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Letter to the Editor

Measurement of activated clotting time and whole hlood heparin concentration during cardiopulmonary bypass To the Editor: We read with interest the manuscript by Komiya and colleagues' concerning the significance of heparin concentration measurement during cardiopulmonary bypass (CPB). Because their index of heparin control during CPB, the average heparin concentration/heparin dose response (HC/HDR), may not be predicted before CPB and would not be practical, we wish to present more practical data concerning heparin control during CPB.2 Ten patients (most having undergone CABG) were divided into two groups: Group one (n=5), additional heparin dose determined based on activated clotting time (ACT, >400 sec); Group two (n=5), additional heparin dose determined based on heparin concentration measurement by Hepcon/HMS (>2.5 mg/kg). Although the concentration of plasmin a2plasmin inhibitor complex (PIC) was not significantly different in the two groups, the thrombin-antithrombin III (TAT) just after CPB was significantly lower in group two than in group one (Group one, 424.4 ± 124.5 Ilg/l; Group two, 186.6 ± 73.5 ug/l; p
The Japanese Journal of Thoracic and Cardiovascular Surgery

Nagoya University School ofMedicine 65 Tsurumai-cho, Showa-ku Nagoya, Japan REFERENCES 1. Komiya T, Ban K, Yamazaki K, Ishii 0, Nakamura T, Kanzaki Y. The significance of heparin concentration measurement during cardiopulmonary bypass. Effect of heparin-coated circuit during normothermic bypass. J Jpn Assn Thorac Surg 1997; 45: 1810-5. 2. Watanabe T, Yasuura K, Maseki T, Oohara Y, Itoh T, Yuasa T, Nishizawa T, Kawaratani Y, Murase M. Activated clotting time and whole blood heparin concentration during cardiopulmonary bypass. Jpn J ArtifOrgans 1997; 26: 349-53. 3. Tabuchi N, de Haan J, Boostran PW, van Oeveren W. Activation of fibrinolysis in the pericardial cavity during cardiopulmonary bypass. J Thorac Cardiovasc Surg 1993; 106: 823-33.

Reply to the Editor: We thank Dr Watanabe for his interest in our recent article. Great variation in the measured heparin dose response (HDR) represent that individual response to heparin is quite different. Consequently, it would be possible that a certain heparin level is adequate for someone but insufficient for another one. From that reason, if one use a heparin administration protocol based on heparin concentration (He) measurement, the lowest HC level must be set sufficiently high in terms of safety. Our protocol had been based on the ratio between HC and HDR (HCIHDR). We proceeded our study to determine an appropriate level of HC/HDR. Forty-nine patients were randomly assigned into two groups. Group H (n=23), HC/HDR had been kept around 0.8 during bypass; Group L (n=26), the HC/HDR had been kept around 0.5. There were no statistical differences in coagulation and fibrinolytic activity during bypass and the postoperative amount of bleeding. We concluded that reduction of heparin may be possible using a heparin-coated circuit during normothermia with this new heparin administration protocol. The con-

Volume 46 Number 6 June 1998

elusion was different from our previous study in which we insisted that the maintenance of HC/HDR at a higher level might be indicated. We speculate that the difference could be attributed to the difference in the heparin-coated circuit in which an artificial lung was also heparin-coated. In our study, we still propose that the heparin administration protocol based on HCIHDR is useful espe-

Letter to the Editor

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cially in order to reduce heparin dose during cardiopulmonary bypass. Tatsuhiko Komiya M.D. Department of Cardiovascular Surgery Kurashiki Central Hospital 1-1-1 Miwa, Kurashiki city Okayama, Japan