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Biomedical subjects

P F Lawrence

Publications and source records attributed to P F Lawrence.

51 records · Page 3Linked to original sources
PubMed1985

Assessment of medical student fund of knowledge in surgery.

A medical student's fund of knowledge can be assessed by either his demonstrated fund of knowledge on a clinical service or an examination at the completion of the clerkship. During the past 2 years we have evaluated each student's fund of knowledge in two ways: clinical assessment by faculty and residents and performance on the National Board of Medical Examiners Part II Special Surgical Examination given at the end of the surgical clerkship. This study compares the clinical assessment of surgical knowledge for all 100 members of the class of 1984 at the University of Utah with other subjective evaluations such as attitudes and college grade point average and objective measures of performance such as premed MCAT score, Part I National Boards score, and the National Boards Special Surgical Examination. The correlation between clinical assessment of knowledge and the Surgical Examination was 0.23, with a range on individual services from -0.42 to 0.45. There was a higher correlation for the total group of 0.56 between fund of knowledge and attitudes, with a range on individual services of -0.04 to 0.72. The correlations between clinical assessment of knowledge and Part I National Boards, college grade point average, and chemistry MCAT score were 0.23, 0.09, and 0.15, respectively. These results indicate that the clinical assessment of fund of knowledge is not a good predictor of performance on the surgical section of the National Boards. Clinical assessment of fund of knowledge appears to be linked more closely to faculty and resident assessment of student attitudes. There are a couple possible explanations for these results: clinicians are measuring different aspects of knowledge than are National Boards or clinicians do not accurately assess knowledge and confuse attitudes such as interest and enthusiasm with fund of knowledge.

Clinical Clerkship↗
PubMed1984

Acute effects of argon laser on human atherosclerotic plaque.

Although the laser has been demonstrated to vaporize coronary artery plaque, there is little information about its ability to resect or vaporize the range of plaques present in peripheral vessels. This study attempts to determine the ability of the argon laser to resect all grades of atherosclerotic plaque, the risk of perforation during plaque resection, the effects on surrounding arteries, and the effect of different transmission media (air, saline solution, and blood) on the delivery of laser energy to the vessel. Seventy-five adult human cadaveric aortic specimens with a range of atherosclerosis from grossly normal artery to extensive calcification with ulceration were exposed to variable energy densities (200 to greater than 20,000 J/cm2) within 48 hours of harvesting. Specimens were examined grossly for the visual effects of laser and microscopically after preparation with hematoxylin-eosin, trichrome, and/or Verhoeff's elastin stains. Our results indicate that normal arteries and noncalcified plaques absorb laser energy and are vaporized. As the atherosclerosis becomes more complex with calcification, calcified regions are not vaporized and cannot be resected. In normal arteries and noncalcified plaque, perforation times were less than 5 seconds. Where palpable calcification was present in atherosclerotic lesions, average perforation time was doubled. In some vessels areas of calcification prevented wall perforation, but areas of subintimal hemorrhage perforated rapidly because of the selective absorption of laser energy by the red color of hemorrhagic tissue. These results remain the same when saline solution is used as a transmission media, although the amount of energy required to achieve the effects is increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Evaluation of technetium-99m phosphate imaging for predicting skin ulcer healing.

We have developed criteria for radionuclide angiography to assess skin ulcer perfusion as an indicator of healing capacity. Twenty-six studies were performed on 21 consecutive patients with nonhealing ulcers of the lower leg; 20 mCi of technetium-99m phosphate was injected intravenously with immediate sequential scintillation camera imaging of the ulcer and surrounding area at 2 second intervals, followed by blood pool and delayed static images. Two radiologists without clinical bias graded the perfusion to the ulcer on the images as normal, increased, or reduced with respect to the opposite limb. Patients were either followed as outpatients for more than 10 days, as inpatients for at least 10 days, or both to determine whether ulcers showed clinical evidence of wound healing with optimal outpatient and in-hospital care. Of the 17 patients whose ulcers healed, imaging with technetium-99m phosphate predicted the outcome in 16. In nine patients the ulcers did not heal. This was correctly predicted by technetium-99m phosphate in eight of the patients. Overall, the sensitivity was 94 percent and the specificity was 89 percent. This technique appears to be a simple, reliable way to predict the microcirculatory adequacy for ulcer healing.

Diphosphates↗
PubMed1983

Determining the content of a surgical curriculum.

The purpose of undergraduate surgical education is to prepare the student for both the residency and eventual practice of medicine. To help determine the surgical knowledge and skills that would eventually the useful to the student, we conducted a survey of residents in training, physicians in practice, and surgical educators (department chairpersons and clerkship directors). Members of the Curriculum Committee of the Association for Surgical Education developed a questionnaire in which the respondents were asked to grade the functional importance of 84 areas of knowledge and 46 skills (0 = unnecessary, 3 = proficiency necessary). Using a modified Delphi technique to collect information, we sent the questionnaire to eight medical school graduation classes of 1975 (730 persons) and 1980 (776 persons) and all department chairpersons and/or clerkship directors (179). The results of the survey (46% response) revealed considerable agreement about the importance of certain skills and areas of knowledge, enabling us to rank order skills and knowledge based on mean responses (0.0 to 3.0). Physicians in practice, residents, and educators believed that certain areas of knowledge (e.g., acute abdominal problems, appendicitis, shock, cancer of the breasts) and skills (e.g., history taking and physical examination, gowning, suture removal) were very important (greater than 2.250, while other areas of knowledge (e.g., transplantation, liver abscess, soft tissue sarcomas) and skills (e.g., insertion of Swan-Ganz catheter, abdominal paracentesis, cricothyroidotomy) were less important (less than 1.3). This approach allows us to assign priorities to areas of knowledge and skills when determining curriculum content and to include functional criteria when developing educational objectives.

Attitude of Health Personnel↗
PubMed1982

Anticoagulation and temporary graft occlusion to determine the need for revascularization following vascular graft infection.

The patient with a patent, infected vascular graft presents a dilemma to the surgeon, who must decide whether revascularization is necessary in addition to removal of the infected graft. When a graft infection points superficially or requires drainage, the graft may be well enough exposed to provide easy access. A technique to determine preoperatively the need for revascularization in two patients with patent, exposed grafts is discussed. Following therapeutic anticoagulation, the exposed grafts were occluded with a screw clamp. Within 1 hour, one patient developed ischemic rest pain, associated with a fall in ankle blood pressure to < 60 mm Hg. Consequently, the patient underwent excision of the infected graft and revascularization with another extraanatomic bypass graft. The second patient, who had moderate intermittent claudication, tolerated clamping of the graft without ischemic symptoms at rest. Revascularization was performed through noninfected tissue, with the knowledge that the graft could be removed if necessary, without causing ischemic rest pain. This technique helps to determine preoperatively whether patients with exposed, infected grafts require revascularization as well as graft excision.

Journal Article↗
PubMed1981

Dinitrochlorobenzene skin test reactivity as a predictor of outcome in transplantation of juvenile onset diabetics.

More than 50% of patients with chronic renal failure will be suppressed in their cell-mediated immune response to 2,4-dinitrochlorobenzene (DNCB). This applies in renal failure attributable to juvenile onset diabetes as well as other types of end stage renal disease. Significantly better kidney survival of both living related and cadaver grafts is seen in diabetic patients who are non-responsive to DNCB. Twelve-month kidney survival for DNCB-negative patients receiving living related allografts is 71% compared with 25% for DNCB-positive patients. Twelve-month kidney survival in cadaver recipients is 39% in DNCB-negative compared with 9% for DNCB-positive patients. Successful second grafts were done in DNCB-negative diabetic patients, however, all second grafts in DNCB-positive patients failed in less than 3 months. DNCB skin test reactivity as a measure of cell-mediated response is a valuable predictor of immunological outcome of transplantation in patients whose renal disease results from juvenile onset diabetes. Patient survival in DNCB nonresponders is nearly twice that of DNCB responders. Differences in outcome following transplantation could not be accounted for by HLA disparity, transfusion history, or other variables known to effect transplant outcome. Kidney and patient survival in DNCB-positive diabetic patients receiving either cadaver or living related allografts is sufficiently low as to identify them as a subpopulation of renal failure patients who should be treated by dialysis, or selected for special protocols which might provide immunological manipulation prior to transplantation to improve their treatment outcome.

Diabetes Mellitus, Type 1↗
PubMed1981

Balloon catheter dilatation in patients with failing arteriovenous fistulas.

Six patients on hemodialysis who had stenotic segments of failing arteriovenous fistulas underwent attempted dilatations with a Grüntzig balloon catheter. In three patients the dilatation was successful: two fistulas were still functioning at the time of this study (10 and 8 months), and one fistula functioned up to the patient's death (2 months). Dilatation was unsuccessful in two patients because the stenosis located adjacent to the arteriovenous anastomosis could not be approached with the balloon. There were no complications secondary to the technique, and the dilatation attempt did not preclude surgical revision when it failed. This technique, which can be performed in ambulatory patients, provides an alternative to surgical revision of the failing arteriovenous fistula.

Arteriovenous Shunt, Surgical↗
PubMed1981

Measurement of intramuscular pressure in the management of massive venous occlusion.

While controversy continues over the exact pathophysiology of and optimal therapy for phlegmasia cerulea dolens, increasing evidence favors the role of elevated interstitial pressure in the generation of extremity ischemia. We report the use of intramuscular pressure measurements in the assessment of a patient suffering massive venous occlusion of one leg. Significant elevations in pressure were found in association with symptomatic ischemia. Successful thrombectomy restored blood flow, relieved symptoms, and produced an immediate decrease in intramuscular pressure. In this disorder, measurement of compartment pressures can be useful in assessing the severity of venous insufficiency and in monitoring the response to therapy.

Adult↗
PubMed1977

Bacteroides bacteremia.

When appropriate culture techniques are employed, Bacteroides bacteremia is found more frequently than might be expected and usually follows contamination from the gastrointestinal or genitourinary tracts. Survival is closely related to the extent of organ impiarment preceding the bacteremia. Proper therapy is based on early recognition of the source of bacteremia and adequate surgical drainage. Antibiotics do not appear to improve survival, particularly when used without drainage. Further studies are needed to identify patients with impaired host resistance who are particularly susceptible to these organisms.

Adult↗
PubMed1976

Closure of massive abdominal wall defects in adults.

Large full-thickness abdominal wall defects may be satisfactorily closed with the temporary use of prosthetic mesh. Within two weeks after placing silastic mesh directly over exposed bowel, a membrane forms below the mesh. When the membrane thickens, central eliptical portions of the mesh are progressively excised, diminishing the size of the defect. Eventually, the mesh may be removed and the defect closed primarily or repaired with permanent prosthetic mesh.

Abdominal Muscles↗
PubMedDate not supplied

Insensitivity of color Doppler flow imaging for detection of acute calf deep venous thrombosis in asymptomatic postoperative patients.

PURPOSE: Although color Doppler flow imaging (CDFI) has been shown to accurately depict calf vein thrombosis in symptomatic patients, this technique has not been proved accurate for detection of calf vein thrombosis in a population restricted to asymptomatic postoperative patients. PATIENTS AND METHODS: To evaluate the accuracy of CDFI in asymptomatic postoperative patients, both CDFI and contrast venography were performed on 78 limbs of 76 patients without symptoms of deep venous thrombosis (DVT) who had undergone either hip or knee replacement. CDFI and venographic examination were interpreted blindly with respect to the results of the other modality or clinical findings. Venography was the standard for comparison of results. RESULTS: Fifty-six percent of CDFI examinations of the calf vein were technically adequate. The remaining studies were compromised technically by limb swelling and/or obesity. For the technically adequate CDFI studies, calf vein thrombosis was detected in eight of 10 patients. Calculated sensitivity in this cohort was 80%, and specificity was 97%. The sensitivity of CDFI for acute calf DVT in all patients, regardless of image quality, was 42%. CONCLUSION: These observations suggest that state-of-the-art CDFI is not an accurate examination for acute calf vein DVT in asymptomatic postoperative patients. CDFI is associated with a high rate of technically compromised studies and relatively low sensitivity in studies that are deemed technically satisfactory. These observations do not preclude the use of CDFI in postoperative patients for detection of thrombus extension into the popliteal vein or for detecting thrombosis of more proximal lower extremity veins.

Female↗
PubMedDate not supplied

Systemic treatment of venous leg ulcers with high doses of pentoxifylline: efficacy in a randomized, placebo-controlled trial.

Several small studies have indicated that the systemic administration of pentoxifylline may accelerate healing of venous leg ulcers. The goal of this study was to further evaluate these findings in a larger scale placebo controlled trial and to explore the effect of the dose of pentoxifylline on healing. The study used a prospective, randomized, double-blind, parallel group placebo controlled design in a multicenter outpatient setting. Patients with one or more venous ulcer were enrolled, with all patients receiving standardized compression bandaging for treatment for their ulcers. Patients were also randomized to receive either pentoxifylline 400 mg, pentoxifylline 800 mg (two 400 mg tablets), or placebo tablets three times a day for up to 24 weeks. The main outcome measure was time to complete healing of all leg ulcers, using life table analysis. The study was completed as planned in 131 patients. Patients receiving 800 mg three times a day of pentoxifylline healed faster than placebo (p = 0.043, Wilcoxon test). The median time to complete healing was 100, 83, and 71 days for placebo, pentoxifylline 400 mg, and pentoxifylline 800 mg three times a day, respectively. Over half of all patients were ulcer free at week 16 (placebo) and at week 12 in both pentoxifylline groups. Whereas the placebo group had only achieved complete healing in half of the cases by week 16, all of the subjects remaining in the group receiving the high dose of pentoxifylline had healed completely. Treatment with pentoxifylline was well tolerated with similar drop-out rates in all three treatment groups. Complete wound closure occurred at least 4 weeks earlier in the majority of patients treated with pentoxifylline by comparison to placebo. A higher dose of pentoxifylline (800 mg three times a day) was more effective than the lower dose. We conclude that pentoxifylline is effective in accelerating healing of leg ulcers.

Adult↗