Verapamil is supposed to suppress the initiation of circus movement supraventricular tachycardia by affecting the atrioventricular node. In electrophysiological tests, programmed stimulation is usually performed by using the same location for pacing and premature stimulus. Spontaneous ectopic activity starts from a different location than the sinus node and can therefore find altered re-entry conditions. In this study a 3D computer model based on Huygen's principle is used for simulation of the spread of excitation in the human heart in combination with a posterobasal, right or left lateral accessory pathway (AP). The effect of verapamil on properties of the atrioventricular node were modelled by prolonging the effective refractory period and basal conduction time. For each of the three APs, ectopic foci at the atrial base and between sinus node and AP were modelled at various coupling intervals for investigating re-entrant activation. In the control state (without verapamil) only orthodromic echoes were found. The maximum echo zone (EZ) range was found near the AP. If stimuli were selected further away from the AP on the atrial basis, the EZ range decreased until no EZ was found. The EZ range decreased from it's maximum value near the AP, towards the difference of the effective refractory periods between AP and AV-node near the sinus node Verapamil abolished the EZ in case of a posteroseptal AP. For a lateral AP the administration of verapamil resulted in an orthodromic and antidromic EZ depending on the atrial premature activation site. A maximum orthodromic EZ was found for premature stimuli near the AP. As stimulus site moved away from the AP, the EZ range first decreased continuously to zero leading eventually to an antidromic EZ. These findings suggest the important influence of the site of premature stimuli with respect to the accessory pathway and AV-node on the inducibility of atrial re-entry.
This paper addresses the requirements of healthcare providers and hospital managers vis-à-vis electronic patient records that can be integrated. It starts from some critical failure factors, found with previous attempts to standardise the electronic health record. Standardisation appears to be the key issue: the subject of standardisation requires delicate positioning. Technology must provide us with the means to obtain the standardised foundation for an integrated health record concept, which can be completely configured and customised to meet the requirements of health professionals and institutions involved. NUCLEUS, project A2025 in the AIM programme, has taken on this endeavour, and with good success. This paper summarises the benefits of this approach for various categories of people interested in using electronic patient records. Moreover, it illustrates NUCLEUS' contribution to achieving seamless integration of care. Furthermore, this paper explains the conceptual innovations that have been achieved in the NUCLEUS project. It consolidates the main concept of Act Management, structuring the professional primary process as well as the interprofessional communication. These concepts are subsequently expanded to include the key elements of the NUCLEUS integrated electronic patient record. Next, the paper reflects on what has appeared to be one of the critical success factors of the electronic patient record: its configuration and customisation facilities. These facilities make it possible to access the patient record at various intuitive aggregation levels and to make the integrated patient record ‘look like’ the individually specialised record of the respective healthcare professionals. Finally, the paper addresses various topics required to facilitate the successful implementation and operation of the NUCLEUS integrated electronic patient record like security, integrity, message communication, distribution, heterogeneity and the context of the hospital information system.
The traditional approach to the development of knowledge-based systems (KBS) has been rule-based, where heuristic knowledge is encoded in a set of production rules. A rule-based reasoning (RBR) system needs a well constructed domain theory as its reasoning basis, and it does not make substantial use of the knowledge embedded in previous cases. An RBR system performs relatively well in a knowledge-rich application environment. Although its capability may be limited when previous experiences are not a good representation of the whole population, a case-based reasoning (CBR) system is capable of using past experiences as problem solving tools, therefore, it is appropriate for an experience-rich domain. In recent years, both RBR and CBR have emerged as important and complementary reasoning methodologies in artificial intelligence. For problem solving in AIDS intervention and prevention, it is useful to integrate RBR and CBR. In this paper, a hybrid KBS which integrates a deductive RBR system and an inductive CBR system is proposed to assess AIDS-risky behaviors.
This paper discusses a new framework and definition for the development of nursing information systems. Graves and Corcoran presented a framework for nursing informatics and defined the science. In this article their framework is expanded to include nursing practice as domain of study and to better integrate the fact that nursing informatics finds its foundation in both the nursing and the informatics disciplines. The expansion is based on both the review of definitions of medical and nursing informatics and of models and descriptions from the informatics discipline. For research purposes, the domain of nursing informatics is defined, and methods for conducting investigations in the area of analysis, modeling and development of nursing information systems are described.
In 1992 the Dutch College of General Practitioners (NHG) started a project, which lasted until May 1994. The project had three major objectives: establishing as exactly as possible what benefits we gain from using an Electronic Medical Dossier (EMD) can we find an influence on the quality of care? Which drawbacks or problems are there, advising on the optimal use of an EMD; What is the best place to record certain data? advising the Working Committee on Informatics (WCIA), of Dutch National Association of General Practitioners (LHV) and NHG on the directions for the new Reference Model 1995. To obtain these goals panel discussions and a questionnaire were used. The project resulted in advice on how to use the EMD in the most efficient way. Also we have learned about the use of GP-information systems and the perception about this usage by the Dutch GPs.
Intent-Based Networking (IBN) is a novel networking paradigm that allows networks to be autonomously configured, continuously assured, and to be highly adaptable to high-level intentions of network users and operators. In IBN systems, conflict detection and policy resolution modules are crucial to intent activation to enforce correct network configurations. To this end, in this study, we propose an extensible intent model, complemented with a conflict detection algorithm. We also propose a policy resolution algorithm that is based on a two-dimensional analysis of intent endpoints and time spans. To better showcase the efficiency of our algorithm, we also developed an enterprise-based IBN intent management web application for network users and administrators. Our evaluation experiments reveal the effectiveness of our algorithms in terms of reliable resolutions and fast response time.
The purpose of the paper was to find and discuss methods for teaching secure communication. A survey to a sample of nursing schools was executed. The teachers were asked to define 'secure communication' and to relate teaching methods used. Theories supporting the proposed methods were discussed. Conclusively it was found that a joint task force including IMIA WG4 and the IMIA and EFMI nursing groups for selecting an educational strategy in teaching 'secure communication' is highly recommended.
It proves difficult to achieve a good measure of security in medical informatics applications. A number of reasons for this are analyzed. It is argued, that standardisation will help in solving this problem to a certain extent, but a more complete solution is possible when this is used in close conjunction with legal instruments (e.g. EU directives) and advice of a less strict nature, like guidelines. On the whole, a pragmatic step-by-step approach is needed, although there are signs that the general environment for these developments is improving.
A new expert system for the analysis of post-cardiosurgical patients in Intensive Care Units is described, and a preliminary validation performed. The inference engine employs a hybrid reasoning method which integrates quantitative and qualitative simulation techniques in an original manner. The long-term knowledge consists of a causal network which reproduces the main relationships between physiological quantities involved in the course after cardiac surgery. Emphasis has been given to respiratory and metabolic, as well as cardiovascular quantities both in the systemic and pulmonary circulations. Preliminary system validation has been performed on a set of 40 cardiosurgical patients, previously classified either at normal-risk (17 patients) or at high-risk (23 patients) by means of statistical classification techniques. In most cases, predictions of the expert system substantially agree with those provided by the more traditional statistical method. The system, however, is also able to furnish detailed explanations on the possible physiological causes responsible for the patient status. In particular, simulation results indicate that a reduction in the cardiac index (19 cases) and an increase in the oxygen utilization coefficient (19 cases) are the most critical alterations in the high-risk patients. The system imputes the reduced cardiac index to a rise in total systemic resistance (15 high-risk patients), a decrease in cardiac strength (2 high-risk patients) or an insufficient filling volume of the systemic circulation (4 high-risk patients). Furthermore, in 6 high-risk patients the depressed cardiac outflow occurs with a reduction in the arterial oxygen content, mainly imputable to an insufficiency of blood hemoglobin content. Finally, two examples of the complete expert system explanatory capabilities are shown with reference to a pair of high-risk patients and discussed.
The computer Controlled Video Perimetry (CCVP) is a computer screening test for detecting visual function loss caused by onchocerciasis, glaucoma, etc. Installed on portable computers, the CCVP has been shown to be high acceptability in field community investigation. However, it is regarded to be difficult in obtaining reliable results from portable computer screening tests because of human behavioural variants and the lack of standard testing environment. In this paper, we propose an architecture for implementing a more reliable CCVP system. In particular, a self-organising neural network is applied to manage measurement noise caused by behavioural factors. A control unit is introduced to manage the overall behaviour of the system. The integrated test system has been used to screen optic nerve disease in onchocercal communities of rural Nigeria and the experimental results obtained from a large number of test records are very encouraging: reliable results from volatile test environments may be obtained using the proposed method.
Based on the reports of the discussion group sessions and their personal impressions the authors present in this article overall observations, conclusions and recommendations of the IMIA Working Group 4 Working Conference “Communicating Health Information in an Insecure World” (Helsinki, September 30-October 3 1995). A draft text of this chapter has been sent to all participants asking them for comments or suggestions, reactions received have been taken into account.
Diagnostic hypercalcaemia discriminant functions, discriminating between clinically significant and non-significant hypercalcaemia, were tested 5 years after their development in order to evaluate the impact of time on their diagnostic capacity. Two populations, consisting of 257 and 129 patients with hypercalcaemia, were consecutively recorded, during six and three months respectively, 5 years apart under similar circumstances. The prevalence of hypercalcaemia was comparable in both populations, being 2.57 and 2.38% respectively (non-significant) (NS). The female/male ratio was 1.9 and 1.7 (NS). The discriminant functions correctly classified 81 and 80% of the women, respectively (NS) and respectively 75% and 64% of the men (NS) in the first and second recorded populations.
Traditional approaches to the generation of finite element meshes are well suited for modeling the homogeneous or mildly heterogeneous domains presented by man-made objects, but are difficult to apply to the complex 3-D domains encountered in some biomedical applications. In this paper, we describe an adaptive algorithm that automates the modeling of these domains. The method differs from traditional approaches in that no explicit description is required of the boundaries between objects with dissimilar material properties. The algorithm uses images of the tissue class to build irregular meshes, and continuity is enforced by constraining the solution at irregular nodes. Local estimates of the error in the flux solution are used to refine the mesh. For an analytic problem with a rapid change along a spherical boundary, the adaptive method converges to a 1% voltage error using 25% of the degrees of freedom required by a uniform refinement, and to a 5% voltage gradient error using 11% of the degrees of freedom. For a defibrillation model in a pig thorax, the voltage gradient solution in the ventricles of the heart converges to within 5% of a uniform mesh solution using less than 8% of the memory and processing resources required by a uniform mesh, which has been the only practical alternative for subject-specific modeling.
Four different neural network algorithms, binary adaptive resonance theory (ART1), self-organizing map, learning vector quantization and back-propagation, were compared in the diagnosis of acute appendicitis with different parameter groups. The results show that supervised learning algorithms learning vector quantization and back-propagation were better than unsupervised algorithms in this medical decision making problem. The best results were obtained with the learning vector quantization. The self-organizing map algorithm showed good specificity, but this was in conjunction with lower sensitivity. The best parameter group was found to be the clinical signs. It seems beneficial to design a decision support system which uses these methods in the decision making process.
Using two examples of installed applications that are widely spread in a large teaching hospital, the awareness of secure communication is highlighted. Teaching to the rotating medical staff is organised on a regular basis. The physicians learn the responsibility they accept when entering the hospital information system (HIS). In a distributed environment, the confidentiality aspects change with the technology when the users perform with on-line helps and graphical interfaces.
The legal position of confidentiality and the safe transmission of medical information is examined in the context of the EU Directive and the technical mechanisms available for addressing these problems.
No computer system or computer network can today be operated without the necessary security measures to secure and protect the electronic assets stored, processed and transmitted using such systems and networks. Very often the effort in managing such security and protection measures are totally underestimated. This paper provides an overview of the security management needed to secure and protect a typical IT system and network. Special reference is made to this management effort in healthcare systems, and the role of the information security officer is also highlighted.
The development of uniform, ethical and internationally enforceable standards for handling computerised electronic patient records is a major requirement for the implementation of the next generation of health information systems. This paper develops a model code of ethics to address this issue.
Medical database security plays an important role in the overall security of medical information systems. The development of appropriate secure database design and operation methodologies is an important problem in the area and a necessary prerequisite for the successful development of such systems. The general framework for medical database security and a number of parameters of the secure medical database design and operation problem are presented and discussed. A secure medical database development methodology is also presented which could help overcome some of the problems currently encountered.
