concentration. Sonoclot’s parameters didn’tsignificantly change with increasing in vitro enoxaparin. The peak of in vivo LMWH was reached after 2 to 4 hours with avariation of peak anti-FXa between 0.3-0.5 IU/mL.Conclusions: ROTEM INTEM CT performed best and was prolonged at anti-FXa from 0.4-0.6 IU/mL. ROTEM INTEM shouldbe tested in neurointensive care to increase the safety of LMWH thromboprophylaxis and possibly to individualize the dosage

Dose-response effects of omega-3 on platelet aggregation: an observational study

ObjectiveThis study aimed to evaluate the dose-response effects of supplemental omega-3 fatty acids on platelet function in healthy volunteers.MethodsTwelve healthy volunteers ingested a normal supplemental dose of 1260 mg omega-3 fatty acids daily for 5 days, followed by a high dose of 2520 mg daily for another 5 days. Multiple electrode aggregometry (MEA) with four different agonists was used to measure platelet aggregation before and after the normal- and high-dose regimes. In vitro spiking using physiological doses of omega-3 fatty acids was also performed to determine whether MEA is capable of detecting a platelet-inhibiting effect due to omega-3 fatty acids.ResultsThere were no differences in platelet aggregation measured by the MEA assay in healthy volunteers after intake of either the normal or high dose of omega-3 fatty acids. In the in vitro experiment, a platelet-inhibiting effect of omega-3 fatty acids was shown by an arachidonic acid agonist in MEA .ConclusionsSupplemental omega-3 fatty acids do not evoke their positive health effects through inhibition of platelet aggregation measurable with MEA

Effects of naturopathic medicines on Multiplate and ROTEM: a prospective experimental pilot study in healthy volunteers

Of patients undergoing surgery, 22 to 57 % have been reported to be using naturopathic medicines. Several of these medicines have been reported to increase bleeding or enhance the effect of other drugs that increase bleeding. The Swedish Medical Products Agency recommends cessation of the use of the naturopathic medicines echinacea, fish oil, ginkgo biloba, ginseng, St. John's wort, valeriana and garlic 2 weeks before surgery. The aim of this pilot study was to examine the effects of these 7 naturopathic medicines in healthy humans by utilising multiple electrode aggregometer (Multiplate) and viscoelastic rotational thromboelastometer (ROTEM) to obtain data for sample size calculation before a larger trial

Analytic continuation by averaging Pad\'e approximants

The ill-posed analytic continuation problem for Green's functions and self-energies is investigated by revisiting the Pad\'{e} approximants technique. We propose to remedy the well-known problems of the Pad\'{e} approximants by performing an average of several continuations, obtained by varying the number of fitted input points and Pad\'{e} coefficients independently. The suggested approach is then applied to several test cases, including Sm and Pr atomic self-energies, the Green's functions of the Hubbard model for a Bethe lattice and of the Haldane model for a nano-ribbon, as well as two special test functions. The sensitivity to numerical noise and the dependence on the precision of the numerical libraries are analysed in detail. The present approach is compared to a number of other techniques, i.e. the non-negative least-square method, the non-negative Tikhonov method and the maximum entropy method, and is shown to perform well for the chosen test cases. This conclusion holds even when the noise on the input data is increased to reach values typical for quantum Monte Carlo simulations. The ability of the algorithm to resolve fine structures is finally illustrated for two relevant test functions.Comment: 10 figure

Fibrinogen and FXIII dose response effects on albumin-induced coagulopathy.

Objectives. Natural colloid albumin induces a lesser degree of dilutional coagulopathy than synthetic colloids. Fibrinogen concentrate has emerged as a promising strategy to treat coagulopathy, and factor XIII (FXIII) works synergistically with fibrinogen to correct coagulopathy following haemodilution with crystalloids. Our objectives were to examine the ability of fibrinogen and FXIII concentrates to reverse albumin-induced dilutional coagulopathy. Methods. High and low concentrations of both fibrinogen and FXIII were used to reverse coagulopathy induced by 1:1 dilution in vitro with 5% albumin of blood samples from healthy volunteers, monitored by rotational thromboelastometry (ROTEM(®)). Results. Haemodilution with albumin significantly attenuated EXTEM maximum clot firmness (MCF), alpha angle (AA), clotting time (CT) and clot formation time (CFT), and FIBTEM MCF (p < 0.001). Following haemodilution, both doses of fibrinogen significantly corrected all ROTEM parameters (p ≤ 0.02), except the lower dose did not correct AA. Compared to the lower dose, the higher dose of fibrinogen significantly improved FIBTEM MCF and EXTEM MCF, AA and CFT (p < 0.001). The lower dose of FXIII did not significantly correct any of the ROTEM parameters, and the high dose only improved EXTEM CT (p = 0.004). All combinations of high/low concentrations of fibrinogen/FXIII significantly improved all ROTEM parameters examined (p ≤ 0.001). Fibrinogen concentration generally had a greater effect on each parameter than did FXIII concentration; the best correction of ROTEM parameters was achieved with high-dose fibrinogen concentrate and either low- or high-dose FXIII. Conclusions. Fibrinogen concentrate successfully corrected initiation, propagation and clot firmness deficits induced by haemodilution with albumin, and FXIII synergistically improved fibrin-based clot strength