SynopsisThe dielectric properties and the d.c. conductivity of poly( vinyl chloride), poly(viny1 acetate), polychlorotrifluoroethylene, and poly(ethy1ene terephthalate) were measured at temperatures above and below the glass transition temperature and a t various pressures up to 3000 atm. The a relaxation associated with the micro-Brownian motion of amorphous chain segments depends strongly upon temperature and pressure, while the B relaxation due to local-mode motion of the frozen main chain shows weak dependence on temperature and pressure. It is found that the free volume concept is valid for description of the temperature and the pressure dependence of the relaxation time for the a process. Activation energy and volume for both relaxation processes are determined from the experimental data. A simple relation between activation energy and volume for the a relaxation and pressure dependence of the glass transition temperature are derived. Temperature and pressure dependence of the d.c. conductivity in the rubbery state are notably different from those in the glassy state. Ionic conduction appears to be dominant in these polymers.
To cite this article: Furukawa S, Nogami K, Ogiwara K, Yada K, Minami H, Shima M. Systematic monitoring of hemostatic management in hemophilia A patients with inhibitor in the perioperative period using rotational thromboelastometry. J Thromb Haemost 2015; 13: 1279-84.Summary. Background: The management of hemophilia A (HA) patients with inhibitors on bypassing therapy remains challenging. In particular, the monitoring of treatment is restricted by the limited reliability and lack of standardization of currently available methods to evaluate the physiological effects of various hemostatic agents. Accurate monitoring of these patients is particularly important in surgical situations. The recently developed comprehensive coagulation assays, including rotational thromboelastometry (ROTEM), may be useful in these circumstances. Objective: We have attempted to establish a systematic monitoring protocol using ROTEM (NATEM triggered by CaCl 2 ) to evaluate the choice and effectiveness of different bypassing agents in the perioperative period. Methods and Results: The hemostatic effects of recombinant factor VIIa (rFVIIa) and activated prothrombin complex concentrates (aPCC) were determined using a three-step procedure (spike, preoperative and perioperative) in eight patients with HA inhibitor admitted for elective surgery and assessed for individually tailored therapy. The ROTEM parameters demonstrated similar improvement to approximately normal levels at each stage after treatment with rFVIIa. Results in the presence of aPCC showed a marked improvement in the spike data, although this appeared to be different from those in the preoperative and perioperative assessments. The information derived from the spike and preoperative findings provided a useful guide for establishing an effective dose of therapeutic material, and facilitated good hemostatic control during and after surgery in all cases. Conclusion:The findings suggest that this systematic analysis using ROTEM could provide a promising strategy for the use of bypassing therapy in HA patients with inhibitor.
von Willebrand factor levels don't always reflect the severity of von Willebrand disease (VWD).
Relationship between new flow system (T‐TAS®) and bleeding score (BS) in type 1 VWD was studied.
Patients with PL‐T10 > 10 min had higher BS and particularly, PL‐T10 > 8 min correlated best.
T‐TAS could be a useful tool for discriminating and predicting the BS in VWD type 1 patients.
Summary
BackgroundThe clinical phenotype of von Willebrand disease (VWD) is heterogeneous, and von Willebrand factor ristocetin cofactor activity (VWF:RCo) does not always reflect clinical severity, especially in VWD type 1. We have reported the potential of a microchip flow‐chamber system (Total‐Thrombus Formation Analysis System [T‐TAS®]) for assessing physiologic hemostasis in VWD.
AimTo evaluate the relationship between T‐TAS, bleeding score (BS) and laboratory test results in type 1 VWD patients.
MethodsMicrochips coated with collagen (platelet chip [PL‐chip]) or collagen/thromboplastin (AR‐chip) were used to assess platelet thrombus formation (PTF) at high shear rates or fibrin‐rich PTF at low shear rates, respectively, in whole blood from 50 patients. The times needed for the flow pressure to increase by 10 kPa and 30 kPa (T10 and T30) from baseline were calculated from flow pressure curves. BS was determined by the use of a standardized questionnaire.
ResultsPL‐T10 values correlated with BS (R2 ~ 0.45) better than VWF:RCo (R2 ~ 0.36), irrespective of the flow rate, whereas AR‐T10 showed only a weak correlation with BS (R2 ~ 0.18). Patients with PL‐T10 > 10 min or AR‐T10 > 30 min had lower VWF levels and higher BS than those with PL‐T10 ≤ 10 min or AR‐T10 ≤ 30 min, and the greatest differences were observed with PL‐T10. Clinical severity appeared to correlate best with PL‐T10 > 8 min. BS was significantly higher in patients with VWF:RCo of < 10 IU dL−1 than in those with VWF:RCo of 10 IU dL−1 to < 25 IU dL−1 and 25–40 IU dL−1. In patients with VWF:RCo of < 10 IU dL−1, BS was significantly higher in those with PL‐T10 > 8 min than in those with PL‐T10 ≤ 8 min.
ConclusionT‐TAS could be a useful technique for discriminating and predicting BS in VWD type 1 patients.
The slope-|min1| parameter could provide a useful index for evaluating very low and absent levels of FVIII and/or the development of FVIII inhibitor in HA-pts.
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