Anderson D R, Lensing A W, Wells P S, Levine M N, Weitz J I, Hirsh J
Hamilton Civic Hospitals Research Centre, Ontario, Canada.
Ann Intern Med. 1993 Jan 1;118(1):25-30. doi: 10.7326/0003-4819-118-1-199301010-00005.
To re-evaluate the accuracy of impedance plethysmography (IPG) for the detection of proximal deep-vein thrombosis (DVT).
A total of 384 of 390 consecutive outpatients referred with their first episode of clinically suspected deep-vein thrombosis.
University-based tertiary care medical center associated with a cancer clinic.
A retrospective analysis of a cohort of patients whose data were recorded and stored prospectively on a computerized data base over a 22-month period.
Patients were evaluated by a physician and underwent IPG testing. Patients with abnormal IPG tests and those with normal IPG results in whom there was a high clinical suspicion of DVT or in whom follow-up IPG testing was not feasible were referred for venography. Venography and IPG results were interpreted by a panel of independent observers. Two models of the IPG instrument were used (Codman 200 and Electrodiagnostic Instruments 800).
Venography (or compression ultrasound) was done in 57 patients with an abnormal IPG test and in 85 patients with normal IPG results. Impedance plethysmography was abnormal in only 37 of 56 patients with confirmed proximal-vein thrombosis (sensitivity, 66%; 95% Cl, 52% to 78%). Of the 57 patients with an abnormal IPG result, 37 had DVT (positive predictive value, 65%). The sensitivity for the detection of proximal DVT did not differ between the IPG 200 and 800 instruments (sensitivity, 63% and 71%, respectively; P > 0.2). Of the 19 proximal-vein thrombi not detected by IPG, 12 (63%) were occlusive and 11 (58%) involved at least the popliteal and superficial femoral veins.
At our center, IPG has a far lower sensitivity for proximal-vein thrombosis than has been previously reported for symptomatic outpatients. The reason for this low sensitivity is unclear. Our findings indicate that centers using IPG as the initial diagnostic test for suspected DVT should be aware of this potential problem and should consider re-evaluating the sensitivity of their IPG machines by performing venography in a cohort of their patients with normal test results.
重新评估阻抗体积描记法（IPG）检测近端深静脉血栓形成（DVT）的准确性。
390例连续门诊患者中，共有384例因首次临床怀疑深静脉血栓形成而就诊。
与癌症诊所相关的大学三级医疗中心。
对一组患者进行回顾性分析，这些患者的数据在22个月期间前瞻性地记录并存储在计算机数据库中。
患者由医生进行评估并接受IPG检测。IPG检测异常的患者以及IPG结果正常但临床高度怀疑DVT或无法进行随访IPG检测的患者被转诊进行静脉造影。静脉造影和IPG结果由一组独立观察者解读。使用了两种型号的IPG仪器（Codman 200和Electrodiagnostic Instruments 800）。
57例IPG检测异常的患者和85例IPG结果正常的患者进行了静脉造影（或压迫超声）。在56例确诊近端静脉血栓形成的患者中，只有37例IPG异常（敏感性为66%；95%可信区间为52%至78%）。在57例IPG结果异常的患者中，37例患有DVT（阳性预测值为65%）。IPG 200和800仪器检测近端DVT的敏感性无差异（敏感性分别为63%和71%；P>0.2）。在IPG未检测到的19例近端静脉血栓中，12例（63%）为闭塞性血栓，11例（58%）至少累及腘静脉和股浅静脉。
在我们中心，IPG对近端静脉血栓形成的敏感性远低于先前报道的有症状门诊患者。这种低敏感性的原因尚不清楚。我们的研究结果表明，将IPG作为疑似DVT初始诊断试验的中心应意识到这一潜在问题，并应考虑通过对一组检测结果正常的患者进行静脉造影来重新评估其IPG机器的敏感性。
