DeBois William J, Liu Junli, Elmer Barbara, Ebrahimi Haleh, Voevidko Lilia, Lee Leonard Y, Krieger Karl H, Isom Wayne W, Girardi Leonard N
New York Presbyterian Hospital-Weill Cornell Medical Center, NY 10021, USA.
J Extra Corpor Technol. 2006 Dec;38(4):307-9.
Anticoagulation for the open heart surgery patient undergoing cardiopulmonary bypass (CPB) is achieved with the use of heparin. The industry standard of activated clotting time (ACT) was used to measure the effect of heparin. The commonly acceptable target time of anticoagulation adequacy is 480 seconds or greater. Some patients, however, exhibit resistance to standard dosing of heparin and do not reach target anticoagulation time (480 seconds). Antithrombin III deficiency has been previously cited as the cause of heparin resistance. Early detection of heparin resistance (HR) may avoid both the delayed start of CPB and inadequate anticoagulation, if emergency bypass is required. An anticoagulation sensitivity test (AST) was developed by adding 12 units of porcine mucosa heparin to the ACT tube (International Technidyne, celite type). Before anticoagulation, 4 mL of blood was drawn from the patient arterial line. Following the manufacturer's instructions, 2 mL of blood was added to each tube (ACT-baseline and ACT-AST). Three minutes after anticoagulation with 4 mg heparin/kg body weight, a second sample (ACT-CPB) was taken to determine anticoagulation adequacy. The ACT times of each sample were recorded for 300 procedures occurring during 2004 and were retrospectively reviewed. Heparin resistance occurred in approximately 20% of the patients (n = 61). In 54 patients, heparin resistance was predicted by the ACT-AST. This was determined by the presence of an ACT-AST time and an ACT-CPB that were both < 480 seconds. The positive predictive value was 90%, with a false positive rate of 3%. Heparin resistance occurs in patients undergoing CPB. We describe a simple and reliable test to avoid the delays of assessing anticoagulation for CPB (90% positive predictive value). Depending on program guidelines, patients can be given additional heparin or antithrombin III derivatives to aid in anticoagulation. An additional ACT must be performed and reach target times before CPB initiation. Testing of patient blood before the time of incision for sensitivity to heparin is a way to avoid a delay that can be critical in the care of the patient. Commercial tests are available, but efficacy data are limited, and they lead to added inventory expense. This method of titrating a diluted heparin additive, mixed with patient blood in a familiar ACT test, has proven to be an inexpensive and reliable test to predict patient's sensitivity to heparin.
对于接受体外循环（CPB）的心脏直视手术患者，通过使用肝素实现抗凝。采用活化凝血时间（ACT）的行业标准来衡量肝素的效果。抗凝充分性的通常可接受目标时间为480秒或更长。然而，一些患者对标准剂量的肝素表现出抵抗，未达到目标抗凝时间（480秒）。抗凝血酶III缺乏症先前被认为是肝素抵抗的原因。如果需要紧急体外循环，早期检测肝素抵抗（HR）可避免CPB延迟启动和抗凝不足。通过向ACT管（国际技术公司，硅藻土型）中加入12单位猪黏膜肝素开发了一种抗凝敏感性试验（AST）。在抗凝前，从患者动脉管路抽取4 mL血液。按照制造商的说明，向每个试管（ACT基线和ACT - AST）中加入2 mL血液。在用4 mg肝素/千克体重进行抗凝3分钟后，采集第二个样本（ACT - CPB）以确定抗凝充分性。记录了2004年期间发生的300例手术中每个样本的ACT时间，并进行了回顾性分析。约20%的患者（n = 61）出现肝素抵抗。在54例患者中，通过ACT - AST预测到肝素抵抗。这是由ACT - AST时间和ACT - CPB均<480秒来确定的。阳性预测值为90%，假阳性率为3%。接受CPB的患者会出现肝素抵抗。我们描述了一种简单可靠的试验，以避免评估CPB抗凝的延迟（阳性预测值90%）。根据方案指南，可给予患者额外的肝素或抗凝血酶III衍生物以辅助抗凝。在CPB启动前必须再次进行ACT并达到目标时间。在切开前检测患者血液对肝素的敏感性是避免可能对患者护理至关重要的延迟的一种方法。有商业检测可用，但疗效数据有限，且会导致额外的库存费用。这种在熟悉的ACT试验中滴定稀释肝素添加剂并与患者血液混合的方法，已被证明是一种预测患者对肝素敏感性的廉价且可靠的检测方法。
