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Br J Anaesth. 2005 Sep;95(3):310-6. Epub 2005 Jul 15.

Effects of protamine and heparin can be detected and easily differentiated by modified thrombelastography (Rotem): an in vitro study.

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  • 1Clinic for Anaesthesia and Intensive Care Medicine, Innsbruck Medical University, Innsbruck, Austria. markus.mittermayr@uibk.ac.at

Abstract

BACKGROUND:

Precise coagulation monitoring might help prevent heparin-protamine mismatch and thus decrease postoperative blood loss. We therefore measured coagulation time (CT) by modified thrombelastography (Rotem) as a possible differential monitor of the effects of heparin and protamine.

METHODS:

Undiluted and diluted blood samples from 26 healthy volunteers were spiked with increasing concentrations of heparin (0.1, 0.2, 0.4, 0.8 and 1 U ml(-1)). In addition, undiluted blood was spiked with protamine hydrochloride (0.1, 0.2, 0.4, 0.8 and 1.6 U ml(-1)), and we tested the effect of protamine on the reversal of heparin 0.4 U ml(-1). Heparin-containing samples were analysed using the heparin-sensitive INTEM test and the heparinase-containing HEPTEM test; protamine series were also analysed with the EXTEM test (tissue factor activation).

RESULTS:

CT by the INTEM test [CT-INTEM; median (min/max)] increased significantly and dose-dependently with increasing concentrations of heparin [control, 175 s (146/226); heparin, 1.0 U ml(-1) 1320 s (559/2100); P<0.001] and protamine [control, 172 s (150/255); protamine, 1.6 U ml(-1) 527 s (300/1345); P<0.0001]. Up to heparin concentrations of 0.4 U ml(-1), results were similar in undiluted and diluted blood samples. As expected, CT-HEPTEM remained within the normal range for all tested heparin concentrations (median 180-183 s), but increased similarly to CT-INTEM for increasing protamine concentrations.

CONCLUSION:

CT measurement using the Rotem technique appears to be a valuable tool for heparin-protamine management. For detection of heparin alone, protamine alone and the two combined, the ratio of CT-INTEM:CT-HEPTEM can be used to distinguish the effects of heparin excess (CT-INTEM:CT-HEPTEM>1) from those of protamine excess (CT-INTEM:CT-HEPTEM=1).

PMID:
16024582
DOI:
10.1093/bja/aei197
[PubMed - indexed for MEDLINE]
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