Wyniki wyszukiwania - BazTech

1

Use of siliconised infant endotracheal tubes reduces work of breathing under turbulent flow

Stankiewicz B., Rawicz M., Darowski M., Zielinski K., Kozarski M., Chwojnowski A.

Biocybernetics and Biomedical Engineering

|

2017

|

Vol. 37, no. 1

59--65

EN

The high resistance of an infant endotracheal tube (ETT) can markedly impair ventilation and gas exchange. Since some manufacturers cover the inner surface of their ETTs with a silicon layer in order to diminish deposition and ease mucous evacuation from airway, via surface roughness decrease, we assessed whether the silicon layer may affect tube resistance, work of breathing and other parameters of ventilation. We compared SUMI (Poland) non-siliconised and siliconised polyvinyl chloride ETTs (2.5, 3.0 and 4.0 mm ID), twenty of each type and size combination. Simulating volume-controlled ventilation with the hybrid (numerical–physical) lung models of a premature infant and a 3-month-old baby peak inspiratory pressure (PIP), peak inspiratory and expiratory flow (PIF, PEF), (patient + ETT) inspiratory and expiratory airway resistance (Rins, Rexp) and work of breathing by ventilator (WOBvt) were measured. Additionally, images of the both type surfaces were taken using Hitachi TM-1000 electron microscope. When 2.5 and 3.0 mm ID ETTs were examined, laminar flow (Re <2300) across the tube was observed, and there were no clinically significant differences in the ventilation param-eters between non-siliconised and siliconised tubes. Whereas, when 4 mm ID ETTs were tested, turbulent flow was observed, and PIP, Rins, Rexp and WOBvt were significantly lower (5%, 17%, 17%, and 7%, respectively) (P < 0.05), but PIF and PEF were significantly higher (8%, 14%) (P < 0.05). Thus, the silicone inner surface of ETT offers less resistance and WOBvt in presence of turbulent flow. However, artifacts observed on the surface of non-siliconised and siliconised ETTs can potentially impair ventilation.

2

A hybrid (hydro-numerical) circulatory model: investigations of mechanical aortic valves and a numerical valve model

Kozarski M., Suwalski P., Zieliński K., Górczyńska K., Szafron B., Pałko K. J., Smoczyński R., Darowski M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2015

|

Vol. 63, nr 3

605--612

EN

In most cases of diseased heart valves, they can be repaired or replaced with biological or mechanical prostheses. Biological prostheses seem to be safer than mechanical ones and are applied with good clinical outcomes. Their disadvantage, when compared with mechanical valves, is durability. In the development and application of mechanical and biological heart valves, a significant role can be played by a Hybrid (Hydro-Numerical) Circulatory Model. The aim of this paper is to demonstrate the opportunities created by the hybrid model for investigations of mechanical heart valves and their computer models under conditions similar to those of the circulatory system. A diode-resistor numerical valve model and three different design mechanical aortic valves were tested. To perform their investigations, computer applications were developed under RT LabView to be run on a PC. Static and dynamic characteristics of the valves were measured and registered - pressure in the numerical time-varying elastance left ventricle (pLV), in the aorta (pas) and flow (f), proving, among other factors, that 1) time delay of pas with respect to pLV is mainly related to the valve’s opening time, and 2) the valves of substantially different designs tested under identical hydrodynamic conditions reveal nearly the same dynamic performance.

3

A new hybrid (hydro-numerical) model of the circulatory system

Darowski M., Kozarski M., Ferrari G., Zieliński K., Górczyńska K., Szczepanowski A., Pałko K. J., Fresiello L., Di Molfetta A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2013

|

Vol. 61, nr 4

993--1003

EN

The paper presents a hybrid (hydro-numerical) circulatory model built to be used as a complementary tool for clinical purposes. It was developed at the Institute of Biocybernetics and Biomedical Engineering - Polish Academy of Sciences (Poland) in co-operation with the Institute of Clinical Physiology - National Council of Research (Italy). Main advantages of the model are: 1) high accuracy and repeatability of parameters setting, characteristic of numerical solutions, 2) maximum flexibility achieved by implementing the largest possible number of the model’s elements in the numerical way, 3) ability to test mechanical heart assist devices provided by special computer applications; in the model two physically different signal environments - numerical and hydraulic - are connected by special impedance transformers interfacing physical and numerical parts of the model; 4) eliminating flowmeters, as the voltage controlled flow sources embedded in the system provide information on flows. In vitro tests were performed to evaluate the circulatory model: a) modelling and simulation of physiological and pathological states parameters vs. left ventricular end-systolic elastance (Emax l) and rest volume (Vol) variations, b) testing the effect of LVAD counterpulsation on circulatory hemodynamics and ventricular energetics; it resulted in the increase of total cardiac output (COLV tot) from pathological value 3.8 to 5.4 l·min−1, mean aortic pressure mPas from 67.8 to 96.1 mmHg and in the decrease of left atrial pressure mPla from 15.7 to 7.7 mmHg and External Work nEW by 37.5%. The model was verified based on literature data.

4

A hybrid (hydro-numerical) cardiovascular model: application to investigate continuous-flow pump assistance effect

Kozarski M., Ferrari G., Zieliński K., Górczyńska K., Pałko K. J., Fresiello L., Di Molfetta A., Darowski M.

Biocybernetics and Biomedical Engineering

|

2012

|

Vol. 32, no. 4

77-91

EN

A hybrid (Hydro-numerical) model of blood circulation developed at the Institute of Biocybernetics and Biomedical Engineering (IBIB) of the Polish Academy of Sciences (PAN) -Warsaw, Poland, in co-operation with the Institute of Clinical Physiology (IFC) of the National Council of Research (CNR) - Rome, Italy, is a basic model of this type solutions commonly accepted by the researchers. It is able to simulate all essential hemodynamic functions of the human cardiovascular system including the heart. During last years, resumption of works on constant-flow non pulsatile rotary pumps to be used as heart support devices is observed because of their small dimensions and easier way of implantation. Control modes of rotary pumps are different and evidently influence heart support effects. The main aim of this paper was to investigate different control systems of rotary pumps in a role of the assist devices. To fulfill this task on the hybrid model, a special computer application was worked out. The investigations included: a) loading characteristics p(q) of the rotary pump assignment at two values of a control voltage - 18V, 24V; b) physiological and pathological states simulation including parallel atrial-aortic assistance by the rotary pump. The results of the simulations obtained on the model treated as a 'virtual patient' are in agreement with the data received in medical conditions.

5

The new hybrid pneumo-electrical piston model of lungs mechanics - preliminary tests

Kozarski M., Zieliński K., Pałko K. J., Stankiewicz B., Bożewicz D., Darowski M.

Biocybernetics and Biomedical Engineering

|

2009

|

Vol. 29, no. 3

3-18

EN

A design principle, construction and results of preliminary tests of a new hybrid physical-electrical model of lungs mechanics has been presented, The methods leading to development of lungs models of different complexity have been also included. The basic component of the model is a voltage controlled Bow source build up with a piston ~ cylinder system driven by a servomotor. This is used to develop a functional module playing a role of an impedance converter transforming an input electrical impedance Z0 of any electrical network connected to its electrical terminals into a pneumatic impedance Zin. Static and dynamic characteristics of the model connected to different pneumatic signal sources have been presented i.e. for the model connected with the respirator (expiration by the respiratory valve) and for the model with free unobstructed expiration. The very good dynamic features (time constant of the piston Bow source less than 1 ms) and a small resultant error of impedance conversion (less than 1%) enable the model to be applied in many application especially when new methods of lung ventilation are developed.

6

Role and applications of circulatory models in cardiovascular pathophysiology

Ferrari G., Kozarski M., De Lazzari C., Górczyńska K., Pałko K. J., Zieliński K., Di Molfetta A., Darowski M.

Biocybernetics and Biomedical Engineering

|

2009

|

Vol. 29, no. 4

3-24

EN

Circulatory models are relevant for research, education and testing of prosthetic devices/components. Independently of its structure that can be numerical, physical or hybrid the models can be used in different areas of cardiovascular pathophysiology. However, the models are often used to reproduce specific circulatory conditions instead of being used as 'systemic' tools. That is to say, the models are used to evaluate the global effects of external disturbances such as pathologies, therapies, special environments or surgery on the circulatory system. Aim of this paper is to illustrate a family of circulatory models developed to represent the whole circulatory system in pathophysiological conditions describing some of the possible applications.

7

Urządzenie ECP-100 do nieinwazyjnego wspomagania układu krążenia wykorzystujące metodę kontrpulsacji zewnętrznej

Bachorz M., Godecki M., Darowski M., Kozarski M.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

|

2009

|

Vol. 15, nr 1

52-53

PL

Urządzenie ECP-100, opracowane przez ITAM Zabrze przy współpracy z 1B1B PAN Warszawa, umożliwia terapię pacjentów z chorobą niedokrwienną serca. Podczas zabiegu pacjent z zestawem mankietów pneumatycznych spoczywa na leżu zabiegowym. Zestaw składa się z trzech mankietów (podobnych do tych stosowanych przy pomiarze ciśnienia), które są owinięte dookoła łydek, ud i pośladków. Mankiety są napełniane sekwencyjnie na początku fazy rozkurczu serca i opróżniane przed fazą skurczu. Napełnianie i opróżnianie mankietów jest zsynchronizowane z przebiegiem EKG, tak by zoptymalizować korzyści terapeutyczne.

8

Open loop hybrid circulatory model: the effect of the arterial lumped parameter loading structure on selected ventricular and circulatory variables

Kozarski M., Ferrari G., Zieliński K., Górczyńska K., Pałko K. J., Tokarz A., Darowski M.

Biocybernetics and Biomedical Engineering

|

2008

|

Vol. 28, no. 1

17-27

EN

Different combinations of the artero-ventricular coupling design (numerical, physical and hybrid) and the arterial system structure (four-element standard, simplified, modified and three-element three-lump "ladder" Windkessel) have been applied in an open loop circulatory model to test their influence on selected ventricular and circulatory variables. Numerical investigations have shown that a four-element Windkessel with an introduced in series lumped inertance can evoke some numerical problems e.g. when combined with the simplified ventricular model containing "ideal" zero switching time heart valves or constant valve resistance during opening. The four-element Windkessel structure modification i.e. replacing the in series inertance by the parallel one, considerably improves the network match. Also the three-element three-lump "ladder" Windkessel has been found very useful in the blood circulation modelling thanks to relatively small input inertance and high input capacitance of its first lump.

9

Hybrid modeling of biomedical systems and measuring nonlinear characteristics of biosignals for improving quality of life

Darowski M., Klonowski W., Kozarski M., Ferrari G., Zieliński K., Stępień R.

Metrology and Measurement Systems

|

2007

|

Vol. 14, nr 1

89-100

EN

The main purpose of this paper is to present some metrological aspects of the new concept of hybrid modeling (combined physical and in silico) of biological systems as well as possible applications of nonlinear (symbolic) biosignal analysis for improving quality of life through modeling and knowledge-based measurements in medicine.

10

Identification of mechanical parameters of respiratory system during ventilatory support of lungs

Pałko K. J., Kozarski M., Darowski M.

Biocybernetics and Biomedical Engineering

|

2005

|

Vol. 25, no. 1

73-81

EN

Identification of mechanical parameters of lungs by using a pressure method with an added compliance is presented in this paper. This method is based on periodically connecting an additional external mechanical compliance to the respirator-lungs circuit, to determine the values of the mechanical parameters of the respiratory system from measurements of the pressure in specific phases of the respiratory cycle. The expiratory flow was measured to estimate the time constant and the respiratory resistance. The identification of the parameters of lungs is connected with the dynamic signal analysis of the pressure courses registered in a very short time (< 200 ms) at the beginning of the expiratory phase, when the respiratory muscles are non-active. The measurement system is driven by the computer, which is also used to analyse the signals received from the lung model. The results confirm that the measurement time of 200 ms is sufficient to determine the lung compliance.

11

Development of hybrid (numerical-physical) models of the cardiovascular system: numerical-electrical and numerical hydraulic applications

Ferrari G., Kozarski M., De Lazzari C., Górczyńska K., Darowski M., Tosti G.

Biocybernetics and Biomedical Engineering

|

2005

|

Vol. 25, no. 4

3-15

EN

Circulatory models are relevant to research, education and prosthetic devices/components testing. Their structure can be both numerical and physical, according to the specific needs. Numerical models are often developed first and then followed or accompanied by physical models. This approach is associated with higher costs, less accuracy and time-consuming development. Circulatory models defined as hybrid (merger of numerical and physical sections) can solve these problems. This paper presents two applications of the hybrid model with the physical section based on two different structures (electrical and hydraulic). The results show that the model can represent hemodynamic relationships in different circulatory conditions, including IABP assistance.

12

The respirator as a user of virtual lungs

Gólczewski T., Kozarski M., Darowski M.

Biocybernetics and Biomedical Engineering

|

2003

|

Vol. 23, no. 2

57-66

EN

The virtual respiratory system (VRS) is proposed for testing physical respirators, new methods of ventilatory support, and scientific hypotheses. VRS may be also helpful in students education and staff training. Method: VRS simulates the relationship between the air flow and the pressure. The main features of the model are: separation of the lungs and the chest, division of the lungs into five lobes, closing bronchi, gravity influence. Real-to-virtual converter is based on the gas flow source, which is controlled by the calculated value of the air flow that should exist, for the measured pressure being the VRS input. Results: several phenomena are discussed, e.g. the influence of compliance nonlinearity and resistance changeability on ventilation, the CPAP efficiency, differences in lobes ventilation, breathing frequency determination.

13

The electropneumatic gyrator as a tool for physical modeling of lungs

Kozarski M., Maras K., Darowski M., Pałko K. J.

Biocybernetics and Biomedical Engineering

|

2003

|

Vol. 23, no. 3

47-54

EN

Unlike classical physical lung models, the model presented in the paper makes it possible to realize any input impedance of lungs representing their complex mechanical structure. The crucial element of the model is the electropneumatic gyrator converting the input impedance of the electrical network, connected to electrical ports of the gyrator, into the inversely proportional pneumatic impedance obtained in its pneumatic channel. The gyrator is built up as a cross-connection of electrically controlled flow and current sources. Experimental investigations demontrated a very good static and dynamic accuracy of the gyratory conversion. The characteristic pressure and flow courses illustrating dynamical behavior of the gyratory model of lungs are also included.

14

The electrohydraulic impedance converter in mock circulatory system design

Kozarski M., Ferrari G., Darowski M., Górczyńska K., Clemente F., Pałko K. J.

Biocybernetics and Biomedical Engineering

|

2003

|

Vol. 23, no. 2

27-34

EN

In the paper a new concept of a mock circulatory circuit design, utilizing the special impedance converter, i.e. the electrohydraulic gyrator, has been presented as well as basic theoretical considerations and simple examples of impedance conversions. Some results of experiments, illustrating physical and systemic features of the electrohydraulic gyrator, have been shown. A simple hybrid windkessel model has been investigated. Obtained results fully confirmed advantages of the presented new concept of a mock circulatory circuit design.

15

Physical modelling of the cardiovascular system : development of a new simulation system based on hybrid (numerical-hydraulic) components

Ferrari G., De Lazzari C., Kozarski M., Clemente F., Górczyńska K., Mimmo R., Tosti G., Guaragno M.

Biocybernetics and Biomedical Engineering

|

2003

|

Vol. 23, no. 2

3-15

EN

Research, education, testing of assist devices and training are among the applications of physical models of the circulation. Unfortunately, they are rather expensive and the scope of their use is structure-dependent as it is not easy to modify them. As numerical models do not have these limitations, our aim is to develop a physical model of the circulation limited to the sections of interest merging them with numerical models representing the remaining parts of the circulatory system. The system under development is therefore a hybrid where physical and numerical sections, merged together, represent the circulatory system. The sections developed till now represent one of the ventricles and part of the arterial tree. This paper is devoted to the description of the hybrid ventricular model and its first applications.

16

Expiratory pressure curve analysis for estimation of lungs mechanics

Darowski M., Pałko T., Jucha A., Kozarski M.

Biocybernetics and Biomedical Engineering

|

2003

|

Vol. 23, no. 1

91-102

EN

The analysis of an expiratory pressure curve by using an extra small pneumatic compliance is presented in this paper. The investigations of dynamic courses were performed for a very short time (<200 ms), and basic mechanical parameters of lungs were calculated. For analysis of measurement signals and monitoring of measurement circuit a new computer system was used. The measurement circuit was based on mechanical lungs model. The results of studies have shown that the applied method can be used for estimation of lungs compliance but to determine an airway resistance from the time constant an additional measurement of the flow rate curve is needed. The discussed method of lungs mechanics estimation in independent of ventilatory support.

17

Lung mechanics measurement independent on ventilatory treatment

Darowski M., Kozarski M.

Biocybernetics and Biomedical Engineering

|

2002

|

Vol. 22, no. 4

115-121

EN

A new method of lungs mechanics calculation has been developed, which is independent on the method of ventilatory support and may be used automatically during long-term treatment. Lungs compliance assessment is based on the periodical measurements od airway pressure during expiration. Airways resistance is calculated from expiratory time constant. The results of preliminary, model studies showed that proposed method has a clinically acceptable accuracy and can be performed by a separate instrument, independent on a type of the respirator used.

18

Cardiovascular, respiratory and veno-lymphatic assistance. Modelling and simulation

Górczyńska K., Darowski M., Kozarski M.

Biocybernetics and Biomedical Engineering

|

2002

|

Vol. 22, no. 2-3

135-175

EN

In the paper some problems concerning investigations conducted at Bioflows Departament of the Institute of Biocybernetics and Biomedical Engineering on cardiovascular , respiratory and veno-lymphatic assistance have been discussed. The investigations were mainly focused on modelling of cardiovascular and respiratory systems, cardiopulmonary interaction and veno-lymphatic non-invasive support. The results of physical and computer simulation of cardiopulmonary assistance and clinical results of veno-lymphatic support studies have been presented.

19

Model studies on respiratory parameters for different lung structures. Part I. Theoretical consideration

Darowski M., Kozarski M., Gólczewski T.

Biocybernetics and Biomedical Engineering

|

2000

|

Vol. 20, no. 2

67-77

EN

A computer model of lungs mechanics has been developed to simulate changes of basic respiratory variables during spontaneous breathing and mechanical ventilation. This non-homogeneous lungs model can be used as a part of hybrid, gyrator model of the respiratory system, which enables to transform static and dynamic properties of the modelled lungs into pneumatic impedance connected to the respirator. The proposed computer model may be presented as a quasi-electrical network, built out of RLC-like elements, in which non-linear mechanical properties of the human respiratory system have been taken into account. Computer simulation showed on-line changes on p-V pIane as a function of tidal volume during spontaneous breathing.

PL

Zaproponowano komputerowy model mechaniki płuc do symulacji zmian podstawowych zmiennych oddechowych podczas oddychania spontanicznego i sztucznej wentylacji. Ten niehomogeniczny model płuc może być użyty jako część hybrydowego, żyratorowego modelu układu oddechowego, który umożliwia trasformację statycznych i dynamicznych własności mechanicznych płuc w impedancję pneumatyczną dołączoną do respiratora. Zaproponowany model komputerowy może być zobrazowany jako quasi-elektryczna sieć zbudowana z elementów odpowiadających w przybliżeniu elementom RLC, w której uwzględniono nieliniowe własności układu oddechowego. Pokazano, jako przykład możliwości modelu, zmiany on-line ciśnień i objętości w klatce piersiowej podczas oddechu spontanicznego o różnej głębokości wdechu.