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Biomedical subjects

F A Anderson

Publications and source records attributed to F A Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1991

A population-based perspective of the hospital incidence and case-fatality rates of deep vein thrombosis and pulmonary embolism. The Worcester DVT Study.

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.

Adolescent↗
PubMed1989

Erroneous measurement of intracranial pressure caused by simultaneous ventricular drainage: a hydrodynamic model study.

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.

Brain↗
PubMed1987

The clinical implications of bilaterally abnormal impedance plethysmography.

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.

Adolescent↗
PubMed1987

Occult malignant neoplasm in patients with deep venous thrombosis.

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.

Aged↗
PubMed1986

Diagnostic approaches for deep vein thrombosis.

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.

Humans↗
PubMed1984

Impedance plethysmography in the diagnosis of arterial and venous disease.

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.

Blood Volume↗
PubMed1983

Noninvasive evaluation of arterial occlusive disease.

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.

Animals↗
PubMed1982

Suspected deep vein thrombosis. Management by impedance plethysmography.

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.

Adolescent↗
PubMedDate not supplied

Diagnostic methods for deep vein thrombosis.

Clinical diagnosis of deep vein thrombosis (DVT) is unreliable, and treatment should not be undertaken without objective confirmation. The traditional 'gold standard' for the diagnosis of DVT has been venography, but ultrasonic imaging has now replaced venography as the new diagnostic standard in many hospitals. A variety of noninvasive physiologic tests are also useful in selected circumstances. These include plethysmography, Doppler flow studies, radioisotope tests, thermography and peripheral blood tests which reflect activation of coagulation or thrombolysis. We describe the clinical application of these diagnostic procedures, both for symptomatic patients suspected to have DVT and for asymptomatic patients at high risk for DVT. The selection of an appropriate diagnostic modality depends upon institutional capabilities, cost-effectiveness and individual patient circumstances.

Computer Systems↗
PubMedDate not supplied

The prevention of venous thromboembolism: a statewide evaluation of practices in Massachusetts.

The objective of this study was to determine the proportion of Massachusetts Medicare patients who received prophylaxis for venous thromboembolism following colectomy, hysterectomy or total hip arthroplasty. The sample frame was all 90 Massachusetts acute care hospitals, and the time frame was 1 April to 30 September 1994. The patients discharged with an International Classification of Disease (ICD-9-CM) discharge diagnostic code (recorded in the Massachusetts Medicare Claims Database) for colectomy, hysterectomy or total hip arthroplasty were used to identify the target patient population. The sample population comprised 1397 patients randomly selected from the target population, including 467 total hip arthroplasties, 474 colectomies, and 456 hysterectomies. Medical records were reviewed by trained nurse abstractors who collected information on the use of prophylaxis for venous thromboembolism. Prophylaxis for venous thromboembolism was employed by surgeons practicing in Massachusetts hospitals in 93 per cent of total hip arthroplasty cases (regional variation 85-98 per cent), 84 per cent of colectomies (regional variation 57-93 per cent), 66 per cent of hysterectomies (regional variation 35-71 per cent), and in 87 per cent of the subset of 111 hysterectomies with malignancy (regional variation 25-100 per cent). The results of this statewide study demonstrated significant regional and hospital-to-hospital variation in use of prophylaxis for venous thromboembolism following major surgery. A lower rate of prophylaxis use was observed in hospitals with fewer than 200 beds and in hospitals that did not have teaching programmes. Hospitals with below-average rates of prophylaxis were targeted for intensive quality improvement interventions.

Anticoagulants↗
PubMedDate not supplied

Venous occlusion plethysmography for the detection of venous thrombosis.

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.

Blood Circulation↗