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Graduated compression stockings and intermittent pneumatic compression boots reduce the incidence of deep vein thrombosis. Recent studies suggest that the simultaneous use of these devices may have a synergistic prophylactic effect; however, conflicting reports also exist. Using duplex imaging, we analyzed the effect on peak venous velocity in the superficial femoral vein produced by the individual and simultaneous use of graduated compression stockings and intermittent pneumatic compression boots. Normal volunteers and postoperative patients were examined. The use of intermittent pneumatic compression boots significantly increased the peak venous velocity relative to rest, whereas the use of graduated compression stockings did not alter the peak venous velocity. Also, the addition of graduated compression stockings to legs already being treated with intermittent pneumatic compression boots did not produce a further augmentation of peak venous velocity. This study demonstrates that the simultaneous use of graduated compression stockings and intermittent pneumatic compression boots does not produce a synergistic augmentation of peak venous velocity in the superficial femoral vein.

Objective: To determine the rate of use of prophylaxis for venous thromboembolism in high-risk hospital patients., Design: A retrospective medical record review., Setting: A community-wide study in 16 short-stay hospitals in central Massachusetts., Patients: A total of 2017 patients with multiple risk factors for venous thromboembolism., Measurements and Main Results: On the basis of age, length of hospitalization, and the presence of at least one additional major risk factor, 17% of 151,349 discharges (25,410 patients) were identified as being at high risk for venous thromboembolism. Eight percent of these discharges were randomly selected for medical record review. Prophylaxis for venous thromboembolism was received by 32% of these high-risk patients. Prophylaxis use among the 16 study hospitals varied widely, ranging from 9% to 56%, and was higher in teaching hospitals than in nonteaching hospitals (44% compared with 19%; P less than 0.001). One or more of the following methods of prophylaxis was used: low-dose heparin (78%), intermittent calf compression (13%), warfarin (12%), and inferior vena caval filter (3%). Use of prophylaxis increased with the number of risk factors identified (P less than 0.001)., Conclusion: Prophylaxis for venous thromboemobolism is underused, particularly in nonteaching hospitals.

A community-wide study was conducted in 16 short-stay hospitals in metropolitan Worcester, Mass, to examine the incidence and case-fatality rates of deep vein thrombosis and pulmonary embolism in patients hospitalized between July 1, 1985, and December 31, 1986. The average annual incidence of deep vein thrombosis alone was 48 per 100,000, while the incidence of pulmonary embolism with or without deep vein thrombosis was 23 per 100,000. The incidence rates of deep vein thrombosis and pulmonary embolism increased exponentially with age. The in-hospital case-fatality rate of venous thromboembolism was 12%. Among patients discharged from the hospital, the long-term case-fatality rates were 19%, 25%, and 30% at 1, 2, and 3 years after hospital discharge. Extrapolation of the data from this population-based study suggests that there are approximately 170,000 new cases of clinically recognized venous thromboembolism in patients treated in short-stay hospitals in the United States each year, and 99,000 hospitalizations for recurrent disease. Because of the silent nature of this disease and the low rate of autopsy in the United States, the total incidence, prevalence, and mortality rates of venous thromboembolism remain elusive.

Venous thromboembolic disease is a common, potentially life-threatening, but preventable complication of surgery. Venographic studies have shown a high incidence of deep vein thrombosis in patients who do not receive prophylaxis. The long-term sequelae of deep vein thrombosis in these patients can be disabling, but the exact prevalence of post-thrombotic complications has not been well documented. Fatal pulmonary embolism has been reported in 0.5% to 1% of patients after major abdominal surgery and in 2% to 6% after total hip replacement. Several methods of prophylaxis against venous thromboembolism have demonstrated efficacy, but a surprising number of patients still do not receive prophylaxis. A medical record review in 16 hospitals recently disclosed that only 32% of high-risk patients received prophylaxis, with a range from 9% in a community hospital to 56% in a major teaching hospital. The possible reasons for this comparatively low rate of utilization are discussed. Current issues and future trends in the prophylaxis of venous thromboembolism are briefly summarized.

Controversy exists as to whether patients suspected of having deep vein thrombosis (DVT) can be studied safely without venography, with its attendant expense, inconvenience, and potential risk. We used impedance plethysmography (IPG) in 1,464 consecutive patients suspected of having DVT, with 96% of these patients with normal IPGs, there were no fatal pulmonary emboli (PE). The incidence of nonfatal PE was 1%. In 284 outpatients suspected of having DVT, but discharged without treatment because of normal IPGs, only one patient returned with subsequent symptoms of DVT (0.4%). Noninvasive testing with IPG is a safe and highly cost-effective alternative to venography for routine management of patients suspected of DVT.

Venous occlusion impedance plethysmography (IPG) is an objective noninvasive test which is widely employed for the detection of deep venous thrombosis (DVT) in the lower extremities. The IPG technique is easily adapted to the evaluation of upper extremity venous thrombosis, as demonstrated in 46 patients with symptoms of axillary and subclavian venous thrombosis (88 limbs) and 26 normal volunteers (52 limbs). Venograms were obtained in 18 patients (22 limbs) and correlated in all cases with the previous IPG interpretation. The test procedure and interpretation criteria for the noninvasive detection of upper extremity deep venous thrombosis are similar to those previously developed for the lower extremities, but with more emphasis on comparison with the contralateral limb. Vascular laboratories performing IPG for lower extremity DVT should be able to employ this test for the detection of upper extremity venous thrombosis as well.

The objective of this paper is to review the theoretical basis and clinical application of electrical impedance plethysmography in the noninvasive evaluation of peripheral arterial and venous disease. Theoretical, experimental and clinical studies have now demonstrated a direct relationship between electrical impedance changes and limb volume changes. Potential sources of error have also been identified. This has led to the development of clinical tests based on impedance plethysmography for the detection of peripheral arterial disease, venous insufficiency and venous outflow obstruction. Impedance plethysmography, using the method of venous occlusion, is presently the most commonly employed noninvasive method for the detection of deep venous thrombosis.

Although impedance plethysmography (IPG) is a test of recognized value in the diagnosis of acute proximal deep venous thrombosis (DVT), its meaning in patients with bilaterally abnormal IPGs is unclear. Consequently, we sought to determine the clinical significance of the bilaterally abnormal IPG in hospitalized patients. In a five-month prospective study, 19% (81/425) of all IPGs done at our institution were bilaterally abnormal (55% of all abnormal IPGs). Acute proximal DVT was found in 26% (14/53) of patients with bilaterally abnormal IPGs who underwent further diagnostic testing. Thirty-five percent of the patients with DVT were found to have either bilateral lower extremity DVT or clots in the inferior vena cava. A numerical score, the venous function index (VFI), was computed for the 101 legs for which further definitive diagnostic evaluations for DVT had been completed. The mean VFI of seven for legs with acute proximal DVT was significantly less than the mean VFI of 13 for legs with no DVT. Fifty percent of legs with a VFI less than or equal to five had DVT, whereas only 7% of legs with a VFI greater than 15 had DVT. The bilaterally abnormal IPG is a common clinical occurrence, is frequently associated with acute DVT, and the VFI is helpful in discriminating legs with acute proximal DVT from normal legs in patients with a bilaterally abnormal IPG.

This article briefly reviews the advantages and limitations of currently available methods for the diagnosis of deep vein thrombosis (DVT). Clinical evaluation alone is inadequate but still useful in assessing the need for further testing. The medical history, especially the detection of risk factors for DVT, is as important as the physical examination. Confirmation by objective diagnostic tests is essential. Venography has been the traditional standard for determining the optimal management of DVT, but has significant limitations which are not widely appreciated. Noninvasive diagnostic methods for DVT are essential for effective management, but the optimal method for a particular hospital depends on the personnel and resources available.

A procedure for observing blood flow during early reactive hyperemia, which uses prolonged venous occlusion following 3 min of arterial occlusion, is described. A mercury strain gauge was applied around the mid-calf and 3 tracings were simultaneously recorded during reactive hyperemia: the change in venous volume, its derivative and amplified pulse waves. The method was evaluated in animals, normal volunteers and in patients with symptoms of arterial insufficiency. This bedside procedure was found to be convenient and practical. Peak flow during reactive hyperemia was found to have an accuracy comparable to the ankle/arm pressure index in distinguishing between normal, stenotic or occluded lower extremity arterial systems. In addition, it proved more accurate than pressure measurements in diabetic patients with incompressible calcified vessels.

Venous occlusion plethysmography (VOP) was originally developed to study the physiology of the arterial circulation in the extremities. Improvements in plethysmographic instruments have now made bedside evaluation of peripheral hemodynamics feasible. In recent years, VOP has been employed for the detection of deep vein thrombosis. Combined analysis of the venous volume increase and the subsequent venous outflow in 3 sec, and measured by impedance plethysmography, has produced a 95% correlation with venography in detecting thrombosis of the popliteal, femoral, and iliac veins in 390 limbs. The method is inadequate for detection of isolated calf thrombi.

An association between venous thrombosis and cancer was first suggested by Armand Trousseau and subsequently confirmed by multiple postmortem studies. In a previous study, patients with pulmonary embolism, as assessed by pulmonary angiography, were at significantly increased risk of occult cancer with a comparison group of patients without pulmonary embolism. This nonconcurrent prospective epidemiologic study extends these findings by demonstrating a significantly increased risk of occult cancer in patients with deep venous thrombosis (DVT) confirmed by impedance plethysmography as compared with those with suspected DVT in whom the diagnosis was ruled out. Differences in the incidence of malignant neoplasms were greatest within the first two years after the diagnosis of DVT, and patients younger than 50 years with venous thrombosis were at particularly increased risk of occult cancer (relative risk, 19.0). These findings indicate that all patients with DVT or pulmonary embolism should have an appropriate diagnostic workup and careful follow-up, particularly with regard to the risk of occult cancer.

Intracranial pressure (ICP) is often measured from intraventricular catheters, a technique that allows therapeutic drainage of ventricular cerebrospinal fluid (CSF) as an aid in controlling ICP and circumventing obstruction. Drainage of CSF simultaneously with ongoing ICP measurement has been advocated as safe and efficient, and devices are commercially available to permit this practice; however, this concept has been seriously challenged, based on clinical observations. The inaccuracy induced by simultaneous CSF drainage and ICP monitoring is quantitated in this report in a mechanical brain model using a standard ventricular catheter. The following conclusions have been confirmed: 1) rapid CSF drainage induces a severe artifactual reduction in measured ICP, more extreme at higher pressures; 2) calibrated slower rates of CSF drainage produce a severe, although less immediate, reduction in measured ICP; 3) severe artifact appears even in the presence of continuous CSF outflow, so a system that measures ICP only in the presence of CSF flow does not prevent artifact; 4) with simultaneous CSF drainage, measured ICP is determined more by the outflow pressure setting than by actual brain pressure; 5) Since ICP elevation of 25 to 30 mm Hg blocks CSF production, even slow fluid drainage at high pressures should ultimately lead to ventricular collapse and severe artifact.