A Prospective Study of Thromboelastography (Teg) and Filter Life During Continuous Veno-Venous Hemofiltration

Abstract

Anticoagulants are commonly used to prolong circuit life during continuous hemofiltration. However, a clear correlation between routinely performed blood coagulability tests and circuit life has not been demonstrated. This lack of correlation may derive from the limited ability of such tests to describe the likelihood of in vivo clotting. We hypothesized that thromboelastography (TEG), which derives its variables from a closer reproduction of in vivo coagulation, would significantly correlate with filter life. Accordingly, we conducted a prospective pilot study of the correlation between filter life and TEG-derived variables in 21 hemofilters used in 6 critically ill patients admitted to a tertiary intensive care unit. It involved the performance of TEG during steady state anticoagulation, measurement of circuit life, and of routine coagulation variables. The results showed that the mean circuit life was 20.7+/-4.0 h despite an average aPTT of 67.7+/-12.8 s and a mean heparin dose of 472.5+/-96.2 IU/h. The mean INR was 1.4+/-1 and the mean platelet count was 118+/-16 x 10(3)/mm3. Although several TEG variables correlated with heparin dose (p < 0.03), no correlation was found between any of the routine coagulation variables or any of the TEG variables and circuit life. In conclusion, no significant correlation between TEG derived variables or routinely measured coagulation variables and circuit life could be demonstrated. These findings suggest that such tests are not useful indicators of circuit anticoagulation adequacy and that factors other than blood coagulability may play a role in circuit failure.

Pre-Dilution vs. Post-Dilution during Continuous Veno-Venous Hemofiltration: Impact on Filter Life and Azotemic Control

“…We also found that heparin dose was an independent variable but that APTT and PT-INR were not, at least for normal or nearly normal values. These results are also consistent with previous studies [15, 17]and APTT has previously been shown to correlate poorly with serum heparin concentration [18]. Although frequent APTT measurements are often recommended for the monitoring or adjustment of heparin dosage to improve the efficacy of heparin-based filter anticoagulation [19], our findings do not support this recommendation.…”

“…However, the observational period was relatively short (totally 19 months) and there were no other practice changes in the conduct of CVVH. Moreover, we observed more than 300 filters, which is more than any other published studies of filter life [8, 9, 10, 15, 17, 20, 21]. Thirdly, we did not measure small solute control (e.g.…”

Circuit Life Versus Bleeding Risk: The Impact of Achieved Activated Partial Thromboplastin Time Versus Achieved Filtration Fraction

“…Heparin protocols that account for heparin sensitivity in the previous circuit, as proposed by Ostermann, are one solution . There has also been interest in using thromboelastograms (TEG) instead of APTT; however, a prospective study found that TEG parameters did not predict circuit survival . Heparin potentiates the anticoagulant activity of AT‐III, the levels of which are reduced in the critically ill (particularly in sepsis).…”

Pharmacological methods for blood stabilization in the extracorporeal circuit (review of literature)

“…Рутинный метод оценки тромбоцитов (например, количество тромбоцитов) не дает никакой информации об их функциональной активности. У критически больных пациентов наблюдаются различные уровни активации или дисфункции тромбоцитов, что также может повлиять на срок службы фильтра [5]. Поэтому, на наш взгляд, перспективным инструментом оценки баланса про/антикоагулянтов до и во время процедуры экстракорпоральной гемокоррекции может стать тромбоэластография.…”