Biomedical subjects

Heather Duncan

Publications and source records attributed to Heather Duncan.

8 recordsLinked to original sources

PubMed2006

The Pediatric Early Warning System score: a severity of illness score to predict urgent medical need in hospitalized children.

PURPOSE: We developed and performed the initial retrospective validation of a pediatric severity of illness score. The score is to preemptively identify hospitalized children who are likely to require resuscitation to treat cardiopulmonary arrest. MATERIALS AND METHODS: The Pediatric Early Warning System (PEWS) score was developed using expert opinion. The score generated contained 20 items, 16 of which were able to be retrospectively abstracted. Validation used a case-control study design in a Canadian university-affiliated pediatric hospital. Eligible patients were younger than 18 years, were admitted to a hospital ward, and had no level-of-care restrictions. Case patients had a code blue called to obtain immediate assistance for treatment of impending or actual cardiopulmonary arrest. Control patients had no code blue event and were not urgently admitted to the intensive care unit within 48 hours of study. A total of 128 controls and 87 cases were compared. RESULTS: The PEWS score area under the receiver operating characteristic curve was 0.90. The sensitivity was 78% and the specificity was 95% at a score of 5. CONCLUSIONS: Application of the score may have identified more than 3 quarters of code blue calls in our hospital with at least an hour's warning. After further refinement and validation, the PEWS score has great potential to increase the efficiency of care delivery and to improve the outcomes of care provided to hospitalized children.

Cardiopulmonary Resuscitation↗

PubMed2004

Applying a new conceptual framework to evaluate tuberculosis surveillance and action performance and measure the costs, Hillsborough County, Florida, 2002.

PURPOSE: Tuberculosis (TB) elimination is an important US public health goal and improving the performance of TB surveillance and action and reducing the costs will help achieve it. But, there exists the need to better evaluate the performance and measure the costs. METHODS: We pilot tested an evaluation strategy in Hillsborough County, Florida using a conceptual framework of TB surveillance and action with eight core and four support activities. To evaluate performance, we developed indicators and validated their accuracy, usefulness, and measurability. To measure the costs, we obtained financial information. RESULTS: In 2001, Hillsborough County reported 78 (7%) of the 1145 Florida TB cases. Nineteen (24%) were previously arrested. While 13 (68%) of the 19 were incarcerated during the 2 years prior to being reported, only 1 (5%) of 19 was reported from the jail. From 111 TB suspects, 219 (25%) of 894 sputum specimens were inadequately collected. Of the $1.08 million annual budget, 22% went for surveillance, 29% for support, and 49% for action. CONCLUSIONS: This conceptual framework allowed measurement of TB surveillance and action performance and cost. The evaluation performed using it revealed missed opportunities for detection of TB cases and wasted resources. This conceptual framework could serve as a model for evaluation of TB surveillance and action.

Cost Allocation↗

PubMed2004

Ex-vivo study of flow dynamics and endothelial cell structure during extended hypothermic machine perfusion preservation of livers.

Liver transplantation is often the only effective treatment for end stage liver diseases resulting from cirrhosis, hepatitis, progressive jaundice, and biliary atresia. Hypothermic machine perfusion (HMP) preservation may enhance donor pool by extending preservation time and reclaiming marginal donor livers including those from non-heart beating donors (NHBD), as demonstrated in the kidney. However, current HMP protocols have not been successful in improving extended preservation of livers and the major cause of preservation injury remains unknown. An intravital microscopy study was conducted to understand the flow dynamics of sinusoidal perfusion during 24h HMP with cold modified University of Wisconsin (UW) solution. Fluorescein isothiocynate (FITC) labeled albumin was utilized to visualize microvascular space and FITC labeled red blood cells (RBCs) were used to visualize flow dynamics during HMP. A heterogeneous flow pattern with regions of red cell stasis was observed after 24-h HMP. To examine the cause of red cell stasis, intravital and confocal microscopy studies of endothelial cells (ECs) structure labeled with DiI acetylated low-density lipoprotein (DiI acLDL) were conducted. These studies suggest that morphological changes in EC structures occurred during 24h HMP, which may cause obstruction to the sinusoidal flow. Histological findings confirm these results. As a result, heterogeneous flow pattern, red cell stasis, and edema occur, which may lead to the failure of these tissues following extended HMP.

Adenosine↗

PubMed2003

Hemodialysis vascular access dysfunction: from pathophysiology to novel therapies.

Hemodialysis vascular access dysfunction is a major cause of morbidity and hospitalization in the hemodialysis population at a cost of over USD 1 billion per annum. Most hemodialysis grafts fail due to a venous stenosis (venous neointimal hyperplasia) which then results in thrombosis of the graft. Despite the magnitude of the clinical problem there are currently no effective therapies for this condition. The current review (a) describes the pathogenesis and pathology of venous stenosis in dialysis access grafts and (b) discusses the development and application of novel therapeutic interventions for this difficult clinical problem. Special emphasis is laid on the fact that PTFE dialysis access grafts could be the ideal clinical model for testing out novel local therapies to block neointimal hyperplasia.

Animals↗

PubMed2003

Vascular brachytherapy for hemodialysis vascular access dysfunction: exploring an unmet clinical need.

Hemodialysis vascular access dysfunction is a major cause of morbidity and hospitalization in the hemodialysis population (230,000 patients in the United States) at a cost of well over 1 billion dollars per annum. Venous stenosis and thrombosis (due to venous neointimal hyperplasia), is the most common cause of hemodialysis vascular access dysfunction. At the clinical level, this manifests in the form of a 50%, one-year primary patency for new grafts, and a dismal 40% 3-month survival for thrombosed grafts. However, despite the magnitude of the clinical problem, there are currently no effective therapies for this condition. We and others have previously demonstrated that venous neointimal hyperplasia in polytetrafluoroethylene (PTFE) dialysis grafts is composed of smooth muscle cells/myofibroblasts, a perigraft macrophage layer and microvessels within the venous neointima. Interestingly, there is strong experimental evidence which demonstrates that radiation therapy blocks the proliferation and activation of all these cell types. In addition, endovascular radiation therapy has already been successfully used to prevent restenosis following coronary angioplasty. The BRAVO trial is a randomized, multi-center, double-blind clinical trial of endovascular radiation in PTFE dialysis grafts, sponsored by the Novoste Corporation. This trial is particularly significant as it is the first large multi-center study that is focused on testing a novel local intervention in the specific setting of dialysis access dysfunction. The rationale behind this study, and its design and the logistics involved, will also be described in this review.

Brachytherapy↗

PubMed2002

Hemodialysis vascular access dysfunction from basic biology to clinical intervention.

Hemodialysis vascular access dysfunction is a major cause of morbidity and hospitalization in the hemodialysis population at a cost of over 1 billion dollars per annum. Venous stenosis and thrombosis as a result of venous neointimal hyperplasia are the major causes of hemodialysis vascular access dysfunction. Despite the magnitude of the clinical problem, there are currently no effective therapies for this condition. We believe that this could be because of an inadequate understanding of the pathogenesis of this condition. At a histological level, venous neointimal hyperplasia (both in human specimens and in a pig model) is characterized by the presence of smooth muscle cells/myofibroblasts, microvessel formation (angiogenesis), and the accumulation of extracellular matrix components, all of which could be potential targets for therapeutic intervention. In particular, polytetrafluoroethylene dialysis access grafts could be the ideal clinical model for testing out novel local therapies to block neointimal hyperplasia. The current review describes the lesion of venous neointimal hyperplasia in human samples and in a pig model and suggests possible future directions for the development of effective local therapies for this condition.

Arteriovenous Shunt, Surgical↗

PubMed2002

Parathyroid hormone suppression by intravenous calcitriol: role of phosphate, calcium, race and diabetes.

BACKGROUND: Parathyroid hormone (PTH) suppression in patients with end-stage renal disease (ESRD) undergoing maintenance hemodialysis is achieved largely by the use of intravenous calcitriol. Aspects of the utility and efficacy of this therapy remain controversial. It is debated whether oral versus intravenous therapy is more effective. Most existing studies examine the effect of calcitriol in isolation, without adjusting for other factors that might influence PTH levels. Thus, the simultaneous role of factors such as dosing, control of serum calcium and phosphorus, and demographic variables such as age, sex, race, and duration of ESRD is not well understood. METHODS: We examined the relationship between the administration of calcitriol and PTH suppression in a cohort of hemodialysis patients at a large urban dialysis facility over a period of 30 months. Hemodialysis patients (n = 155) who received at least 3 months of treatment in this facility were included. RESULTS: Using a time sensitive multiple linear regression modeling technique, we found that second and subsequent PTH levels were positively correlated with black race (P < 0.0001) and serum phosphate (P < 0.03) and strongly negatively correlated with serum calcium (P< 0.0001) and diabetes (P< 0.0039). Drug dose (in micrograms per kilogram per month) was weakly negatively correlated (P < 0.04). Unlike previous studies, we adjusted for the simultaneous confounding influence of demographic and laboratory variables, as well as for drug dose normalized for body weight. CONCLUSIONS: This analysis suggests that calcitriol therapy in hemodialysis patients is adversely affected by higher phosphate levels and needs to account for such patient characteristics as race and diabetes and such laboratory variables as calcium and phosphate control. Finally, as has been recently suggested by others, the patient's race may require us to aim for different PTH target levels with therapy.

Algorithms↗

PubMedDate not supplied

The intertester and intratester reliability of hand volumetrics.

The purpose of this study was to examine the intertester and intratester reliability of hand volumetric measurements comparing two different protocols. The first protocol involved three clinicians at an outpatient facility interpreting the manufacturer's volumeter instructions. At the second university site, three testers utilized a modified version of the American Society of Hand Therapists' recommended protocol. Three measurements were taken of each of 30 nonedematous hands per site. Reliability was assessed using only the first measurement and using the mean of the three measurements. Results for both protocols revealed very high intertester reliability (ICC=0.99) whether using the first measurement or the mean of three measurements. Intratester reliability was also very high (ICC=0.99) using either protocol. Standard error of measurement values are included and additional variables, which may affect the reliability of hand volumetrics, are discussed. The authors conclude that there is high reliability with volumetric measurements.

Adult↗