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Correspondence  |   September 1997
Detection of Heparin in Salvaged Blood
Author Notes
  • Department of Anesthesiology; Baylor College of Medicine; Houston, Texas 77030.
Article Information
Correspondence
Correspondence   |   September 1997
Detection of Heparin in Salvaged Blood
Anesthesiology 9 1997, Vol.87, 719-720. doi:
Anesthesiology 9 1997, Vol.87, 719-720. doi:
To the Editor:-Autotransfusion devices or "Cell-Savers" are frequently used after termination of cardiopulmonary bypass (CPB) to process blood remaining in the extracorporeal circuit. Although the packed RBC product produced by these devices contain insignificant amounts of heparin, [1] many anesthesiologists still administer additional protamine to reverse heparin that may remain in "cell-saver" blood, a practice that could potentially lead to excess protamine administration.
The Hepcon[registered sign]/HMS (Medtronic, Inc., Blood Management Business, Parker, CO) performs a variety of functions related to anticoagulation management during cardiovascular surgery, including ACT and a heparin assay. [2] The latter is performed by heparin/protamine titration, in which blood is automatically dispensed to individual channels containing thromboplastin reagent and different concentrations of protamine. After mixing of these components in a reaction chamber, termed "run time," the first channel in which clot formation is detected is then used to calculate the heparin concentration. If the run time exceeds 249 s, the test is not considered valid because depletion of coagulation factors (or rarely, deterioration of cartridge reagents) may have occurred.
Some anesthesiologists have tried to use the Hepcon[registered sign]/HMS to determine the presence of heparin in "cell-saver" blood. Unfortunately, assays for heparin that require the presence of either coagulation proteins or antithrombin III should not work on "cell-saver" blood because washing also removes these components. A recent experiment confirmed this.
Blood remaining in the extracorporeal circuit after termination of CPB was processed by an autotransfusion device (BRAT[registered sign], Cobe Laboratories, Arvada, CO) using a 1-l wash cycle. Two independent blood samples from different devices were analyzed for heparin using a 4 channel Heparin Assay "Yellow" cartridge (test range, 0.0-1.5 mg/kg) with simultaneous measurement of ACT. A test concentration of 0.0 mg/kg was obtained in both samples. However, on examination of individual channel times in the Hepcon[registered sign]/HMS cartridge, three out of four recorded channel run times exceeded 400 s. In addition, blood failed to coagulate in ACT channels, exceeding 600 s.
Although the Hepcon[registered sign]/HMS reported the absence of heparin in both "cell-saver" blood samples, this result was inaccurate. In addition, no warning system existed on the display screen to advise the user that channel run times exceeding 249 s indicated depletion of coagulation factors.
Paul G. Loubser, M.D.
Department of Anesthesiology; Baylor College of Medicine; Houston, Texas 77030
(Accepted for publication June 24, 1997.)
REFERENCES
Gravlee GP, Hopkins MB, Yetter CR, Buss DH: Heparin content of washed red blood cells from the cardiopulmonary circuit. J Cardiothor Vasc Anesth 1992; 6:140-2.
Moore RA: Intraoperative evaluation of hemostasis, Blood: Hemostasis, Transfusion and Alternatives in the Perioperative Period. Edited by Lake CL, Moore RA. New York, Raven Press, 1995, pp 179-201.