Identifikacija parametra plućne cirkulacije u modelu s koncentriranim parametrima

master's thesis

• Title (english): Parameter identification in a lumped model of pulmonary circulation
• Author: Latica Pletikapić
• Mentor: Zdravko Virag (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2014-12-01, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Modeliranje strujanja krvi u krvožilnom sustavu doprinosi boljem razumijevanju funkcije krvotoka, što omogućuje bolju dijagnostiku, planiranje kirurških operacija, predviđanje ishoda operacija i praćenju postoperativnih procesa. Matematički modeli krvotoka se dijele na modele s koncentriranim parametrima, jednodimenzijske, trodimenzijske i hibridne modele (koji su kombinacija prethodna tri). Plućnu cirkulaciju je moguće relativno točno modelirati najjednostavnijim modelom s koncentriranim parametrima, a parametri modela se mogu odrediti iz mjerenja tlakova u desnoj klijetki, plućnoj arteriji i okluzivnog plućnog tlaka, te ultrazvučnog mjerenja brzine strujanja krvi kroz plućni ventil. U radu je razvijen matematički model strujanja kroz plućni ventil na temelju mjerenih tlakova u desnom ventriklu i plućnoj arteriji. Pretpostavljeno je da se nakon sklapanja zalistaka ventil ponaša poput elastičnog sustava s masom i prigušenjem. Tako dobiveni protok je iskorišten za identifikaciju parametara modela plućne cirkulacije zajedno s mjerenim plućnim okluzivnim tlakom (engl. wedge pressure). Model je dvokomorni s ukupno šest parametara, a parametri su određeni metodom najmanjih kvadrata tako da izračunati tlak u plućnoj arteriji najmanje odstupa od mjerenog. Razvijena metoda je primijenjena na četiri pacijenta s različitim bolestima te se u rezultatima uočavaju velike razlike. Rekonstrukcija mjerenog tlaka je za vrijeme ejekcije relativno dobra, ali efekti prije otvaranja plućnog ventila i u vrijeme zatvaranja nisu dobro objašnjeni predloženim modelom. Analiza osjetljivosti dijastoličkog i sistoličkog tlaka pokazuje da na njihov porast najveći utjecaj ima simultano povećanje plućnog otpora i smanjenje popustljivosti plućne arterije. Obrnuto vrijedi za njihovo smanjenje.

Abstract (english)

Modeling of blod flow in the cardiovascular system contributes to a better understanding of the functions of circulatory system, which allows better diagnosis, planning surgical operations, predicting the outcome of surgery and postoperative follow-up process. Mathematical blood flow models are divided into models with concentrated parameters, one-, three-dimensional and hybrid models (which are a combination of the previous three). Pulmonary circulation can be relatively accurately modeled by the simplest model with concentrated parameters where the model parameters can be determined from measurements of pressure in the right ventricle, pulmonary artery pressure, pulmonary wedge pressure, and ultrasonic measurement of blood flow velocity through the pulmonary valve. In this paper, a mathematical model of the blood flow through the pulmonary valve is developed on the basis of the measured pressures in the right ventricle and the pulmonary artery. It is assumed that, after the conclusion of valves, valve behaves like an elastic system with mass and damping. The resulting flow is used to identify the model parameters of pulmonary circulation together with measured pulmonary wedge pressure. The model is bicameral with six parameters, and parameters are determined by the least squares method so that the calculated pressure in the pulmonary artery least deviates from measured. The developed method is applied to four patients with different diseases and the observed model parameters vary in a large range. Reconstruction of the measured pressure during ejection is relatively good but the phenomena before the opening and immediately after the closing of the pulmonary valve are not well explained by the proposed model. Sensitivity analysis of diastolic and systolic blood pressure shows that their increase is most influenced by the simultaneous increase in pulmonary resistance and decrease in the pulmonary artery compliance. The opposite is valid, for their reduction.

• Keywords: kateterizacija desnog srca; strujanje kroz plućni zalistak; plućni okluzivni tlak
• Keywords (english): right heart catheterization; pulmonary valve blood flow; pulmonary wedge pressure
• Language: croatian
• URN:NBN: urn:nbn:hr:235:149454
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2019-05-27 10:04:02