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1
PUTIGNANO, OSCAR. « Development of a Cherenkov based diagnostic for gamma-rays from fusion plasmas and advanced medical applications ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/402358.
Texte intégralRésumé :
Lo scopo di questa tesi, iniziata a novembre 2019, è lo sviluppo di un rivelatore Cherenkov per misurare i raggi gamma da 17 MeV emessi dalla reazione di fusione D-T.
Con l'espandersi della pandemia da COVID-19 nel nord Italia, a metà febbraio 2020, è divenuto evidente che il piano iniziale del mio lavoro di tesi dovesse essere fortemente cambiato, a causa della cancellazione delle attività sperimentali che avrebbero dovuto svolgersi nei laboratori UNIMIB/CNR a Milano e al Joint European Torus nel Regno Unito.
In accordo con i miei tutor ho iniziato, insieme ad altri ricercatori, a lavorare su base volontaria ad un progetto denominato Mechanical Ventilator Milano (MVM).
Il progetto MVM ha coinvolto un gruppo internazionale di più di 150 scienziati e ha prodotto in meno di tre mesi un ventilatore meccanico certificato dalla Food and Drugs Administration per uso su pazienti affetti da COVID-19 in terapia intensiva.
L'attività su MVM ha portato, circa un anno dopo, allo sviluppo di un nuovo sensore di ossigeno veloce per applicazioni mediche.
Il sensore è in grado di misurare il consumo di ossigeno di un individuo in tempo reale e durante un singolo respiro.
La tesi è divisa in tre parti.
La prima parte si concentra sullo sviluppo di un contatore di raggi gamma ottimizzato per la misura della potenza di fusione in un reattore a confinamento magnetico.
Il gruppo di ricerca in cui mi sono inserito sta sviluppando un metodo innovativo per la misura della potenza prodotta dalle reazioni di fusione basato sulla rivelazione dei raggi gamma da 17 MeV prodotti durante la reazione D+T->5He*.
Tipicamente il nucleo di 5He* decade emettendo una particella alfa e un neutrone, ma può anche diseccitarsi sullo stato fondamentale dell'5He, prima che questo si disintegri in una particella alfa e un neutrone, con una probabilità di 10^-5.
Questi raggi gamma sono stati misurati al JET nella campagna DT appena conclusa con uno spettrometro gamma basato su un cristallo di LaBr3 e una acquisizione dati digitale veloce.
Poiché l'efficienza ai raggi gamma e ai neutroni del LaBr3 è simile, è stato necessario usare un attentatore neutronico dedicato per osservare il debole segnale dovuto ai raggi gamma.
Per superare i problemi dovuti alla sensibilità del LaBr3 ai neutroni ho progettato un rivelatore gamma a gas ottimizzato per funzionare in presenza di un intenso fondo neutronico.
il rivelatore è basato sull'effetto Cherenkov e le simulazioni indicano che è 10^6 volte più sensibile ai raggi gamma che ai neutroni.
Il prossimo passo sarà quello di costruire un prototipo del rivelatore per validare le simulazioni e provarlo su una sorgente di neutroni D-T.
La seconda parte della tesi descrive lo sviluppo del sensore IFOx, un sensore di ossigeno ultra-veloce che può essere utilizzato per l'analisi polmonare.
Poiché il principio di funzionamento del sensore è simile a quello di uno scintillatore, è un esempio di trasferimento di conoscenze dal campo delle diagnostiche nucleari ad applicazioni diverse.
Il prototipo del sensore è caratterizzato da un'eccellente risposta temporale ed è stato utilizzato per misurare la Capacità Funzionale Residua in volontari sani.
I risultati eccellenti del test sui volontari sani hanno aperto la via per uno studio clinico su pazienti intubati, durante il quale il sensore verrà integrato con un ventilatore polmonare.
L'ultima parte della tesi riguarda MVM e descrive la progettazione di un ventilatore che necessita poche parti e che può essere costruito in tempi brevi anche durante una interruzione della catena di approvvigionamento dei materiali.
Ho contribuito al progetto grazie alla mia esperienza sui sistemi gas e sui controlli software in tempo reale, e ho partecipato alle misure necessarie ad ottenere la calibrazione.
I risultati principali che hanno portato alla certificazione per uso umano da parte della Comunità Europea sono descritti nella tesi.Aim of this thesis, begun in November 2019, is the development of an innovative Cerenkov detector for measurements of 17 MeV gamma-rays emitted by the D-T fusion reaction in an intense neutron field. With the spread of the COVID-19 pandemics in Northern Italy in February 2020, it became clear that the original program planned for my PhD work had to be significantly changed, since experimental activities to be carried out in the UNIMIB/CNR laboratories in Milan and at the Joint European Torus in the UK had to be cancelled. In agreement with my tutors I volunteered together with other scientists to contribute to a project called Mechanical Ventilator Milan (MVM). The MVM project involved an international team of more than 150 scientists and has produced over the very short period of less than three months a mechanical ventilator approved by the American Food and Drug Administration for use at the intensive care unit of hospitals to treat patients affected by COVID-19. The activities of the MVM project led to the development of a new fast oxygen sensor for medical application, about one year later. The sensor measures the oxygen consumption in real time during a single breath. The thesis is organized in three parts. The first part is focused on the development of a gamma-ray counter optimized for the measurement of the D-T fusion power produced in a magnetic confinement fusion device. The research team I have joined is developing a novel technique for the measurement of DT fusion power in a magnetic confinement device based on the detection of 17 MeV gamma-rays also produced by the D+T->5He* reaction. The 5He* nucleus promptly decays usually emitting an alpha particle and a neutron, but it may de-excite to the ground level emitting a gamma-ray with a probability of the order of 10^-5. These gamma-rays have been detected in the recent DT campaign at JET with a gamma spectrometer based on LaBr3 and a fast digital data acquisition. Since the efficiency of the scintillator to high energy gamma-rays and neutrons are comparable, the use of a dedicated LiH based neutron attenuator to observe the weak gamma-ray signal is needed. To overcome the limitations posed by the sensitivity of LaBr3 detectors to neutrons, I designed a gamma-ray gas detector optimized to work in the presence of an intense neutron field. The detector is based on the Cherenkov effect and simulations indicate that it is 10^6 times more sensitive to gamma-rays than to neutrons. The next step would be to build a prototype of the detector to validate the simulation results and to test it on a D-T neutron source. The second part of the thesis describes the design and build of the IFOx sensor, an ultra-fast oxygen sensor that can be used for lung analysis by working in the so called mainstream configuration. Since the working principle of the IFOx sensor somewhat resembles the one of a scintillator detector, this is an example of knowledge transfer from nuclear diagnostics to a different application. The prototype that was built features excellence time response and was used in a trial study on healthy volunteers to measure the Functional Residual Capacity. The excellent results of the trial study on healthy volunteers has opened up the possibility to carry out a clinical study on intensive care unit patients in the near future, by integrating the oxygen sensor with mechanical ventilators. The last part of the thesis is about the MVM project and describes the ventilator design aimed to the production of a ventilator composed of a few parts so that it can be rapidly built on large scales even during the disruption of the components supply chain. I was able to contribute to the project thanks to my knowledge of gas systems, advanced real time controls, and I participated in the measurement required for the certification. The key results that led to a full certification for usage on patient by the European Commission are also described in this work.
2
Carteaux, Guillaume. « Optimisation des interactions patient-ventilateur en ventilation assistée : intérêt des nouveaux algorithmes de ventilation ». Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC0027/document.
Texte intégralRésumé :
En ventilation assistée, les interactions patient-ventilateur, qui sont associés au pronostic, dépendent pour partie des algorithmes de ventilation. Objectifs : Caractériser l'intérêt potentiel des nouveaux algorithmes de ventilation dans l'optimisation des interactions patient-ventilateur : 1) en ventilation invasive, deux modes et leurs algorithmes nous ont semblé novateurs et nous avons cherché à personnaliser l'assistance du ventilateur en fonction de l'effort respiratoire du patient au cours de ces modes proportionnels : ventilation assistée proportionnelle (PAV+) et ventilation assistée neurale (NAVA) ; 2) en ventilation non-invasive (VNI) nous avons évalué si les algorithmes VNI des ventilateurs de réanimation et des ventilateurs dédiés à la VNI diminuaient l'incidence des asynchronies patient-ventilateur. Méthodes : 1) En PAV+ nous avons décrit un moyen de recalculer le pic de pression musculaire réalisée par le patient à chaque inspiration à partir du gain réglé et de la pression des voies aériennes monitorée par le respirateur. Nous avons alors évalué la faisabilité clinique d'ajuster l'assistance en ciblant un intervalle jugé normal de pression musculaire. 2) Nous avons comparé une titration de l'assistance en NAVA et en aide inspiratoire (AI) en se basant sur les indices d'effort respiratoire. 3 et 4) En VNI, nous avons évalué l'incidence des asynchronies patient-ventilateur avec et sans l'utilisation d'algorithmes VNI : sur banc d'essai au cours de conditions expérimentales reproduisant la présence de fuites autour de l'interface ; en clinique chez des patients de réanimation. Résultats : En PAV+, ajuster le gain dans le but de cibler un effort respiratoire normal était faisable, simple et souvent suffisant pour ventiler les patients depuis le sevrage de la ventilation mécanique jusqu'à l'extubation. En NAVA, l'analyse des indices d'effort respiratoire a permis de préciser les bornes d'utilisation et de comparer les interactions patient-ventilateur avec l'AI dans des intervalles d'assistance semblables. En VNI, nos données pointaient l'hétérogénéité des algorithmes VNI sur les ventilateurs de réanimation et retrouvaient une meilleure synchronisation patient-ventilateur avec l'utilisation de ventilateurs dédiés à la VNI pour des qualités de pressurisation par ailleurs identiques. Conclusions : En ventilation invasive, personnaliser l'assistance des modes proportionnels optimise les interactions patient-ventilateur et il est possible de cibler une zone d'effort respiratoire normale en PAV+. En VNI, les ventilateurs dédiés améliorent la synchronisation patient-ventilateur plus encore que les algorithmes VNI sur les ventilateurs de réanimation, dont l'efficacité varie grandement selon le ventilateur considéréDuring assisted mechanical ventilation, patient-ventilator interactions, which are associated with outcome, partly depend on ventilation algorithms.Objectives: : 1) during invasive mechanical ventilation, two modes offered real innovations and we wanted to assess whether the assistance could be customized depending on the patient's respiratory effort during proportional ventilatory modes: proportional assist ventilation with load-adjustable gain factors (PAV+) and neurally adjusted ventilator assist (NAVA); 2) during noninvasive ventilation (NIV): to assess whether NIV algorithms implemented on ICU and dedicated NIV ventilators decrease the incidence of patient-ventilator asynchrony.Methods: 1) In PAV+ we described a way to calculate the muscle pressure value from the values of both the gain adjusted by the clinician and the airway pressure. We then assessed the clinical feasibility of adjusting the gain with the goal of maintaining the muscle pressure within a normal range. 2) We compared titration of assistance between neurally adjusted ventilator assist (NAVA) and pressure support ventilation (PSV) based on respiratory effort indices. During NIV, we assessed the incidence of patient-ventilator asynchrony with and without the use of NIV algorithms: 1) using a bench model; 2) and in the clinical settings.Results: During PAV+, adjusting the gain with the goal of targeting a normal range of respiratory effort was feasible, simple, and most often sufficient to ventilate patients from the onset of partial ventilatory support until extubation. During NAVA, the analysis of respiratory effort indices allowed us to precise the boundaries within which the NAVA level should be adjusted and to compare patient-ventilator interactions with PSV within similar ranges of assistance. During NIV, our data stressed the heterogeneity of NIV algorithms implemented on ICU ventilators. We therefore reported that dedicated NIV ventilators allowed better patient-ventilator synchronization than ICU ventilators, even with their NIV algorithms engaged.Conclusions: During invasive mechanical ventilation, customizing the assistance during proportional ventilatory modes with the goal of targeting a normal range of respiratory effort optimizes patient-ventilator interactions and is feasible with PAV+. During NIV, dedicated NIV ventilators allow better patient-ventilator synchrony than ICU ventilators, even with their NIV algorithm engaged. ICU ventilators' NIV algorithms efficiency is however highly variable among ventilators
3
Sperber, Jesper. « Protective Mechanical Ventilation in Inflammatory and Ventilator-Associated Pneumonia Models ». Doctoral thesis, Uppsala universitet, Infektionssjukdomar, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-282602.
Texte intégralRésumé :
Severe infections, trauma or major surgery can each cause a state of systemic inflammation. These causes for systemic inflammation often coexist and complicate each other. Mechanical ventilation is commonly used during major surgical procedures and when respiratory functions are failing in the intensive care setting. Although necessary, the use of mechanical ventilation can cause injury to the lungs and other organs especially under states of systemic inflammation. Moreover, a course of mechanical ventilator therapy can be complicated by ventilator-associated pneumonia, a factor greatly influencing mortality. The efforts to avoid additional ventilator-induced injury to patients are embodied in the expression ‘protective ventilation’. With the use of pig models we have examined the impact of protective ventilation on systemic inflammation, on organ-specific inflammation and on bacterial growth during pneumonia. Additionally, with a 30-hour ventilator-associated pneumonia model we examined the influence of mechanical ventilation and systemic inflammation on bacterial growth. Systemic inflammation was initiated with surgery and enhanced with endotoxin. The bacterium used was Pseudomonas aeruginosa. We found that protective ventilation during systemic inflammation attenuated the systemic inflammatory cytokine responses and reduced secondary organ damage. Moreover, the attenuated inflammatory responses were seen on the organ specific level, most clearly as reduced counts of inflammatory cytokines from the liver. Protective ventilation entailed lower bacterial counts in lung tissue after 6 hours of pneumonia. Mechanical ventilation for 24 h, before a bacterial challenge into the lungs, increased bacterial counts in lung tissue after 6 h. The addition of systemic inflammation by endotoxin during 24 h increased the bacterial counts even more. For comparison, these experiments used control groups with clinically common ventilator settings. Summarily, these results support the use of protective ventilation as a means to reduce systemic inflammation and organ injury, and to optimize bacterial clearance in states of systemic inflammation and pneumonia.
4
Thille, Arnaud. « Asynchronies patient-ventilateur au cours de la ventilation assistée ». Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00667286.
Texte intégralRésumé :
Des asynchronies patient-ventilateur sont fréquemment observées en ventilation assistée. Objectif : Déterminer l'incidence et les facteurs favorisants des asynchronies, venant du patient, du ventilateur ou des réglages, et préciser le réglage optimal du ventilateur. Méthodes : Nous avons évalué l'incidence des asynchronies avec une méthode simple et non invasive basée sur l'analyse des courbes du ventilateur. Chez les patients qui présentaient des efforts inefficaces, nous avons mesuré l'effort inspiratoire avec une sonde œsophagienne afin d'optimiser le réglage du ventilateur. Nous avons évalué l'impact du mode ventilatoire sur la qualité du sommeil avec une polysomnographie complète. Enfin, tous les ventilateurs de réanimation ont été testés sur banc afin de comparer les performances en termes de trigger et pressurisation. Résultats : Près d'un quart des patients présentaient des asynchronies fréquentes. La durée de ventilation de ces patients était plus longue et le sevrage plus difficile. Les efforts inefficaces, qui représentaient les asynchronies les plus fréquentes, étaient favorisés par une assistance ventilatoire excessive. La réduction du niveau d'aide inspiratoire (AI) permettait d'éliminer quasi-complètement les efforts inefficaces, sans augmenter l'effort inspiratoire et sans modifier la vraie fréquence respiratoire du patient. Le mode ventilatoire n'avait pas d'influence sur la qualité du sommeil et les asynchronies. Les efforts inefficaces survenaient aussi bien en AI qu'en ventilation assistée contrôlée. Avec un niveau d'AI adéquat, les apnées centrales étaient peu nombreuses et n'avaient pas d'influence sur la qualité du sommeil. Les performances insuffisantes observées avec certains ventilateurs peuvent également altérer la synchronisation. Conclusion : Les asynchronies patient-ventilateur sont fréquentes et associées à une durée de ventilation prolongée. Une " dose de ventilation " excessive favorise les efforts inefficaces, mais un réglage optimal du ventilateur permet de minimiser ces asynchronies. Cette thèse est un support pour déterminer dans une étude plus large si une synchronisation adéquate peut réduire la durée de ventilation.
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Lyazidi, Aissam. « Évaluation des performances et des limitations des ventilateurs sur banc d'essai ». Thesis, Paris Est, 2010. http://www.theses.fr/2010PEST1073.
Texte intégralRésumé :
Les ventilateurs ont connu des progrès technologiques considérables grâce à l'application de concepts physiologiques, à l'électronique, à l'informatique et la miniaturisation. Leurs conceptions et performances intrinsèques, en revanche, ont pu rester inégales sur certains points. L'objectif de ce travail a été d'évaluer sur un banc d'essai, avec un protocole, adapté aux problématiques soulevées en pratique clinique, tous les ventilateurs de réanimation, transport et de ventilation non invasive de façon rigoureuse et reproductible. Les résultats montrent que 1) l'erreur sur le volume réellement délivré est très fréquente et correspond facilement à 1ml/kg de volume supplémentaire ; le VT indiqué sur les ventilateurs est inférieur au VT réellement délivré ; 2) les performances des nouveaux ventilateurs ne présentent pas d'améliorations significatives par rapport aux meilleurs ventilateurs testés en 2000; les ventilateurs à turbine sont identiques ou proches des meilleurs ventilateurs conventionnels ; 3) les ventilateurs dédiés à la ventilation non invasive montrent de meilleures performances pour s'adapter à la présence de fuites ; 4) la ventilation par percussion intra-pulmonaire superposée à la ventilation conventionnelle peut réduire l'apport de l'humidification, influencer les volumes administrés et induire une pression expiratoire positive intrinsèque. Les tests sur banc montrent une grande hétérogénéité des performances. Une veille technologique semble indispensable pour évaluer tout nouveau ventilateurThe ventilators have markedly improved thanks to progress in respiratory physiology, in informatics and miniaturization. However, their intrinsic performances remain unequal. The aim was to evaluate ventilators performances on reproducible bench test studies adapted to clinical questions. Tests show that 1) the error of really delivered volume is approximately 1 ml/kg of additional volume; the tidal volume (VT) indicated on the ventilators was lower than the real delivered VT ; 2) Performances of new ventilators are comparable to the best ventilators tested in 2000 ; turbine ventilators are quite similar to best conventional ventilators ; 3) The ventilators dedicated to non invasive ventilation showed better performances to cope with leaks 4) The intrapulmonary percussive ventilation superimposed on conventional ventilation can reduce humidity, increase volumes and can generate intrinsic positive expiratory pressure. The bench tests showed a large heterogeneity of performances. A technological watch seems essential to evaluate all new ventilators
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Hult, Erin L. (Erin Luelle) 1982. « Experimental simulation of wind driven cross-ventilation in a naturally ventilated building ». Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32808.
Texte intégralRésumé :
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 29).
A device was designed and constructed to simulate cross-ventilation through a building due to natural wind. The wind driver device was designed for use with a one tenth scale model of an open floor plan office building in Luton, England. The air flow patterns produced by the wind driver were observed, and the uniformity of the velocity of the flows into the model windows was measured for the three settings of the wind driver fans. The temperatures and velocities of flows on the interior of the building and at the exhaust windows were also examined. The wind driver device was capable of producing uniform velocities across the face of the model to within 20 to 27%, depending on the fan setting. The consistency of certain features of the velocity distributions produced by the wind driver operating at different speeds suggest that improvements made to the design of the wind driver could lower this variation to about 15%. The velocities measured on the interior of the model seem consistent with interior velocities in the Luton building, although further experimentation is needed to confirm this trend. Cross-ventilation was effective in reducing interior model temperatures by up to 10⁰C from the natural convection case.
by Erin L. Hult.
S.B.
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Balaji, Ravishankar. « Breathing Entrainment and Mechanical Ventilation in Rats ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1307743446.
Texte intégral
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Júnior, Marcus Henrique Victor. « Implementation and assessment of a novel mechanical ventilatory system following a noisy ventilation regime ». Instituto Tecnológico de Aeronáutica, 2014. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3151.
Texte intégralRésumé :
This study concerns the development of a novel mechanical ventilation system, with a view to analysing the results of a new mechanical ventilation technique, referred to noisy ventilation. Additionally, the study addresses the assessment of the system, involving the estimation of certain mechanical parameters of the respiratory system under noisy ventilation and discusses a pilot trial in vivo, with a pig. During acute respiratory failure, intubation and invasive mechanical ventilation may be life saving procedures. The general aim of mechanical ventilation is to provide adequate gas exchange support, while not damaging the respiratory system. This technique is one of the most important life support tools in the intensive care unit. However, it may also be harmful by causing ventilator induced lung injury and other undesirable effects. There is a growing interest in the development and use of variable mechanical ventilation performing variable volume and variable pressure controlled ventilation. The reasons are that this technique can improve lung functions and reduce lung damage, when compared to standard mechanical ventilation. Moreover, variable ventilation can improve lung mechanics and gas exchanges. The new ventilation system has to have the capabilities to perform a noisy ventilation regime, besides the standard mechanical ventilation. The development started with commercial devices: a mechanical ventilator and a personal computer, whose roles were to execute the noisy ventilation regime and to implement the new ventilation pattern by means of a ventilation routine, commanding the mechanical ventilator. After these two components were working together, a bench test was performed, in which a calibrated measuring device and a mechanical lung simulator were utilized. Considering that the system was working properly, it was possible to validate it by analysing the results. As the mechanical properties of the respiratory system are important quantities to know, a parameter estimation method was developed, with a view to estimating some relevant properties, such as compliance, positive end--expiratory pressure, resistance and others. The estimates were related to the adopted model for the respiratory system. In this study, four models were discussed: first order linear model, flow dependent resistance model, volume dependent elastance model and second order linear model. For each one, all parameters were estimated and the outcomes from each estimation were compared with the others, with a view to finding relationships between them and to evaluating the goodness of each model. Furthermore, as some parameters could be adjusted directly in the devices, adjusted and estimated values could also be compared. Finally, one trial in vivo was performed, with a view to assessing the behaviour of the system in a real situation and to showing the developed system to the research team. The system was set to work in a noisy and in a standard ventilation regime. It showed reasonable results in terms of quality of ventilation as well as reliability and maintainability of the ventilatory regime, during the whole test period. The developed parameter estimation methods were utilized to estimate the mechanical respiratory properties of the animal under test and to find cross relationships between these outcomes and others, such as those from blood gas, ultrasonography and electrical impedance tomography.
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Svantesson, Cecilia. « Respiratory mechanics during mechanical ventilation in health and in disease ». Lund : Dept. of Clinical Psychology, Lund University, 1997. http://catalog.hathitrust.org/api/volumes/oclc/38987113.html.
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Elshafie, Ghazi Abdelgadir E. « Ventilatory mechanics in thoracic surgery ». Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7141/.
Texte intégralRésumé :
This thesis proved that chest wall motion analysis technology could be used in thoracic surgery to answer a number of clinical and physiological questions. We used it either as a diagnostic tool or for the evaluation of an intervention outcome. We divided its use as a diagnostic tool into two categories; 1- diagnosis before surgery and 2- diagnosis after surgery. In the evaluation of an intervention outcome, we divided its use after a number of interventions: 1. Cosmetic Surgery: Chapter 5: The Effect of Pectus Carinatum (Pigeon Chest) Repair on Chest Wall Mechanics 2. Prognostic Surgery: a) Chapter 4: The Effect of Chest Wall Reconstruction on Chest Wall Mechanics b) Chapter 10: Late Changes in Chest Wall Mechanics Post Lung Resection: The Effect of Lung Cancer Resection In COPD patients 3. Palliative Surgery: a) Chapter 6: The Effect of Lung Volume Reduction Surgery on Chest Wall Mechanics b) Chapter 3: The Effect of Diaphragmatic Plication (Fixation) on Chest Wall Mechanics 4. Post-operative Intervention: Chapter 8: The Effect of Thoracic Nerve Blocks on Chest Wall Mechanics.
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Koombua, Kittisak. « Multiscale Modeling of Airway Inflammation Induced by Mechanical Ventilation ». VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1841.
Texte intégralRésumé :
Mechanical ventilation (MV) is a system that partially or fully assists patients whose respiratory system fails to achieve a gas exchange function. However, MV can cause a ventilator-associated lung injury (VALI) or even contribute to a multiple organ dysfunction syndrome (MODS) in acute respiratory distress syndrome (ARDS) patients. Despite advances in today technologies, mortality rates for ARDS patient are still high. A better understanding of the interactions between airflow from mechanical ventilator and the airway could provide useful information used to develop a better strategy to ventilate patients. The mechanisms, which mechanical ventilation induces airway inflammation, are complex processes and cover a wide range of spatial scales. The multiscale model of the airway have been developed combining the computational models at organ, tissue, and cellular levels. A model at the organ level was used to study behaviors of the airway during mechanical ventilation. Strain distributions in each layer of the airway were investigated using a model at the tissue level. The cellular inflammatory responses during mechanical ventilation were investigated through the cellular automata (CA) model incorporating all biophysical processes during inflammatory responses. The multiscale modeling framework started by obtaining airway displacements from the organ-level model. They were then transferred to the tissue-level model for determining the strain distributions in each airway layer. The strain levels in each layer were then transferred to the cellular-level model for inflammatory responses due to strain levels. The ratio of the number of damage cells to healthy cells was obtained through the cellular-level model. This ratio, in turn, modulated changes in the Young’s modulus of elasticity at the tissue and organ levels. The simulation results showed that high tidal volume (1400 cc) during mechanical ventilation can cause tissue injury due to high concentration of activated immune cells and low tidal volume during mechanical ventilation (700 cc) can prevent tissue injury during mechanical ventilation and can mitigate tissue injury from the high tidal volume ventilation. The multiscale model developed in this research could provide useful information about how mechanical ventilation contributes to airway inflammation so that a better strategy to ventilate patients can be developed.
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van, Drunen Erwin Johan. « Mechanical Ventilation Modelling and Optimisation ». Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8400.
Texte intégralRésumé :
Acute Respiratory Distress Syndrome (ARDS) is associated with lung inflammation and fluid filling, resulting in a stiffer lung with reduced intrapulmonary gas volume. ARDS patients are admitted to the Intensive Care Unit (ICU) and require Mechanical Ventilation (MV) for breathing support. Positive End Expiratory Pressure (PEEP) is applied to aid recovery by improving gas exchange and maintaining recruited lung volume. However, high PEEP risks further lung injury due to overstretching of healthy lung units, and low PEEP risks further lung injury due to the repetitive opening and closing of lung units. Thus, selecting PEEP is a balance between avoiding over-stretching and repetitive opening of alveoli. Furthermore, specific protocols to determine optimal PEEP do not currently exist, resulting in variable PEEP selection. Thus, ensuring an optimal PEEP would have significant impact on patient mortality, and the cost and duration of MV therapy.
Two important metrics that can be used to aid MV therapy are the elastance of the lungs as a function of PEEP, and the quantity of recruited lung volume as a function of PEEP. This thesis describes several models and model-based methods that can be used to select optimal PEEP in the ICU. Firstly, a single compartment lung model is investigated for its ability to capture the respiratory mechanics of a mechanically ventilated ARDS patient. This model is then expanded upon, leading to a novel method of mapping and visualising dynamic respiratory system elastance. Considering how elastance changes, both within a breath and throughout the course of care, provides a new clinical perspective. Next, a model using only the expiratory portion of the breathing cycle is developed and presented, providing an alternative means to track changes in disease state throughout MV therapy. Finally, four model-based methods are compared based on their capability of estimating the quantity of recruited lung volume due to PEEP.
The models and model-based methods described in this thesis enable rapid parameter identification from readily available clinical data, providing a means of tracking lung condition and selecting optimal patient-specific PEEP. Each model is validated using data from clinical ICU patients and/or experimental ARDS animal models.
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Turowski, Paweł [Verfasser]. « Molecular mechanisms of ventilator-induced acute kidney injury : Mechanical ventilation can modulate neutrophil recruitment to the kidney / Paweł Turowski ». Gießen : Universitätsbibliothek, 2012. http://d-nb.info/1064838820/34.
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Heyer, Laurent. « L'interaction patient-ventilateur : application technique d'une analyse biologique ». Phd thesis, Université Joseph Fourier (Grenoble ; 1971-2015), 2009. http://www.theses.fr/2009GRE10184.
Texte intégralRésumé :
Par assistance respiratoire mécanique partielle. Nous avons essayé de préciser la description du système hybride {Patient, Ventilateur} afin de construire un outil clinique de surveillance de l'IPV. Dans un premier temps, nous avons proposé d'aborder l'IPV comme la phénoménologie locale d'un réseau biologique communicant. L'IPV est alors la traduction de la communication établie à travers l'appareil respiratoire entre un oscillateur biologique et un oscillateur mécanique. Cette approche biologique permet à la fois d'utiliser les résultats de la théorie de la communication pour élaborer un score de désynchronisation, et de construire l'outil nécessaire pour calculer ce score en clinique. L'outil est un détecteur non-invasif de l'activité musculaire à partir de l'estimation de la pression musculaire par un modèle de la mécanique du système ventilatoire dont le traitement de signal est suffisamment robuste pour permettre son automatisation. Nous avons ensuite validé ces constructions chez des patients sous assistance partielle. Le score de désynchronisation est spécifiquement augmenté par la combinaison d'altérations de la voie de communication ou de la génération de l'activité inspiratoire à transmettre. La quantification automatique de l'IPV par un score spécifique de désynchronisation, reflet de l'altération de la transmission de l'information entre le patient et son ventilateur, et par une détection de l'activité inspiratoire, reflet du message à transmettre, devrait permettre d'améliorer l'analyse clinique du comportement des patients sous assistance partielleOptimal Patient/Ventilator Interactions (PVI) is a determinant factor for pressure support therapy. We studied the hybrid system {Patient, Ventilator} in order to develop a clinical tool for PVI monitoring. In the first part, we described IPV as the expression of a local communication in a biological network. PVI reflect the communication process trough the respiratory system between a biological oscillator and a mechanical oscillator. This biological approach allows application of Shannon theory for the development of a de-synchronization score and the definition of an appropriate inspiratory muscle effort detector. For this purpose, we developed an automatic non-invasive detector based on a robust muscular pressure estimates continuously assessed with the help of passive mechanical respiratory models updated cycle by cycle. In the second part, we assessed these developments in patients under pressure support ventilation. The de-synchronization score was increased as the transmission channel was altered by additional noise or as the information source, the inspiratory effort, was decreased. An automatic titration of IPV by a de-synchronization score that assess channel transmission efficiency or by an inspiratory muscle effort detector that assess message generator efficiency might be helpful for respiratory function monitoring in patients under pressure support
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Austin, Paul Nelson. « Imposed Work of Breathing and Breathing Comfort of Nonintubated Volunters Breathing with Three Portable Ventilators and a Critical Care Ventilator ». University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997382634.
Texte intégral
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Dungi, Santosh Roopak. « Effectiveness of Ventilating Headboards in Protecting Health-Care Workers in Hospital Rooms ». University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881263.
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Walsh, Brian Kendall. « Computer-aided mechanical ventilation ». Thesis, Rush University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10111109.
Texte intégralRésumé :
Statement of the problem: The systematic implementation of evidence-based practice through the use of guidelines, checklists and protocols has been shown to mitigate the risks associated with MV, yet variation in practice remains prevalent. Recent advances in MV, physiologic monitoring, device-to-device communication, computer processing and software engineering have allowed for the development of an automated point-of-care access to real-time goal setting and practice variance identification. Our aim was to assess the utility of a computer-aided MV (CAMV) system that displays variances and scores the overall MV course. Methods: A retrospective categorization of the ventilation and oxygenation statuses of patients within our pediatric intensive care unit (PICU) over a 2 '/z years period utilizing 15 rule-based algorithms was initiated as a proof of concept. Goals were predetermined based on generally accepted values. All patient categories were calculated and presented as a percent of recording time. Following the feasibility study, a retrospective observational study (baseline), followed by two sequential interventions made over a 2-month period was conducted. Phase I comprised a survey of goals of MV by clinicians caring for patients being monitored by the CAMV system. Phase II intervention was the setting and monitoring of goals of MV with a web browser based data visualization system (T3). An outcome measurement tool was developed to score each MV course. The MV score (MVS) evaluated four outcomes: (1) acceptable ventilation, (2) acceptable oxygenation, (3) barotrauma free and (4) volutrauma-free states as a percent of recording time. Results: Pilot consisted of 222 patients. The Baseline phase evaluated 130 patients, Phase I enrolled 31 patients and Phase II enrolled 36 patients. There were no differences in demographic characteristics between cohorts. One hundred and seventy-one surveys were completed in Phase I. An increase in the use of T3 by 87% was observed in Phase II from Phase I. MVS improved by 8.4% in Phase I and 11.3% in Phase II from Baseline. The largest improvement was in the volutraumafree category. MVS was 9% higher on average in those who survived. Conclusion: The use of CAMV was associated with an improvement in MVS. Further research is needed to determine if improvements in MVS through a targeted, process-oriented intervention such as CAMV will lead to improved patient outcomes.
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Howe, Kimberly Palazzo. « Mechanical Ventilation Antioxidant Trial ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1112877564.
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Ward, Paul. « A computational and experimental study on respiratory oscillation mechanics for the control of mechanical ventilation ». Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435804.
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Connick, Owen. « The fluid mechanics of hybrid ventilation ». Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/39347.
Texte intégralRésumé :
A low-energy ventilation system is often incorporated as one of the major energy saving measures in sustainable building design. These systems often employ a hybrid strategy in which mechanical equipment, governed by a computer controlled building management system, is used to assist or manage a naturally-driven airflow - the latter occurring due to the density difference between warm air inside and cooler air outside the room. Hybrid ventilation flows are poorly understood and the principal aim of the research was to enhance our understanding of the fluid mechanics through complementary theoretical and experimental modelling. The research begins by comparing solely natural and solely mechanical ventilation of a room. The hybrid ventilation of a room is then considered under the combined effect of naturally occurring and mechanically imposed pressure differences, in which a mechanical fan imposes a fixed airflow rate through one vent, thereby altering the natural pressure distribution. Simplified theoretical models, to describe the ventilation airflow rate through a room and the resulting mean air temperature, were developed for solely natural ventila- tion, solely mechanical ventilation and, finally, hybrid ventilation. At each stage the theoretical model was compared with results from small-scale experiments, and good agreement was demonstrated. From the theoretical investigation, the neutral pressure level emerged as a key pa- rameter in determining the characteristics of the ventilation airflow. Moreover, it was found that the airflow rate through an open vent can be controlled remotely by managing the position of the neutral pressure level, and that this can be achieved by varying the magnitude of the mechanically imposed airflow rate. Experimental investigations revealed that, as the neutral pressure level approached the plane of a vent, quasi-steady pulsing flows and bi-directional or exchange flows were observed. The complicated fluid dynamics involved in these flows provides inspiration for significant future work.
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Silva, Alexandre Rodrigues da. « Hardware de ventilador pulmonar ». Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-03052012-121527/.
Texte intégralRésumé :
Este trabalho visou mostrar o desenvolvimento de um ventilador pulmonar mecânico, focando principalmente na parte de hardware necessária para que este equipamento pudesse funcionar. Ventilação mecânica é a modalidade da medicina mais importante no cuidado a pacientes criticamente enfermos. O ventilador é um equipamento utilizado principalmente em unidades de terapia intensiva, que basicamente coloca uma mistura de ar e oxigênio para dentro do pulmão de um paciente incapacitado de fazer isto naturalmente, quer seja por força de uma doença que o impossibilita de fazê-lo, ou por uma cirurgia, a qual impossibilitou o movimento do músculo do diafragma para que o ar entrasse no pulmão naturalmente. Este projeto cobriu uma descrição abrangente sobre este ventilador, sua transformação de ar comprimido e oxigênio provenientes de um cilindro em uma mistura controlada de fluxos que entra no pulmão para a inspiração de um volume, ou para atingir uma pressão determinada, e a saída desta mistura, mantendo no pulmão uma pressão também controlada. Foi desenvolvido um protótipo de hardware e firmware para este aparelho, e o intuito foi mostrar o processo de transformação da ideia inicial e as necessidades de projeto em um aparelho testado e certificado para uso no mercado.This work aimed to present the development of a pulmonary mechanical ventilator, mainly focusing on the hardware part needed in order for this device to work. Mechanical ventilation is the most important medical mode concerning the care of patients that are critically ill. The ventilator is a device very much used in intensive care units (ICUs), and it basically delivers an air and oxygen mixture to the patients lungs that is normally unable to do so naturally, either because the patient is seriously ill that prevents him/her to do so, or due to surgery, in this case prevented the movement of the diaphragm muscle so the air could be naturally delivered to the lung. This work covered a comprehensive description about this ventilator, its transformation of compressed air and oxygen coming from a cylinder in a controlled mixture of flows that enters the lung for the inspiration of a volume, or to achieve a determined pressure, and the output of this mixture, maintaining a controlled pressure in the lung too. A hardware and firmware prototype was developed for this device. The aim was to show the transformation process from the main idea and the need for a project of a tested and certified device to be used in the market.
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Hammash, Muna Hassan. « CARDIAC RHYTHM DURING MECHANICAL VENTILATION AND WEANING FROM VENTILATION ». UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/56.
Texte intégralRésumé :
The transition from mechanical ventilation (MV) to spontaneous ventilation during weaning is associated with hemodynamic alterations and autonomic nervous system (ANS) alterations (reflected by heart rate variability [HRV]). Although cardiac dysrhythmias are an important manifestation of hemodynamic alterations, development of dysrhythmias during MV and weaning and subsequent impact on length of MV has received little attention.
The purposes of this dissertation were to 1) evaluate the relationship of heart rate variability (HRV) during weaning to the development of cardiac dysrhythmias and 2) determine the relationship of cardiac dysrhythmias to length of MV.
A convenience sample of 35 patients (66.7% men; mean age 53.3 years) who required MV was enrolled in this study. Continuous 3-lead electrocardiographic data were collected for 24 hours at baseline during MV and for the first 2 hours during the initial weaning trial. HRV was evaluated using spectral power analysis.
Twenty- seven patients out of 30 were exposed to a combination of pressure support (8-15 cm H2O) and continuous positive airway pressure 5 cm H2O during weaning trial. Three patients self- extubated and received supplemental oxygen through either a partial rebreathing or non-rebreathing mask. Low frequency (LF) power HRV decreased, while high frequency (HF) and very low frequency (VLF) power HRV did not change during weaning. Multiple regression analyses showed that LF and HF HRV were significant predictors of occurrence of ventricular and supraventricular ectopic beats during weaning, while VLF power predicted occurrence of ventricular ectopic beats only. The mean of occurrence of supraventricular ectopic beats per hour during weaning was double the mean at baseline, while the mean of ventricular ectopic beats per hour did not change. Mean number of supraventricular ectopic beats per hour during weaning was a significant predictor of length of MV.
This dissertation has fulfilled an important gap in the evidence base for cardiac dysrhythmias during weaning from MV. Cardiac dysrhythmias and HRV alterations should be systemically evaluated during MV and weaning trials in order to decrease length of MV.
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Borges, João Batista. « Regional Lung Kinetics of Ventilator-Induced Lung Injury and Protective-Ventilation Strategies Studied by Dynamic Positron Emission Tomography ». Doctoral thesis, Uppsala universitet, Hedenstiernalaboratoriet, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230022.
Texte intégralRésumé :
Mechanical ventilation in itself can harm the lung and cause ventilator-induced lung injury (VILI), which can induce or aggravate acute respiratory distress syndrome (ARDS). Much debate remains over pivotal concepts regarding the pathophysiology of VILI, especially about the precise contribution, kinetics, and primary role of potential VILI mechanisms. Consequently, it remains largely unknown how best to design a well-timed and full-bodied mechanical ventilation strategy. Little is known also about small airways dysfunction in ARDS. Dynamic positron emission tomography (PET) with [18F]fluoro-2-deoxy-D-glucose (18F-FDG) can be used to image cellular metabolism, which during lung inflammation mainly reflects neutrophil activity, allowing the study of regional lung inflammation in vivo. We studied the regional evolution of inflammation using dynamic PET/CT imaging of 18F-FDG in VILI and during different lung-protective mechanical ventilation strategies. By dynamic CT we investigated also the location and magnitude of peripheral airway closure and alveolar collapse under high and low distending pressures and high and low inspiratory oxygen fraction. Piglets were submitted to an experimental model of early ARDS combining repeated lung lavages and injurious mechanical ventilation. The animals were subsequently studied during sustained VILI, or submitted to distinct approaches of lung-protective mechanical ventilation: the one recommended by the ARDS Network (ARDSNet), or to one defined as open lung approach (OLA). The normally and poorly aerated regions - corresponding to intermediate gravitational zones - were the primary targets of the inflammatory process accompanying early VILI, which may be attributed to the small volume of the aerated lung that receives most of ventilation. The ARDSNet strategy did not attenuate global pulmonary inflammation during 27h and led to a concentration of inflammatory activity in the upper and poorly aerated lung regions. The OLA, in comparison with the ARDSNet approach, resulted in sustained and better gas exchange and lung mechanics. Moreover, the OLA strategy resulted in less global and regional inflammation. Dynamic CT data suggested that a significant amount of airway closure and related reabsorption atelectasis occurs in acute lung injury. Whether potential distal bronchioles injury (“bronchiolotrauma”) is a critical and decisive element in ventilator-associated lung injury is a matter for future studies.
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Young, Peter Jeffrey. « Pulmonary aspiration in mechanical ventilation ». Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323263.
Texte intégralRésumé :
Pulmonary aspiration in mechanical ventilation occurs despite appropriate inflation of the tracheal tube cuff. After anaesthesiath is can causep ostoperative and, in critically ill patients, ventilator-associated pneumonia. Cuff over-inflation exerts excessive pressure on the tracheal mucosa causing injury. High volume low pressure (HVLP) cuffs permit wall pressure control as the intracuff pressure (CP) is the tracheal wall pressure (TWP). Unfortunately, at the cuff wall, folds and channels and, therefore, fluid leakage occur. Low volume high pressure (LVHP) cuffs develop neither folds nor associated leakage, but TWP is not easily inferred from CP and excessive pressures can result in tracheal injury. This thesis examines the problem of aspiration in a model, in anaesthetised patients and in the critically ill. In the model, protection against leakage resulted from positive end-expiratory pressure and cuff lubrication. Two tracheal cuff prototypes are introduced. Firstly, the compliant HVLP cuff is one with a tapered shape made of highly compliant material. Within the model this produced a circumferential band at the cuff wall without folds thus effectively eliminating channels and leakage. Secondly, the prototype pressure limited cuff (PLC) is a latex LVHP cuff with inflation characteristics such that TWP can be inferred from CP and maintained at an acceptable level. Within the model the PLC prevented leakage at acceptable TWPs. For clinical use a constant pressure inflation device is required to provide uninterrupted protection, although notably HVLP cuffs allow leakage despite this. The PLC prevented dye aspiration in 100% of tracheally intubated critically ill patients compared with 13% of the control HVLP group (p<0.01). A silicone cuff with similar inflation characteristics, yet improved biocompatability and shelf life, prevented dye aspiration in 100% of patients with tracheostomies compared to 0% of the HVLP control group (p=0.001). HVLP cuff lubrication delayed dye aspiration for 1 to 5 days (p<0.05).
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Mortimer, A. J. « High frequency jet ventilation : Mechanics and gas exchange ». Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373490.
Texte intégral
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Bengtsson, Patrik, et Joel Blomfelt. « Variabel Ventilation ». Thesis, KTH, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-190163.
Texte intégralRésumé :
A lot of people today spend most of their lives indoors. Both at home and at work time is spent in areas where the climate is not governed by the weather but by ventilation systems meant to create a suitable indoor climate. Despite having such a central part in society the subject of ventilation seldom gets very much attention, and in the current situation it is not a foregone conclusion that indoor air quality and climate is satisfactory. Those who build the homes and premises normally explain this as a result of cost considerations, but essentially the situation originates from other issues. A more accurate explanation is that there are some problems concerning the planning stage of ventilation systems, which implies both a highly simplified designing approach and the price, not the function and quality, being decisive. The problems have been confirmed by several sources and research is in progress within the area in order to address the underlying issues. Among other things, various types of test-bed housing is constructed in several parts of the world, designed for measurement and data collection in a real living environment. Such projects can both verify different system´s function and promote the development of new innovations, but also help in creating well-justified research material regarding, among other things, different ventilation solutions such as for example variable ventilation. One of these projects, called KTH Live-in Lab, is located at KTH in Stockholm. This report presents a work regarding comparisons of different ventilation solutions for such a student apartment as constructed in the ongoing research project KTH Live-in Lab. The work focuses on both finding a suitable system and then link the results to an adequate combination for use with variable ventilation. In order to deal with today´s problems within the area, the work is focused on deviating from the current conventional approach and ventilation design. The result is illustrated digitally in the form of computer simulations of air flow in a virtual model of the apartment, and comparisons led both to a number of conclusions, and proposals of suitable and unconventional solutions. For non-variable ventilation systems, a suitable system consisted of one ventilation inlet placed at ceiling level and two outlets whereof one at ceiling level and one at floor level. For variable ventilation, the results showed that the system solution should suitably be combined with the ability to switch to an inlet at floor level at nights and other scenarios without activity and movement in the apartment. Other conclusions are mainly about findings regarding how certain design variations affect the characteristics of the ventilation system.Många människor spenderar idag större delen av sitt liv inomhus. Det är vanligt att man både hemma och på jobbet vistas i utrymmen där klimatet inte styrs av väder och vind utan av ventilationssystem som är tänkta att skapa ett lämpligt inomhusklimat. Trots ventilationens centrala del av samhället hamnar ämnet dock ofta i skymundan, och i dagens läge är det ingen självklarhet att inomhusklimaten och dess luftkvalité är tillfredställande. Av dem som bygger bostäderna och lokalerna förklaras detta ofta bero på kostnadsaspekter, men i grund och botten är det annat som ligger till grund för dagens situation. En bättre förklaring är att det finns viss problematik kring ventilationens planeringsskede, vilket innebär ett väldigt förenklat arbetssätt och att kostnad prioriteras framför funktion och kvalité. Problemen har bekräftats från flera håll och forskning pågår inom området i syfte att möta de bakomliggande orsakerna. Bland annat uppförs på flera håll i världen olika typer av testbädd-bostäder utformade för mätning och datainsamling i en verklig boendemiljö. Med hjälp av dessa kan man både verifiera olika systems funktion och gynna framtagning av nya innovationer och välgrundat forskningsmaterial gällande bland annat olika ventilationslösningar som exempelvis variabel ventilation. Ett av dessa projekt, med namnet KTH Live-in Lab, utförs på KTH i Stockholm. I denna rapport presenteras ett arbete gällande jämförelser av olika ventilationslösningar för en sådan studentlägenhet som uppförs i det pågående bygg- och forskningsprojektet KTH Live-in Lab. Arbetet fokuseras på att dels hitta en lämplig ventilationslösning och sedan även koppla resultatet till en möjlig kombination att använda för variabel ventilation. I syfte att möta dagens problematik fokuserades på att frångå dagens konventionella arbetssätt och ventilationsdesign. Resultatet illustreras digitalt i form av datorsimuleringar av luftflöden i en virtuell modell av bostaden, och jämförelserna ledde till ett antal slutsatser och förslag på lämpliga okonventionella lösningar. För icke-variabel ventilation var det lämpligt att placera ett inlopp i taknivå, samt två utlopp varav ett i taknivå och ett i golvnivå. För variabel ventilation visade det sig att denna systemlösning bör kombineras med möjlighet att växla inloppet till lågt inlopp på nätter och andra scenarion utan aktivitet och rörelse i bostaden. Övriga slutsatser gäller vilka egenskaper som bör varieras beroende på vad man vill uppnå med ventilationen.
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Ouellet, Paul. « Évaluation d'une perfusion d'algosédation guidée soit par l'échelle de Ramsay soit par la technologie BIS sur le temps d'émergence et sur la synchronie patient-ventilateur auprès d'adultes non communicatifs durant la phase aiguë de ventilation mécanique en soins critiques ». Thèse, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6249.
Texte intégralRésumé :
Résumé : Cette thèse s’intéresse au temps d’émergence et aux asynchronies patient-ventilateur à l’origine de lésions pulmonaires chez des patients en soins critiques sous algosédation durant la phase aiguë de la ventilation mécanique. L’originalité de cette recherche consiste à comparer un protocole d’algosédation guidé par l’échelle de Ramsay (le standard) à celui guidé par la technologie BIS. Méthodologie. Suivant un devis mixte inter groupe et intrasujets, cette recherche comporte deux groupes de patients adultes et se déroule sur une période de quatre ans. Le premier groupe comprend 23 patients dont le protocole d’algosédation est guidé par l’échelle de Ramsay. Le second groupe compte 18 patients soumis à la même stratégie de ventilation et au même protocole d’algosédation mais guidé cette fois-ci par la technologie BIS. Mesures. Le temps d ’émergence pour un retour à la ventilation spontanée soutenue (TEVSS) suivant l’arrêt de la perfusion de l’algosédation et les interactions patient-ventilateur (synchronies et asynchronies) durant la phase aiguë de ventilation constituent les variables dépendantes. Résultats. Le groupe bénéficiant de la technologie BIS présente un TEVSS médian de 3,1 heures comparé à 22,5 heures pour le groupe guidé par l’échelle de Ramsay (valeur p=0,001). De plus, le groupe bénéficiant de la technologie BIS présente 11% de moins d’asynchronies patient-ventilateur que celui guidé par l’échelle de Ramsay (valeur p<0,001). En outre, parmi les paramètres de la technologie BIS, l’électromyogramme (EMG) s’avère l’élément le plus robuste à prédire l’asynchronie patient-ventilateur. Conclusion. La réduction du TEVSS ainsi que la diminution des asynchronies patient-ventilateur démontrent un avantage considérable à utiliser la technologie BIS en soins critiques chez les patients adultes non communicatifs durant la phase aiguë de ventilation mécanique. De plus, l’EMG de la technologie BIS permettrait vraisemblablement de déceler de façon précoce l’expression préclinique de la douleur. Enfin, cette thèse propose un algorithme de contrôle de l’algosédation en soins critiques en référence à la technologie BIS. // Abstract : This thesis focuses on emergence time from algosédation (for which a prolongation increases complex investigations and costs) and on patient-ventilator interaction (related to lung injuries) in critical care patients undergoing mechanical ventilation with algosedation perfusion during the acute phase of ventilator support. More specifically, the originality of this research stems from the simultaneous comparison of the emergence time for a retum of sustained spontaneous breathing and the presence of asynchronies, by eomparing algosedation guided by the Ramsay scale (gold standard) in a first group and by the BIS technology in a second group. Methodology. Following a mixed design of an inter group, intra subject, this research is performed in two groups of adults over a period of four years. The first group consists of 23 patients where algosedation is guided with the Ramsay scale whereas the second group consists of 18 patients with the same ventilation strategy and same algosédation protocol but guided using the BIS technology. This research evaluates the effectiveness of both instruments to guide algosedation during the acute phase of ventilation. Measures. Dependent variables consist of the emergence time for a sustained spontaneous breathing following cessation o f algosedation and patient-ventilator interaction (asynchronies) during the acute phase of ventilatory support. Results. The group guided with BIS technology has a median emergence time for a sustained spontaneous breathing of 3.1 hours compared to 22.5 hours for the Ramsay scale guided group (p value=0.001). Furthermore, patients benefiting from the BIS technology presented 11% less asynchrony than those with the Ramsay scale (p value <0.001). More specifically, among BIS technology parameters, electromyography (EMG) appeared the best indicator to predict patient-ventilator asynchrony in both groups. Conclusion. In the second group, the reduction in the emergence time for a sustained spontaneous breathing and the decrease of patient-ventilator asynchronies mandates the use o f BIS technology in critical care to guidee algosedation among non-communicative adults during the acute phase of ventilatory support. EMG from the BIS technology might be able to detect pre-clinical pain expression. This thesis also favors the implementation of a décision algorithm in the control of algosedation in critical care.
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Powelson, Stephen K. (Stephen Kirby). « Design and prototyping of a low-cost portable mechanical ventilator ». Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59954.
Texte intégralRésumé :
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. [10]).
This paper describes the design and prototyping of a low-cost portable mechanical ventilator for use in mass casualty cases and resource-poor environments. The ventilator delivers breaths by compressing a conventional bag-valve mask (BVM) with a pivoting cam arm, eliminating the need for a human operator for the BVM. An initial prototype was built out of acrylic, measuring 11.25 x 6.7 x 8 inches (285 x 170 x 200 mm) and weighing 9 lbs (4.1 kg). It is driven by a stepper motor powered by a 14.8 VDC battery and features an adjustable tidal volume of up to 900 mL, adjustable breaths per minute (bpm) of 5-30, and inhalation to exhalation time ratio (i:e ratio) options of 1:2, 1:3 and 1:4. Tidal volume, breaths per minute and i:e ratio are set via user-friendly knobs, and the settings are displayed on an LCD screen. The prototype also features an assist-control mode and an alarm to indicate over-pressurization of the system. Future iterations of the device will be fully calibrated to medical standards and include all desired ventilator features. Future iterations will be further optimised for low power-consumption and will be designed for manufacture and assembly. With a prototyping cost of only $420, the bulk-manufacturing price for the ventilator is estimated to be less than $100. Through this prototype, the strategy of cam-actuated BVM compression is proven to be a viable option to achieve low-cost, low-power portable ventilator technology that provides essential ventilator features at a fraction of the cost of existing technology. Keywords: Ventilator, Bag Valve Mask (BVM), Low-Cost, Low-Power, Portable and Automatic.
by Stephen K. Powelson.
S.B.
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Chenvidyakarn, Torwong. « The fluid mechanics of pre-cooled natural ventilation ». Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614695.
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Yuta, Toshinori. « Minimal Model of Lung Mechanics for Optimising Ventilator Therapy in Critical Care ». Thesis, University of Canterbury. Mechanical Engineering, 2007. http://hdl.handle.net/10092/1608.
Texte intégralRésumé :
Positive pressure mechanical ventilation (MV) has been utilised in the care of critically ill patients for over 50 years. MV essentially provides for oxygen delivery and carbon dioxide removal by the lungs in patient with respiratory failure or insufficiency from any cause. However, MV can be injurious to the lungs, particularly when high tidal pressures or volumes are used in the management of Acute Respiratory Distress Syndrome (ARDS) or similar acute lung injuries. The hallmark of ARDS is extensive alveolar collapse resulting in hypoxemia and carbon dioxide retention. Application of Positive End Expiratory Pressure (PEEP) is used to prevent derecruitment of alveolar units. Hence, there is a delicate trade-off between applied pressure and volume and benefit of lung recruitment. Current clinical practice lacks a practical method to easily determine the patient specific condition at the bedside without excessive extra tests and intervention. Hence, individual patient treatment is primarily a mixture of "one size- fits-all" protocols and/or the clinician's intuition and experience. A quasi-static, minimal model of lung mechanics is developed based on fundamental lung physiology and mechanics. The model consists of different components that represent a particular mechanism of the lung physiology, and the total lung mechanics are derived by combining them in a physiologically relevant and logical manner. Three system models are developed with varying levels of physiological detail and clinical practicality. The final system model is designed to be directly relevant in current ICU practice using readily available non-invasive data. The model is validated against a physiologically accurate mechanical simulator and clinical data, with both approaches producing clinically significant results. Initial validation using mechanical simulator data showed the model's versatility and ability to capture all physiologically relevant mechanics. Validation using clinical data showed its practicality as a clinical tool, its robustness to noise and/or unmodelled mechanics, and its ability to capture patient specific responses to change in therapy. The model's capability as a predictive clinical tool was assessed with an average prediction error of less than 9% and well within clinical significance. Furthermore, the system model identified parameters that directly indicate and track patient condition, as well as their responsiveness to the treatment, which is a unique and potentially valuable clinical result. Full clinical validation is required, however the model shows significant potential to be fully adopted as a part of standard ventilator treatment in critical care.
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Chiew, Yeong Shiong. « Model-Based Mechanical Ventilation for the Critically Ill ». Thesis, University of Canterbury. Mechanical Engineering, 2013. http://hdl.handle.net/10092/8311.
Texte intégralRésumé :
Mechanical ventilation (MV) is the primary form of therapeutic support for patients with acute respiratory failure (ARF) or acute respiratory distress syndrome (ARDS) until the underlying disease is resolved. However, as patient disease state and response to MV are highly variable, clinicians often rely on experience to set MV. The result is more variable care, as there are currently no standard approaches to MV settings. As a result of the common occurrence of MV and variability in care, MV is one of the most expensive treatments in critical care. Thus, an approach capable of guiding patient-specific MV is required and this approach could potentially save significant cost.
This research focuses on developing models and model-based approaches to analyse and guide patient-specific MV care. Four models and metrics are developed, and each model is tested in experimental or clinical trials developed for the purpose. Each builds the understanding and methods necessary for an overall approach to guide MV in a wide range of patients.
The first model, a minimal recruitment model, captures the recruitment of an injured lung and its response to positive end expiratory pressure (PEEP). However, the model was only previously validated in diagnosed ARDS patients, and was not proven to capture behaviours seen in healthy patients. This deficiency could potentially negate its ability to track disease state, which is crucial in providing rapid diagnosis and patient-specific MV in response to changes in patient condition. Hence, the lack of validation in disease state progression monitoring from ARDS to healthy, or vice-versa, severely limits its application in real-time monitoring and decision support. To address this issue, an experimental ARDS animal model is developed to validate the model across the transition between healthy and diseased states.
The second model, a single compartment linear lung model, models the lung as a conducting airway connected to an elastic compartment. This model is used to estimate the respiratory mechanics (Elastance and Resistance) of an ARDS animal model during disease progression and recruitment manoeuvres. This model is later extended to capture high resolution, patient-specific time-varying respiratory mechanics during each breathing cycle. This extended model is tested in ARDS patients, and was used to titrate patient-specific PEEP using a minimum elastance metric that balances recruitment and the risk of lung overdistension and ventilation-induced injury.
Studies have revealed that promoting patients to breathe spontaneously during MV can improve patient outcomes. Thus, there is significant clinical trend towards using partially assisted ventilation modes, rather than fully supported ventilation modes. In this study, the patient-ventilator interaction of a state of the art partially assisted ventilation mode, known as neurally adjusted ventilatory assist (NAVA), is investigated and compared with pressure support ventilation (PS). The matching of patient-specific inspiratory demand and ventilator supplied tidal volume for these two ventilation modes is assessed using a novel Range90 metric. NAVA consistently showed better matching than PS, indicating that NAVA has better ability to provide patient-specific ventilator tidal volume to match variable patient-specific demand. Hence, this new analysis highlights a critical benefit of partially assisted ventilation and thus the need to extend model-based methods to this patient group.
NAVA ventilation has been shown to improve patient-ventilator interaction compared to conventional PS. However, the patient-specific, optimal NAVA level remains unknown, and the best described method to set NAVA is complicated and clinically impractical. The Range90 metric is thus extended to analyse the matching ability of different NAVA levels, where it is found that response to different NAVA levels is highly patient-specific. Similar to the fully sedated MV case, and thus requiring models and metrics to help titrate care. More importantly, Range90 is shown to provide an alternative metric to help titrate patient-specific optimal NAVA level and this analysis further highlights the need for extended model-based methods to better guide these emerging partially assisted MV modes.
Traditionally, the respiratory mechanics of the spontaneously breathing (SB) patient cannot be estimated without significant additional invasive equipment and tests that interrupt normal care and are clinically intensive to carry out. Thus, respiratory mechanics and model-based methods are rarely used to guide partially assisted MV. Thus, there is significant clinical interest to use respiratory mechanics to guide MV in SB patients. The single compartment model is extended to effectively capture the trajectory of time-varying elastance for SB patients. Results show that without additional invasive equipment, the model was able estimate unique and clinically useful respiratory mechanics in SB patients. Hence, the extended single compartment model can be used as ‘a one model fits all’ means to guide patient-specific MV continuously and consistently, for all types of patient and ventilation modes, without interrupting care.
Overall, the model-based approaches presented in this thesis are capable of capturing physiologically relevant patient-specific parameters, and thus, characterise patient disease state and response to MV. With additional, larger scale clinical trials to test the performance and the impact of model-based methods on clinical outcome, the models can aid clinicians to guide MV decision making in the heterogeneous ICU population. Hence, this thesis develops, extends and validates several fundamental model-based metrics, models and methods to enable standardized patient-specific MV to improve outcome and reduce the variability and cost of care.
32
Kawati, Rafael. « Evaluation of Respiratory Mechanics by Flow Signal Analysis : With Emphasis on Detecting Partial Endotracheal Tube Obstruction During Mechanical Ventilation ». Doctoral thesis, Uppsala University, Anaesthesiology and Intensive Care, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6343.
Texte intégralRésumé :
Evaluating respiratory mechanics during dynamic conditions without interrupting ongoing ventilation and flow, adds to the information obtained from the mechanics derived from static (= no flow) conditions, i.e., the flow signal has the potential to provide information on the properties of the respiratory system (including the tubing system). Hence monitoring the changes in the flow signal during ongoing mechanical ventilation would give information about the dynamic mechanics of the respiratory system. Any change in the mechanics of the respiratory system including the endotracheal tube (ETT) and the ventilatory circuit would affect the shape of the flow signal.
Knowledge of the airway pressure distal to the ETT at the carina level (= tracheal pressure) is required for calculating the extra resistive load exerted by the endotracheal tube in order to compensate for it. In a porcine model, the flow signal was used to non-invasively calculate tracheal pressure. There was good agreement between calculated and measured tracheal pressure with different modes of ventilation. However, calculation of tracheal pressure assumes that the inner diameter of the ETT is known, and this assumption is not met if the inner diameter is narrowed by secretions. Flow that passes a narrowed tube is decelerated and this is most pronounced with the high flow of early expiration, yielding a typical time constant over expiratory volume pattern that is easy to recognize during mechanical ventilation. This pattern reliably detected partial endotracheal obstruction during volume and pressure controlled mechanical ventilation.
A change in compliance of the respiratory system modifies the elastic recoil and this also affects the rate of the expiratory flow and the shape of its signal. In a porcine model, lung volume gains on the flow signal generated by the heartbeats (cardiogenic oscillations) provided information about the compliance of the respiratory system during ongoing mechanical ventilation
In conclusion analyzing the flow signal during ongoing ventilation can be a cheap, non-invasive and reliable tool to monitor the elastic and resistive properties of the respiratory system including the endotracheal tube.
33
Kawati, Rafael. « Evaluation or respiratory mechanics by flow signal analysis : with emphasis on detecting partial endotracheal tube obstruction during mechanical ventilation / ». Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6364.
Texte intégral
34
Herrmann, Jacob. « Frequency-dependent ventilation heterogeneity in the acutely injured lung ». Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6590.
Texte intégralRésumé :
The goal of lung-protective mechanical ventilation is to provide life-sustaining support of gas exchange while minimizing the risk of ventilator-induced lung injury. Multi-frequency oscillatory ventilation (MFOV) was proposed as an alternative lung-protective modality, in which multiple frequencies of pressure and flow oscillations are delivered simultaneously at the airway opening and allowed to distribute throughout the lung in accordance with regional mechanical properties. The distribution of oscillatory flow is frequency-dependent, such that regions overventilated at one frequency may be underventilated at another. Thus the central thesis of this work was that ventilation heterogeneity is frequency-dependent, and therefore ventilation with multiple simultaneous frequencies can be optimized to reduce the risk of ventilator-induced lung injury. Simulations in computational models of distributed oscillatory flow and gas transport demonstrated the sensitivity of regional ventilation heterogeneity to subject size, ventilation frequency, and injury severity. Although the risk of injury in the model associated with strain or strain rate individually was minimized by single-frequency ventilation, the risk of injury associated with mechanical power in lung parenchymal tissue was minimized by MFOV. In an experimental model of acute lung injury, MFOV was associated with reductions in the magnitude and spatial gradient of regional lung strain estimated by four-dimensional CT image registration, as well as increased rates of regional gas transport estimated by wash-in of xenon tracer gas. In conclusion, computational models demonstrated the potential for optimization of MFOV waveforms, and experimental trials demonstrated evidence of improved regional ventilation during MFOV.
35
Kostic, Peter. « New methods for optimization of mechanical ventilation ». Doctoral thesis, Uppsala universitet, Anestesiologi och intensivvård, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-249172.
Texte intégralRésumé :
Mechanical ventilation saves lives, but it is an intervention fraught with the potential for serious complications. Prevention of these complications has become the focus of research and critical care in the last twenty years. This thesis presents the first use, or the application under new conditions, of three technologies that could contribute to optimization of mechanical ventilation. Optoelectronic plethysmography was used in Papers I and II for continuous assessment of changes in chest wall volume, configuration, and motion in the perioperative period. A forced oscillation technique (FOT) was used in Paper III to evaluate a novel positive end-expiratory pressure (PEEP) optimization strategy. Finally, in Paper IV, FOT in conjunction with an optical sensor based on a self-mixing laser interferometer (LIR) was used to study the oscillatory mechanics of the respiratory system and to measure the chest wall displacement. In Paper I, propofol anesthesia decreased end-expiratory chest wall volume (VeeCW) during induction, with a more pronounced effect on the abdominal compartment than on the rib cage. The main novel findings were an increased relative contribution of the rib cage to ventilation after induction of anesthesia, and the fact that the rib cage initiates post-apneic ventilation. In Paper II, a combination of recruitment maneuvers, PEEP, and reduced fraction of inspired oxygen, was found to preserve lung volume during and after anesthesia. Furthermore, the decrease in VeeCW during emergence from anesthesia, associated with activation of the expiratory muscles, suggested that active expiration may contribute to decreased functional residual capacity, during emergence from anesthesia. In the lavage model of lung injury studied in Paper III, a PEEP optimization strategy based on maximizing oscillatory reactance measured by FOT resulted in improved lung mechanics, increased oxygenation, and reduced histopathologic evidence of ventilator-induced lung injury. Paper IV showed that it is possible to apply both FOT and LIR simultaneously in various conditions ranging from awake quiet breathing to general anesthesia with controlled mechanical ventilation. In the case of LIR, an impedance map representing different regions of the chest wall showed reproducible changes during the different stages that suggested a high sensitivity of the LIR-based measurements.
36
SPADARO, SAVINO. « Diaphragmatic dysfunctionin criticallyill patients undergone mechanical ventilation ». Doctoral thesis, Università di Foggia, 2017. http://hdl.handle.net/11369/363289.
Texte intégralRésumé :
INTRODUCTION. Prolonged mechanical ventilation (MV) can cause mus-
cle atrophy and adversely affect diaphragmatic force-generating capacity, a con-
dition referred to as ventilator-induced diaphragmatic dysfunction (VIDD). Dia-
phragmatic ultrasound has been proposed as a bedside daily monitoring of dia-
phragm function; however, to date there are no specific serum biomarkers for
muscular damage and dysfunction. Foster et al. suggested that skeletal troponin
I (sTnI) could be a sensitive marker to detect early signs of muscle injury. OB-
JECTIVES. Firstly, to study the trend of a novel biomarker (sTnI) in mechani-
cally ventilated ICU patients; secondly, to determine whether this trend was as-
sociated with the development of VIDD as assessed with diaphragmatic ultra-
sound.
METHODS. Serial serum samples were obtained from 24 mechanically ven-
tilated ICU patients at 24 (T0), 48 (T1) and 72 (T3) hours after admission. Pa-
tients were not considered for inclusion if they had a history of neuromuscular
disease or a previously documented diaphragm paralysis. Specimens were ana-
lysed and specific isoforms for sTnI (slow (ssTnI) and fast (fsTnI)) were assayed
by commercially available ELISA kits (Human TNNI ELISA kit, Mybiosource).
Simultaneously, in 16 patients diaphragmatic displacement (DD), thickness at
end expiration (T
EE
) and thickening fraction (TF) were measured with ultrasound.
Data are reported as median [IQR]. Values were compared using Friedman's
analysis for repeated measures and Wilcoxon test for paired samples; p < 0.05
was considered statistically significant.
RESULTS. Ventilatory variables did not change over time. The two sTnI
isoforms had a different behaviour over time: ssTnI levels remained unchanged
during the course of MV (p=0.957), while sfTnI significantly decreased over time
(p<0.003), with the lowest level after 72 hours from admission (T0 vs T2, p =
0.004). Both DD (p = 0.004) and TF (< 0.0001) decreased over time, while T
EE remained stable. We found a statistically significant correlation between the per-
cent change from baseline of sfTnI and TF at 72 hours from admission (r = 0.661,
p = 0.007).
CONCLUSIONS. Our results seem to demonstrate that both sTnI and ultra-
sound describe adequately the decrease in diaphragmatic function over time in
mechanically ventilated ICU patients. Moreover, fsTnI seems to be better corre-
lated with echographical signs of diaphragmatic dysfunction.
37
Tomasi, Roberta. « Energy performance, comfort and ventilation effectiveness of radiant systems coupled with mechanical ventilation ». Doctoral thesis, Università degli studi di Padova, 2012. http://hdl.handle.net/11577/3422467.
Texte intégralRésumé :
This work presents the results of different numerical and experimental studies about energy performance, thermal comfort and ventilation effectiveness of radiant systems combined with different types of mechanical ventilation. Experimental studies have been carried out in Italy, in a test room in the laboratories of the company RHOSS S.p.A in Codroipo (Udine) and in Denmark, in a test room in the laboratories of the International Centre for Indoor Environment and Energy (ICIEE), at DTU (Danish Technical University), in Lyngby.
Radiant systems in residential and in office buildings are increasingly used because of the low heating or cooling demand and, at the same time, for the good thermal comfort they assure.
The thermal output estimation of radiant system in steady state condition needs the determination of the convective heat transfer coefficient from the surface to the room; a critical review among the correlations available in literature have been carried out and correlations for heated ceiling and cooled floor have been presented. Furthermore the variation of convective heat transfer coefficients, depending on the considered ventilation systems, has been estimated by means of the Computational Fluid Dynamics (CFD) technique.
The energy performance and thermal behavior of radiant systems during transient conditions have been predicted by using experimental tests and numerical calculations with the software Digithon that was developed by the University of Padua. In this work the validation of this software by comparison with experimental data has been presented.
In new and renovated buildings the high tightness and high insulation determine a potential risk of poor indoor air quality and condensation at the surfaces; for this reason an efficient ventilation system is necessary to provide for fresh air in the rooms. In a low polluted building air quality depends on human bioeffluents, among which carbon dioxide is considered the most significant one. By using numerical simulations (CFD) the effects of the supply and extract air terminals on contaminants distribution in offices equipped with a cooled ceiling has been investigated. Besides, in order to fully characterize the indoor climate of residential rooms or offices, an extensive experimental study has been carried out in a test room to determine both thermal comfort and ventilation effectiveness for different solutions of mixing ventilation and displacement ventilation combined with floor radiant systems. In particular, the effects of supply and extract air terminals positions by using low air change rates in mixing ventilation and the effects of different ventilation rates with displacement ventilations terminals have been analyzed. Results from experiments have been used for the validation of a CFD model for the prediction of air distribution in rooms equipped with mixed or displacement ventilation, combined with heating/cooling floor systems.In questo lavoro di dottorato vengono presentati i risultati di uno studio sui sistemi radianti per il raffrescamento ed il riscaldamento in ambito civile e sulla loro integrazione con opportuni sistemi di ventilazione meccanica. Le prestazioni energetiche in regime stazionario e transitorio, così come le prestazioni di comfort termico e di qualità dell’aria garantita, sono state studiate mediante l’ausilio di prove sperimentali, di simulazioni fluidodinamiche e di altri codici di calcolo. Gli studi sperimentali sono stati realizzati in parte in Italia, presso i laboratori dell’azienda RHOSS S.p.A di Codroipo (Udine), e in parte presso i laboratori dell’ICIEE (International Centre for Indoor Environment and Energy), dell’Università Tecnica di Danimarca, (DTU) a Lyngby (DK). L’aspetto più rilevante di questo lavoro è legato alla sempre maggiore diffusione dei sistemi radianti come soluzione per il riscaldamento ed il raffrescamento di ambienti interni, in quanto combinano vantaggi energetici ad elevati livelli di comfort termico. Per ragioni dovute alla piccola differenza di temperatura tra l’ambiente e il fluido termovettore, i sistemi radianti si interfacciano molto bene con caldaie a condensazione, pompe di calore, sistemi free cooling, collettori solari e altre sorgenti rinnovabili e soluzioni ad alta efficienza energetica. Il calcolo della resa termica di tali sistemi viene eseguito mediante le equazioni valide per la convezione in regime stazionario, come quelle fornite dalle norme Europee EN 1264 ed EN 15377. In letteratura esistono numerose correlazioni valide per il calcolo della potenza convettiva di superfici orizzontali e verticali e di superfici interne di stanze reali; le norme EN 1264 ed EN 15377 consigliano correlazioni diverse e lo stesso accade per codici si simulazione energetica degli edifici. Ad oggi non è disponibile una chiara definizione di coefficiente di scambio termico convettivo per i sistemi radianti, specialmente per quanto riguarda pavimenti freddi e soffitti caldi. Il primo obiettivo di questa tesi è stato di realizzare un’analisi critica delle correlazioni disponibili in letteratura adatte ai sistemi radianti e di proporre delle equazioni per ogni configurazione di riscaldamento o raffrescamento da soffitto, pavimento o parete. In ambito residenziale il pavimento radiante rappresenta una delle soluzioni più richieste grazie all’elevato livello di comfort termico garantito; tuttavia, al fine di migliorare la qualità dell’aria e specialmente a causa della necessità di deumidificare l’aria in estate per evitare formazione di condensa, accanto al sistema radiante andrebbe installato un sistema di ventilazione meccanica. L’aria primaria in estate è solitamente a temperatura più bassa della temperatura della stanza e dotata di una certa velocità; nel caso di immissione da bocchette installate vicino ad una superficie radiante, lo scambio convettivo potrebbe venire variato rispetto ad una soluzione senza ventilazione. Mediante uno studio con simulazioni fluidodinamiche CFD è stato possibile valutare l’incremento dello scambio convettivo da un soffitto freddo mediante lo sfruttamento di aria primaria. I sistemi radianti, in particolare i sistemi a soffitto, rappresentano un’ottima soluzione per rimuovere i carichi termici degli uffici durante il periodo estivo, ma allo stesso tempo possono essere usati per il riscaldamento invernale degli stessi con buone prestazioni energetiche e di comfort termico. La differenza sostanziale è che durante la stagione invernale il sistema radiante si trova a lavorare prevalentemente in regime stazionario, mentre durante la stagione estiva i carichi esterni dovuti alla radiazione solare e all’escursione diurna, accompagnati da carichi interni dovuti all’occupazione umana, determinano condizioni piuttosto variabili durante la giornata. Il comportamento di sistemi radianti a regimi stazionari e transitori sono state studiate mediante prove in camera climatica; inoltre un modello di calcolo chiamato Digithon, sviluppato all’interno del Dipartimento di Fisica Tecnica dell’Università di Padova, è stato validato mediante un confronto con dati sperimentali. Seguendo un’opportuna procedura, riportata nella tesi, è stato possibile impostare dei profili di carico che simulano una tipica giornata estiva o invernale su una parete della stanza ed è stato studiato come il soffitto radiante reagisca per cercare di mantenere una certa temperatura di comfort nella stanza. Al fine di mantenere una buona qualità dell’aria, evitare la formazione di condensa, ma anche per incrementare la capacità di raffrescamento quando richiesto, i sistemi radianti per gli uffici andrebbero sempre associati a sistemi di ventilazione meccanica. Accanto ai tradizionali sistemi a soffitto con ventilazione a miscelazione, le soluzioni con ventilazione a dislocamento accoppiate a sistemi a pavimento o a soffitto sono alternative di crescente interesse per gli uffici. In edifici dove sia bassa la quantità di inquinanti emessi dai materiali edili, dai mobili e dalle attrezzature, la quantità di bioeffluenti dagli occupanti, dei quali l’anidride carbonica CO2 è normalmente usata come principale indicatore, è determinante per la qualità dell’aria interna. La capacità di rimozione dei contaminanti e, parallelamente, la capacità di immettere aria pulita negli ambienti sono espresse dall’efficienza di ventilazione (ventilation effectiveness). Mediante simulazione fluidodinamiche CFD è stato possibile confrontare l’efficienza di rimozione dei contaminanti utilizzando diverse soluzioni di ventilazione a dislocamento piuttosto che soluzioni tradizionali a miscelazione. La qualità di un ambiente interno andrebbe misurata in termini sia di comfort termico garantito all’occupante che di qualità dell’aria. Attraverso prove sperimentali in laboratorio, i principali indici di comfort termico e di efficienza di ventilazione sono stati determinati per diverse configurazioni di ventilazione a miscelazione e di ventilazione a dislocamento in ambienti rappresentativi di applicazioni residenziali o del terziario. I risultati sono stati in seguito utilizzati per effettuare una validazione di un modello fluidodinamico (CFD) creato per la previsione del movimento dell’aria in ambienti residenziali o uffici.
38
Pastore, C. V. « VENTILAZIONE MECCANICA E VOLUTRAUMA : STUDIO IN VIVO IN UN MODELLO SUINO ». Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150177.
Texte intégralRésumé :
Mechanical ventilation is an essential support for patients with acute lung pathologies, such as acute respiratory distress syndrome and acute lung injury, and it is generally applied in chirurgical practice. Specialists are however aware that, despite of its “life saving” role, this practice presents several negative side effects. Recently one of the most serious negative effects of mechanical ventilation, called Ventilatory Induced Lung Injury (VILI), has been detected and better analysed. This syndrome, initially associated with barotrauma, has been recently defined as volutrauma, meaning a damage of lung parenchyma caused by mechanical stress deriving from overdistension induced by high tidal volumes (VT).
The aim of the present study was to evaluate the onset of ventilatory induced lung injury in a clinically relevant, validated and well-studied model, which closely mimics the human physiology and the ventilator setting currently used in the clinical arena. The study was performed using 18 pigs were involved, divided into three groups (n=6): two groups were mechanically ventilated (VT 20 ml/kg and 8 ml/kg), and one group was spontaneously breathing (SB). The duration of the experiments was 240 minutes. Hemogasanalysis and all main respiratory and circulatory parameters were detected every 30 minutes. Metalloproteinases 2 and 9 expression and activation and ET-1 levels were observed in the bronchoalveolar lavage fluid. At the end of the experiment, the animals were sacrificed and autoptic samples of lung, kidney and liver for histological and zymographic analysis were obtained. The results showed serious alterations of lung mechanics and structure induced by high VT, although the protective strategies as low VT were not immune from negative side effects. Respiratory function worsening was observed in spontaneously breathing subjects, too. Therefore, our study demonstrates that, both animals undergoing mechanical ventilation with high volumes and non-assisted breathing animals develop a massive lung edema, as revealed by extra-vascular lung water values. As expected, the alveolar over-distension induced ultrastructural cellular abnormalities only in animals subjected to high VT and not in those where lung distension was limited, as in our VT8 group, or absent, as in SB group.
Our data show irrefutably that the severe edema formation noticed in spontaneously breathing animals was clearly related to the increase in pulmonary arterial pressure, which induced the extravasation of fluid into lung parenchyma.
Moreover, we have evaluated the changes in lung mechanics and metalloproteinases production and activation in three different types of lung damages evoked by mechanical, hypoxic and septic stress. Under that, 24 pigs were studied, randomly divided into four groups (n=6): control group (pigs spontaneously breathing), mechanical stress group (pigs ventilated with high VT), hypoxic group (pigs inhaled with an hypoxic gas mixture), septic group (pigs i.v. infused with E.coli LPS). All the animals were studied for 240 minutes. Hemogasanalysis and main respiratory and circulatory parameters were detected every 20 minutes. At the end of the experiment, subjects were sacrificed and autoptic samples of lung for histological and zymographic analysis were obtained. The changes in physiological parameters were in line with morphological lung alterations. Zymographic analysis showed a strong activation of MMP-2 but no activation of MMP-9 in control, mechanical and hypoxic stress groups. The septic stress group has reflected a specular situation with activation of MMP-9 and low levels of MMP-2, which was present only in the inactivated form. The present study has underlined an acute modulation of MMPs in lung tissues and MMPs different behaviour facing different stimulations.
In conclusion, it is clear that mechanical ventilation strategies profoundly affects lung parenchyma integrity and functionality, and the choice of a ventilation strategy that avoids these damages, ensuring at the same time an appropriate exchange of gases, is strongly encouraged.
39
Liu, Hui. « The application of alveolar microscope on alveolar mechanics of ventilator-induced lung injury ». [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:25-opus-61847.
Texte intégral
40
Coisel, Yannaël. « Ventilation mécanique en anesthésie réanimation : évaluation des nouveaux modes ventilatoires en médecine péri-opératoire ». Thesis, Montpellier 1, 2014. http://www.theses.fr/2014MON1T011/document.
Texte intégralRésumé :
Chez un patient, les muscles respiratoires sont mis au repos lors de la défaillance de la fonction respiratoire, que cette défaillance soit involontaire (maladie, accident…) ou volontaire (anesthésie générale). Le patient est alors relié à un ventilateur artificiel, machine qui se charge de le faire respirer. Il existe de très nombreux types de ventilateurs artificiels, de qualité inégale, et chaque dispositif propose de multiples réglages pour ventiler le patient : les modes ventilatoires. Ces machines et leurs modes ventilatoires sont commercialisés et utilisés quotidiennement, mais très peu ont été évalués en situation clinique et leurs performances restent à démontrer. L'interaction de ces modes ventilatoires avec les muscles respiratoires du patient est ainsi actuellement méconnue. Dans ce travail, premièrement nous avons fait un état des lieux des pratiques de la ventilation mécanique en médecine péri-opératoire (patients au bloc opératoire et réanimation) ; secondairement, nous avons évalué sur banc d'essai au laboratoire les performances techniques des ventilateurs d'anesthésie et de réanimation de dernière génération dans des conditions statiques (ventilation contrôlée dans différentes conditions de pathologies pulmonaires) et dans des conditions dynamiques (ventilation spontanée assistée dans différentes situations de sevrage ventilatoire) et établi des critères de choix d'un ventilateur ; dans une troisième partie nous avons analysé chez le patient de réanimation au cours du sevrage de la ventilation mécanique le fonctionnement et le comportement des modes ventilatoires les plus évolués (Neurally Adjusted Ventilatory Assist (NAVA), Proportionnal Adaptive Ventilation + (PAV+), Adaptative Support Ventilation (ASV), Intellivent, Noisy-PSV) en comparaison avec le mode de référence qu'est la Ventilation Spontanée en Aide Inspiratoire (Pressure Support Ventilation). Finalement, nous présentons les perspectives de recherche et bénéfices potentiels attendus issus de ces études à travers nos projets de travaux expérimentaux et cliniquesIn case of respiratory failure, the patient's respiratory muscles are put at rest. The patient is then linked to an artificial ventilator, which makes him breath. There are a huge number of artificial ventilators, of varying quality, and each device offers many different settings : the ventilatory modes. These devices and their ventilatory modes are marketed and used daily, but few of them have ever been evaluated in a clinical situation and their performances still need to be proven. Interactions between these ventilatory modes and respiratory muscles are presently unknown. In this work, we first made an inventory of mechanical ventilation in peri-operative medicine (patients in operating rooms and in intensive care units). Then, we evaluated on a bench test the technical performances of the latest generation of anesthesia and intensive care ventilators, in static conditions (controlled ventilation in different pathologic pulmonary conditions) and in dynamic conditions (assisted spontaneous breathing in different weaning situations), and we established criteria to check before choosing a ventilator. Third, we analysed the behaviour of several advanced ventilatory modes (Neurally Adjusted Ventilatory Assist (NAVA), Proportional Assist Ventilation Plus (PAV+), Adaptive Support Ventilation (ASV), Intellivent, Noisy-PSV) during ventilator weaning of intensive care patients compared to the reference weaning mode : Pressure Support Ventilation. Finally, we present research perspectives and potential benefits from our studies through our experimental and clinical project
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Kilander, Johanna, et Madeleine Frisell. « Variable expiration control for an intensive care ventilator ». Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157761.
Texte intégralRésumé :
Critical care patients are often connected to ventilators, to support or replace their breathing. The ventilators deliver a mixture of gas to the patient by applying a specific volume or pressure, and then the patient exhales passively. This thesis is based of the hypothesis that a slower reduction of the expiration pressure could benefit intensive care patients connected to a ventilator. To enable research within the area, a device which can control the expiration is needed. In this thesis project, an expiration valve was controlled to create different pressure patterns during expiration. To facilitate the research and the usage of the expiration control, an application software was created with the purpose to simulate relevant pressure, flow and volume curves. The prototype is an expiration cassette created for the ventilator Servo-i by Maquet Getinge Group. To enable flexibility, the prototype is external and no information is transmitted from or to the ventilator. The prototype has its own flow and pressure sensors. The different pressure patterns which the prototype uses are designed as a linear decrease and as if a constant resistance was added to the system. The user can also create their own pressure pattern, by deciding 20 pressure points in the duration of two seconds. The simulation application was designed with the ability to simulate the same pressure patterns available with the prototype. By using a lung model, it is possible to simulate the ideal pressure, flow and volume in the lungs which can be expected from the chosen expiration control. During the implementation, two different types of lung models were evaluated in order to determine the specificity required. The prototype was tested with settings which were chosen to challenge the performance of the control. Some problematic areas were detected, such as high pressures or large volumes. However, the prototype was judged to perform well enough to be used in animal trials. The lung model used for the simulation application was a simple model of the lung, consisting of a resistor and a capacitor in series. The simulations were compared with the real system with the purpose to get an indication on the difference between theory and reality. The application presents the expected behavior when using the expiration control. However, it should be kept in mind by the user that the application represents a theoretical model.
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Kolandaivelu, Kumaran. « Development of a miniature high frequency ventilator for genetically engineered newborn mice ». Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/60745.
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Vimláti, László. « Benefits of Spontaneous Breathing : Compared with Mechanical Ventilation ». Doctoral thesis, Uppsala universitet, Anestesiologi och intensivvård, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182564.
Texte intégralRésumé :
When spontaneous breathing (SB) is allowed during mechanical ventilation (MV), atelectatic lung areas are recruited and oxygenation improves thereby. Whether unsupported SB at its natural pattern (without PEEP and at low pressure/small tidal volume) equally recruits and improves oxygenation, and if so by which mechanism, has not been studied. A porcine lung collapse model was designed to study this question. The cardiac output dependency of the pulmonary shunt was investigated with healthy lungs and with major shunt (during one-lung ventilation) and with SB, MV and continuous positive airway pressure (CPAP). The hypoxic pulmonary vasoconstriction (HPV) was blocked with sodium nitroprusside (SNP) to see whether HPV is the only mechanism available for ventilation/perfusion (VA/Q) matching during MV and SB. In all experiments, respiratory rate and tidal volume during MV were matched to SB. Oxygenation was assessed by serial blood gas measurements, recruitment by thoracic CTs; pulmonary shunt was assessed by multiple inert gas elimination or venous admixture. SB attained better oxygenation and lower pulmonary shunt compared with MV, although it did not recruit collapsed lung. Pulmonary shunt did not correlate with cardiac output during SB, whereas a correlation was found during MV and CPAP. With blocked HPV, pulmonary shunt was considerably lower during SB than MV. In conclusion, SB improves VA/Q matching as compared with MV, even when no recruitment occurs. In contrast to MV and CPAP, cardiac output has no major effect on pulmonary shunt during SB. The improved VA/Q matching during SB despite a blocked HPV might indicate the presence of a SB-specific mechanism that improves pulmonary blood flow redistribution towards ventilated lung regions independent of or supplementary to HPV.
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Mishra, Ankit Nidhishchandra. « Mechanical Ventilation and Optimisation through Analytical Lung Model ». Thesis, University of Canterbury. Mechanical Engineering, 2012. http://hdl.handle.net/10092/7005.
Texte intégralRésumé :
Mechanical Ventilation (MV) therapy is one of the most common treatments offered to
patients with respiratory failure in ICU. MV assists patient recovery by completely or
partially taking over the breathing process and helping with oxygen delivery and removal
of carbon dioxide. However, inappropriate MV settings mismatched to a given patient’s
condition can cause further damage. On the other hand, suboptimal MV settings can
increase the length of stay of the patient in ICU and increase the cost of treatment.
Acute Respiratory Distress Syndrome (ARDS) is a major form of Acute Lung Injury (ALI)
where clinicians offer a supportive environment for patient recovery by application of MV.
ARDS is characterised by inflamed and fluid filled lungs that result in alveolar collapse
and thus severe hypoxemia. Application of positive end expiratory pressure (PEEP) is
employed to recruit and retain lung units to maximise gas exchange. However, a delicate
trade-off is required between maximising gas exchange and preventing further unintended
damage to the lungs, when determining optimum PEEP level.
Currently, no specific protocols to determine optimum PEEP level exist and selection of
PEEP is dependent on medical intuition and experience, primarily due to lack of easy
methods to determine patient – specific condition at the patient’s bedside. A mathematical
recruitment model is developed in Labview to help determine patient – specific condition
based on fundamental lung physiology and engineering principals in this thesis. The model
utilises readily available clinical data to determine parameters that identify underlying
patient – specific lung characteristics and conditions. Changes in these parameters can be
monitored over time and compared between patients to determine the severity of the
disease and evolution of disease with time.
A second model is developed to determine dynamic functional residual capacity (dFRC),
that represents the extra volume retained in a lung through application of PEEP. The model
extends previous efforts in the field that applied the stress – strain theory to lung
mechanics to estimate dFRC. This model estimates the patient’s dFRC using readily
available clinical data (PV data) and can be monitored over time to determine changes in a
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given patient’s condition. The dFRC model introduces a new parameter, , which is
considered a population constant for the particular PEEP. The model offers an easy and
reliable method to determine dFRC since other methods are normally invasive or require
interruption of MV.
The models developed were validated against real – time clinical data obtained through
clinical trials. The recruitment model was found to fit the clinical data well with error
values within acceptable limits. It also enabled identification of parameters that reflect the
underlying patient – specific lung condition. The dFRC model was able to estimate the
dFRC for a patient with high level of accuracy for clinically applicable PEEP levels. The
two models work well in conjunction with each other and provide a novel and easy method
to clinicians to determine patient – specific lung characteristics and ultimately determine
optimal MV treatment parameters, especially PEEP.
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Sands, Kirsty M. « Dynamics of oral biofilms associated with mechanical ventilation ». Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/97010/.
Texte intégralRésumé :
Critically ill patients often require mechanical ventilation (MV) to facilitate treatment for respiratory failure or airway protection when consciousness is impaired. Whilst the endotracheal tube (ETT) is an essential interface between the patient and ventilator, it may promote VAP by impeding host defence mechanisms and by translocating microorganisms from dental plaque to the lower airways. Ventilator-associated pneumonia (VAP), which may be challenging to diagnose, is the most frequent hospital-acquired infection in critical care. It has been reported that when patients receive MV the composition of dental plaque changes to include respiratory pathogens such as Meticillin-Resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. The primary aim of this research was to confirm that dental plaque communities altered during MV and to identify the potential causes of these changes. A combination of culture-based microbiology, community profiling molecular techniques and proteomic analysis of saliva was performed to analyse the microbiological content of the oral cavity, and to also quantify changes in dental plaque composition and saliva. For the first time, this study comprehensively analysed the dental plaque of mechanically ventilated patients and documented considerable species richness and diversity. Numerous potential respiratory pathogens were detected including Staphylococcus aureus, P. aeruginosa and Streptococcus pneumoniae in approximately one-third of mechanically ventilated patients. In addition, salivary flow rate was decreased and both the salivary pH and concentration of pro-inflammatory cytokines were significantly elevated during intubation. Dental plaque is a reservoir for VAP, and preventing or reducing respiratory colonisation may play a role in the management of ventilated patients. Interventions to prevent colonisation could include the modulation of salivary parameters such as pH and volume and further work may lead to the identification of specific proteins that are significant. Reducing the incidence of VAP will not only reduce mortality in the ICU, but will also have a great impact on hospital economics by reducing inpatient stay.
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Frazier, Susan K. « Right Heart Hemodynamics During Weaning From Mechanical Ventilation / ». The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487933648650383.
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Rolle, Trenicka. « Lung Alveolar and Tissue Analysis Under Mechanical Ventilation ». VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3398.
Texte intégralRésumé :
Mechanical ventilation has been a major therapy used by physicians in support of surgery as well as for treating patients with reduced lung function. Despite its many positive outcomes and ability to maintain life, in many cases, it has also led to increased injury of the lungs, further exacerbating the diseased state. Numerous studies have investigated the effects of long term ventilation with respect to lungs, however, the connection between the global deformation of the whole organ and the strains reaching the alveolar walls remains unclear. The walls of lung alveoli also called the alveolar septum are characterized as a multilayer heterogeneous biological tissue. In cases where damage to this parenchymal structure insist, alveolar overdistension occurs. Therefore, damage is most profound at the alveolar level and the deformation as a result of such mechanical forces must be investigated thoroughly. This study investigates a three-dimensional lung alveolar model from generations 22 (alveolar ducts) through 24 (alveoli sacs) in order to estimate the strain/stress levels under mechanical ventilation conditions. Additionally, a multilayer alveolar tissue model was generated to investigate localized damage at the alveolar wall. Using ANSYS, a commercial finite element software package, a fluid-structure interaction analysis (FSI) was performed on both models. Various cases were simulated that included a normal healthy lung, normal lung with structural changes to model disease and normal lung with mechanical property changes to model aging. In the alveolar tissue analysis, strains obtained from the aged lung alveolar analysis were applied as a boundary condition and used to obtain the mechanical forces exerted as a result. This work seeks to give both a qualitative and quantitative description of the stress/strain fields exerted at the alveolar region of the lungs. Regions of stress/strain concentration will be identified in order to gain perspective on where excess damage may occur. Such damage can lead to overdistension and possible collapse of a single alveolus. Furthermore, such regions of intensified stress/strain are translated to the cellular level and offset a signaling cascade. Hence, this work will provide distributions of mechanical forces across alveolar and tissue models as well as significant quantifications of damaging stresses and strains.
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Amorim, Raquel Margarida da Cruz. « O Desmame Precoce da Pessoa submetida a Ventilação Mecânica Invasiva : O Impacto das Intervenções de Enfermagem de Reabilitação ». Master's thesis, Instituto Politécnico de Setúbal. Escola Superior de Saúde, 2019. http://hdl.handle.net/10400.26/29374.
Texte intégralRésumé :
Mestrado em Enfermagem, Área de especialização: Enfermagem de ReabilitaçãoA Ventilação Mecânica Invasiva é reconhecida como processo terapêutico adjuvante à pessoa acometida de insuficiência respiratória. Em correlação com os seus benefícios, existe a probabilidade de ocorrência de complicações a nível respiratório e motor. Neste contexto, é realçada a importância de realizar um desmame ventilatório precoce. A eficácia e eficiência do desmame ventilatório, requerem do Enfermeiro Especialista em Enfermagem de Reabilitação as competências para elaborar, desenvolver e implementar um plano de intervenção individual, baseado numa avaliação criteriosa do doente. Este relatório surge no decurso da análise ao processo de aquisição e sedimentação de competências comuns do Enfermeiro Especialista, específicas em Enfermagem de Reabilitação, bem como a obtenção de competências de mestre. Este processo foi realizado através das várias fases do plano de intervenção aplicado ao doente submetido a Ventilação Mecânica Invasiva, com o objetivo de desenvolver competências científicas, técnicas e humanas especializadas, ao longo do processo de desmame ventilatório.
Mechanical Invasive Ventilation is recognized as an adjuvant therapeutic process for the person suffering from respiratory failure. In correlation with its benefits, there is a probability of respiratory and motor complications. In this context, the importance of early weaning is emphasized. The efficacy and efficiency of ventilatory weaning require the Nurse Specialist in Rehabilitation Nursing the skills to design, develop and implement an individual intervention plan, based on a careful evaluation of the patient. This report arises during the analysis of the process of acquisition and solidification of common competences of the Specialist Nurse, specific in Rehabilitation Nursing, as well as the acquisition of master's competences. This process was carried out through the various phases of the intervention plan applied to the patient submitted to Mechanical Invasive Ventilation, with the objective of developing specialized scientific, technical and human skills throughout the ventilatory weaning process.
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Craven, Thomas Henry John. « Resolving uncertainty in acute respiratory illness using optical molecular imaging ». Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/29507.
Texte intégralRésumé :
Ventilator associated pneumonia (VAP) and acute respiratory distress syndrome (ARDS) are two respiratory conditions unique to mechanically ventilated patients. The diagnosis of these conditions, and therefore any subsequent treatment, are befuddled by uncertainty. VAP rates vary considerably according to the diagnostic or surveillance criteria used. The pathogenesis of ARDS is well understood but when the internationally agreed consensus criteria are employed, the histological hallmarks are absent about half the time, indicating a disconnection between the clinical diagnosis and what is known about the biology of this condition. It is argued that tests of biological function should be considered in addition to clinical characteristics in order to improve the utility of diagnosis. Given that the pathological sequelae of both VAP and ARDS are driven by an over exuberant host neutrophil response, the activated neutrophil was selected as a potential biological imaging target. Optical molecular imaging uses visible and near visible wavelengths from the electromagnetic spectrum to derive or visualize information based on the optical properties of the target tissue. Optical wavelengths are safe and cheap to work with, producing much higher resolution images than those relying on x-rays or gamma radiation. The imaging modality can be coupled with exogenously applied chemistry to identify specific biological targets or processes. The hypothesis that optical molecular imaging could be used to detect activated neutrophils in real time in the alveolar region of patients was tested. A bespoke optical molecular imaging agent called Neutrophil Activation Probe (NAP), designed in-house, was used to test the hypothesis. NAP is a dendrimeric compound delivered to the alveolar region of a patient in microdoses (≤100 micrograms), becoming fluorescent only on contact with activated neutrophils, and can be detected by optical endomicroscopy. Both the imaging agent and the endomicroscope are delivered to the distal lung via routine bronchoscopy. The agent was tested extensively in the laboratory to demonstrate function, specificity, and safety. Ex vivo testing took place using human and ovine lungs. A regulated dose escalation Phase I clinical trial of investigational medicinal product (CTIMP) in healthy volunteers, patients with bronchiectasis, and mechanically ventilated patients with a pulmonary infiltrate on chest radiography (NCT01532024) was designed and conducted. The aim of the Phase I study was to demonstrate the safety of the technique and to confirm proof of concept. In order to support the requirement for a technique that interrogates alveolar neutrophils two supplementary clinical studies were performed. Firstly, two VAP surveillance techniques (CDC surveillance and HELICS European VAP surveillance) were compared with clinically diagnosed VAP across consecutive admissions in two large tertiary centres for one year. Secondly, the utility of circulating neutrophils to permit discrimination between acute respiratory illnesses was examined. Blood samples from mechanically ventilated patients with and without ARDS underwent flow cytometric assessment using eight clusters of differentiation and internal markers of activation to determine neutrophil phenotype. All clinical studies received the appropriate regulatory, ethical, and/or Caldicott guardian approval prior to commencement. NAP became fluorescent only in the presence of three processes specific to neutrophil activation: active pinocytosis, progressive alkalinization of the phagolysosome, and the activity of human neutrophil elastase. High optical signal was detected following the application of NAP in the alveolar regions of explanted lungs from patients with cystic fibrosis, known to be rich in activated neutrophils. Using an ex vivo ovine lung ventilation and perfusion model optical signal was demonstrated following segmental lung injury. The safety and specificity of the technique in a small cohort of healthy volunteers and mechanically ventilated patients was demonstrated. The technique was tested on a small cohort of patients with bronchiectasis, which provided the first opportunity to obtain broncho-alveolar lavage samples for laboratory correlation. Fluorescent signal was shown in the lavaged neutrophils, labeling that could only have taken place in the alveolar region. The supportive clinical studies found the concordance between actual VAP events was virtually zero even though the reported VAP rates were similar. Furthermore, the rate at which clinicians initiate antibiotics for VAP was approximately five times higher than either surveillance VAP rate. The study of circulating neutrophils from the blood of healthy volunteers and mechanically ventilated patients with and without ARDS indicated circulating neutrophil activation phenotype was not capable of discriminating between clinically diagnosed ARDS and other acute respiratory illnesses. In summary, an ambitious programme of work was completed to develop and support an optical molecular imaging technique that meets the rigorous requirements for human application and can be applied at the bedside to yield immediate visual results. The spatiotemporal relationship of neutrophil activation in real time both in the laboratory and in volunteers and patients was visualized. The visualization of neutrophil activation at such a resolution has never been achieved before in humans, healthy or unhealthy. The Phase I study was not powered to determine utility but recruitment has begun to a Phase II CTIMP (NCT02804854) to investigate the utility, accuracy, and precision of the imaging technique in a large cohort of mechanically ventilated patients. Ultimately, it is proposed that the technique will facilitate diagnosis, stratify patients for treatment and monitor treatment response using this technique.
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Zhang, Lei, et 张磊. « Dispersion of coughed droplets in crowded indoor environment ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47049935.
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