Au Canada, on estime que 30 000 chirurgies cardiaques sont effectuées chaque année (1). L'insuffisance ventriculaire droite demeure une complication courante chez les patients subissant une chirurgie cardiaque. L'incidence de l’insuffisance ventriculaire droite périopératoire aiguë sévère peut aller de 0,1 % après une cardiotomie à 20 à 30 % après l'implantation d'un dispositif d'assistance ventriculaire gauche (2). La survenue d'une défaillance ventriculaire droite est encore plus fréquente en présence d'hypertension pulmonaire. Les conséquences de l'insuffisance ventriculaire droite en chirurgie cardiaque comprennent une détérioration périopératoire et des effets indésirables tels qu'un sevrage difficile de la circulation extracorporelle, une utilisation accrue d'agents vasoactifs intraveineux, et un risque accru de mortalité. Par conséquent, le diagnostic et le traitement de l’hypertension pulmonaire et de la dysfonction ventriculaire droite sont essentiels dans la période périopératoire pour éviter les complications. La surveillance simultanée et en continue des courbes de pression de l’artère pulmonaire et du ventricule droit à l'aide du cathétérisme de l'artère pulmonaire est un outil de surveillance important chez les patients en chirurgie cardiaque pour la détection précoce d'un dysfonctionnement du ventricule droit et pour évaluer la réponse au traitement. Les stratégies thérapeutiques dans ce contexte devraient se concentrer sur la réduction de la postcharge du ventricule droit et l'amélioration de la fonction du ventricule droit tout en évitant l'hypotension systémique. Les hypothèses de cette thèse sont les suivantes : 1) les vasodilatateurs inhalés sont supérieurs aux agents administrés par voie intraveineuse pour le traitement et la gestion de l’hypertension pulmonaire en chirurgie cardiaque, 2) la combinaison d'époprosténol inhalé et de la milrinone inhalée (iE&iM) est une stratégie efficace pour faciliter le sevrage de la circulation extracorporelle et pour réduire les besoins en inotropes intraveineux, 3) tous les patients n'ont pas une réponse vasodilatatrice positive à la combinaison de l’iE&iM, 4) la réponse à l’iE&iM est associée à des changements des courbes de pression du ventricule droit et de l’artère pulmonaire, et 5) le gradient de la chambre de chasse du ventricule droit et la vitesse d’augmentation de la pression intraventriculaire droite (dP/dt) ont le potentiel d'être des marqueurs pharmacodynamiques de la réponse au traitement. Le travail compris dans cette thèse consiste en 3 études. La première est une revue systématique et méta-analyse d'essais contrôlés randomisés démontrant que l'administration de vasodilatateurs inhalés pour le traitement de l’hypertension pulmonaire pendant la chirurgie cardiaque est associée à une amélioration de la performance du ventricule droit comparé aux agents administrés par voie intraveineuse. La deuxième étude est une analyse de cohorte rétrospective de 128 patients recevant l’iE&iM avant la circulation extracorporelle. Cette étude a démontré une réponse vasodilatatrice au traitement par l’iE&iM chez 77% des patients. Une réponse favorable était associée à un sevrage facile de la circulation extracorporelle plus fréquent et à une utilisation plus faible d'inotropes intraveineux. De plus, cette étude a également démontré qu'une hypertension pulmonaire plus sévère est prédictive d'une réponse vasodilatatrice pulmonaire positive, tandis qu'un European System for Cardiac Operative Risk Evaluation score (EuroSCORE) II élevé est un prédicteur de non-réponse au traitement. La dernière étude de cette thèse est une étude de cohorte prospective incluant 26 patients recevant iE&iM avec surveillance continue de la courbe de pression du ventricule droit démontrant l'innocuité et l'efficacité de cette approche thérapeutique dans l'amélioration de la fonction ventriculaire droite. / In Canada there is an estimated 30,000 cardiac surgeries that are performed each year (1). Right ventricular failure (RVF) remains a common complication in patients undergoing cardiac surgery. The incidence of severe acute perioperative RVF can range from 0.1% after cardiotomy to 20-30% after left ventricular assist device implantation (2). The occurrence of RVF is even more frequent in the presence of pulmonary hypertension (PH). Consequences of RVF in cardiac surgery include perioperative deterioration and adverse outcomes such as difficult separation from cardiopulmonary bypass (CPB), increased use of intravenous (IV) vasoactive agents and an increased risk of mortality. Therefore, the diagnosis and treatment of PH and right ventricular (RV) dysfunction is essential in the perioperative period to circumvent complications. Continuous and simultaneous monitoring of both pulmonary artery pressure (Ppa) and RV pressure (Prv) waveforms using pulmonary artery catheterization is an important monitoring tool in cardiac surgery patients for early detection of RV dysfunction and for evaluating response to treatment. Therapeutic strategies in this context should focus on reducing RV afterload and improving RV function while avoiding systemic hypotension. The hypotheses of this thesis are the following: 1) inhaled aerosolized vasodilators are superior to IV administered agents for the treatment and management of PH in cardiac surgery, 2) the combination of inhaled epoprostenol and inhaled milrinone (iE&iM) is an effective strategy to facilitate separation from CPB and reduce the requirements for IV inotropes, 3) not all patients have a positive vasodilator response to iE&iM, 4) response to iE&iM is associated with changes in RV and PA pressure waveforms, and 5) RV outflow tract (RVOT) gradient and RV maximal rate of pressure rise during early systole (dP/dt) have the potential to be pharmacodynamic markers of response to treatment. The work comprised in this thesis consist of 3 studies. The first is a systematic review and meta-analysis of randomized controlled trials showing that administration of inhaled vasodilators for the treatment of PH during cardiac surgery is associated with improved RV performance compared to IV administered agents. The second study is a retrospective cohort analysis of 128 patients receiving iE&iM before CPB. This study showed that 77% of patients have a vasodilator response to iE&iM treatment. A favorable vasodilator response was associated with more frequent easy separation from CPB and lower use of IV inotropes post-CPB. In addition, more severe PH at baseline is shown to be predictive of a positive pulmonary vasodilator response while high European System for Cardiac Operative Risk Evaluation score (EuroSCORE) II is a predictor of non-response to treatment. The last study of this thesis is a prospective cohort study including 26 patients receiving iE&iM with continuous monitoring of Prv waveform demonstrating the safety and efficacy of this treatment approach in improving RV function.

INTRODUCTION: Airway inflammatory response is widely believed to be a central mechanism in the development of adverse health effects related to air pollution exposure. Increased ventilation and inspiratory flow rates due to physical activity in the presence of air pollution will increase the inhaled dose of air pollutants. However, physical activity can also affect lung function and may moderate the relationship between air pollution and lung function. The mechanisms that underpin the complex interplay between air pollution, physical activity, and lung function may be more sensitive to the inhaled dose of air pollution than to ambient air pollution exposure alone. Despite this, the majority of literature on the topic measures only the ambient concentration of air pollution. AIM: This study aims to characterize the relationship between inhaled air pollution dose, physical activity, and respiratory response markers of lung function, oxidative stress and inflammation among healthy adolescents. Respiratory response measures include exhaled nitric oxide (eNO), percent oxidized exhaled breath condensate glutathione (%GSSG), percent oxidized exhaled breath condensate cysteine (%CYSS), the percentage of total oxidized compounds (%Oxidized), and changes in pulmonary function, namely, forced vital capacity (FVC), forced expiratory volume (FEV1), and forced expiratory flow (FEF25-75). Air pollution measures include cumulative inhaled doses of fine particulate matter (PM2.5), ozone (O3), black carbon (BC), and particle number total (PNT). METHODS: Using a non-probability sample of high school athletes, outcomes were measured prior to and after participation in extracurricular sports practice. The inhaled dose of air pollutants during the sports practice was estimated for each participant using a novel method developed by Dr. Roby Greenwald. This observational study estimates the association between air pollution dose and outcome measures using general linear mixed models with an unstructured covariance structure and a random intercept for subject to account for repeated measures within subjects. All data analysis was completed using SAS. RESULTS: A one IQR (i.e. 345.64 µg) increase in O3 inhaled dose is associated with a 29.16% average decrease from baseline in %Oxidized. A one IQR (i.e. 2.368E+10 particle) increase in PNT inhaled dose is associated with an average decrease in FEF25-75 of 0.168 L/second from baseline. The relationship between PNT inhaled dose and eNO is moderated by activity level, with increasing activity levels attenuating the relationship. Similarly, the relationship between O3 inhaled dose and %CYSS is attenuated by activity level, with increasing activity levels corresponding to smaller changes from baseline for a constant O3 inhaled dose. DISCUSSION: Someone who inhales a high cumulative dose despite a low activity level is likely breathing in a higher concentration of air pollution in a shorter period of time than a person who receives the same dose with a high activity level. The moderating effects of activity level suggest that peaks of high concentration doses of air pollution may overwhelm cells’ endogenous redox balance resulting in increased airway inflammation. Further research that examines the relationships between dose peaks over time and inflammation could help to determine whether a high concentration dose over a short period of time has a different effect than a lower concentration dose over a longer period of time.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Lung cellular disposition and anti-inflammatory pharmacology of inhaled corticosteroids (ICSs) is complex, comprised of a cascade of aerosol deposition and dissolution, followed by cellular uptake for local pharmacological action. This project hypothesized that the kinetics of dissolution for certain ICS aerosols generated from inhaler products were kinetically rate-determined for their cellular uptake and local pharmacological action. A novel dissolution testing system was developed to determine the dissolution kinetics for the ICS aerosols. A total of 5 ICSs aerosols generated from 6 inhaler products were collected in 2.1-3.3 or 4.7-5.8 µm of aerodynamic diameters at 0.7-19.8 µg on filter membranes by impaction using the Andersen cascade impactor. The filter membrane was then placed on the donor side of the transwell insert, with its face down, and the ICS dissolution in the limited 40 µL of the donor fluid was monitored over time. The dissolution kinetics overall conformed to the rank order of the aqueous solubility, while also being affected by ICS aerosol’s mass, size, formulation and dosage forms. For the readily soluble triamcinolone acetonide (TA), the kinetics was first-order, reaching ≥89 % dissolution in 5 h. In contrast, for the least soluble fluticasone propionate (FP), the kinetics was zero-order, reaching only 3 % dissolution in 10 h. The project then developed an air-interface culture of human bronchial epithelial cell line, Calu-3. Well-differentiated monolayers were formed with sufficiently “tight” barrier for restrictive solute diffusion while their mucosal surface was maintained semi-dry with 39.7±12.1 µL of the mucosal lining fluid in the 4.5 cm2 transwells. These monolayers were transfected with reporter plasmid of pNFκB-Luc to assess in vitro anti-inflammation via repression of pro-inflammatory NFκB by direct FP or TA aerosol deposition. The FP aerosols at 0.9 µg successfully exhibited significant 35.7±6.3 % repression. Notably, however, an identical ~0.5 µg of FP and TA aerosols caused comparable 15.5±2.2 and 10.4±2.6 % repression, respectively, despite FP’s 10-fold greater “intrinsic” anti-inflammatory potency over TA, reported in the literature. This was attributed to FP’s slow dissolution resulting in only 4.7 % cellular uptake, compared to 32.6 % for the TA aerosols. Hence, the FP aerosols were shown to be rate-determined by dissolution on the lung cell surface, resulting in reduced anti-inflammatory actions, which was not the case for the readily soluble TA aerosols.

"Gaseous nitric oxide, in concentrations between 0 and 20 ppm, is currently being used to treat patients with post-surgical complications and respiratory disorders. Currently available instruments are expensive and have problems that limit their usefulness for this application. This thesis discusses the development of an inexpensive, direct and continuous sensor for the measurement of inhaled nitric oxide. The prototype sensor incorporates a 0.125 cm, gas permeable, flow-thru liquid cell into a probe that can be incorporated into a ventilator circuit. Sensor operation is based on the complexation reaction of NO with cytochrome-c (Fe III), a biologically derived heme. The complex is monitored spectrophotometrically in the visible region of the spectrum at 563 nm by an optical spectrograph card. LabVIEW is used for all hardware control, signal acquisition, data processing, display and storage. The sensor has a sensitivity of 2x10-4 Abs/ppm, where Abs denotes absorbance units, a minimum detectable limit of 1.5 ppm, resolution of 0.5 ppm, is stable over the course of 8 hours, has less than 1 ppm error and a response time of less than 2 minutes. All aspects of sensor design and development will be discussed."

This thesis examines the overarching theme of inhaled corticosteroid (ICS) dose response effects on a variety of asthma outcome measures; with further importance placed on the application of these findings to personalising ICS dosing for the individual asthmatic. The introduction provides a detailed summary of the current recommendations for the treatment of adult asthma, with particular reference to the mechanism of action and clinical utility of ICS for the treatment of asthma. Current methods of assessing ICS dose response are presented, as well as the common influences that affect these responses. Novel therapeutic theories and the identification of specific asthmatic phenotypes are also introduced, in order to demonstrate the shift towards personalising treatment for asthma. The first two studies examine the dose response of ICS on two specific factors that influence asthma. The third study presents an examination of pharmacological manipulation of the ICS dose response using an additional agent. The following two studies address: how asthma outcomes relate to each other in patients receiving ICS; in addition to an overall assessment of the ICS dose response across a broad range of both ICS moieties and outcome measures. The final study examines for any detrimental effect of an ICS dose ramp on bone metabolism, an important potential long-term adverse effect of higher ICS dosing. The discussion draws together all the results obtained in relation to ICS dose response in asthma, and how these apply to current clinical practice for the individual patient. Furthermore, hypotheses are generated for areas of future study based on the findings from this work.

Particles that deposit in the respiratory airways can come from many sources, such as environmental pollution, particles created in the workplace, and inhalers that are designed to deliver medicines to the lungs. Once these particles deposit in the respiratory airways, they can interact in a variety of ways. Some particles are toxic and can cause damage to lung tissues, others may have little to no effect on health, and some may provide some benefit or therapy. Once particles land in the respiratory airways, the interactions they have with proteins can impact where they go and how they behave. This thesis explores how particles that are inhaled may impact health through toxicity to lung cells. Aerosols produced from photooxidation of decamethylcyclopenta-siloxane, an ingredient common in personal care products, were exposed to lung cells using an air-liquid interface exposure system to assess if these aerosols impact lung cell health. No significant impacts on lung cell health were observed. Copper oxide, a component of cigarette smoke, urban particulate matter, and e-cigarette vapor, was assessed for its role in lung disease. Copper oxide nanoparticles were exposed to lung cells, and their viability, expression of a platelet activating factor receptor (PAFR), and susceptibility to infection with a pneumonia-causing bacterium (S. pneumoniae) were measured. Copper oxide nanoparticles were found to be toxic to lung cells. At some doses, increases in PAFR were observed, but no clear differences in susceptibility to bacterial infection were observed. This research improves knowledge of how inhaled materials can impact health, providing insight into how particles from human-derived sources affect the lungs. This thesis further explores how particles behave in the thin layer of fluid that covers the respiratory epithelium. This fluid contains a complex mixture of proteins, and this work aims to identify some of the ways these proteins interact with particles and influence behavior. This was accomplished by first investigating how individual proteins from this fluid interact with particles. Particle behavior was studied after exposure to these proteins, as well as the lung cell responses to the particles before and after interaction with individual proteins. These lung proteins were found to induce aggregation, significantly alter surface charge, and reduce cell uptake of particles. After studying how individual proteins might specifically affect particle behavior, particles were exposed to bronchoalveolar lavage fluid (BALF), a diluted lung fluid collected by rinsing lungs with saline. Particle responses to proteins in this fluid were compared to those in serum, a protein-rich blood extract. These studies identified differences in how various surface-functionalized polystyrene particles aggregated in BALF compared to serum. When particles were exposed to serum or BALF, they tended to be less likely to associate with lung cells. With some particle types studied, there were significant differences in how much BALF or serum reduced cell attachment and uptake. In addition to demonstrating that lung fluids impact particle behavior in a manner that differs from serum, a method was developed to increase the concentration of the proteins in BALF to partially undo the dilution that occurs during collection. After studying how protein adsorption can cause aggregation, cover up particle surfaces, and reduce attachment and uptake by lung cells, a polymer coating was synthesized to reduce particle interactions with these proteins and assist in stabilizing particles in lung fluids. This coating was tested in both BALF and serum to demonstrate its general utility at reducing undesired interactions with proteins in biological fluids and was found to enhance particle stability in lung fluids as well as saline. This research enhances understanding of how particles behave in the respiratory airways, providing tools to further study how particles behave in lung fluids and demonstrating a polymer coating that is useful in this environment.

Cell-mediated immunity (CMI) in the lung has not been well characterized due to the lack of applicable tests. A major objective was to define pulmonary CMI serially in immunized and control lung lobes using the leukocyte procoagulant (LPCA) assay in young adult dogs. This was compared to a standard, but less reproducible CMI assay, macrophage migration inhibition facet (MIF). The CMI response, as measured by the LPCA assay, peaked in the blood 7 days after lung immunization. The pulmonary CMI response measured with cells obtained by bronchial lavage from the immunized and control lung lobes peaked at 9 to 12 days after intrapulmonary immunization with 10xx sheep red blood cells (SRBC). This peak pulmonary immune response corresponded with the day of lymphocyte influx into the lung. An attempt was made to increase the level of CMI in the lung by administration of muramyl dipeptide by two different routes. The administration of the adjuvant muramyl dipeptide (MDP) into the lung or given intravenously suppressed the CMI response in the lung after instillation of antigen (10xx SRBC). Four dogs were exposed to 239Puu2 when the dogs were one year old. When the dogs were 6 to 7 years old the pulmonary CMI was evaluated after lung immunization. Age-matched control dogs were immunized for comparisons. The noticeable difference between the control and plutonium-exposed dogs was the dramatic cellular chancres produced in the control and immunized lung lobes of the plutonium-exposed dogs. Inhalation or plutonium in addition to sequential lavages produced high numbers of neutrophils to be recruited to the lung. However. the effects of inhaled 239Pu02 on pulmonary CMI of 6 to 7-year-old dogs were obscured by the low pulmonary immune response in the age-matched control dogs. The age-matched control dogs showed no cellular changes in either the saline lung lobe or the immunized lung lobe. This result was attributed to the age of the dogs. The control dogs produced high amounts or immunoglobulins as measured in the serum. however. they could not recruit these serum immunoglobulins into the lung. The plutonium-exposed dogs showed a similar immunoglobulin immune response. The effects of naturally occurring tumors or those produced by inhaled radioactive compounds were evaluated tor their effects on the procoagulant activity assay and spontaneous macrophage migration. The procoagulant activity of the lung is significantly increased if a tumor is present in the lung. The migration area of the cell population lavaged from the tumor-bearing lung lobe was significantly increased over control lobe migration areas.

Master of Science in Medicine / Rationale: Asthma management aims to achieve optimal control on the minimal effective dose of medication. We assessed the effectiveness of two algorithms to guide ICS dose in well-controlled patients on ICS+LABA in a double-blind study, comparing dose adjustment guided by exhaled nitric oxide (eNO) to clinical care algorithm(CCA) based on symptoms and lung function. Methods: We randomised non-smoking adult asthmatics on minimum FP dose 100μgs daily +LABA to ICS adjustment using eNO or CCA, assessed over 5 visits during 8 months treatment. Primary endpoints were asthma-free days and asthma related quality of life (QOL). Analysis was by mixed model regression and generalised estimating equations with log link. Results: 69 subjects were randomised (eNO:34, CCA:35) and 58 completed the study. At baseline mean FEV1 was 94% pred., mean eNO (200ml/sec) 7.1 ppb, median ACQ6 score 0.33. Median ICS dose was 500 μg (IQR 100-500) at baseline and 100 μg on both eNO (IQR 100-200) and CCA arms (IQR 100–100) at end of study. There were no significant differences between eNO and CCA groups in asthma-free days (RR=0.92, 95% CI 0.8–1.01), AQL (RRAQL<median = 0.95, 95% CI 0.8–1.1) or exacerbation-free days (HR = 1.03, 95%CI 0.6–1.7). Neither clinic FEV1 (overall mean difference FEV1 % pred. -0.24%, 95% CI -2.2–1.7) nor a.m. PEF (mean difference 1.94 L/min (95% CI -2.9–6.8) were significantly different. Similar proportions of subjects were treated for ≥1 exacerbation (eNO: 50%, 95% CI 32.1–67.9; CCA: 60%, 95% CI 43.9–76.2). Conclusion: Substantial reductions in ICS doses were achieved in well controlled asthmatics on ICS+LABA, with no significant differences in outcomes between eNO or clinically based algorithms.

Purpose: To determine the vascular reactivity (VR) capacity and visual function (VF) response to potent vasoconstrictor and vasodilatory provocations of retinal arterioles in healthy subjects. Methods: One hyperoxic hypocapnic and two graded hypoxic hypercapnic stimuli were administered. VR in response to gas provocation was assessed using the Canon Laser Blood Flowmeter. VF was assessed using high and low contrast ETDRS logMAR charts, Medmont C-100, and H.R.R. Pseudoisochromatic Plates. Results: Flow reduced by 23% (p=0.0001) during hyperoxic hypocapnia and increased by 18% (p=0.0129) during hypoxic hypercapnia. During hyperoxic hypocapnia, high contrast VA improved by -0.026 (p=0.0372). During hypoxic hypercapnia, high and low contrast VA were reduced (+0.033, p=0.0110; +0.025, p=0.0058, respectively). Colour vision was unaffected. Conclusions: The retinal arterioles demonstrated a greater capacity for vasoconstriction than vasodilation in response to the stimuli used in our study. Hyperoxic hypocapnia improved high contrast VA while hypoxic hypercapnia reduced high and low contrast VA.