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1

The respirator as a user of virtual lungs

Gólczewski T., Kozarski M., Darowski M.

Biocybernetics and Biomedical Engineering

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2003

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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.

2

The influence of ventilatory support on coronary flow and oxygen consumption in different circulatory conditions

De Lazzari C., Darowski M., Ferrari G., Mimmo R., Guaragno M., Tosti G.

Biocybernetics and Biomedical Engineering

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2003

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Vol. 23, no. 1

103-110

EN

The aim of this work is to predict the influence of mechanical ventilation on cardiac output, coronary flow and left ventricular myocardial oxygen consumption in different circulatory conditions. To study this interaction we used a computer simulator of human cardiovascular system in which lumped parameters models were used to reproduce the circulatory phenomena in terms of pressure and volume relationships. Variable elastance models reproduce the Starling's law of the heart, for each ventricle. In the study the left ventricular elastance assumed two different values. Symetric arterial resistance was changed during the simulation. The influenece of mechanical ventilation was introduced by positive mean thoracic pressure. Positive thoracic pressure, changes of peripheral resistance and different ventricular elastance values have a significant influence on cardiac output, coronary flow and myocardial oxygen consumption.

3

Influence of ventilatory mode on respiration parameters - investigation on virtual lungs

Gólczewski T., Darowski M.

Biocybernetics and Biomedical Engineering

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2003

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Vol. 23, no. 3

63-72

EN

In the paper influence of different artificial ventilation modes (pressure-controlled, volume-controlled with constant and with decelerating flow, and power-controlled, i.e. adaptive) on chosen respiratory parameters (peak and mean pressure in lungs, peak gas flow, distribution of lungs ventilation) were analyzed in cases of permanent and sudden obstruction. The comparison has proved that the adaptive mode generally has some advantages over routinely used ventilatory modes, if influence on all the respiratory parameters together is taken into account: all the parameters achieve moderate values for the adaptive mode, while at least one parameter achieves a big value for each other mode. Thus, the adaptive mode causes the smallest total health hazard.

4

Expiratory pressure curve analysis for estimation of lungs mechanics

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

Biocybernetics and Biomedical Engineering

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2003

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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.

5

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

Górczyńska K., Darowski M., Kozarski M.

Biocybernetics and Biomedical Engineering

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2002

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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.