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Biomedical subjects

T Timmers

Publications and source records attributed to T Timmers.

At least 19 recordsLinked to original sources
PubMed1998

The graduate training in medical information sciences in the Academic Medical Centre at the University of Amsterdam.

Since its inception in 1987, the 4-year Medical Information Sciences (MIS) curriculum at the Academic Medical Centre (AMC), Amsterdam has gone through several major changes. The present curriculum started in 1994. The course takes 4 years, the first 3 years are programmed in integrated modules of 7 weeks in duration each. In these modules much attention is given to interactive teaching, problem based learning and private study. Typical for the Amsterdam curriculum is a strong emphasis on the role and significance of data and information in health care and its management. The authors see information technology per se as auxiliary to this orientation. Presently, about 150 students follow the courses.

Curriculum↗
PubMed1998

Improvement of sperm count and motility after ligation of varicoceles detected with colour Doppler ultrasonography.

The debate regarding the efficacy of varicocele ligation for improvement of semen parameters and pregnancy rates is ongoing. In addition, no consensus exists as to the benefit of treatment of subclinical varicoceles. The aim of this study was to investigate, retrospectively, the effect of high ligation of both subclinical and clinical varicoceles on sperm count and motility. The value of several factors from history-taking and physical examination for the prediction of successful varicocelectomy was analysed. A total of 139 patients, operated on for a unilateral varicocele on the left side, were studied. Varicoceles were subclinical in 73 patients, based on colour Doppler ultrasonography, and 66 varicoceles were clinical, based on palpation in addition to ultrasonography. Comparison of semen parameters before and after surgery revealed a significant improvement. The median sperm count increased from 10.0 to 14.7, and from 18.2 to 28.6 million/ejaculate, in patients with subclinical and clinical varicoceles, respectively (p < 0.001). The percentage improvement in median sperm count in subclinical varicoceles was not statistically different from the improvement in clinical varicoceles. Mean progressive motility improved significantly after ligation (p < 0.001). The improvement in motility in subclinical varicoceles, from 16 to 23%, was significantly larger than the 24 to 27% improvement in clinical varicoceles. The increase in sperm count was related positively to testicular volume before surgery (p < 0.05). The increase in sperm motility was significantly lower in patients with a history of cryptorchidism (n = 22, p < 0.05). The present data show that ligation of varicoceles detected using Doppler ultrasonography, whether palpable or not, results in an increase in sperm concentration and motility.

Adult↗
PubMed1997

Restructuring routinely collected patient data: ORCA applied to andrology.

Hospital information systems do not always cover all required detail per specialty. This may lead to scattering of data over disparate systems and the paper record. The ORCA (Open Record for CAre) CPR offers a generic structure for record sharing, and record keeping tailored to specific needs. We studied whether a semantic integration of existing and new data was possible, using the ORCA structure. Existing andrology data, originating from separate sources, were utilized for this purpose. During normalization, validation and explication steps, latent problems in the source data were exposed and removed, followed by a merge with new data items. By conversion of source data to ORCA, a unique representation of medical concepts in the database was attained, facilitating retrieval of univocal data for multiple purposes. We conclude that the expansion to the andrology domain, including transparent integration of existing data, provides support for the generality of ORCA.

Ambulatory Care Information Systems↗
PubMed1995

Morphological, haemodynamic, and clinical variables as predictors for management of isolated ventricular septal defect.

OBJECTIVE: To assess the predictive impact of morphological, haemodynamic, and clinical variables in the management of patients with isolated ventricular septal defect. DESIGN: Retrospective analysis of variables by a sophisticated database management system. PATIENTS AND METHODS: 263 consecutive patients with isolated ventricular septal defect diagnosed by echocardiography. The morphological type and haemodynamic character of the ventricular septal defect was characterised in each patient. In addition, variables were introduced to represent the need for diuretics, growth, and potential delay in growth. In 43 patients (16.3%) the ventricular septal defect was closed surgically; 220 patients (83.7%) were managed conservatively and spontaneous closure of the ventricular septal defect occurred in 65 (29.5%). There were no deaths. RESULTS: All patients managed surgically had non-restrictive defects and were operated on during the first year of life. A few patients with non-restrictive defects were managed conservatively. The two groups differed significantly only with respect to mean growth delay (0.65 (0.27) v 0.9 (0.21), P < 0.001). Only the morphology of the ventricular septal defect significantly (P < 0.001) influenced the probability of closure. CONCLUSIONS: Findings imply that early surgical closure of ventricular septal defect is indicated in patients with non-restrictive ventricular septal defect and severe growth delay. Other patients should be managed conservatively. In these patients the morphological type of the defect determines the probability of spontaneous closure and provides an estimate of the period over which decreased in size or closure can be expected.

Child, Preschool↗
PubMed1995

ARIS: integrating multi-source data for research in andrology.

Although the concept of distributed systems for the storage of patient data is more and more commonly accepted, for some considerable time yet most patient data will be stored in centralized rather than departmental systems. An important advantage of storage in a central system is hospital-wide access to much of the patient data. Disadvantages are however that these data cannot be reviewed through one user interface, and that the structure of the data does not lend itself to exploitation for other purposes. We describe the implementation of an Andrology Research Information System in which these data are integrated in a well-structured database facilitating multiple views on the patient data through a graphical user interface, and clinical research, quality control and summary reports. The data can be analyzed directly using the Hermes workstation. In this way the strengths of the centralized system are combined with those of the dedicated ARIS system.

Computer Graphics↗
PubMed1995

SmaCS: smart classification system for the design, maintenance and use of complex terminologies. Application in pediatric cardiology.

The development of a generic Smart Classification System (SmaCS) for the design, construction, maintenance, and use of complex controlled terminologies is described. The ability of SmaCS to create and maintain terminologies that are combinations of structured terms and domain-specific knowledge is an important aspect of its design. SmaCS can therefore be used both for both controlled data-collection, using integrity rules included in the terminology, and intelligent data-retrieval. The design and implementation of SmaCS and application in the domain of pediatric cardiology are described.

Cardiology↗
PubMed1995

Problems with integrating legacy systems.

The economic and organizational impact of imposing state-of-the-art technology to the large number of proprietary legacy systems operational in most hospitals requires integrated clinical professional workstations to provide flexible encapsulation mechanisms for these systems rather than reengineering these systems to this new technology. In this paper the implications of different input/output and translation models of legacy systems for their integration into a clinical workstation is described. Examples of legacy systems that have been integrated in the HERMES clinical workstation are presented as examples of the range of difficulties one might encounter. The features that an integrated workstation should offer for integrating a broad range of legacy systems are also addressed in this paper.

Computer Systems↗
PubMed1995

Smart Classification System (SmaCS): design, implementation, and application for congenital heart disease terminology.

The development of a generic Smart Classification System (SmaCS) for the design, construction, maintenance, and use of complex controlled terminologies is described. SmaCS is used to create a knowledge-base containing more than 2,500 items for the description of abnormalities, treatments, complications, etc. within the domain of congenital heart disease. The purpose of the combination of domain specific knowledge and terminology is to provide a tool useful for both data entry and the subsequent analysis of the data collected.

Artificial Intelligence↗
PubMed1994

HERMES: a health care workstation integration architecture.

An architecture is described that facilitates integration of existing databases and applications without modifying them. By means of this architecture, data from different sources dispersed in a network can be combined and directly used in existing applications or applications that have been developed specially for integration. This feature of combining data from different sources into one workstation is viewed as the enabling technology on which computer-based patient records can be built. The abstraction of computer-, network- and application-specific details is completely dealt with by the integration architecture. This integration architecture has been developed with extendibility and flexibility in mind, and allows for a growth-path towards application of the open system paradigm in medicine.

Computer Communication Networks↗
PubMed1994

Multiple imputation as a missing data machine.

This paper deals with problems concerning missing data in clinical databases. After signalling some shortcomings of popular solutions to incomplete data problems, we outline the concepts behind multiple imputation. Multiple imputation is a statistically sound method for handling incomplete data. Application of multiple imputation requires a lot of work and not every user is able to do this. A transparent implementation of multiple imputation is necessary. Such an implementation is possible in the HERMES medical workstation. A remaining problem is to find proper imputations.

Algorithms↗
PubMed1994

Beyond clients and servers.

Computer scientists working in medical informatics have to face the problem that software offered by industry is more and more adopted for clinical use by medical professionals. A new challenge arises of how to combine commercial solutions with typical medical software that already exists for some years and proved to be reliable with these off-the-shelf solutions [1]. With the HERMES project, this new challenge was accepted and possible solutions to integrate existing legacy systems with state-of-the-art commercial solutions have been investigated. After a period of prototyping to assess possible alternative solutions, a system based on an indirect client-server model was implemented with help of the industry. In this paper, its architecture is described together with the most important features currently covered. Based on the HERMES architecture, both systems for clinical data analysis and patient care (cardiology) are currently developed.

Computer Systems↗
PubMed1994

A cooperative model for integration in a cardiology outpatient clinic.

With the increasing amount of digitally stored patient information, such as images and findings, the possibility and need arise for a system which is able to both store and display this information in a structured, user-friendly way. In the common situation where different information systems are used within one department, this means that the various information systems have to be integrated. However, integration requires more complex management of data, processes and windows. This management can be handled by a Workspace Manager, which controls inter-application tasks, and interaction with the user. Furthermore, this Workspace Manager supports the user with the definition of complex tasks such as collecting problem-related patient information from the various remote systems. In an outpatient clinic for cardiology this architecture is used to achieve cooperative integration of an open Computer Patient Record with a range of information-specific services.

Ambulatory Care Facilities↗
PubMed1993

A prototype integrated medical workstation environment.

In this paper the requirements, design, and implementation of a prototype integrated medical workstation environment are outlined. The aim of the workstation is to provide user-friendly, task-oriented support for clinicians, based on existing software and data. The prototype project has been started to investigate the technical possibilities of graphical user-interfaces, network technology, client-server approaches, and software encapsulation. Experience with the prototype encouraged discussion on both the limitations and the essential features for an integrated medical workstation.

Computer Graphics↗
PubMed1993

Does an integrated medical workstation really help clinicians?--A formal user evaluation.

A formal user evaluation of an integrated medical workstation for support of clinical data analysis is described. Twenty-six users participated in an assessment study that consisted of a self-instruction course, followed by an experiment in which six clinical data analysis problems had to be solved, and the assessment was concluded with an evaluation form. To facilitate an objective and quantitative assessment, the time spent to the course and to the problems, as well as completeness, correctness, number of solving attempts and persistence were measured. Not all problems were solved by all participants. From an analysis of the measurements, the following conclusions were drawn. (1) Clinicians correctly solved about 69% of all problems tackled. However, they skipped 33% of the problems. (2) Non-clinicians correctly solved 87% of the tackled problems and skipped only 10%. (3) The performance of users not experienced in clinical data analysis was raised to the level of those with clinical data analysis experience. (4) An inventory which can be used to direct future developments was made of the errors of interaction. This assessment study has contributed to gaining insight into the conceptual problems and practical bottlenecks clinicians have with clinical data analysis.

Clinical Medicine↗
PubMed1993

User evaluation of an integrated medical workstation for clinical data analysis.

Results are presented of the user evaluation of an integrated medical workstation for support of clinical research. Twenty-seven users were recruited from medical and scientific staff of the University Hospital Dijkzigt, the Faculty of Medicine of the Erasmus University Rotterdam, and from other Dutch medical institutions; and all were given a written, self-contained tutorial. Subsequently, an experiment was done in which six clinical data analysis problems had to be solved and an evaluation form was filled out. The aim of this user evaluation was to obtain insight in the benefits of integration for support of clinical data analysis for clinicians and biomedical researchers. The problems were divided into two sets, with gradually more complex problems. In the first set users were guided in a stepwise fashion to solve the problems. In the second set each stepwise problem had an open counterpart. During the evaluation, the workstation continuously recorded the user's actions. From these results significant differences became apparent between clinicians and non-clinicians for the correctness (means 54% and 81%, respectively, p = 0.04), completeness (means 64% and 88%, respectively, p = 0.01), and number of problems solved (means 67% and 90%, respectively, p = 0.02). These differences were absent for the stepwise problems. Physicians tend to skip more problems than biomedical researchers. No statistically significant differences were found between users with and without clinical data analysis experience, for correctness (means 74% and 72%, respectively, p = 0.95), and completeness (means 82% and 79%, respectively, p = 0.40).(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Systems↗
PubMed1993

A new architecture for integration of heterogeneous software components.

An architecture is described that integrates existing applications in a network-wide system. The architecture follows the new open software paradigm, and defines kernel and application services that collaboratively solve the tasks of end-users and provide them with an intuitive user-interface. This paper describes the message language and the kernel mechanism for addressing application services. The architecture has been developed as much as possible to conform with current standards.

Computer Communication Networks↗