DOI: 10.1097/00000539-199902001-00067
,
Issn Print: 0003-2999
Publication Date: 1999/02/01
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Excerpt
INTRODUCTION: Aprotinin, a serine protease inhibitor, has been shown to improve haemostasis during and after cardiopulmonary bypass by inhibiting plasmin- and kallikrein-mediated fibrinolysis. As aprotinin prolongs coagulation assays which depend on contact activation, e.g. the activated partial thromboplastin time (APTT) and celite-activated contact time (cACT), Hunt et al [1] have recommended cACT>or=to 750s as a criterion to initiate CPB when antifibrinolytic levels of aprotinin (150-200 KIU/ml) is present. Recently, High-Dose Thrombin Time (HiTT), which is unaffected by aprotinin, has been advocated to assess adequacy of heparinisation for CPB in aprotinin-treated cardiac surgical patients. [2]
We aimed (1) to assess the post-CPB complications of having a prebypass ACT<700s in the presence of aprotinin and (2) to determine the correlation between HiTT and cACT in aprotinin-treated cardiac surgical patients.
METHODS: 37 consecutive ASA I-III patients with increased bleeding risk were given aprotinin (106 kallikrein inactivator units (KIU) intravenously and 106 KIU added to the pump prime) at induction for elective cardiac surgery by the same surgeon. HiTT and cACT were checked 5 minutes after a heparin bolus (bHep) of 2-4 mg/kg. The estimated ACT (eACT) from HiTT (using manufacturer's tables) was noted. Sufficient heparin was given to achieve HiTT>or=to 168s (equivalent to a circulating heparin level of 3 IU/ml of blood) before CPB was commenced. The patients were divided into group A (cACT>or=to 700s) and group H (cACT<700s). The total amount of heparin (tHep) used for the entire operation was recorded. Sufficient protamine returned cACT to normal values at the termination of CPB. We studied the postoperative complications in these 2 groups. The results were analyzed using the Krushkal-Wallis test with P<0.05 taken as the level of significance.
RESULTS: Group A (cACT>or=to 700s)(n=26) and group H (cACT<700s)(n=11) had no significant differences in demographic data, tHep or protamine required, postoperative chest drain bleeding or amount of blood products given. None developed renal failure, cerebrovascular accidents or acute myocardial infarction. There was no correlation between HiTT and cACT after bHep (p=0.25). The estimated cACT from HiTT (using charts supplied by the manufacturer) had no correlation with cACT (p=0.42).
DISCUSSION: (1) We found no increased incidence of postoperative complications when CPB was initiated with cACT<700s in the presence of aprotinin. (2) There is no correlation between HiTT and cACT after a bolus of heparin. (3) The estimated ACT from charts supplied by the manufacturer does not correlate with cACT.
