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The combined effect of cell salvage reinfusion volume and hemodilution on thromboelastogram values during coronary artery bypass grafting : a thesis submitted to the faculty of the Milwaukee School of Engineering in partial fulfillment of the requirements for the degree of Master of Science / by Jennifer M. Tounshendeaux.

by Tounshendeaux, Jennifer M. author , Milwaukee School of Engineering

Blood -- Transfusion -- Safety measures

Cardiopulmonary bypass -- Adverse effects

Coronary artery bypass

33 leaves : illustrations ; 29 cm.

Introduction -- Background -- The impact of cardiopulmonary bypass and cell salvage on hemostasis -- The use of thromboelastography to assess coagulation -- Hypotheses -- Methods -- Results -- Discussion -- Conclusions -- Recommendations -- References -- Appendix A: statistical analysis.

The re-use of shed blood, called cell salvage, has become common during cardiac surgeries requiring the use of cardiopulmonary bypass (CPB). Cell salvage allows for preservation of hematocrit caused by hemodilution while lessening the use of homologous blood products. Although cell salvage decreases the necessity for blood transfusion, it is unclear whether or not the reinfusion of cell saver blood causes a disruption of hemostasis, or if the combination of cell salvage and overall hemodilution alters coagulation. Literature using traditional coagulation panels and indirect measure of hemostasis suggest that there may be an increase in fibrinolysis and postoperative bleeding in cardiac patients when cell salvage is used during surgery. However, these methods of quantifying the disruption of hemostasis are complicated by various factors, including Coumadin therapy or residual heparin present after bypass, which makes isolating the effect of cell salvage difficult. Thromboelastogram testing allows for the complete depiction of a coagulation profile, and because it corrects for anticoagulant use, it can better identify how other interventions affect hemostasis. The goal of this study was to compare presurgical and postsurgical thromboelastogram values from patients who underwent CPB with the use of cell salvage to determine the impact of cell salvage on clot profiles. Data were collected from the records of patients who underwent coronary artery bypass grafting using cardiopulmonary bypass (including the use of cell salvage) at Aurora St. Luke's Medical Center from December 2011 through August 2013. The population sample was limited to first time surgical candidates who also underwent harvesting of a single mammary artery. Patients with preoperative thromboelastogram values outside of the normal range and/or received intraoperative or postoperative blood product transfusions were excluded.

Changes in pre- to postoperative thromboelastogram were evaluated to determine if hemodilution and/or cell saver reinfusion volumes were significant predictors within the sample (N=196). Student's t-tests found that there was a significant decrease in the TEG maximum amplitude value (from 68.1 ± 8.5 mm preoperative to 63.1 ± 6.7 mm postoperative, p<0.05), which signifies a decrease in clot strength, during surgery. Multiple regression analysis was performed to determine significant predictors of this change. Hemodilution, which was represented by change in hematocrit, was a significant predictor (p<0.05) of change in maximum amplitude.

It can be concluded that cell saver reinfusion volumes within the represented range (676.2 ± 305.4 mL) can be utilized without concern for the development of coagulopathies in this population. However, precautions should be taken in order to reduce hemodilution as much as possible in order to avoid resulting coagulopathies.

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