Tremey B, Szekely B, Schlumberger S, François D, Liu N, Sievert K, Fischler M
Department of Anaesthesiology, Hôpital Foch, Suresnes, France.
Br J Anaesth. 2006 Oct;97(4):453-9. doi: 10.1093/bja/ael194. Epub 2006 Jul 27.
Activated clotting time (ACT) is currently used to monitor high concentrations of heparin anticoagulation. A new instrument, the Hemochron Jr Signature device, has been specifically designed to measure ACT in low-range heparin plasma concentrations (ACT-LR). The purpose of this study was to compare ACT-LR with anti-Xa activity in patients receiving low-dose i.v. heparin during vascular surgery.
Thirty patients, undergoing arterial vascular surgery, were included in the study and received unfractionated heparin (initial dose 50 u kg(-1)). One hundred and thirty-two pairs of blood samples were simultaneously collected during surgery to determine ACT-LR and anti-Xa activity. Pearson correlation, Kappa test, ROC curve and a specific clinical interpretation of the correlation were performed.
ACT-LR ranged from 68 to 380 s, anti-Xa activity from 0 to 1.45 u ml(-1). We observed a strong correlation between anti-Xa activity and ACT-LR (r(2)=0.87; P<0.0001). Accuracy of ACT-LR was good for anti-Xa activity up to 0.6 u ml(-1) (Kappa, 0.94; accuracy, 97%) and 0.8 u ml(-1) (Kappa, 0.79; accuracy, 90%), and poor for anti-Xa activity above 1 u ml(-1) (Kappa, 0.59). A clinical interpretation of the correlation graph found 98% of measured ACT-LR values to be accurate.
Hemochron Jr Signature provides measurements of ACT-LR, which are accurate for monitoring heparin anticoagulation at anti-Xa activity below 0.8 u ml(-1).
活化凝血时间（ACT）目前用于监测高浓度肝素抗凝。一种新仪器，即Hemochron Jr Signature设备，专门设计用于测量低范围肝素血浆浓度下的ACT（ACT-LR）。本研究的目的是比较接受血管手术期间低剂量静脉注射肝素患者的ACT-LR与抗Xa活性。
30例接受动脉血管手术的患者纳入本研究，并接受普通肝素（初始剂量50 U kg⁻¹）。手术期间同时采集132对血样以测定ACT-LR和抗Xa活性。进行了Pearson相关性分析、Kappa检验、ROC曲线分析以及相关性的具体临床解读。
ACT-LR范围为68至380秒，抗Xa活性范围为0至1.45 U ml⁻¹。我们观察到抗Xa活性与ACT-LR之间存在强相关性（r² = 0.87；P < 0.0001）。ACT-LR对于抗Xa活性高达0.6 U ml⁻¹时准确性良好（Kappa值为0.94；准确性为97%），对于抗Xa活性为0.8 U ml⁻¹时也良好（Kappa值为0.79；准确性为90%），而对于抗Xa活性高于1 U ml⁻¹时准确性较差（Kappa值为0.59）。相关性图的临床解读发现98%的测量ACT-LR值是准确的。
Hemochron Jr Signature可提供ACT-LR测量值，在抗Xa活性低于0.8 U ml⁻¹时，对于监测肝素抗凝是准确的。
