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Biomedical subjects

J R Beck

Publications and source records attributed to J R Beck.

At least 37 records · Page 2Linked to original sources
PubMed1999

Inhaled nitric oxide improves hemodynamics in patients with acute pulmonary hypertension after high-risk cardiac surgery.

Severe pulmonary hypertension and right-sided circulatory failure (RSCF) represent an increasing cause of morbidity and mortality in patients undergoing high-risk cardiac surgery. Increased pulmonary vascular resistance in the setting of cardiopulmonary bypass (CPB) may further lead to decrease blood flow across the pulmonary vascular bed; thereby decreasing left ventricular filling and cardiac output. Current management techniques for RSCF include both nonspecific vasodilator and inotropic agents (often limited by systemic hypotension) and the placement of right ventricular assist devices (associated with increased perioperative morbidity). Inhaled nitric oxide (NOi) represents a novel, specific pulmonary vasodilator that has been proven efficacious in these clinical settings. We evaluated 34 patients in 38 operations who underwent cardiac surgery at Columbia Presbyterian Medical Center, and who received NOi (20 ppm) through a modified ventilatory circuit for hemodynamically significant elevations in pulmonary vascular resistance. Nine patients underwent cardiac transplantation, three patients bilateral lung transplantation, 16 patients left ventricular assist device placement and 10 patients routine cardiac surgery. Patients receiving NOi exhibited substantial reductions in mean pulmonary artery pressure (mPAP) (34.6 +/- 2.0 to 26.0 +/- 1.7 mmHg, p < 0.0001), with improvements in systemic hemodynamics, mean arterial pressure (68 +/- 3.1 to 75.9 +/- 2.0 mmHg, p = 0.006). In five cases, patients could not be weaned from CPB until NOi was administered. Patients were maintained on NOi from 6 to 240 h postoperatively (median duration 36 h). Inhaled NO induces substantial reductions in mPAP and increases in both cardiac index and systemic blood pressure in patients displaying elevated pulmonary hemodynamics after high-risk cardiac surgery. NO is, therefore, a useful adjunct in these patients in whom acute pulmonary hypertension threatens right ventricular function and hemodynamic stability.

Acute Disease↗
PubMed1999

Treatment of primary peritoneal mesothelioma by hyperthemic intraperitoneal chemotherapy.

Perfusion of the peritoneal cavity with chemotherapy agents under hyperthermic conditions has been utilized by several investigators in the treatment of intra-abdominal malignancies. Based on the concept that hyperthermia may potentiate the cytotoxic effects of chemotherapeutic agents, we embarked on a clinical trial of two-stage peritoneal chemotherapy for patients with primary peritoneal mesothelioma, a neoplasm unresponsive to traditional systemic chemotherapeutic regimens. In stage I, patients underwent surgical debulking of gross disease and placement of an intraperitoneal infusion catheter, through which intraperitoneal chemotherapy was administered for four months. Stage II consisted of debulking of residual tumor, placement of two transabdominal perfusion cannulae and administration of high-dose intraperitoneal chemotherapy at 40 degrees C using a simple, disposable perfusion circuit. Flow rates were maintained at 1 l/min, and inflow and outflow temperatures maintained at 42 and 40 degrees C, respectively. To date, three patients have undergone both phases of the protocol, with no perioperative complications related to either hyperthermia or end-organ toxicity. One patient died of progressive disease after three months, and two patients are alive and well. One patient developed a small bowel anastomotic leak three weeks after operation. In summary, intraoperative hyperthermic peritoneal chemotherapy may play a role in novel approaches to the treatment of peritoneal malignancies previously unresponsive to traditional chemotherapeutic regimens.

Adult↗
PubMed1999

The effects of a fixed-fee reimbursement system introduced by the Federal Government on laboratory testing in the United States.

Rapid growth of health care expenditures during the 1970s in the United States led to implementation of a prospective payment system (PPS) based on diagnosis-related groups (DRG) for Medicare inpatient reimbursement in 1983. With the introduction of DRG/PPS, hospitals encouraged earlier discharges and discouraged admission of patients who may require expensive services. Patient care has moved into more outpatient and non-hospital settings which have been less regulated and paid on a cost-reimbursement basis. The change of reimbursement system has converted hospital laboratories from "profit center" under the fee-for-service reimbursement practice to possible "cost center" at least for inpatient laboratory services with the advent of DRG/PPS. Hospitals have reduced laboratory operating expenses by constraining laboratory growth and development. Laboratory testing in non-hospital settings such as physicians' office laboratories, which were exempt from license and quality control by governmental regulations, has increased exponentially since implementation of DRG/PPS. To improve the quality of laboratory testing in such unregulated laboratories, the federal government has promulgated the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88), requiring on-site survey and license under CLIA '88 for all laboratories in the United States regardless of the size, complexity, or location of laboratory. Implementation of DRG/PPS resulted in a temporary success in reducing Medicare Part A budget growth, but had only a small impact to slow the actual growth of total national health care expenditures or laboratory-related expenditures. Nevertheless, the change of reimbursement practice has created a large incentive to reduce unnecessary resource utilization, and cost-effective laboratory testing has become an essential concept during the DRG/PPS era.

Clinical Laboratory Techniques↗
PubMed1999

Common diagnostic test panels for clinical evaluation of new primary care outpatients in Japan: a cost-effectiveness evaluation.

BACKGROUND: The Japan Society of Clinical Pathology (JSCP) has developed a guideline for common diagnostic test utilization in new primary care outpatients. To determine the scientific and economic validity of the JSCP panel testing system, we analyzed cost-effectiveness parameters of test panels advocated. METHODS: The "Essential Laboratory Tests" panel (2) [ELT(2) panel], a package of common diagnostic tests added to the ELT(1) baseline health-status screening panel, was applied to 540 new outpatients who visited the Comprehensive Medicine Clinics in an academic medical center during 1991 to 1997. A "useful result" (UR) of testing was defined as a finding that contributed to a change in a physician's diagnosis- or decision-making, relating to a "tentative initial diagnosis" (TID) obtained from history and physical examination alone. RESULTS: Clinical usefulness was demonstrated in 259 patients with ELT(2), in whom 398 URs were generated. Clinical effectiveness (UR/TID) ranged from 1.65 (hematological) to 0.088 (neurological disease), with a cost disparity from yen1251 ( approximately $10) to yen23 037 ( approximately $200) per UR. A total of 1137 tests generated URs. We further assessed the clinical effectiveness and economic efficiency (cost/UR) of ELT(1) and restructured panels. Use of the ELT(1) alone generated 244 URs in 167 patients. The poor efficiency of the ELT(1) panel was markedly improved with the addition of certain ELT(2)-specific tests in liver/pancreatobiliary, metabolic/endocrine, and cardiovascular disease groups. CONCLUSIONS: A wide disparity in the utility of ELT panels in different patient groups does not support the JSCP recommendation of their routine use for new outpatients. Selective test combinations should be used in selected patient groups.

Adolescent↗
PubMed1999

Naive Bayesian-based nomogram for prediction of prostate cancer recurrence.

This paper introduces a schema with naive-Bayesian classifier and patient weighting technique to develop a prostate cancer recurrence prediction model from patient data. We propose the graphical presentation of naive-Bayesian classifier with a nomogram, which can be used both for prediction or can provide means to data analysis. The resulting model was experimentally evaluated; the results were favorable both in terms of interpretability and predictive accuracy.

Bayes Theorem↗
PubMed1998

Experiments to determine whether recursive partitioning (CART) or an artificial neural network overcomes theoretical limitations of Cox proportional hazards regression.

New computationally intensive tools for medical survival analyses include recursive patitioning (also called CART) and artificial neural networks. A challenge that remains is to better understand the behavior of these techniques in effort to know when they will be effective tools. Theoretically they may overcome limitations of the traditional multivariable survival technique, the Cox proportional hazards regression model. Experiments were designed to test whether the new tools would, in practice, overcome these limitations. Two datasets in which theory suggests CART and the neural network should outperform the Cox model were selected. The first was a published leukemia dataset manipulated to have a strong interaction that CART should detect. The second was a published cirrhosis dataset with pronounced nonlinear effects that a neural network should fit. Repeated sampling of 50 training and testing subsets was applied to each technique. The concordance index C was calculated as a measure of predictive accuracy by each technique on the testing dataset. In the interaction dataset, CART outperformed Cox (P < 0.05) with a C improvement of 0.1 (95% CI, 0.08 to 0.12). In the nonlinear dataset, the neural network outperformed the Cox model (P < 0.05), but by a very slight amount (0.015). As predicted by theory, CART and the neural network were able to overcome limitations of the Cox model. Experiments like these are important to increase our understanding of when one of these new techniques will outperform the standard Cox model. Further research is necessary to predict which technique will do best a priori and to assess the magnitude of superiority.

Databases, Factual↗
PubMed1998

Prolonged treatment with interferon in patients with histologically mild chronic hepatitis C: a decision analysis.

Short courses (6 months) of interferon (IFN) are highly cost-effective in patients with histologically mild chronic hepatitis C. However, IFN treatment lasting 12-24 months is now the standard of care. We utilized a previously published and validated model of the natural history of chronic hepatitis C and the treatment outcomes from two large multicentre treatment trials of IFN-alpha 2b, given for 6 months or 18-24 months, to estimate the incremental cost-effectiveness of prolonged IFN treatment in patients with histologically mild chronic hepatitis C (formerly chronic persistent or mild chronic active hepatitis). In the two treatment trials, pooled analysis of the patients with mild hepatitis showed that 36.4% of them normalized serum alanine aminotransferase and remained virus negative (sustained response) after completing an 18-24 month course of IFN vs 15.3% for a 6-month course and no response in the absence of treatment. The model then estimated that for patients aged 20-50 years, the discounted marginal cost per year of life gained by long-term IFN treatment ranged from US $735 to US $8856, and the gain in life expectancy ranged from 4.35 years to 0.75 years, respectively, compared with an untreated age-matched cohort. Compared with treatment for only 6 months, the incremental marginal cost per life year gained by longer treatment at age 20-50 years ranged from $938 to $9957. The treatment and healthcare costs, sustained response rates and the rate of progression during early disease were identified as significant variables in sensitivity analyses. However, longer treatment always showed a survival benefit compared with 6 months of IFN or no treatment, and the cost of longer treatment is reasonable compared with that for a 6-month course.

Adult↗
PubMed1998

Clinical evaluation of setting pump occlusion by the dynamic method: effect on flow.

Pump manufacturers recommend setting roller pump occlusion such that the level of a 100 cm column of crystalloid drops 2.5 cm/min (Sarns, 8000 Modular Perfusion System, operator's manual, roller pump software version 2.3L. May 1993; 2.1-2.14). Though this almost occlusive setting ensures accurate pump flow, it has been shown to cause more hemolysis than nonocclusive pumps (Noon GP, Kane LE, Feldman L et al. Reduction of blood trauma in roller pumps for long-term perfusion. World J Surg 1985; 9: 65-71). We conducted a clinical study (n = 19) to compare the standard occlusion method with the dynamic method and to determine the accuracy of flow for the nonocclusive pump. Standard occlusion was set by clamping the pump tubing distal to the arterial line filter and timing the drop in pump outlet pressure as indicated by a pressure transducer connected to the filter. The occlusion setting, expressed in mmHg/s, was recorded for each roller at two specific points along the raceway. The pump was then set nonocclusively with the dynamic method using the Better Header (BH) (Circulatory Technology, Oyster Bay, NY, USA). Readings of the change in pressure in the same two selected points on the raceway were taken. The latter was repeated after discontinuation of bypass. Flow was recorded throughout the procedure from both roller pump output display and a flow meter (Model #109 Transonic, Ithaca, NY, USA). The average drop in pump outlet pressure for the standard method was 1.3 +/- 4.0 (range 0-18 mmHg/s), and for the dynamic method was 38 +/- 28 (range 1.2-89 mmHg/s). Off bypass, the average reading was 44 +/- 38 (range 2.0-103 mmHg/s). Regression analysis indicates that patient flow, when corrected for retrograde flow by the dynamic method, equals 1.003 x revolutions per minute + 40 ml/min (r2 = 0.964). The average error between indicated pump flow, corrected for retrograde flow, was -1% (range from -6.7 to 6.6%). We conclude that the BH allows nonocclusive setting (30 times less than our standard method) without sacrificing pump flow accuracy.

Cardiopulmonary Bypass↗
PubMed1997

Estimates of the cost-effectiveness of a single course of interferon-alpha 2b in patients with histologically mild chronic hepatitis C.

BACKGROUND: Chronic hepatitis C is a major cause of illness and death in the United States. Interferon-alpha 2b can induce clinical, biochemical, and virologic remission in some patients with chronic hepatitis C, but the long-term cost-effectiveness of this treatment, particularly in patients with histologically mild disease, is unknown. OBJECTIVE: To estimate the cost-effectiveness of interferon-alpha 2b in mild chronic hepatitis C. DESIGN: Meta-analysis of five prospective trials and cost-effectiveness analysis. Projection of the clinical and economic outcomes expected from loss of hepatitis C virus was done by using a Markov simulation. The potential effect of uncertainty in the model assumptions was tested by using sensitivity analyses. DATA SOURCES: Search of the MEDLINE database, opinions of expert panels, hospital cost data, and adjusted physician charges. PATIENTS: Hypothetical cohorts with histologically mild chronic hepatitis C. INTERVENTION: The model assumed a single 6-month course of recombinant interferon-alpha 2b. MEASUREMENTS: Life expectancy, quality-adjusted life expectancy, costs, and marginal cost-effectiveness ratios from a managed care perspective. RESULTS: In 27% of patients with mild chronic hepatitis C treated with interferon-alpha 2b for 6 months, serum alanine aminotransferase levels permanently returned to normal and viral status remained negative. The model estimated that interferon-alpha 2b treatment in this population should increase life expectancy by 3.1 years if given at 20 years of age, by 1.5 years at 35 years of age, and by 22 days at 70 years of age; discounted marginal cost-effectiveness ratios are $500, $1900, and $62,000 per year of life gained, respectively. Varying the long-term response rates and progression rates for mild and moderate chronic hepatitis to near zero in sensitivity analyses substantially affected the results: Ratios ranged from $31,000 for a 20-year-old patient to $640,000 for a 70-year-old patient. CONCLUSIONS: On the basis of estimations in this mathematical model of the natural history of chronic hepatitis C, treating mild chronic hepatitis with interferon-alpha 2b should prolong life expectancy at a reasonable marginal cost per year of life gained, particularly in younger patients.

Alanine Transaminase↗
PubMed1996

Cost-effectiveness of interferon-alpha and conventional chemotherapy in chronic myelogenous leukemia.

OBJECTIVE: To compare the cost-effectiveness of interferon-alpha with that of hydroxyurea as initial therapy for patients with chronic myelogenous leukemia (CML) in the chronic phase. DESIGN: A decision analysis and Markov model that described the natural history of the therapeutic process. The Markov model contained two treatment arms (interferon-alpha and hydroxyurea) and eight states of health (complete hematologic remission with cytogenetic response, complete hematologic remission without cytogenetic response, partial hematologic remission, chronic phase without hematologic remission, accelerated phase, blast crisis, bone marrow transplantation, and death). Probabilities, costs, and utilities were obtained from published clinical studies and clinical investigators. MEASUREMENT: Quality-adjusted years of life saved and costs and qualities discounted at 5% per year. SETTING: University medical centers in North America and Europe. PATIENTS: Meta-analysis of results from patients studied in clinical trials. RESULTS: The model's predictions of median survival (69 months with interferon-alpha therapy and 58 months with hydroxyurea therapy) were derived from data in the recent literature. In patients 50 years of age, interferon-alpha improved life expectancy over hydroxyurea by approximately 18 months. The marginal cost-effectiveness of interferon-alpha (incremental discounted cost of interferon-alpha compared with that of conventional therapy) was $34800 per quality-adjusted year of life saved. The model was sensitive to the monthly cost of interferon-alpha therapy (if the cost of interferon-alpha is reduced by one third, the cost-effectiveness becomes $19300 per quality-adjusted year of life saved) but was not particularly sensitive to the costs associated with blast crisis or bone marrow transplantation. The other significant variable was quality of life during therapy with interferon-alpha; when this measure was varied from 70% to 100% of the quality of life during hydroxyurea therapy, cost-effectiveness changed from $123200 to $25620 per quality-adjusted year of life saved. When the quality of life associated with interferon-alpha was less than 62% of the quality of life associated with hydroxyurea, the discounted quality-adjusted life expectancy with interferon-alpha was less than that with hydroxyurea. CONCLUSION: Compared with hydroxyurea, interferon-alpha is, in most clinical scenarios, a cost-effective initial therapy for patients with chronic-phase CML who can tolerate the drug.

Antineoplastic Agents↗
PubMed1996

Workflow computing. Improving management and efficiency of pathology diagnostic services.

Traditionally, information technology in health care has helped practitioners to collect, store, and present information and also to add a degree of automation to simple tasks (instrument interfaces supporting result entry, for example). Thus commercially available information systems do little to support the need to model, execute, monitor, coordinate, and revise the various complex clinical processes required to support health-care delivery. Workflow computing, which is already implemented and improving the efficiency of operations in several nonmedical industries, can address the need to manage complex clinical processes. Workflow computing not only provides a means to define and manage the events, roles, and information integral to health-care delivery but also supports the explicit implementation of policy or rules appropriate to the process. This article explains how workflow computing may be applied to health-care and the inherent advantages of the technology, and it defines workflow system requirements for use in health-care delivery with special reference to diagnostic pathology.

Ambulatory Care↗
PubMed1995

Perfusion technique for treatment of right heart failure.

A simple heparin-bonded circuit to facilitate a femoral vein to femoral artery shunt for the treatment of right-sided circulatory failure is proposed. Desaturated venous blood is shunted to the left-sided circulation to increase systemic blood pressure at the expense of saturation. The circuit comprised 1/4 inch x 3/32 inch tubing with a paediatric Bio-Medicus centrifugal pump head allowing adequate regulation of flow. Paediatric Bio-Medicus cannulae provide flows between 500 and 2000 ml/min. Measurements of pulmonary artery pressure, central venous pressure, arterial pressure, arterial saturation and cardiac output were recorded. In the four case studies presented, the treatment included unloading of the right ventricle with venous to arterial shunting. Likewise, eight Holstein calves underwent shunt utilization after placement of a left ventricular assist device and induction of right ventricular failure. The future use of this device may be instrumental in aiding the cardiothoracic surgical team in the treatment of right-sided circulatory failure.

Adult↗
PubMed1995

Artificial neural networks for medical classification decisions.

Neural networks are growing in popularity. However, empirically comparing them with traditional methods of solving medical classification decisions is not trivial. Following a brief description and comparison with the statistical technique, discriminant analysis, the methodology for comparing neural networks with discriminant analysis is described. The advantages and disadvantages of neural networks are summarized to support a conclusion that neural networks are beneficial and destined to proliferate. Areas of fruitful future research are identified.

Decision Making, Computer-Assisted↗
PubMed1995

A proposed architecture for ambulatory systems development.

We have developed an architecture and application framework known as the Ambulatory Services Architecture (ASA) for computerized management of patient records for ambulatory care. Our primary design goals included the development of an architecture that will be readily adaptable to advances in technology needed to enhance computerized patient record systems (e.g., multimedia, human-computer interfaces such as voice-to-text, and a fully distributed objects, etc.) and a data model and database implementation capable of providing the flexibility and extensibility needed to support a broad spectrum of specialty medical practices. This report describes the data model, access control, and the client/server components of the Ambulatory Services Architecture.

Ambulatory Care Information Systems↗
PubMed1995

Reorganization of the information technology program at a United States medical school: is there a lesson for academic medical informatics in Japan?

Reorganization of the information technology program at Baylor College of Medicine commenced with the goal of obtaining a client-focused organization instead of a classically departmental structure. Legacy organizations independently established by request or serendipity had gaps and overlaps in services and could no longer respond to new issues, such as integration of several hospitals, resource sharing of health care delivery, administration of a shared library, and an academic informatics program. The renewal of the information technology program has led to departments of Telecommunications, Enterprise Services, Client Services, and Medical Informatics, and has also allowed cross-departmental projects led by a technology architect. In contrast with that of Baylor, the approach of the Yamaguchi University School of Medicine in Japan may be construed as economic efficiency at the cost of client services. Effective client services by friendly and efficient staff groups is the most important factor for an academic information technology program, if the goal is to reorganize in anticipation of future challenges to the medical center.

Computer Systems↗
PubMed1995

Collaborative social and medical service application.

Baylor College of Medicine has five Teen Health Clinics (THC) dispersed throughout Harris county. The population served by the clinics includes inner-city adolescent boys and girls 19 years of age and under. Patients receive services such as family planning, sexually transmitted disease screening and treatment, perinatal care, counseling, and support services. Adolescents may receive services at any one of the clinics at no cost to the adolescent or their dependents. Given the geographical distribution of the clinics and the reliance on paper-based records, client services cannot be provided efficiently or expeditiously. According to the statistics developed by Clinic staff, ineffective coordination of service needs and client schedules undermine the follow-up needed for effective care. For example, a counselor will often need to balance a school schedule, clinic visits, well baby follow-up, and the Best Friends Program for a new mother. In addition, the lack of ready access to patient information impairs the ability of clinical and social service staff to provide continuity of care. In fact, some cases of client dropout are attributable to these difficulties. We have developed the Collaborative Social and Medical Service Application (CSMSA) to facilitate the provision of social and medical services to this population. The CSMSA is a domain-specific application based on a robust infrastructure known as the Ambulatory Services Architecture (ASA). This system is designed to support integrated social and ambulatory care. The ASA is a Baylor developed application framework and architecture for the computerization of the patient medical record in the ambulatory care setting. The working environment for the CSMSA user is an integrated desktop which provides an operating environment for both third-party applications and the CSMSA, as well as a fundamental set of services. The integrated desktop services include a mechanism for object organization or grouping, a facility for the management of desktop objects including disposal and storage, and an embedded search utility to assist in the location of desktop objects as well as other application objects. The access control mechanism will provide the security for the desktop environment by requiring the user to log into and out of the environment. This security mechanism will also enable/disable CSMSA tools based on the user's role at the clinic. The CSMSA is designed to provide work process, functionality and data access appropriate to the responsibilities of the user, e.g., a THC clerk may have permission to view a patient's orders but does not have the facility to create an order. Patient context is defined through a patient browser containing the master patient index or a user defined patient list. Patient encounters are managed using forms based on the process for each encounter type (e.g., initial visit). Forms are used for data entry and for queries. Data entry forms are only committed to the patient database (i.e., making the patient data available to other users who have permission to access the data) when the user approves the data. The CSMSA provides a means to suspend an entry into a chart by saving incomplete or non-committed data entry forms as part of the desktop state which is restored when the user logs into the system. CSMSA was designed to provide a robust, expandable application capable of accommodating the changes in health care and social services delivery while encompassing evolving software standards and new technology. This goal was achieved using object-oriented methodologies and technologies, combined with an object-oriented database management system as the foundation of our server to facilitate the evolution of our data model.

Adolescent↗
PubMed1994

Facilitation of health care delivery through enhanced communications.

To realize the advantages of advanced computing technology in medicine we will have to blend computing and communications facilities into a seamless entity that can support ubiquitous computing for medical use. Work-group computing applications, high speed networks linking a multiplicity of servers, and mobile computing platforms can provide the next generation of devices and services for the physician. Ultimately, the biggest challenge for communications and computing in medicine will be found in the requirement for standards in semantics and syntax in the highest levels of the OSI model. We present here our view of the functional requirements for physician communications and computing to meet standard medical practice in Western societies.

Communication↗