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Biomedical subjects

S W Christensen

Publications and source records attributed to S W Christensen.

16 recordsLinked to original sources
PubMed1997

Triplex US in the diagnosis of asymptomatic deep venous thrombosis.

PURPOSE: To evaluate the accuracy of triplex ultrasound (TUS) compared with venography as a screening test for deep venous thrombosis (DVT), and to evaluate interobserver variation in the interpretation of the venographic studies. MATERIAL AND METHODS: A total of 133 postoperative hip fracture patients, asymptomatic of DVT, were prospectively examined with TUS and venography. All venograms were reviewed blindly and in case of disagreement a consensus was arrived at. RESULTS: The incidence of DVT was 20%, with isolated calf vein thrombi in 63% of the cases. There were 7 false-negative and one false-positive result/s at TUS, with a sensitivity of 74%, specificity of 99% and accuracy of 97%. The kappa values ranged from 0.58 to 0.82. The false-negative results were all caused by missed calf vein thrombi in technically inadequate examinations. At sonography 2% of vein segments were noninterpretable, compared to 29% at venography. CONCLUSION: Venous US is less sensitive as a test for DVT in this study of asymptomatic patients than in earlier studies on symptomatic patients. Still, sonographic screening of high-risk patients would be both effective and cost effective. Fresh thrombi may cause a false-negative compression test.

Aged↗
PubMed1992

Sensitivity to change for low-ANC eastern US lakes and streams and brook trout populations under alternative sulfate deposition scenarios.

A weight-of-evidence approach was used by the US National Acid Precipitation Assessment Program (NAPAP) to assess the sensitivity of chemistry and biology of lakes and streams to hypothesized changes in sulfate deposition over the next 50 years. The analyses focused on projected effects in response to differences in the magnitude and the timing of changes in sulfate deposition in the north-eastern United States, the Mid-Appalachian Highlands, and the Southern Blue Ridge Province. A number of tools was used to provide the weight of evidence that is required to have confidence in an assessment that has many uncertainties because of the complexity of the systems for which the projections of future conditions were made and because of limited historical data. The MAGIC model provided the projections of chemical changes in response to alternative deposition scenarios. Projected chemical conditions were input into biological models that evaluate effects on fish populations. The sensitivity of water chemistry and brook trout resources to the hypothesized changes in deposition was found to be greatest in the Adirondacks and Mid-Atlantic Highlands. Under the hypothesized sulfur deposition reduction scenarios, chemical conditions suitable for fish were projected to improve 20-30 years sooner than with the scenario that assumed no new legislated controls. Other lines of evidence, e.g. other models, field observations, and paleolimnological findings, were used to evaluate uncertainty in the projections. Model parameter/calibration uncertainty for the chemical models and population sampling uncertainty were explicitly quantified. Model structural uncertainties were bracketed using model comparisons, recent measured changes, and paleolimnological reconstructions of historical changes in lake chemistry.

Journal Article↗
PubMed1991

Transurethral resection of very large prostates. A retrospective study.

Twenty-one patients with benign prostatic hypertrophy (BPH), and a weight of transurethrally resected tissue exceeding 80 g (Group 1), were compared to a control group of 30 patients with a weight of resected tissue less than 80 g (Group 2) with regard to the peri- and postoperative course and the symptomatic and urodynamic results of surgery. All patients were followed 12 months postoperatively. In both groups more than 90% of the patients were satisfied with the results of the operation. However, the obstructive symptoms were better relieved than the irritative symptoms. The group who had large resections performed had a longer operating time and a greater perioperative blood loss than the group of minor resections. No differences were found with regard to other peri- or postoperative complications or subjective results. Transurethral resection is safe and efficient in treating BPH, also with very large prostates.

Aged↗
PubMed1991

Prophylaxis of deep venous thrombosis after acute abdominal operation.

Two hundred and forty-five patients who underwent acute extensive abdominal operations were randomized into three regimens to achieve optimal prophylaxis of postoperative thromboembolic complications. All of the patients were screened by the 125I-fibrinogen uptake test for seven days and if the phlebographic findings were positive. Of 81 patients receiving low dose heparin, 12 had thromboembolism. Of 79 receiving a combination of low dose heparin and graded compression stockings, two had thromboembolism, and of 85 receiving a combination of dextran and graded compression stockings, 13 had this complication. This difference is significant in favor of the second treatment (p = 0.013). It is concluded that the combination of low dose heparin and graded compression stockings is an effective way to prevent thromboembolism after acute abdominal operations.

Adult↗
PubMed1989

Arterial embolization in patients with renal carcinoma.

The literature concerning embolization of the renal artery in patients with renal cell carcinoma is reviewed. Based on this review it is concluded that the method is useful in this patient group as it will facilitate the surgical procedure if nephrectomy is performed afterwards. Used as a palliative method, embolization reduces haematuria. It was not possible to draw conclusions concerning survival rates or eventual immuno-stimulating effects of embolization.

Carcinoma, Renal Cell↗
PubMed1989

Prostatic-type polyp in the bladder. A case report.

A case of prostatic-type polyp in the wall of the urinary bladder in a 73-year-old male is presented. The literature concerning ectopic prostatic tissue in the urinary tract is reviewed and it is concluded that the lesion is benign. However, recurrence has been reported in two cases. The etiology and pathogenesis is unknown.

Aged↗
PubMed1989

Non-elite marathon runners: health, training and injuries.

A questionnaire was given to all participants of the Wonderful Copenhagen Marathon 1986 regarding demographic information, health, training, previous injuries and methods used to prevent these. A total load of 2158 Danish runners participated and 1426 (68 per cent) replied. Fifty per cent of the runners were training 30-60 km per week and 25 per cent more than 60 km per week. Forty-one per cent were members of running clubs. The runners were equally distributed between all social groups. Most runners were slim (mean BMI 22.3 +/- 1.87 (SD)), healthy, non-smokers who rarely suffered from serious injuries, but 31 per cent had had injuries that prevented them from training during the last year. Nearly all performed stretching exercises and methods to avoid injuries. Fifty per cent of the runners tried to optimize their performance by changing their diet in the days before the run. Seventeen per cent used the classical high carbohydrate diet and 33 per cent other special diets.

Adolescent↗
PubMed1989

Prevention of thromboembolism following elective hip surgery. The value of regional anesthesia and graded compression stockings.

Ninety-eight patients scheduled for elective hip arthroplasty receiving either general or regional anesthesia and graded compression stockings as the only thromboprophylactic treatment were screened for postoperative deep-venous thrombosis with 99mTc-plasmin scintimetry. The diagnosis of deep-venous thrombosis was established by phlebography and the diagnosis of pulmonary embolism by pulmonary perfusion and ventilation scintigraphy. Of 65 patients surgically treated under general anesthesia, 20 (31%) developed deep-venous thrombosis and six developed pulmonary embolism. Of 33 patients surgically treated using regional anesthesia, three (9%) developed deep-venous thrombosis and one developed a pulmonary embolus. The number of patients developing deep-venous thrombosis was significantly lower in the group receiving regional anesthesia compared with the group receiving general anesthesia. The results indicate the beneficial effects on the incidence of postoperative thromboembolic complications following elective hip surgery from the use of regional anesthesia and graded compression stockings.

Adult↗
PubMed1989

Prevention of deep venous thrombosis following total hip replacement, using epidural analgesia.

Fifty-five patients undergoing total hip replacement using epidural analgesia were allocated to the combination of low dose heparin and dihydroergotamine (5.000 IU heparin and 0.5 mg dihydroergotamine given subcutaneously every twelve hours) (n = 27) or to placebo (n = 28). All patients wore thigh-length graded compression stockings. The patients were screened for deep venous thrombosis by means of the 99mTc-plasmin test and the diagnosis of deep-vein thrombosis was confirmed by ascending phlebography. Three patients in each group developed unilateral deep-venous thrombosis. One patient in each group developed non-fatal pulmonary embolism.

Aged↗
PubMed1987

Contact thermography, 99mTc-plasmin scintimetry and 99mTc-plasmin scintigraphy as screening methods for deep venous thrombosis following major hip surgery.

Fifty-six patients scheduled for total hip alloplasty were screened for deep venous thrombosis by means of 99mTc-plasmin scintimetry, 99mTc-plasmin scintigraphy and contact thermography. Investigations were performed on the seventh postoperative day, and a total of 112 legs were examined. Bilateral ascending phlebography was used as reference procedure, and the criteria for deep venous thrombosis were intraluminal filling defects at phlebography. Six patients developed unilateral deep venous thrombosis. All three screening procedures revealed many false positive and several false negative results. The nosographic sensitivity/specificity was 33%/75% for scintimetry, 50%/91% for scintigraphy and 33%/87% for contact thermography, respectively. It is concluded that all three tests are of no value as screening methods for deep venous thrombosis following major elective hip surgery.

False Negative Reactions↗
PubMed1987

Bleeding after hip arthroplasty not increased by heparin plus dihydroergotamine.

We measured the postoperative bleeding following total hip replacement when low-dose heparin plus dihydroergotamine was used for preventing postoperative deep-venous thrombosis. The patients were allocated by random numbers to either 5,000 IU heparin and 0.5 mg dihydroergotamine injected subcutaneously twice daily or to placebo injections. The mean postoperative bleeding in the anticoagulation group of 91 patients was 583 ml and in the placebo group of 103 patients 529 ml, i.e., there was no difference between the two groups.

Adult↗
PubMed1987

Proximal humeral fractures. Late results in relation to classification and treatment.

One hundred and eighty-eight proximal humeral fractures were reviewed retrospectively in relation to the Neer classification and the treatment given. The displacement criteria were found to have prognostic significance. Minimally displaced fractures had excellent outcome, whereas the results following any treatment of the displaced fractures were unsatisfactory in about one half of the cases. The indications for closed or open treatment can only be defined by prospective studies, and the methods of treatment should be improved.

Adult↗
PubMed1986

Plate fixation of proximal humeral fractures.

We performed open reduction and internal fixation with a T-buttress plate in 32 fractures of the proximal humerus with severe displacement and/or fracture dislocation. In 27 cases acceptable reduction was achieved. In four cases infection developed, and the implant was removed in five cases because of impingement of the plate under the acromion and in two cases because of loosening. There was no nonunion, but four humeral head necroses. At the re examination of 20 patients after 2-7 years, nine were excellent or satisfactory and eleven unsatisfactory or poor. We conclude that the buttress plate offers satisfactory reduction and good stability at a high risk for complications. The indications for this method should be carefully considered, notably in the elderly, and the operation should only be performed by experienced orthopedic surgeons.

Adult↗
PubMedDate not supplied

Data and metadata reporting standards for the U.S. Environmental Protection Agency's PM Supersites Research Program.

The EPA Supersites Research Program needs consistency of metadata and data structures to facilitate information sharing among investigators, analysts, and ultimately secondary data users. Under the auspices of NARSTO a successful mechanism was created to develop and implement reporting standards. The development effort included working closely with Supersites data coordinators, investigators, and technical experts, and also leveraging from existing data standards and practices. Overall, the standards are getting good acceptance from the atmospheric research community.

Cities↗