LETTER
Impedance Plethysmography and DVT Diagnosis
Cedric J. Carter
1 August 1993 | Volume 119 Issue 3 | Pages 246-247
TO THE EDITOR:
In their recent article on the use of IPG for the management of clinically suspected DVT, Anderson and colleagues [1] report results of a retrospective study that greatly differs from previous prospective studies.
The earlier prospective studies from McMaster University that compared IPG with obligate ascending venography for the diagnosis of DVT were done for the sole purpose of evaluating the accuracy of IPG [2]. The essential ongoing monitoring of the day-to-day quality of IPG is not possible with a retrospective study.
The investigators from Holland [3] who examined the safety of serial IPG for the management of suspected DVT did the study knowing that patient safety required the most accurate IPG result possible. In contrast, Anderson and colleagues [1] performed IPG knowing that at least one other objective confirmatory test would follow. This is a very different investigational environment and could decrease the rigor of IPG application.
The comparison of their findings to an Italian study of IPG for DVT management [4], in which four fatal pulmonary emboli occurred, may not be relevant because the Italian researchers used a different type of IPG machine.
Thus, it is difficult to relate the new findings with IPG to earlier studies. Interestingly, the results obtained from the initial study of compression duplex Doppler are similar to those from early studies of IPG [5].
1. Anderson DR, Lensing AW, Wells PS, Levine MN, Weitz JI, Hirsh J. Limitations of impedance plethysmography in the diagnosis of clinically suspected deep-vein thrombosis. Ann Intern Med. 1993; 118:25-30.
2. Hull RD, Raskob GE, LeClerc JR, Jay RM, Hirsh J. The diagnosis of clinically suspected venous thrombosis. Clin Chest Med. 1984; 5:439-44.
3. Huisman MV, Buller HR, ten Cate JW, Vreeken J. Serial impedance plethysmography for suspected venous thrombosis. N Engl J Med. 1986; 314:823-8.
4. Prandoni P, Lensing AW, Buller HR, Carta M, Vigo M, Cogo A. Failure of computerized impedance plethysmography in the diagnostic management of patients with suspected deep vein thrombosis. Thromb Haemost. 1991; 65:233-6.
5. Lensing AW, Prandoni P, Brandjes D, Huisman PM, Vigo M, Tomassella G, et al. Detection of deep venous thrombosis by real-time B-mode ultrasonography. N Engl J Med. 1989; 320:342-5.
About Letters
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
Top
References
Article
