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Biomedical subjects

D Koutsouris

Publications and source records attributed to D Koutsouris.

At least 19 recordsLinked to original sources
PubMed2000

Simulated generation of evoked potentials components using networks with distinct excitatory and inhibitory neurons.

Long latency evoked potentials (EP's) are electrical potentials related to brain information processing mechanisms. In this paper, three-layered neurophysiologically based artificial neural network model is presented whose neurons obey to Dale's law. The first two layers of the network can memorize and recall sparsely coded patterns, oscillating at biologically plausible frequencies. Excitatory low-pass filtering synapses, from the second to the third layer, create evoked current dipoles, when the network retrieves memories related to stimuli. Based on psychophysiological indications, simulated intracranial dipoles are straightforwardly transformed into long latency EP components such as N100 and P300 that match laboratory-measured scalp EP's.

Biomedical Engineering↗
PubMed2000

Education and training in the MEDICOM system.

MEDICOM system is a world wide telematics application for electronic commerce of medical devices. It has been designed so as to provide the health care professionals with a central Internet access to up-to-date information about medical equipment from multiple manufacturers, in a particular easy and friendly way. Moreover, the Medicom system will serve the health care professionals' requirements for high-quality information about specific products in a form of multimedia presentations and that of a secure communication channel with the community of manufacturers, especially for post marketing surveillance. The system will provide the medical staff (physicians and technicians) with demonstrations of the operation procedures and the functioning of high-tech equipment in a form of virtual models. Moreover, through the medicom system the end users of medical devices can have access to on line libraries and participate in special newsgroups. This paper discusses the architectural structure of the MEDICOM system with emphasis to its educational and training functionality.

Commerce↗
PubMed2000

Mobile Medical Data (MOMEDA)--a Personalized Medical Information System.

MOMEDA is a two-years project supported by the European Commission (Telematics Applications Programme of DGXIII--Health Care Sector). The main objectives of the project are the development of a compact personal information terminal for hospital and home care environments that could be used by patients and a demonstrator that allows the consulting physician to access electronic patient record data from outside the hospital, using a hand held companion device connected to GSM network. Special attention is paid to a Personalized Medical Information System (PMIS) which will allow patients to access customized disease-specific information material that will enable them to fully understand in a simple and constructive form what their medical problem is, what the planned procedures are, what lifestyle they should follow during and after their hospitalization, thus becoming more qualified partners in the recovery process. Considering the fact that in most cases informed and educated patients are usually satisfied patients when the treatment is finished, patient satisfaction can be also accomplished. The design considerations for the PMIS system are presented and the implementation is discussed.

Computer Security↗
PubMed2000

Intranet health clinic: Web-based medical support services employing XML.

In this paper, the implementation of an Internet-based telematic service for medical support is presented, which operates in pilot form within the INTRANET HEALTH CLINIC project--a two-year project supported by the European Commission under the Health Telematics Programme. The aim of the application is to offer high quality care to users of health services over inexpensive communication pathways, using Internet-based, interactive communication tools, like remote access to medical records and transmission of multimedia information. The XML technology was employed to achieve customised views on patient data, according to the access rights of different users. Strict security and access control policy were implemented to ensure secure transmission of medical data through the Internet. The system is designed to collaborate with existing clinical patient record systems and to be adjustable to different medical applications. Current pilot implementations are under clinical evaluation and include oncological patients (Greece), Lupus Erythrematosis (Canada), Obstetrics (Belgium) and Chronic Obstructive Pulmonary disease (Spain).

Computer Communication Networks↗
PubMed2000

Vital signs monitoring from home with open systems.

This study investigates the applicability of a novel codification scheme based on two healthcare informatics standards (namely the VITAL (ENV 13734) and DICOM Sup. 30 Waveform Interchange) in addressing the robust interchange of waveform and medical data in remote healthcare applications. To further address system validation and clinical acceptance issues, pilots were set-up between home-monitoring stations and a hospital-based telemedicine consultation center. The pilots focused in assessing applicability, technical feasibility and performance of the proposed codification scheme based on the two standards. This paper presents the system and services requirements as studied for a home-care application, the design goals for the preservation of security stature, the practical issues of validation and the results of integrating these codification schemes into a commercial patient connected device.

Computer Systems↗
PubMed1999

A new method for measuring red blood cell aggregation using pattern recognition techniques on backscattered ultrasound Doppler signals.

In order to study the important phenomenon of aggregation of red blood cell in vitro, an original ultrasound Doppler in vitro technique has been designed and developed in our laboratory. In the experiments held with this new technique, erythrocyte aggregation was examined by adding dextrans of different molecular weights and concentrations for a wide range of hematocrit values. Consequently, a large data base of backscattered ultrasound Doppler signals is created. In these signals, various pattern recognition methods have been applied, mainly morphological and statistical ones. It results from the employed analysis that the envelope, energy and area characteristics of the obtained backscattered signals are quite good indicators of the degree of RBCs aggregation. In this way, we have been able to: (a) Establish a quantitative relation between the presence of various dextrans and the degree of aggregation. (b) Determine the distribution of the size of the formed aggregates in the various experimental solutions. (c) Obtain a most accurate relation between ultrasound backscattering and actual size of the corresponding observed aggregates.

Erythrocyte Aggregation↗
PubMed1998

A novel emergency telemedicine system based on wireless communication technology--AMBULANCE.

Recent studies conclude that early and specialized prehospital management contributes to emergency case survival. We have developed a portable medical device that allows telediagnosis, long distance support, and teleconsultation of mobile healthcare providers by expert physicians. The device allows the transmission of vital biosignals and still images of the patient from the emergency site to the consultation site using the GSM mobile telephony network. The device can telematically "bring" an expert specialist doctor at the site of the medical emergency, allow him/her to evaluate patient data, and issue directions to the emergency personnel on treatment procedures until the patient is brought to be hospital. Legal reasons mandated the inclusion at the consultation site of a multimedia database able to store and manage the data collected by the system. The performance of the system has been validated in four different countries using a controlled medical protocol and a set of 100 patients per country treated has been collected and analyzed.

Emergency Medical Services↗
PubMed1998

Design and development of a multimedia database for emergency telemedicine.

Recent studies conclude that early and specialised pre-hospital patient management contributes to emergency cases survival. Recent developments in telecommunication and medical informatics by means of telemedicine can be extremely useful to accomplish such tasks in a cost-effective manner. Along that direction, we have designed a portable device for emergency telemedicine. This device is able to telematically "bring" the expert doctor at the emergency site, have him perform an accurate diagnosis, and subsequently direct the Emergency Medical Technicians on how to treat the patient until he arrives to the hospital. The need for storing and archiving all data being interchanged during the telemedicine sessions is very crucial for clinical, legal and administrative purposes. For this, we have developed a multimedia database able to store and manage the data collected by the AMBULANCE system. The database was equipped with a user-friendly graphical interface to enable use from computer naive users. Furthermore, the database has the possibility to display, in an standard way, ECG's, X-ray, CT and MRI images. The application is password protected with a three-level hierarchy access for users with different privileges. The scope of this application is to enhance the capabilities of the doctor on duty for a more precise and prompt diagnosis. The application has the ability to store audio files related to each emergency case and still images of the scene. Finally, this database can become a useful multimedia tool which will work together with the AMBULANCE portable device, the HIS and the PACS of the hospital. The system has been validated in selected non-critical cases and proved to be functional and successful in enhancing the ability of the doctor's on duty for prompt and accurate diagnosis and specialised pre-hospital treatment.

Ambulances↗
PubMed1998

Loading of intact rabbit erythrocytes with fluorophores and the enzyme pronase by means of electroporation.

The application of electric field pulses in cell suspensions is known to alter membrane integrity, resulting in increased membrane permeabilization. This field-induced membrane poration provides the means to load cells with a variety of external substances, useful for clinical applications. In this work, intact rabbit erythrocytes were successfully loaded with low molecular weight fluorescent probes and with the high molecular weight enzyme pronase, which has been shown to mimic the effects of insulin. Attachment of the enzyme onto the cell surface was also achieved by modifying the applied pulse parameters. Both applications were efficient and accompanied by high cell survival rates. In this way, biological carriers loaded with active substances were produced, offering the potentials for useful clinical applications, either for diagnostic or therapeutic purposes.

Animals↗
PubMed1997

CT-based software for 3-D localization and reconstruction in stepping source brachytherapy.

This paper describes innovative software for catheter localization and three-dimensional (3-D) reconstruction in stepping source brachytherapy applications. Patient information is a set of computed tomography (CT) slices scanned during the implantation of brachytherapy catheters. Catheter geometry and patient anatomy are exported for use with dose calculation software modules. The errors produced by the system are also encouragingly low. Time saving was achieved, in terms of other traditional reconstruction techniques. Various automated procedures, 3-D graphics and a user-friendly GUI, have contributed to providing a powerful, comprehensive software tool, directly useable in the clinical practice.

Brachytherapy↗
PubMed1997

An augmented reality system for health care provision via telematics support.

We are developing a prototype portable health care support device for Emergency Telemedicine. This device can telematically "bring" a specialist doctor at the site of a medical emergency, allow him to evaluate patient data and issue directions to the emergency personnel on treatment procedures until the patient is brought to hospital. The portable device is carried by a paramedic technician in "wearable" form, allowing the technician to perform his normal duties while communicating with the specialist at the hospital site. This augmented reality system allows for maximum utilisation of available resources and offers a complete, practical solution for increasing survival rates before and during the transportation of accident victims to hospital.

Emergency Medical Services↗
PubMed1996

The CARDIO-LOGOS system for ECG training and diagnosis.

A new approach in ECG training is presented. The overall approach is based on a combination of the "page-turning architecture", the "reference model" and AI techniques. A thorough analysis of the training requirements in this field has been carried out; the results determined the educational scenarios and the associated evaluation sessions. The system (CARDIO-LOGOS) is intended to be used mainly by internal medicine physicians and general practitioners, as well as by medical students. The layered structure of the whole CBT application together with the advanced learning strategies and the interactive multimedia technology offer a flexible environment that encourages experimentation and supports individualised training for a wide variety of users.

Computer Simulation↗
PubMed1995

Determination of RBC flow clogging via micropore filters.

Using a prototype system we determine the dynamic behaviour of the clogging effect of an erythrocyte suspension flow via micropore filters. The system functions as a simple electronic device and a characteristic curve of the change in height of the level of RBC suspension which flows through the filter versus time is plotted.

Erythrocytes↗
PubMed1995

A comparative study of pulsed Nd:YAG and CO2 laser effect on aortic valves.

Laser angioplasty is a promising new technology, which sometimes offers the surgeon an alternative tool to conventional therapy. One of the main prerequisites of using powerful pulsed lasers in angioplasty is the optimum choice of the irradiation parameters (the wavelength, the pulse shape and duration, the energy parameters). Infrared lasers have numerous applications in surgery. Among them the pulsed CO2 laser emitting at 10.6 microns and the pulsed Nd:YAG laser emitting at 1.064 microns are the most widely used, since the delivery of laser energy in short pulses of high peak pulse power limits distant thermal effects. The CO2 laser wavelength is greatly absorbed by tissue water, while the Nd:YAG laser wavelength is poorly absorbed by water or other tissue chromophores, affecting deeper the tissue. The CO2 laser incises effectively the tissue, but presents inadequate coagulation, while the Nd:YAG laser seems to present better coagulation properties. In this work, a comparative study of pulsed Nd:YAG and CO2 lasers in ablating cardiovascular tissue, is presented. The irradiation regime of the two lasers is determined, for the specific tissue and/or pathology. Also the depth of thermally induced coagulation is measured. The results are presented according to the efficacy of each laser for incision and/or coagulation.

Angioplasty, Laser↗
PubMed1995

A generic environment for linear and nonlinear ECG processing.

Every aspect of cardiac function such as contractibility, depolarization and repolarization of cardiac cells, firing rate of pacemaker cells, is under a complex neurohumoral regulation. Especially the autonomic neuron system through the interplay of its two opposing components, sympathetic and parasympathetic (vagal), is controlling cardiac function on a beat to beat basis. Moreover, the interaction of sympathetic and parasympathetic systems is a non-linear function, with sympathetic tone modulating the response of vagal activation. It has been shown that the power of frequency components and especially the ratio of low to high frequency power spectra of heart rate variability are reliable indicators of sympathovagal balance (A. Malliani et al. 1991. Cardiovascular Neural regulation explored in the frequency domain. Circulation, 84 (2) 482-484. The most known algorithms of linear and non-linear signal processing have been applied to the ECG data recorded from healthy and high risk individuals. These methods together with the study and analysis of QRS frequency spectrum will lead to very useful conclusions with diagnostic and prognostic information. In this paper we will briefly describe the mathematical aspect of these algorithms presenting their results for normal and pathological ECG signals.

Adult↗
PubMed1990

Erythrocyte deformability in diabetes and erythrocyte membrane lipid composition.

Erythrocyte deformability was assessed in 40 diabetic patients, 24 insulin-dependent (IDD) and 16 non-insulin-dependent (NIDD), by measuring the initial filtration flow rate of whole blood, isolated red blood cells (RBC), and isolated RBC membranes with the Hanss hemorheometer, and its relationship to the plasma and ghost membrane lipid composition was investigated. RBC deformability was significantly reduced, whereas the deformability of the isolated RBC membranes did not differ significantly from the controls. In the plasma, the triglycerides were high, the high-density lipoprotein (HDL) cholesterol was reduced, and the ratio of total cholesterol over HDL cholesterol was high as compared with the controls. The RBC lipid composition expressed in mumol lipids/10(10) RBC showed significantly lower levels of free cholesterol, sphingomyelines, and phosphatidylcholine, which are the lipids principally located on the outer layer of the RBC membranes. These data suggest that in both IDD and NIDD patients, there may be a relation between these modifications in the RBC lipid composition and rheological impairment of the RBC.

Cholesterol↗