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Using α-Angle and A10 ROTEM Parameters for Earlier Information on Clotting Status in Surgery, Postpartum Hemorrhage, and ICU Patients

Toffaletti, John G. PhD; Buckner, Kelly A. BS

doi: 10.1097/POC.0000000000000188
Original Articles

Background We determined if the earlier ROTEM (rotational thromboelastometry) parameters (α-angle and amplitude at 10 minutes [A10]) could replace the later-reported maximum amplitude (maximum clot firmness [MCF]) in cardiothoracic surgery (C/T OR), postpartum hemorrhage (PPH), and intensive care unit (ICU) patients.

Methods We retrospectively analyzed 300 sets of EXTEM and FIBTEM results ordered on 100 C/T OR, 100 PPH, and 100 ICU patients for correlations among the α-angle, A10, MCF, fibrinogen, and platelet counts.

Results The A10EX and A10FIB correlated highly to the respective MCFEX and MCFFIB in all patient groups. The A10EX parameter correlated significantly to both fibrinogen and platelet levels, and the A10FIB correlated highly to the fibrinogen levels. Because the difference between the A10EX and the A10FIB (PLTEM) is related to platelet activity, we found that the PLTEM correlated highly to the platelet count for all PPH (r = 0.80), C/T OR (r = 0.70), and ICU patients (r = 0.66). The EXTEM α-angle (α-EX) is an excellent indicator of the A10EX, with an α-EX of 65 degrees or greater (ie, normal) giving a greater than 96% probability that the A10EX was 44 mm or greater and an α-EX value below 65 mm giving an 86% probability that the A10EX was less than 44 mm.

Conclusions The A10EX and A10FIB could replace the MCF results in all patient groups, and the α-EX was an early indicator of the A10EX. Finally, in a separate group of 62 comparisons, the α-FIB showed promise as an early indicator of the A10FIB and the fibrinogen levels.

From the Department of Pathology/Clinical Laboratories, Duke University Health System, Durham, NC.

Reprints: John G. Toffaletti, PhD, PO Box 3015, Duke University Medical Center, Durham, NC 27710. E-mail:

J.G.T. receives grant support from Instrumentation Laboratory, which acquired TEM Systems during the course of this study. However, no funding or personnel from that source were involved with this study. K.A.B. declares no conflict of interest.

Authors' Contributions: J.G.T. directed the research, reviewed the data, and wrote the manuscript. K.A.B. reviewed ROTEM results to obtain the data, prepared the figures, and reviewed the manuscript.

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