Home-Diagnosis of Deep Venous Thrombosis with Impedance Plethysmography

Deep Vein Thrombosis in Intravenous Drug Users: An Invisible Global Health Burden

The prevalence of intravenous drug use has increased in the past decade and it represents an important risk factor for deep vein thrombosis. Intravenous drug use is a global problem, with the main culprit being heroin. Peer pressure and poverty in high-risk groups such as sex workers, females, and young adults raise the risk of intravenous drug use, which expresses itself in the form of venous thromboembolism eventually. Deep vein thrombosis typically manifests itself eight years after the initial intravenous drug administration, rendering it a silent killer. Aiming to review and summarize existing articles in this context, we performed an exhaustive literature search online on PubMed and Google Scholar indexes using the keywords "Deep Venous Thrombosis (DVT)" and "Intravenous Drug Users (IVDU)." English articles that addressed epidemiology, pathogenesis, clinical manifestations, diagnosis, differential diagnosis, management, and outcomes of DVT, including those in IVDU, were selected and analyzed. The pathogenesis of DVT development in IVDU is mainly attributed to the interplay of trauma to the vessel by repeated injection and the injected drug itself. The right-sided femoral vein is the most common vein affected. Prevalent clinical presentations include local pain, swelling, and redness with typical systemic symptoms including fever, cough, dyspnea, and chest pain on top of addiction features. There appeared to be a delay in reporting symptoms, which was most likely due to the social stigma attached to IVDU. There are over 50 conditions that present with swollen and painful limbs comparable to DVT in IVDU, making precise diagnosis critical for timely treatment. Venous ultrasound is the method of choice for diagnosing DVT. Extended anticoagulant therapy with low-molecular-weight heparin combined with warfarin is the recommended treatment. Intravenous drug abusers having DVT are affected by multiple complications and poorer outcomes such as slower recovery, recurrent venous thromboembolism (VTE), and a longer hospital stay, which put them at higher risk of morbidity, mortality, reduced productivity, and economic burden.

Peripheral vascular disease assessment in the lower limb: a review of current and emerging non-invasive diagnostic methods

BACKGROUND

Worldwide, at least 200 million people are affected by peripheral vascular diseases (PVDs), including peripheral arterial disease (PAD), chronic venous insufficiency (CVI) and deep vein thrombosis (DVT). The high prevalence and serious consequences of PVDs have led to the development of several diagnostic tools and clinical guidelines to assist timely diagnosis and patient management. Given the increasing number of diagnostic methods available, a comprehensive review of available technologies is timely in order to understand their limitations and direct future development effort.

MAIN BODY

This paper reviews the available diagnostic methods for PAD, CVI, and DVT with a focus on non-invasive modalities. Each method is critically evaluated in terms of sensitivity, specificity, accuracy, ease of use, procedure time duration, and training requirements where applicable.

CONCLUSION

This review emphasizes the limitations of existing methods, highlighting a latent need for the development of new non-invasive, efficient diagnostic methods. Some newly emerging technologies are identified, in particular wearable sensors, which demonstrate considerable potential to address the need for simple, cost-effective, accurate and timely diagnosis of PVDs.

Diagnosis and Treatment of Lower Extremity Deep Vein Thrombosis: Korean Practice Guidelines

Lower extremity deep vein thrombosis is a serious medical condition that can result in death or major disability due to pulmonary embolism or post-thrombotic syndrome. Appropriate diagnosis and treatment are required to improve symptoms and salvage the affected limb. Early thrombus clearance rapidly resolves symptoms related to venous obstruction, restores valve function and reduces the incidence of post-thrombotic syndrome. Recently, endovascular treatment has been established as a standard method for early thrombus removal. However, there are a variety of views regarding the indications and procedures among medical institutions and operators. Therefore, we intend to provide evidence-based guidelines for diagnosis and treatment of lower extremity deep vein thrombosis by multidisciplinary consensus. These guidelines are the result of a close collaboration between interventional radiologists and vascular surgeons. The goals of these guidelines are to improve treatment, to serve as a guide to the clinician, and consequently to contribute to public health care.

Developments in diagnosis and classification of venous disorders: non-invasive diagnosis

PURPOSE

This review examines the many techniques that have been used for the non-invasive diagnosis of acute and chronic venous disease and was conducted by members of the Committee on Research of the American Venous Forum. It proposes to identify those techniques with the greatest clinical potential, to suggest algorithms for the clinical application of non-invasive techniques in the identification of acute deep venous thrombosis and chronic venous insufficiency, and to identify areas of deficient knowledge and potential areas for future research initiatives.

METHODS

Review of pertinent clinical and research material.

RESULTS

Impedance plethysmography and ultrasonic imaging are the primary non-invasive tools used in the diagnosis of acute deep venous thrombosis. At present, ultrasonic imaging techniques are recommended on the basis of greater diagnostic accuracy in recent comparative clinical trials. Data would suggest that serial evaluation should probably be viewed as the preferred option for symptomatic patients with a negative initial examination and the presence of risk factors or physical findings suggesting a proximal deep venous obstruction/thrombosis. Chronic venous disease is the result of valvular incompetence, with or without associated venous obstruction. Duplex imaging can be used to determine the location and extent of reflux; however, there are reported procedural variations in the performance and interpretation of such studies. Recent innovations in air plethysmography may provide a means of quantifying volume changes, and permit an objective characterization of venous reflux and calf pump efficiency.

CONCLUSIONS

There are still significant questions that need to be answered by well-designed research initiatives. Research applications that incorporate non-invasive diagnostic techniques may involve the diagnosis, treatment and natural history of acute deep venous obstruction/thrombosis and chronic venous insufficiency, assessment prior to and following venous reconstruction, and the basic science aspects of acute and chronic venous disease. At present, a lack of common standards is, by far, the greatest impediment to an organized research approach to venous disease.

Diagnostic management of venous thromboembolism

The accuracy of diagnostic methods for the diagnosis of deep vein thrombosis and pulmonary embolism in symptomatic patients is critically reviewed. In addition, the safety of withholding anticoagulant therapy from patients with suspected deep vein thrombosis or pulmonary embolism in whom the qualified diagnostic strategy was normal is evaluated by determining the frequency of venous thromboembolic complications during 3 months of follow-up. It is shown that the currently used available diagnostic techniques for deep vein thrombosis are all able to identify the majority of patients who indeed have venous thrombosis. However, as result of its accuracy and practical advantages, compression ultrasound is the test of choice in the evaluation of symptomatic patients. Patients with a normal test outcome should be re-tested to detect the small proportion of patients with proximally extending calf vein thrombosis. In the strategy of repeated diagnostic testing, impedance plethysmography could be used as an alternative to ultrasonography. To obtain a reduction in repeat tests various diagnostic strategies have been evaluated and it was shown that these strategies, using non-invasive tests, can be as accurate and safe as the invasive reference strategy. The safeties of the various strategies were very similar; however, important differences were observed with respect to the practical implementation of the various diagnostic strategies. Simplification of the repeated testing strategy by using a D-dimer assay and/or a clinical decision rule seems to be promising. The reference standard for the diagnosis of pulmonary embolism remains pulmonary angiography. Several strategies based on non-invasive diagnostic methods have been evaluated for their safety and complexability. Perfusion-ventilation lung scanning is the most thoroughly evaluated non-invasive technique so far. It seems safe to withhold anticoagulant therapy in patients suspected of pulmonary embolism with a normal perfusion lung scan result; however, further testing is needed in the case of a non-diagnostic perfusion-ventilation lung scan result. At this moment angiography is the method of choice in this category of patients. D-dimer assays, clinical decision rules and ultrasound examinations of the legs seem to have a high potential to limit the need for angiography. Also, spiral computerized tomography and magnetic resonance imaging are promising techniques, but their role in the diagnostic management of pulmonary embolism is still uncertain.

Improved selection criteria for ordering stat venous ultrasounds from the emergency department

BACKGROUND

The accuracy and convenience of venous ultrasound (VU) to exclude deep vein thrombosis (DVT) has led to indiscriminate use and low positive yield rates.

METHODS

A total of 256 patients were referred from our emergency department (ED) for stat VU during a 2-year period (1995 to 1996). The VUs were interpreted as normal in 198 (77%). Positive findings were discovered in 58 (23%), with DVT accounting for 43 (17%). Retrospective multivariant analysis was used to identify predictive indicators.

RESULTS

Unilateral leg swelling/edema identified 36 of 40 (90%) patients with DVT and 8 of 10 (80%) with other thrombotic disorders (saphenous and/or chronic venous thrombosis). A history of leg pain with prior DVT or recent trauma < or =3 days' duration increased DVT duration to 98% (39 of 40). Using these criteria, a 47% charge reduction would have been recognized.

CONCLUSIONS

Improving ED screening criteria can safely increase yield rate and reduce charges with minimal loss of VU sensitivity.

Diagnosis of deep vein thrombosis

In this chapter, various tests have been discussed in the diagnosis of DVT and have been classified according to various patient categories. To summarize, the following guidelines may be of clinical use in the management of patients with suspected DVT. Acute, First Event of Suspected DVT These patients often suffer from occluding, proximal thrombi. Therefore, noninvasive tests such as CUS or IPG are most suitable for these patients. If an abnormal CUS or IPG result is found, the diagnosis is virtually proven, and this may serve as a basis to treat the patient with anticoagulants. If a normal CUS or IPG result is obtained, serial testing is indicated to detect extending calf vein thrombi or nonoccluding DVT, which becomes occlusive at follow up. Anticoagulants may be withheld safely if the test remains normal within 1 week. Acute, Recurrent Suspected DVT These patients may have residual thrombi present, which makes the noninvasive tests (CUS/IPG) less useful. However, if a normal noninvasive test was documented previous to the acute recurrent event, this test may be used. If an abnormal test result is found in the presence of a documented, normal previous-test outcome, this may serve as a basis for anticoagulant therapy. Although no formal studies have been performed to evaluate the safety of withholding anticoagulants if a normal CUS or IPG result is obtained, serial testing is likely to be adequate in these circumstances. Phlebography is the only truly evaluated approach, and this could be considered in all suspected recurrent DVT. Furthermore, contrast venography is the test of choice to discern acute from old thrombi. Asymptomatic DVT in High-Risk Patients The majority of these thrombi are mostly localized in the calf veins only and are often nonocclusive. This makes noninvasive tests unreliable for their detection. Therefore, only contrast venography should be used in this patient category.

The significance of venography in the management of patients with clinically suspected pulmonary embolism

The accurate diagnosis of pulmonary embolism causes many problems. Clinical signs are non-specific, and ventilation-perfusion lung scanning has high sensitivity but variable specificity. In more than 90% of cases a pulmonary embolus is derived from deep venous thrombosis in the lower extremities. We have performed a prospective study to evaluate venography in the management of patients with suspected pulmonary embolism. A total of 169 patients were included in the study, and a ventilation-perfusion scan was performed in all cases. Forty-four (26%) patients had a normal scan and treatment was not given (group A). The other 125 (74%) patients, who had an abnormal scan, underwent bilateral venography. Venous thrombosis was demonstrated in 63 patients, and they were treated with oral anticoagulants for 3 months (group B). The remaining 62 patients, who showed no venous thrombosis, did not receive anticoagulant therapy (group C). During follow-up, 1 patient in group A, 3 patients in group B and 1 patient in group C developed a new deep venous thrombosis. One patient in group B suffered a pulmonary embolus. It is concluded that venography of the lower extremities can be of additional value in the management of patients with pulmonary embolism when the lung scan does not provide sufficient information.

Pulmonary embolism. How to 'nail down' the diagnosis

Pulmonary embolism is a common problem in hospitalized patients. Because its initial symptoms may be nonspecific, pulmonary embolism may be difficult to diagnose. A high index of suspicion, together with careful selection of diagnostic tests, is essential. An algorithm for clinical assessment of suspected pulmonary embolism is presented here.

Contrast venography: from gold standard to 'golden backup' in clinically suspected deep vein thrombosis

In a series of 180 patients, clinically suspected of having deep venous thrombosis (DVT), contrast venography was compared with radionuclide phlebography, duplex ultrasonography and strain gauge plethysmography. In most patients lung scintigraphy was also performed to detect pulmonary embolism (PE). Venography was performed on a routine basis. All venograms were read by at least two observers (radiologists or radiologist/resident) and an inter-observer agreement was reached of 96% with a kappa value of 0.935. In six patients venography was technically impossible or inadequate, 58% of the patients actually had DVT and 26% developed pulmonary embolism (PE). Of the patients with proven DVT, 43% developed PE. Of the three other methods duplex scanning scored the best for the detection of proximal thrombosis, with 92%, 90% and 9.2, and strain gauge plethysmography the worst, with values of 72%, 78% and 3.2 for, respectively, sensitivity, specificity and positive likelihood ratio's. On the basis of the presented material and the current literature it is concluded that the choice for a screening test for proximal thrombosis could best be made on the basis of (local) availability, cost-effectiveness and patient comfort. Duplex ultra-sonography is tipped as the most promising method, accepting that distal thrombosis (calf veins) does not play an important role in PE. Contrast venography should be used as a 'golden backup' in any case of doubt.

Diagnostic accuracy of computerized impedance plethysmography in the diagnosis of symptomatic deep vein thrombosis: a controlled venographic study

The aim of our study was to evaluate the sensitivity, the specificity, and the positive and negative predictive values of a recently developed computerized impedance plethysmography (CIP) in the diagnosis of deep vein thrombosis (DVT); 117 consecutive outpatients with a clinical suspicion of DVT were evaluated. After informed consent was obtained, a CIP and, within twenty-four hours, a venography of the symptomatic lower limb were performed in each patient. The results of CIP were compared with the results of contrast venography, which was considered as the gold standard. As far as the diagnosis of both proximal and distal DVT was concerned, the accuracy of CIP was 88.5%; the sensitivity and specificity were 95.1% and 83.6%, respectively; the positive and negative predictive values were 81.2% and 95.8%, respectively. When the diagnosis of only proximal deep vein thrombosis was considered, the accuracy of CIP was 88.8%; the sensitivity and specificity were 97.1% and 83.6%, respectively; the positive and negative predictive values were 79.0% and 97.8%, respectively. The authors conclude that the newly developed CIP has a diagnostic accuracy similar to that of traditional impedance plethysmography. Moreover, being completely automated and portable, CIP can play an important role in the bedside diagnosis of DVT.

Serial impedance plethysmography for suspected deep venous thrombosis in outpatients. The Amsterdam General Practitioner Study

Diagnosis of deep venous thrombosis by clinical signs and symptoms is unreliable, but contrast venography is relatively expensive and invasive. We therefore evaluated the use of impedance plethysmography as a noninvasive alternative in 426 consecutive outpatients with clinically suspected acute deep venous thrombosis. Four sequential impedance plethysmograms were obtained on days 1, 2, 5, and 10 of the study. In 289 patients (68 percent), the results of all four studies were normal, and these patients were not treated with anticoagulants. One of these patients may have had a minor pulmonary embolus during the 10-day study period. During a six-month follow-up of all patients, none of the 289 patients whose plethysmograms were normal died of venous thromboembolism or presented with suspected pulmonary embolism. In 137 patients (32 percent), the impedance plethysmograms were abnormal; 117 (85 percent) had the abnormal results on their first test, and 20 (15 percent) had them on subsequent tests. All patients with abnormal plethysmograms also underwent contrast venography, which confirmed the diagnosis of deep venous thrombosis in 92 percent. We conclude that the diagnostic accuracy of repeated impedance plethysmography compares favorably with that of venography and that the technique is a safe and effective noninvasive approach to the diagnosis and care of outpatients with clinically suspected acute deep venous thrombosis.

Accuracy of strain-gauge plethysmography as a diagnostic test in clinically suspected deep venous thrombosis

Strain-gauge plethysmography (SGP) is currently employed in the diagnosis of deep venous thrombosis (DVT), but its accuracy has not been adequately tested. In this study we evaluated SGP against venography in 209 consecutive patients referred to us because of clinically suspected DVT of lower limbs. Venography was performed bilaterally if symptoms or signs suggesting DVT were present in both limbs. It was always performed after SGP and independently assessed. A total of 269 limbs could be evaluated with both SGP and venography, which disclosed DVT in 128 limbs of 110 patients. There were 109 proximal and 19 distal DVT. Out of the 128 limbs with DVT, SGP was positive in 114 (sensitivity = 89%) using Maximal Venous Outflow (MVO) as the diagnostic parameter, and positive in 116 (sensitivity = 91%) using an index obtained multiplying MVO for Venous Capacitance (VC). Out of the 141 venographically negative limbs, there were 6 false positive results using MVO and 9 using MVO X VC (specificity = 96% and 94% respectively). SGP sensitivity in acute proximal venous thrombosis was 97%, while it was about 60% in distal DVT. Most false positive results occurred in patients with edema of cardiac origin. SGP appears to be a useful diagnostic test in suspected DVT of lower limbs, particularly when both MVO and the index MVO X VC are used.