White Hayden, Sosnowski Kellie, Bird Robert, Jones Mark, Solano Connie
Division of Critical Care, Logan Hospital and Griffiths University, Meadowbrook, Queensland, Australia.
Blood Coagul Fibrinolysis. 2012 Jun;23(4):304-10. doi: 10.1097/MBC.0b013e32835274c0.
Low molecular weight heparins (LMWHs) are used for prevention and management of vascular thrombosis. In general, monitoring of anticoagulant activity is not required, however, certain populations may be susceptible to overdosing or underdosing. As anti-activated factor X(anti-Xa) activity testing is not readily available, it was our aim to investigate the usefulness of thromboelastography (TEG; Haemoscope Corporation, Skokie, Illinois, USA) for the assessment of coagulation in patients on LMWH. All patients admitted to the coronary care unit on therapeutic dose of enoxaparin were included (1 mg/kg twice daily). Blood samples were collected 4 h after the morning dose of enoxaparin once the participant had received at least three doses. When anti-Xa activity was classified as low (0-0.5), correct (0.5-1.0) or high (>1.0), the distribution of reaction time (R) and dose per kg showed little association with anti-Xa activity. The difference between mean R for the high anti-Xa group and the correct anti-Xa group was statistically nonsignificant using two-sample t-test (P = 0.26). A linear regression model showed no evidence of association between dose per kg and anti-Xa (P = 0.95). However, there was evidence of positive association between dose per kg and R (P = 0.011) wherein a 10% increase in dose per kg was associated with an increase in R of 2.7 (95% confidence interval 0.6-4.7). There was no evidence of association between R and anti-Xa (P = 0.38). TEG was unable to be used to predict anti-Xa activity. However, TEG R was prolonged in more than 90% patients and correlated with dose of enoxaparin. As enoxaparin dose correlated poorly with anti-Xa activity, a more global test might be necessary to adjust dosing of LMWH in sick, hospitalized patients.
低分子量肝素（LMWHs）用于预防和治疗血管血栓形成。一般来说，不需要监测抗凝活性，然而，某些人群可能易出现用药过量或用药不足的情况。由于抗活化因子X（抗Xa）活性检测不易获得，我们旨在研究血栓弹力图（TEG；美国伊利诺伊州斯科基市Haemoscope公司）在评估接受LMWH治疗患者凝血功能方面的实用性。纳入所有接受治疗剂量依诺肝素（每日两次，每次1mg/kg）入住冠心病监护病房的患者。在参与者至少接受三剂依诺肝素后，于早晨剂量用药4小时后采集血样。当抗Xa活性分为低（0 - 0.5）、正常（0.5 - 1.0）或高（>1.0）时，反应时间（R）和每千克剂量的分布与抗Xa活性几乎没有关联。使用两样本t检验，高抗Xa组和正常抗Xa组的平均R值差异无统计学意义（P = 0.26）。线性回归模型显示每千克剂量与抗Xa之间无关联证据（P = 0.95）。然而，有证据表明每千克剂量与R之间存在正相关（P = 0.011），即每千克剂量增加10%与R增加2.7相关（95%置信区间0.6 - 4.7）。R与抗Xa之间无关联证据（P = 0.38）。TEG无法用于预测抗Xa活性。然而，超过90%的患者TEG R延长，且与依诺肝素剂量相关。由于依诺肝素剂量与抗Xa活性相关性较差，对于病情较重的住院患者，可能需要更全面的检测来调整LMWH的剂量。
