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Biomedical subjects

R W Barnes

Publications and source records attributed to R W Barnes.

At least 55 records · Page 3Linked to original sources
PubMed1992

Ultrasonic measurement of the elastic modulus of the common carotid artery. The Atherosclerosis Risk in Communities (ARIC) Study.

BACKGROUND AND PURPOSE: The Atherosclerosis Risk in Communities Study is a prospective investigation of the etiology and natural history of atherosclerosis and the etiology of clinical disease in four US communities. METHODS: Noninvasive ultrasonic methods were used to determine mean wall thickness (WT), radius (R), and circumferential arterial strain (CAS) in the left common carotid artery of 3,321 white male and female study participants between the ages of 45 and 64 years. The mean and standard deviation of Young's elastic modulus (Y) in 5-year age groups were determined for each sex by combining the ultrasonic data with concurrent noninvasive measurements of pulse pressure (PP) in the right brachial artery using the equation Y = (R/WT) x (PP/CAS). RESULTS: Significant (p = 0.0001) age group differences in Y were observed in both sexes, with the mean value increasing from 701 kPa in women and 771 kPa in men in the 45-49-year-old age group to 965 and 983 kPa, respectively, in the 60-64-year-old age group. Significant (p = 0.0001) age group differences were also observed for WT, the WT/R ratio, PP, CAS, and the PP/CAS ratio in both sexes. A sex difference in Y was detected (male greater than female, p = 0.0006) only in the 45-49-year-old age group. Significant (p less than 0.0001) sex differences were found, with men having a greater lumen diameter calculated as 2 x (R - WT), a greater WT, and a greater 2R in all age groups. The WT/R ratio did not differ in both sexes in all age groups. CONCLUSIONS: Knowledge of the arterial wall elastic modulus and the parameters required for its determination can provide important insight into structural changes occurring within the arterial wall with age and sex, and possibly with the onset of very early arterial disease.

Aging↗
PubMed1992

Reproducibility of noninvasive ultrasonic measurement of carotid atherosclerosis. The Asymptomatic Carotid Artery Plaque Study.

BACKGROUND AND PURPOSE: To determine the effect of a lipid-lowering agent and/or a low-dose antithrombotic agent on the progression of early-stage carotid atherosclerosis, noninvasive B-mode ultrasound was used to measure intimal-medial thickness in asymptomatic individuals with moderately elevated lipids as part of the ongoing multicenter Asymptomatic Carotid Artery Plaque Study. METHODS: Uniform ultrasonic scanning and reading protocols were implemented to obtain maximum intimal-medial thickness measurements in 12 standard segments in patients having a small to moderate wall thickness (1.5-3.5 mm) in at least one of the carotid arteries. Paired B-mode image recordings on 858 patients, performed 1 month apart and read at a core laboratory (each pair by the same reader), determined both within-sonographer (W, n = 405) and between-sonographer (B, n = 453) reproducibility. RESULTS: The primary end point (mean +/- SD), defined in each individual as the mean value of the 12 maximum intimal-medial thickness measurements, was 1.31 +/- 0.21 mm (W) and 1.32 +/- 0.22 (B) at the time of the second examination. The mean difference in the primary end point (exam 2-exam 1) was -0.01 +/- 0.13 mm (W) and 0.00 +/- 0.15 mm (B). The Pearson correlation coefficients were 0.79 (W) and 0.75 (B). In 90% of the patients, the absolute difference in the primary end point was less than 0.22 mm (W) and less than 0.24 mm (B). Variability of the secondary end point, defined as the single largest intimal-medial thickness measurement in a patient, was between three and four times larger than the variability for the primary end point. Differences in sonographer performance between clinical centers were very small. CONCLUSIONS: The results demonstrate that standardized noninvasive ultrasonic techniques yield highly reproducible measures of carotid intimal-medial thickness, which can serve as a measure of carotid atherosclerosis in clinical trials that monitor small rates of lesion progression.

Adult↗
PubMed1992

Is anticoagulation indicated for asymptomatic postoperative calf vein thrombosis?

The purpose of this study was to determine the effect of anticoagulation on the incidence of thrombotic propagation and pulmonary embolism in patients with calf vein thrombosis after total hip or total knee arthroplasty. Patients undergoing arthroplasties had prospective surveillance for postoperative deep vein thrombosis by both bilateral contrast venography and venous duplex scanning. Calf vein thrombosis was documented by venography in 42 patients (50 limbs), including 29 of 253 patients undergoing total hip arthroplasty (11.4%) and 13 of 99 patients undergoing total knee arthroplasty (13%). Of patients on whom follow-up duplex scans were performed, heparin followed by warfarin anticoagulation was used in 11 (13 limbs) and withheld in 21 (25 limbs). Propagation of thrombosis to the popliteal or superficial femoral vein or both was detected by serial duplex scanning in 3 of 13 treated limbs (23%) and 2 of 25 untreated limbs (8%), (p = 0.43). All thrombus propagations were detected within 2 weeks of the operative procedure. There were no pulmonary emboli or deaths. Propagation of asymptomatic calf vein thrombosis after arthroplasty was not influenced by anticoagulation, suggesting that postoperative calf vein thrombosis need not be routinely treated. Serial venous duplex scanning is useful to identify the occasional patient in whom thrombotic propagation requiring anticoagulation develops.

Aged↗
PubMed1991

Hyperparathyroidism presenting as an unusual cause of lower extremity gangrene.

Vascular surgeons are often consulted on the management of lower extremity ulcerations and gangrene which are commonly due to atherosclerotic arterial occlusive disease or to chronic venous insufficiency. The following report describes an unusual case of severe lower extremity cutaneous gangrene associated with secondary hyperparathyroidism and a review of the literature.

Amputation, Surgical↗
PubMed1991

Noninvasive diagnostic assessment of peripheral vascular disease.

Noninvasive techniques have assumed an increasingly important role in the management of patients with vascular disease. Both ultrasonic and plethysmographic instruments allow objective evaluation of vascular disorders by the measurement of segmental limb blood pressures, analysis of blood velocity disturbances, recording of digit or limb pulse waveforms, or imaging of vascular disease, with or without Doppler flow analysis or color-flow mapping. These techniques have been applied for screening asymptomatic individuals, diagnosis of symptomatic patients, monitoring of interventional or surgical procedures, and follow-up of the natural history or the efficacy of medical, interventional, or surgical therapy of vascular disease. This article reviews the clinical application of these modalities to patients with peripheral arterial disease and briefly discusses cost-effectiveness and potential abuses of noninvasive technology.

Arterial Occlusive Diseases↗
PubMed1991

Duplex scanning versus venography as a screening examination in total hip arthroplasty patients.

Combined B-mode/Doppler (duplex) scanning and venography were compared in routine perioperative screening for proximal deep vein thrombosis (DVT) in 158 total hip arthroplasty (THA) patients. Preoperative scans were performed in the first 60 patients; the low preoperative prevalence of 2% for proximal DVT was thought not to warrant routine preoperative scanning. Postoperatively, duplex scanning had a sensitivity of 79%, a specificity of 98%, and an accuracy of 97% when venography was considered as the gold standard. The postoperative incidence of proximal DVT was 12% in this group of THA patients treated with mechanical and pharmacologic prophylaxis. Including calf vein thrombosis, 30% had DVT postoperatively. This study demonstrates the efficacy of duplex scanning for diagnosing proximal DVT and describes an effective noninvasive method of screening THA patients for the presence of proximal DVT.

False Negative Reactions↗
PubMed1991

Use of a tunneling device to aid in positioning of a graft.

A tunneling device can be used to ensure easy placement of a prosthetic or autogenous graft. This can be done without the danger of the graft twisting, kinking or having the clips and ties pulled off. The often frustrating problem of ensuring that the arterial graft lies properly in position can be greatly simplified with the use of this technique.

Anastomosis, Surgical↗
PubMed1991

Recurrent intracaval renal cell carcinoma: the role of intravascular ultrasonography.

The presence of extension into the vena cava does not preclude curative resection for extensive renal cell carcinomas. However, preoperative assessment of (1) the proximal extent of the tumor and (2) the degree of adherence within the vena cava is necessary to plan operative strategies. The following report describes the successful use of intravascular ultrasonography in the preoperative evaluation of a patient with recurrent renal cell carcinoma with vena caval extension.

Carcinoma, Renal Cell↗
PubMed1990

The next generation of surgical residencies. What are the challenges and the opportunities?

I suggest restructuring general surgical residencies to facilitate training of surgical specialists and subspecialists. Basic surgical education for 1 or 2 years should provide a foundation of fundamental cognitive, technical, and patient management skills useful for all surgery residents, regardless of discipline. Intermediate surgical education for an additional 2 or 3 years should amplify cognitive, technical, and clinical skills and senior responsibility in general surgery for individuals entering a general surgical subspecialty or for advanced general surgery training. Residents seeking a career in advanced general surgery would take 2 additional years of training in advanced surgery. Such individuals could pursue additional subspecialty training and research experience to qualify as academic surgical scientists. Implementation of such innovations in general surgical education awaits the cooperative joint efforts of appropriate accrediting and certifying organizations, specialty societies, and surgical program directors.

General Surgery↗
PubMed1990

Minimizing problems between vascular trainees and general surgery residents.

The current problems and conflicts associated with training of vascular and general surgery residents exemplify the larger dilemma of educating subspecialists while preserving the wellspring of general surgery. Previous vascular fellowship programs during the era of evolution of our subspecialty were characterized by clinical preceptorships or research programs with little thought about the impact on training of general surgery residents. The current era of educational safeguards permits approved vascular training programs provided that adequate educational experience, operative caseload, and appropriate supervision are ensured for both the vascular and general surgical trainee. The future portends significant changes in general surgical and subspecialty training to enhance the career goals of all surgical residents. Such evolutionary changes are necessary to not only capitalize on the benefits of subspecialty care but also enhance the professional standing and expertise of the general surgeon. These modifications in training programs will require the coordinated efforts of major societal, governmental, accrediting, and certifying organizations.

Accreditation↗
PubMed1990

Traumatic left renal artery stenosis managed with splenorenal bypass: case report.

Splenorenal arterial bypass is a well established technique for the treatment of left renal artery occlusive disease. The following is a case report of the use of splenorenal bypass in the management of concomitant traumatic left renal artery intimal dissection and splenic laceration. Arteriographic and intraoperative findings are presented as well as a review of pertinent literature.

Humans↗
PubMed1990

Radiation absorbed from dental implant radiography: a comparison of linear tomography, CT scan, and panoramic and intra-oral techniques.

Absorbed radiation dose in bone marrow, thyroid, salivary gland, eye, and skin entrance was determined by placement of lithium fluoride thermoluminescent dosimeters (TLD's) at selected anatomical sites within and on a human-like x-ray phantom. The phantom was exposed to radiation from linear tomographic and computer-assisted tomographic (CT) simulated dental implant radiographic examinations. The mean dose was determined for each anatomical site. Resulting dose measurements from linear tomography and computer-assisted tomography are compared with reported panoramic and intra-oral doses. CT examination delivered the greatest dose, while linear tomography was generally lowest. Panoramic and intra-oral doses were similar to those of linear tomography.

Dental Implantation, Endosseous↗
PubMed1990

Is routine duplex examination after carotid endarterectomy justified?

Routine follow-up of patients after carotid endarterectomy with duplex scanning is commonly practiced, yet the clinical significance of identifying those with asymptomatic restenosis is unclear. To address this issue we reviewed 120 consecutive patients who underwent 143 carotid endarterectomies from August 1983 to December 1988. One hundred one patients (118 operations) were available for clinical follow-up, and the overall incidence of recurrent symptoms was 6% (6/101). Sixty-three of these patients (78 carotid endarterectomies) had postoperative duplex examination. Two had evidence of residual disease from the time of surgery and were not included in further analysis. Significant recurrent stenosis (greater than 50% diameter reduction) developed in 14 of the remaining 76 arteries (18.2%). Twelve of 14 stenoses remained asymptomatic during follow-up from 18 to 72 months (mean 47.0 months) and did not undergo reoperation. Recurrent ipsilateral hemispheric symptoms developed in two patients with restenosis (14.3%). Four of the 62 arteries without significant recurrent stenosis developed ipsilateral symptoms (6.5%), but none required reoperation during follow-up from 1 to 71 months (mean 31.6 months). Life-table analysis showed no increased risk of transient ischemic attack, stroke, or death in patients with restenosis. This study supports regular clinical follow-up after carotid endarterectomy with emphasis on patient education in the recognition of symptoms. Although duplex scanning may be useful to follow known contralateral asymptomatic disease or evaluate those with recurrent symptoms, its routine use to identify patients with asymptomatic restenosis after carotid endarterectomy may be unnecessary.

Aged↗