A complex model of mechanically ventilated ARDS lungs is proposed in the paper. This analogue is based on a combination of four components that describe breathing mechanics: morphology, mechanical properties of surfactant, tissue and chest wall characteristics. Physical-mathematical formulas attained from experimental data have been translated into their electrical equivalents and implemented in MultiSim software. To examine the adequacy of the forward model to the properties and behaviour of mechanically ventilated lungs in patients with ARDS symptoms, several computer simulations have been performed and reported in the paper. Inhomogeneous characteristics observed in the physical properties of ARDS lungs were mapped in a multi-lobe model and the measured outputs were compared with the data from physiological reports. In this way clinicians and scientists can obtain the knowledge on the moment of airway zone reopening/closure expressed as a function of pressure, volume or even time. In the paper, these trends were assessed for inhomogeneous distributions (proper for ARDS) of surfactant properties and airway geometry in consecutive lung lobes. The proposed model enables monitoring of temporal alveolar dynamics in successive lobes as well as those occurring at a higher level of lung structure organization, i.e. in a point P0 which can be used for collection of respiratory data during indirect management of recruitment/de-recruitment processes in ARDS lungs. The complex model and synthetic data generated for various parametrization scenarios make possible prospective studies on designing an indirect mode of alveolar zone management, i.e. with a minimized risk of repeated alveolar recruitment/de-recruitment and mechanical overstraining of lung tissues.
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Założenia wstępne formułujące ideę nieinwazyjnego algorytmu przerywanego przepływu powietrza, dedykowanego do pomiaru mechaniki oddychania, prowadzą do istotnych przeszacowań indeksu diagnostycznego (Rint) w bazowej wersji metody. Zasadniczym źródłem ograniczenia są prosta (jednoelementowa) fizyko-matematyczna reprezentacja systemu oraz stosowany algorytm (ekstrapolacji wstecznej) przetwarzania danych eksperymentalnych. W artykule, najpierw w sposób analityczny a następnie w drodze symulacji komputerowych, wykazano możliwość separacji składowych odpowiedzi z tkanek płuc i dróg oddechowych. Ponadto, w sposób ilościowy pokazano udział oporu klatki piersiowej w całkowitej odpowiedzi systemu na quasi-skokowe pobudzenie zaworem przerwaniowym. Uzyskane wyniki są elementem pośredniczącym w przejściu pomiędzy klasyczną i wzbogaconą wersją algorytmu okluzyjnego.
EN
Preliminary assumptions postulated for the idea of the airflow interrupter technique, dedicated for respiratory mechanics measurement, lead to significant overestimation of the diagnostic index (Rjnt) in a basal version of the method. Essential sources of that limitation are simple (one-element) physical-mathematical representation of the system and the back-extrapolative algorithm used for experimental data processing. Analytic considerations have been firstly provided in the paper and next the possibility to separate airway and tissue component in the pressure-flow outpul has been shown during airflow interruption using computer simulation. Moreover, quantitative assessment of thoracic loading in the resistive response of the system on quasi-step excitation by valve closing has been documented. Results can be perceived as a linkage between the classical and enhanced version of the occlusional algorithm.
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Telemedicine is one of the most innovative and promising applications of technology in contemporary medicine. Telemedical systems, a sort of distributed measurement systems, are used for continuous or periodic monitoring of human vital signals in the environment of living. This approach has several advantages in comparison to traditional medical care: e.g. patients experience fewer hospitalizations, emergency room visits, lost time from work, the costs of treatment are reduced, and the quality of life is improved. Currently, chronic respiratory diseases comprise one of the most serious public health problems. Simultaneously patients suffering from these diseases are well suitable for home monitoring. This paper describes the design and technical realization of a telemedical system that has been developed as a platform suitable for monitoring patients with chronic pulmonary diseases and fitted to Polish conditions. The paper focuses on the system's architecture, included medical tests, adopted hardware and software, and preliminary internal evaluation. The performed tests demonstrated good overall performance of the system. At present further work goes on to put it into practice.
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The paper presents a methodology of complex electrical model formulation for the respiratory system during airflow interruption. Adequacy of both structural and parametric description to the real physiological system has been taken care of. Properties of the valve-transducer unit, upper airways, bronchial tree, lung tissue chest wall and abdomen have been noted in an equivalent description of the electrical circuit. The resulting analog, combining more than 180 parameters, gives the possibility to imitate conditions of normal breathing and airflow interruption. A qualitative verification of the model has been conducted in the time and frequency domain, based on reported numerous experimental findings. The proposed linear description of the respiratory system can be the source of synthetic data for a verification of the interrupter method and for the procedure of model reduction to its identifiable form.
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The purpose of this modeling paper is to show and, in some extent, to explore the utility of one nonlinear tool, the recurrence plot, in assessing physiological systems and states, for example of the respiratory system. During investigations, the authors first explore the question of interrelations between regular and disordered processes, implying remarkable influences of noise on rhythmicity of the physiological systems, here: the respiratory system. Next, the signals acquired in the Bonhoeffer-van der Pol model of the central respiratory generator are the basis for data analysis; accordingly to Paydarfar et al., computational studies of the equations (1), whose qualitative behaviour is representative of many excitable system, are able to show phase responses adequate to experimental findings in the animal, in the context of phase resetting of the central respiratory oscillator. The applied topological (qualitative) description and its quantitative measures of complexity document the important sensitivity to temporal variations of the data set compositions.
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A new issue of the respiratory mechanics evaluation by the frequency mode of the interrupter technique is undertaken in the paper. The aim of the computer-aided research is to show the abilities to separate airways and tissue properties of the respiratory system. The proposed evaluation procedure of the identification quality in the modified DuBois model proves the possibility to conduct repeatable measurements of the important diagnostic indexes. The obtained precision of the parametric description of the investigated physiological system suggests the need to continue the work in the outlined direction. Their final effect can be a portable device with applicability to clinically diffcult subjects - infants and pre-school children.
Charakterystyczne wzorce czasowej zmienności są przejawem zdefiniowanej właściwości systemów złożonych [[9], [17]], także tych biologicznych, których interesującym przypadkiem jest układ oddechowy. U wykazujących ogólną systemową stabilność złożonych systemów biologicznych stwierdzić jednakże można relacje pomiędzy wystąpieniem stanu patologicznego a zmianą indywidualnej trajektorii zachowań w przestrzeni obserwacji. Artykuł podejmuje problematykę możliwości pomiaru regularności oraz ich zmian w kontekście analizy złożoności. Posługując się sztucznie wygenerowanymi danymi, autorzy wstępnie szacują potencjał wybranych narzędzi teoretycznych do pracy z sygnałami rejestrowanymi w układzie oddechowym. Szczególnie interesujące wyniki uzyskano dla miar entropijnych, a także dla grafów rekurencyjnych, będących wyrazem topologicznej reprezentacji złożoności systemów. Przedstawione wyniki wstępne sugerują potrzebę kontynuacji prac, tak w obszarze samych narzędzi jak i czysto aplikacyjnym.
EN
Characteristic patterns of temporal variations manifest a defining feature of complex systems [[9], [17]], also this biological ones, among which the respiratory system is an interesting example. For the group of the complex biological systems, with characteristic property of general systemic stability, yet it can be stated the relationship between the appearance of a pathological state and the change of the individual trajectory of behaviour in the space of observations. The paper deals with the issues of ability to measure regularities, their changes in the context of complex analysis. Using artificially generated data, the authors have tentatively estimated the potential of the chosen theoretical tools to the work with the signals accessible in the respiratory system. Especially interesting results were obtained for the entropy measures as well as for the recurrent graphs, which are the topological representation of system complexity. The presented, introductory results suggest the need to continue the investigations, both in the area of the tools and purely appliqué one.
Artykuł zawiera opis sprzętowej i programowej konfiguracji stanowiska dedykowanego do pomiarów mechaniki oddychania techniką przerwaniową. Zainteresowanie pada tutaj na programowe rozwiązania dopuszczające elastyczne prace badawcze w obszarze kontroli układu oddechowego. Dla przedstawionego projektu wyznaczono dalsze kierunki rozwoju.
EN
The paper shows the description of the hardware and software configuration of the station, dedicated to respiratory mechanics measurements by the interrupter technique. Interest is located here in programming solutions allowing for flexible research in the area of the respiratory system control. For the presented project, it has been suggested further directions of development.
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The latest papers have been suggesting that the dynamics of transient state should be taken into account as the phenomena which occur in a respiratory system are interpreted (quantitatively and qualitatively). The infuence of geometry and closure valve characteristic on the precision of obtained estimators of its parameters has been analyzed in the paper for the chosen model structure of the system. Results of simulation studies show that minimalization of mean-squared uncertainty dMSE of the model elements estimation is obtained as valve closing (opening) time is shortened and its complete closure time is extended so that a linear increase in pressure Pao is included.
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In the paper, the stage for the evaluation of the respiratory mechanics by occlusion techniques is described. It consists of the hardware-software module of post-interrupter data acquisition, numerical procedures of the collected signal analysis and computational models, enabling a quantitative/qualitative verification of the relations between the lung structure, pathology and measurement results. Flexibility of the designed set-up guarantees the possibility to test the classical versions of the interrupter technique, its modified author's variant - enhanced interrupter technique and also the future developmental work in the appointed research area.
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The fIow interrupter technique is an attractive method of respiratory mechanics measurement. Lack of reliable algorithms for processing of the data measured as well as a low level of the routine informativity schemes disqualify the method as a useful tool in clinical and diagnostic practice. The theoretical basis of the enhanced interrupter technique (EIT) prepared by the authors is a chance to change the role of the technique in the set of available measurement methods. In the report, computer investigations showing an advantage of EIT over the most popular methods of the postocclusional data analysis, characterised in literature, are presented. Beside the evidence of an improvement of the basic algorithm informativity, also an increased accuracy of the results in the simulation experiment organised by the authors has been shown.
W artykule zaprezentowano metodologię tworzenia liniowego modelu układu oddechowego w czasie przerwania przepływu powietrza. Lokalne charakterystyki mechaniczne każdego kanału oddechowego zrealizowano w oparciu o analogie elektryczne, a parametry wyodrębnionych obwodów określono na podstawie danych fizjologicznych. Geometria drzewa oskrzelowego odzwierciedla sugerowaną przez Weibela symetrię, natomiast model tkanek płuc, klatki piersiowej i brzucha uwzględnia wiskoelastyczne właściwości wyróżnionych kompartmentów. Symulacje komputerowe zarówno spokojnego oddychania jak i przerwania przepływu powietrza potwierdziły adekwatność zaproponowanego analogu do układu fizjologicznego.
EN
The paper presents methodology of formation of a linear model for the respiratory system during airflow interruption. Local mechanical characteristics of each airway are realized by means of an electrical analogies and parameters of a distinguished circuits are determined from local physiological data. Geometry of the bronchial tree reflects symmetry, which was suggested by Weibel, and model of a lung tissue, chest wall and abdomen includes viscoelastic properties of the compartments. Computer simulations both quiet breathing and airflow interuption confirm adequacy of the proposed analogue to the physiological system.
Przedstawiono szerokopasmowy system przewodowego dostępu abonenckiego XpressLink. Opisano nowe rozwiązania techniki szerokopasmowej xDSL oraz możliwości jej zastosowania.
EN
The article presents broadband subscriber access network system XpressLink. The description refers to the new solutions of the broadband xDSL technique and possibilities of their using.
Przedstawiono, należący do rodziny Multiiink, system sieci dostępu abonenckiego FastLink. Opisano nowe rozwiązania techniki szerokopasmowej xDSL zawarte w nowej generacji tego systemu oraz przedstawiono metody jej implementacji.
EN
The article presents access network system FastLink from the Multilink family equipment. The descriptions refers to the new solutions included in the new generation of the system and possibilities of their implementation.
W pracy przedstawiono technikę przerywania przepływu wykorzystywaną w pomiarach oporu dróg oddechowych oraz podstawowe problemy z nią związane. Wykorzystując zmodyfikowany model zastępczy układu oddechowego zaproponowany przez Duboisa i in. [4], przeprowadzono analizę własności identyfikacji jego parametrow w dziedzinie czasu i częstotliwości. Opisane prace stanowią kontynuację badań poświęconych ocenie metrologicznej techniki przerywania przepływu.
EN
The interrupter technique for measurement of respiratoty system resistance has been presented and its main problems concerned. The analysis of identification properties for parameters of a modified electrical analogue for the respiratory system proposed by Dubois et al. [4] has been performed, both in the time and frequency domain. This work is a continuation of the investigation focused on metrological evaluation of the interrupter technique.
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