Intensive Care Med (1989) 15:238-240 Intensive Care Medicine © Springer-Verlag 1989

Evaluation of Doppler examination for diagnosis of catheter-related deep vein thrombosis F. Bonne t 1, J.F. Lor i fe rne 1, J.P. Texier 2, M. Texier 2, A. Salvat 1 and N. Vasile 3

1Associate Professor of Anesthesiology, 2Assistant in Vascular Surgery, 3 Professor of Radiology, Hfpital Henri Mondor, Creteil, France

Received: 23 March 1988; accepted: 28 July 1988

Abstract. The accuracy o f D o p p l e r examina t ion was evaluated for the d iagnos is o f ca the ter - re la ted venous t h rombos i s in 40 pos topera t ive pat ients . Deep vein th rombos i s was detected by venography in 15 pa t ien ts and con f i rmed by the D o p p l e r technique in a doub le b l ind study. On ly one false-posi t ive and one false-neg- ative result were ob ta ined with the Dopp le r technique. This technique appears to be va luable for the ear ly di- agnosis o f ca theter- re la ted vein thrombosis , even in a s y m p t o m a t i c pat ients .

Key words: D o p p l e r equ ipmen t - Cent ra l venous catheters - Compl i ca t ions - Venous th rombos i s

Deep vein th rombos i s is a wel l -known compl i ca t i on o f central venous ca the ter p lacement , which is assoc ia ted with an increased incidence o f sept icemia [1, 2]. Un- for tunately, the cl inical d iagnos is is of ten unre l iab le because s y m p t o m s appea r late in the evolut ion o f the venous t h rombos i s [3]. W h e n a sys temat ic eva lua t ion is p e r f o r m e d by venography, the f requency o f th rom- bosis developing as a result o f centra l venous catheters ranges be tween 26% and 67% [4, 5]. A t present , an ac- cura te d iagnos is can be es tabl ished on ly by means o f ph lebography , bu t this technique canno t be re l iably p e r f o r m e d at the beds ide and is no t easi ly repeated. The D o p p l e r technique has been extensively app l i ed to the d iagnos is o f lower l imb venous t h rombos i s [ 6 - 9]. This technique has the advan tage o f being a non- inva- sive, safe and s imple me thod . In addi t ion , it can be re- pea ted f requent ly at the beds ide in pat ients at r isk o f developing venous thrombosis . The current s tudy was p e r f o r m e d to evaluate the accuracy o f the D o p p l e r technique in de te rmin ing the d iagnos is o f catheter-re- la ted venous th rombos is .

Patients and methods

Forty patients (28 men, 12 women, mean age 63.2+ 15.5 years) were studied. All patients had undergone abdominal surgery. Central ve- nous polyurethane catheters were inserted in the theatre before sur- gery and the position of the catheter was checked by a chest X-ray, confirming that the tip of the catheter was in the superior vena cava in all cases. The site of the venous access was the antecubital vein 26 cases, the internal jugular vein 6 cases and the subclavian vein 8 cases. Postoperatively, all patients received subcutaneous calcium heparin, 5000 IU three times a day for prevention of postoperative thrombophlebitis.

Patients were assessed daily and examined for local signs of thrombophlebitis, defined as tenderness and erythema at the punc- ture site and along the vein, edema and collateral circulation, and for signs of infection (fever, raised white cell count, bacteremia, or septicemia). After withdrawal, the catheter tips were cultured systematically. Venography was performed between the 5th and 6th day following the catheter placement, or before, if the catheter was to be removed, if no longer required for fluid infusion. Sixty millili- ters of low osmolality contrast medium (Hexabrix, laboratory Guerbet, Paris, France), was injected intravenously, at a rate of 5 ml/s. The injection was performed simultaneously via the periph-

Fig. 1. Thrombosis of the left subclavian vein with the development of a collateral circulation

F. Bonnet et al.: Evaluation of Doppler examination

eral ipsilateral extremity and through the catheter. Ten to 12 X-ray films were taken at a rate of one per second, allowing visualization of the axillary vein, the subclavian vein, the superior vena cava and the internal jugular vein (Fig. 1). The venograms were interpreted by a radiologist, who was unaware of the results of the Doppler exam- ination. The diagnosis of thrombosis of a main vein was made when a constant intraluminal lacuna was demonstrated or when the lack of visualization of the main vein was associated with the develop- ment of extensive collateral circulation.

The Doppler examination was performed on the day of the venography, about I h before. A two-frequency ( 4 - 8 MHz) direc- tional continuous Doppler (stereo 448) was used by two of the authors (J. P. Texier, M. Texier) who are fully experienced in the technique. Axillary, jugular and subclavian veins were studied and compared with the opposite side and changes in subclavian vein flow were studied during spontaneous breathing (Fig. 2). Expiration is usually associated with a decrease in flow signal, followed by a progressive increase during inspiration (Fig. 2). Flow was also stud- ied after transient compression of the vein and after compression of the muscles of the appropriate forearm or upper arm. After release of the compression the velocity of venous flow increases promptly when the main vein is patent. The development of abnormal collat- eral veins on the arm and the hemithorax was also evaluated with the 8 MHz probe. Normally, a collateral flow is not detected. When a main vein thrombosis occurs, an abnormal collateral flow may be documented.

Thrombosis of a main vein was diagnosed when no flow signal could be detected. It was confirmed by a lack of change in venous flow upstream from the thrombosis, either on deep breathing or with compression/decompression of the subclavian vein (lack of in- crease in venous flow downstream to the thrombosis after compres- sion of the muscles of the forearm) and by the demonstration of a collateral circulation (Fig. 3).

Statistical analysis was performed using the chi-square test. Sen- sitivity was defined as the ratio of thrombosis detected by the Dopp- ler to the total number of vein thromboses detected by venography. Speciflty was defined as the ratio of Doppler negative investigations to negative venography investigations.

Results

Evidence of thrombosis was diagnosed on venography in 15 of 40 patients. The sites of thrombosis according

Fig. 2. Normal results o f venous Doppler of the right subclavian vein: note that venous flow increases with inspiration and decreases with expiration or during the Valsalva maneuver

239

Table 1. Extension of vein thrombosis related to catheter placement

Site of Basilic Right Subclavian Brachiocephalic thrombosis axillary jugular vein trunk

Site of vein vein insertion

Basilic vein (n = 26) 9 - 7 3 Right jugular vein (n = 6) - 1 0 1 Subclavian vein (n = 8) - - 5 l

to catheter placement are shown in Table 1. No corre- lation was seen between the presence of deep vein thrombosis and the age of the patients, the type of the surgical procedure, the presence of fever, raised white cell count, thrombocythemia, or inter-current infec- tion. Also, no correlation was seen between the dura- tion of catheter placement (but the finding of a vein thrombosis after venography led to catheter removal, shortening the time of catheter placement, even in asymptomatic patients). Local symptoms of redness, tenderness, venous induration and edema were noted in only 2 patients at the time of venography.

Four of the 15 patients with catheter-related deep vein thrombosis and 1 of the 25 patients without ve- nous thrombosis had a positive blood culture. This difference was significant. In 3 cases, culture of the catheters grew organisms that were also detected in the blood cultures.

The Doppler results correlated with venography findings in 38 patients, in 24 patients both Doppler and venography were normal; in 14 patients both Doppler and venography confirmed a deep vein thrombosis. One false-negative and one false-positive result by the Doppler technique were noted. The sensi-

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3 distal compression

Fig. 3. Thrombosis of the left subclavian vein: note the lack of respi- ratory variation and lack of response to distal compression

240 E Bonnet et al.: Evaluation of Doppler examination

tivity of the Doppler technique was 0.93 and the speci- ficity 0.96. The Doppler also allowed a diagnosis in 12 of the 13 patients without clinical symptoms of deep vein thrombosis. Abnormal collateral veins, confirmed by venography, were discovered by the Doppler tech- nique. Only 2 of these patients had clinical evidence of

collateral veins on the arm and upper hemithorax.

Discussion

Thrombosis and the potential infectious complica- tions of permanent venous catheters are a major con- cern for clinicians. Venous thromboses are more fre- quent with polyurethane catheters than with silicone catheters [10]. In this study, polyethylene catheters were used because they were intended for short-term postoperative use. Even in this situation and despite the use of low-dose heparin, we have demonstrated a high incidence of catheter-related venous thrombosis, as has previously been shown by others [5]. As previ- ously reported the occurrence of deep vein thrombosis is associated with bacterial growth in blood cultures [3]. A thrombus may form on the catheter and/or the vessel walls and extend until complete venous occlu- sion occurs. Unfortunately, clinical signs of thrombo- sis occur infrequently and often too late in the evolu- tion of venous thrombosis to permit early diagnosis [5, 11].

This study shows that the Doppler technique is an accurate method of detecting catheter-related deep vein thrombosis, even when the clinical signs are lack- ing.

The absence a Doppler flow signal from a vein be- ing studied is strongly suggestive of occlusion of that vein compared to the opposite side. The development of a collateral circulation confirms that finding in the majority of cases. False-positive results may be due to a diminished venous signal related to the incorrect set- ting of the probe. False-negative results may be due to the detection of collateral vessels misinterpreted as the venous flow in the main deep vein. The one false-nega- tive result from the Doppler examination was documented at the beginning of the study, and in- creasing experience with the technique may have im- proved its accuracy. In this study, Doppler examin- ations were performe d by trained physicians; this cer- tainly accounts for the high sensitivity and specificity documented. Other techniques associated with Dopp- ler such as echographic examination of the venous trunk might also improve the accuracy of the tech- nique even in inexperienced hands. The Doppler flow

detector is readily available in many hospitals and rep- resents a valuable primary examination for the di- agnosis of venous thrombosis. It is a non-invasive technique which causes minimal disturbance to the patient, and the procedure may be repeated frequently.

Early removal of central venous catheter has been advocated to avoid septic and thrombotic complica- tions. Doppler examination might avoid the inappro- priate replacement of catheters in sites of thrombosis, which could lead to other traumatic complications [121.

In conclusion, the venous Doppler examination appears to be a valuable technique for the early detec- tion of catheter-related venous thrombosis. We pro- pose that it is a useful screening procedure, but the best results are achieved when the technique is per- formed by experienced physicians.

References

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Dr. E Bonnet D~partement d'Anesth6sie R6animation II H6pital Henri Mondor F-94010 Creteil Cedex France