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Biomedical subjects

D Koutsouris

Publications and source records attributed to D Koutsouris.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1989

Determination of erythrocyte transit times through micropores. II. Influence of experimental and physicochemical factors.

A new red blood cell filtration system, termed the Cell Transit Time Analyzer (CTTA), has been developed in order to measure the individual transit times of a large number of cells through cylindrical micropores in special "oligopore" filters; the system operates on the electrical conductometric principle and employs special computer software to provide several measures of the resulting transit time histogram. Using this system with filters having pore diameters of 4.5 or 5.0 microns and length to diameter ratios of 3.0 to 4.7, we have evaluated the effects of several experimental factors on the flow behavior of normal and modified human RBC. Our results indicate: 1) linear RBC pressure-flow behavior over a driving pressure range of 2 to 10.5 cm H2O with zero velocity intercepts at delta P = 0, thus suggesting the Poiseuille-like nature of the flow; 2) resistance to flow or "apparent viscosities" for normal RBC which are between 3.1 to 3.9 cPoise and are independent of driving pressure and pore geometry; 3) increased flow resistance (i.e., increased transit times) for old versus young RBC and for RBC made less deformable by DNP-induced crenation or by heat treatment at 48 degrees C; 4) increased mean transit time and poorer reproducibility when using EDTA rather than heparin as the anticoagulant agent. Further, using mixtures of heat-treated and normal RBC and various percentile values of the transit time histogram, we have been able to demonstrate the presence of sub-populations of rigid cells and thus the value of measurements which allow statistical analyses of RBC populations.

2,4-Dinitrophenol↗
PubMed1988

Determination of erythrocyte transit times through micropores. I--Basic operational principles.

To study the transit times of each red blood cell passing through cylindrical micropores and in order to evaluate sub-population of cells with regard to their deformability, we have developed a new system called the cell transit time analyser (CTTA). By using an AC voltage (100 KHz) across a special filter, we measure the electrical conductance change produced by the cells passing through the pores under a known driving pressure. This computer based device provides the distribution of transit times tau for 2000 cells in 1 minute and as a result the mean transit time [tau]. Experiments with red cells were designed to evaluate the flow behavior of both normal cells and cells whose mechanical properties were artificially altered. Cell volume was changed by use of non-isotonic media. Cell shape and cell volume were modified by varying the pH of the suspending buffer. Results of these experiments are: 1) a skew distribution of transit times towards high tau values for both control cells and artificially altered cells is observed: 2) [tau] is minimum for isotonic conditions and increases sharply for either hypotonic or hypertonic media: 3) [tau] is minimum at physiological pH and increases for either acid or alcaline changes of pH.

Blood Flow Velocity↗
PubMed1988

Determination of erythrocyte transit times through micropores. II-- Influence of experimental and physicochemical factors.

A new red blood cell filtration system, termed the Cell Transit Time Analyzer (CTTA), has been developed in order to measure the individual transit times of a large number of cells through cylindrical micropores in special "oligopore" filters: the system operates on the electrical conductometric principle and employs special computer software to provide several measures of the resulting transit time histogram. Using this system with filters having pore diameters of 4.5 or 5.0 cm and length to diameter ratios of 3.0 to 4.7, we have evaluated the effects of several experimental factors on the flow behavior of normal and modified human RBC. Our results indicate : 1) linear PBC pressure - flow behavior over a driving pressure range of 2 to 10.5 cm H2O with zero velocity intercepts at delta P = 0, thus suggesting the Poiseuille - like nature of the flow; 2) resistance to flow or "apparent viscosities" for normal RBC which are between 3.1 to 3.9 cPoise and are independent of driving pressure and pore geometry; 3) increased flow resistance (i.e., increased transit times) for old versus young RBC and for RBC made less deformable by DNP-induced crenation or by heat treatment at 48 degrees C; 4) increased mean transit time and poorer reproducibility when using EDTA rather than heparin as the anticoagulant agent. Further, using mixtures of heat-treated and normal RBC and various percentile values of the transit time histogram. We have been able to demonstrate the presence of sub-populations of rigid cells and thus the value of measurements which allow statistical analyses of RBC populations.

Anticoagulants↗
PubMed1985

[Deformability of thawed erythrocytes: introduction of a new preservative solution].

Recently, KANE et al. (Centre de Transfusion Sanguine, Strasbourg) designed an original preservative medium, called ESOC, allowing a prolonged storage of thawed RBC. We studied on 15 days the evolution of thawed RBC deformability, while RBC where kept preserved, on the one hand in this ESOC solution, on the other hand in physiologic water, without any preservative medium. We tried to correlate this rheological evolution with cellular ATP, cellular 2,3-DPG and membrane proteins evolution. Deformability was measured by filterability with an Hemorheometre. The results are given as a rigidity index, IR. In ESOC, IR and cellular ATP stay in normal values during the 15 days. In physiologic water, deformability decreases strongly and IR is out of normal values after the fifth day. Cellular ATP decreases out of normal values as soon as the third day. 2,3-DPG decreases in both media. Membrane proteins electrophoresis does not show any difference neither in ESOC nor in physiological water, all fifteen days long. We only observed parallelism between deformability and cellular ATP and IR was higher than normal values. We found no correlation between deformability and 2,3-DPG. We also can conclude, with this study, that ESOC allows a good preservation of thawed RBC and by this way complies with the needs for delayed transfusion in current practice.

2,3-Diphosphoglycerate↗
PubMed1985

Physico-chemical factors of erythrocyte deformability.

The aim of this study is to assess the role of different physico-chemical factors on the deformability measurements by using the initial filtration flow rate method, and to differentiate between the membrane or internal origin of some rigidity changes. The deformability is maximum for the physiological pH value and it decreases sharply for hypotonic and hypertonic buffer. For normal RBC, the deformability is independent of the pO2 level and a small decrease is observed for increasing pCO2 values (with constant pH). A theoretical model of filtration for the "Hemorheometre" will be also developed.

Carbon Dioxide↗