Tromboelastografia

The Association Between Thromboelastographic Parameters and Total Estimated Blood Loss in Patients Undergoing Elective Cesarean Delivery
Alexander Butwick, FRCA, Vicki Ting, MD, Lindsey Atkinson Ralls, MD, Scott Harter, MD, and Edward Riley, MD
BACKGROUND: In this study, we assessed the relationship between coagulation parameters using kaolin-activated thromboelastography (TEG ) and totalestimated blood loss (EBL) in patients undergoing elective cesarean delivery (CD). METHODS: TEG parameters were recorded in 52 patients before and after elective CD. Laboratory markers of coagulation (prothrombin time, activated partial thromboplastin time, fibrinogen) were also assessed in a smaller subset (21 patients). Correlation and linear regression analysis was used to assess the relationshipamong TEG parameters, relevant clinical variables, and total EBL. Secondary analysis included comparisons of TEG and coagulation profiles pre-CD versus post-CD. RESULTS: EBL weakly correlated with percentage change in maximum amplitude (r 0.3; P 0.04) and post-CD maximum rate of thrombus generation (r 0.31; P 0.02). Post-CD values for split point, reaction time, time to maximum rate of thrombingeneration, prothrombin time, and activated partial thromboplastin time were significantly increased compared with baseline values (P 0.05). Post-CD angle, maximum amplitude, total thrombus generation, fibrinogen, and platelet counts were significantly decreased compared with baseline values (P 0.05). CONCLUSIONS: There is a weak association between clot strength (as assessed by kaolinactivated TEG ) andEBL in patients undergoing elective CD under neuraxial anesthesia, and a modest reduction in the degree of maternal hypercoagulability occurs in the early postpartum period after elective CD. (Anesth Analg 2011;112:1041–7)

atients undergoing cesarean delivery (CD) are susceptible to varying degrees of blood loss during the intraoperative period, especially after the period of placentalseparation and delivery. Thus, the hypercoagulable changes that occur during pregnancy are important in reducing the magnitude of blood loss that occurs during parturition.1 Thromboelastography (TEG ) is a real-time monitor of whole blood coagulation, which provides unique information about the different phases of the clot formation process,2 and TEG and rotational thromboelastometry have detected thehypercoagulable state associated with pregnancy3–5 and the postpartum period.3,6,7 In addition, the assessment of the velocity profile of thrombus generation by TEG has been used to provide additional data for characterizing time-dependent measures of thrombin generation.8,9 Previous studies assessing TEG in cardiac patients have indicated that maximum amplitude (MA) is closely
From the Department ofAnesthesia, Stanford University School of Medicine, Stanford, California. Accepted for publication January 10, 2011. Supported internally by the Department of Anesthesia, Stanford University School of Medicine. This report was previously presented, in part, at the 41st Annual Meeting of the Society of Obstetric Anesthesia and Perinatology, Chicago, IL, May 2009. The authors declare no conflictsof interest. Reprints will not be available from the authors. Address correspondence to Alexander Butwick, FRCA, Department of Anesthesia (MC: 5640), Stanford University School of Medicine, 300 Pasteur Dr., Stanford, CA 94305. Address e-mail to ajbut@stanford.edu. Copyright © 2011 International Anesthesia Research Society
DOI: 10.1213/ANE.0b013e318210fc64

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associated with earlypostoperative bleeding after cardiopulmonary bypass.10,11 In the obstetric population, a close correlation between fibrinogen and FIBTEM test (using rotational thromboelastography) has been recently reported in patients with postpartum hemorrhage.12 Although there is better understanding of the risk factors associated with postpartum hemorrhage after CD,13,14 it is uncertain whether maternal coagulation...