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Biomedical subjects

K Simmons

Publications and source records attributed to K Simmons.

At least 19 recordsLinked to original sources
PubMed1995

Assessment of abdominal aortic aneurysm with magnetic resonance imaging.

Pre-operative imaging of abdominal aortic aneurysms (AAA) is important in determining suitability for operation and operative approach. Ultrasound imaging is an excellent screening modality but is relatively poor at identifying renal arteries and the extent of iliac involvement. Computed tomography scanning with intravenous contrast and arteriography are invasive modalities that are associated with a small risk. Magnetic resonance imaging (MRI) offers the potential of accurate anatomical definition without use of contrast agents and passage of an intra-arterial catheter. Eight patients who had their AAA evaluated with MRI are reported. All had renal arteries accurately defined, intra-aneurysmal thrombosis was well delineated, and iliac extension was correctly identified in four cases. The initial experience has been most encouraging and the authors consider that MRI may become the investigation of choice for pre-operative AAA assessment.

Aged↗
PubMed1993

Management of postoperative intra-abdominal abscesses by routine percutaneous drainage.

Postoperative intra-abdominal abscess (IAA) is a dreaded surgical complication. Percutaneous drainage (PD) has been offered as an alternative to surgical drainage for IAA because of the perceived lower morbidity and mortality rates. Seventeen consecutive unselected instances of IAA were reviewed to determine the value of the routine use of PD. Two patients with obvious anastomotic dehiscence and one with a retroperitoneal abscess were believed to be inappropriate for PD. Patients who could be managed by PD (group 1, n = 6) were similar to patients undergoing PD plus surgical drainage (group 2, n = 8) with respect to age, initial procedure, interval from operation to diagnosis of IAA and extent of organ failure. However, in group 2, more abscesses were greater than 5 centimeters (16.7 versus 62.5 percent), associated with polymicrobial growth (0.0 versus 50.0 percent), associated with enteric organisms (16.7 versus 100 percent; p < 0.05), accompanied by anastomotic dehiscence (16.7 versus 62.50 percent) and followed by a greater degree of mortality (16.7 versus 50 percent). Overall, only 33 percent of IAA were successful managed with PD alone. We conclude from these data that PD is of value only in selected instances of IAA. If an anastomotic dehiscence is a possibility, the patient should be managed operatively.

Abdomen↗
PubMed1989

Developmental and individual differences in performance on phonological synthesis tasks.

This study was conducted in order to examine the role of individual differences in working memory and lexical access in accounting for age and reading skill related differences in performance on phonological synthesis tasks. The performance of 28 kindergarten, first-, and second-grade children with normal reading skills, as well as that of 28 reading-disabled second graders, was compared under four testing conditions. The testing conditions were formed by completely crossing rate of presentation of phoneme strings with type of stimulus to be blended (real or nonword). Both independent variables affected performance on the blending tasks, with better performance obtained at faster presentation rates and with real words. There was a developmental discontinuity in overall performance, with the kindergarten children obtaining substantially lower scores than the first or second graders. In the comparison of second-grade good and poor readers, there was a significant interaction between groups, presentation rates, and type of stimulus. The findings are discussed in terms of their implications for a general model of performance on the sound blending task, as well as their value for interpreting individual differences on the task.

Awareness↗
PubMed1988

Corrective measures and pregnancy outcome in in vitro fertilization in patients with severe sperm morphology abnormalities.

Sperm morphology evaluated by new, strict criteria is a good predictor of outcome in in vitro fertilization (IVF). This study aimed (1) to determine whether the fertilization rate of preovulatory oocytes in patients with abnormal morphology can be improved by increasing insemination concentration at the time of IVF and (2) to evaluate the pregnancy outcome in patients with abnormal sperm morphology. Three groups were studied: (1) normal morphology, (2) good prognosis pattern, and (3) poor prognosis pattern. All other sperm parameters were normal. Group 3 had a lower overall fertilization rate, lower pregnancy rate/cycle, and lower ongoing pregnancy rate/cycle. Groups 2 and 3 showed a higher miscarriage rate, although not significantly different from group 1. By increasing insemination concentration from 2- to 10-fold, the fertilization rate in group 3 increased from 14.5% to 62.6%. However, pregnancy outcome did not improve. We conclude that patients with severe sperm head abnormalities have a lower ability to establish successful pregnancies, even though fertilization may be achieved.

Abortion, Spontaneous↗
PubMed1986

Percutaneous transluminal angioplasty for severe lower extremity ischaemia.

Percutaneous transluminal angioplasty (PTA) was attempted on 70 occasions in 63 consecutive patients presenting with advanced ischaemia. The procedure was technically successful in 64 (91%) with haemodynamic improvement in 39 (56%) and clinical improvement maintained at 6 months in 51 (73%). Follow-up ranged from 6 months to 4 years and life-table analysis showed 60% success at 1 year and 58% success at 2 years. Overall limb salvage was 76%. Complications occurred in 6 (9%) and in one case this lead to amputation. The relationship of a number of associated factors to outcome was assessed. The presence of cardiac disease requiring treatment for failure or angina was a highly significant adverse factor (P less than 0.001). Decreasing age and greater extent of disease were also significant adverse factors (P less than 0.05). Therefore, because of its low morbidity and cost, PTA can be seen as a useful procedure in patients presenting with advanced peripheral vascular disease.

Adult↗
PubMed1986

Percutaneous transhepatic dilatation in the management of bile duct strictures.

Despite improvements in surgical techniques, some complex bile duct strictures continue to present difficult management problems. Strictures recurring after previous biliary-enteric bypass, those associated with established biliary cirrhosis or coexistent malignancy, and those that follow hepatic resection may pose almost insuperable technical and physiological problems. Percutaneous transhepatic balloon dilatation will not solve all problems, but can help in some instances. Six patients are presented in whom this technique has been used in attempts to overcome particular problems. The strengths and weaknesses of the method are discussed.

Adult↗