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Biomedical subjects

R D Hull

Publications and source records attributed to R D Hull.

138 records · Page 8Linked to original sources
PubMed1983

The diagnosis of acute, recurrent, deep-vein thrombosis: a diagnostic challenge.

Recurrent venous thrombosis presents a diagnostic challenge. Venography, impedance plethysmography and fibrinogen leg scanning all have potential limitations, and their role in this context has not been evaluated. We performed a prospective cohort study evaluating impedance plethysmography and leg scanning, plus venography, using outcome on long-term follow-up as the end point in 270 patients with clinically suspected recurrent deep-vein thrombosis. Anticoagulant treatment was withheld in the 181 patients negative by noninvasive testing and was given in patients positive by impedance plethysmography if leg scanning was positive or if intraluminal filling defects were detected by venography. The validity of this approach was tested by long-term follow-up. Three of 181 patients (1.7%) negative by noninvasive testing had a recurrence, compared with 18 of 89 (20%) with positive findings (p less than 0.001). Our objective diagnostic approach has high clinical utility; an objective rationale for withholding or giving treatment was established in 95% of patients.

Acute Disease↗
PubMed1983

Pulmonary angiography, ventilation lung scanning, and venography for clinically suspected pulmonary embolism with abnormal perfusion lung scan.

Inherent contradictions in current diagnostic recommendations for pulmonary embolism have created considerable confusion and controversy. To resolve these contradictions, we did a prospective study of ventilation-perfusion scanning, pulmonary angiography, and venography in consecutive patients with clinically suspected pulmonary embolism and abnormal perfusion scans. Ventilation scanning increased the probability of pulmonary embolism in patients with large perfusion defects and ventilation mismatch, but a ventilation-perfusion match was not helpful in ruling out pulmonary embolism. Small perfusion defects with mismatch had neither sufficiently high nor low probability to be of diagnostic value. The observed frequency of proximal vein thrombosis (19% to 51%) and its association with the range of ventilation-perfusion defects have important implications for management of pulmonary embolism. Pulmonary angiography is required in combination with venography in most patients with perfusion abnormalities because the probability of pulmonary embolism is neither sufficiently high nor low to confirm or exclude pulmonary embolism.

Adolescent↗
PubMed1983

Strategies to diagnosis and screening of deep venous thrombosis and pulmonary embolism.

The clinical diagnosis of venous thrombosis or pulmonary embolism is unreliable and must be confirmed by objective methods. The available objective diagnostic tests which have been evaluated for deep vein thrombosis and shown to be of value are venography, IPG, and (125I)-fibrinogen leg scanning. All these methods have certain disadvantages, but the potential advantages of accurate diagnosis using a combination of non-invasive tests as an alternative to venography are considerable. This approach is cost-effective, because it avoids unnecessary hospital admissions and reserves anticoagulant treatment for those in whom diagnosis of deep venous thrombosis is confirmed. Non-invasive techniques can also be used to screen high risk surgical patients for whom no inexpensive, effective, safe form of prophylaxis is available. The correct diagnostic approach in suspected pulmonary embolism remains to be established. The initial screening by perfusion lung scan with ventilation studies, followed by either the demonstration of pulmonary emboli with angiography, or the demonstration of peripheral deep venous thrombosis, is considered to be the safest approach.

Fibrinogen↗
PubMed1982

Cost-effectiveness of primary and secondary prevention of fatal pulmonary embolism in high-risk surgical patients.

Because death due to pulmonary embolism is relatively rare following general surgery, many question the need for prophylaxis. In addition, there has been reluctance to apply new interventions whose cost-effectiveness has not been adequately evaluated. A cost-effectiveness analysis based on over 1000 high-risk patients undergoing abdominothoracic surgery, with effectiveness measured in terms of numbers of deaths from pulmonary embolism averted, has shown subcutaneous administration of heparin in low doses starting 2 hours before the operation to be the most cost-effective of several active approaches to prophylaxis. It averted seven of the eight deaths expected without active prophylaxis per 1000 such patients and cost half as much as the traditional approach of intervening only when venous thromboembolism becomes clinically apparent. Intravenous administration of dextran, although effective, was expensive, and leg scanning with iodine-125-labelled fibrinogen was extremely expensive. Intermittent pneumatic compression of the legs was inexpensive, but, as with leg scanning, its effectiveness has not been determined in randomized trials.

Adult↗
PubMed1980

A comparison of four personal sampling methods for the determination of mercury vapor.

Four sampling and analytical methods for mercury vapor were compared to each other in terms of precision and accuracy. The four sampling medias used were the 3M passive Mercury Vapor Monitor, the Los Alamos tandem sampling tube, the hopcalite tube, and the iodine impregnated charcoal tube. Six samples from each method were collected at nominal mercury concentrations of 0.05, 0.1, and 0.2 mg/m3. The hopcalite and 3M monitors gave comparable results at all three concentrations while the Los Alamos method gave similar results at the two highest concentrations. The iodine charcoal tube method was the only one exhibiting poor precision when tube loadings were less than 3 micrograms of mercury.

Air Pollutants↗
PubMedDate not supplied

Relation between the time to achieve the lower limit of the APTT therapeutic range and recurrent venous thromboembolism during heparin treatment for deep vein thrombosis.

BACKGROUND: Randomized trials have demonstrated the importance of achieving adequate heparinization early in the course of therapy. Recently, some authors reported a pooled analysis of selected studies in the literature that suggested that there is no convincing evidence that the risk of recurrent venous thromboembolism is critically dependent on achieving a therapeutic activated partial thromboplastin time result at 24 to 48 hours. METHODS: We provide the analyses of patient groups entered into our series of 3 consecutive double-blind randomized trials evaluating initial heparin therapy for proximal deep venous thrombosis. RESULTS: Logistic regression analysis of the patient groups receiving the less intense initial intravenous heparin dose of 30,000 U/24 h demonstrated that subtherapy for 24 hours predicted the onset of venous thromboembolic events. Failure to achieve a therapeutic activated partial thromboplastin time by 24 hours was associated with a 23.3% frequency of venous thromboembolism vs 4% to 6% for those whose activated partial thromboplastin time exceeded the therapeutic threshold by 24 hours (P=.02). Time-to-event analysis shows the increased frequency of recurrent venous thromboembolic events during the period of study in patients who were subtherapeutic for 24 hours compared with those who were therapeutic (P=.001). CONCLUSIONS: Our findings reaffirm the clinical importance of rapidly achieving therapeutic levels of heparin. Patients who failed to achieve the therapeutic threshold by 24 hours were at an increased risk of subsequent recurrent venous thromboembolism. These findings are independently supported by the results of a randomized trial comparing different intensities of initial heparin treatment by continuous infusion.

Anticoagulants↗