L’arrêt cardiaque (AC) extrahospitalier est un problème majeur de santé publique, malgré la mise en place d’une véritable « chaine de survie ». Les durées de réanimation sont souvent prolongées et aboutissent à des séquelles irréversibles avec un assombrissement dramatique du pronostic. Dans de nombreuses situations, l’AC ne parvient pas à être réanimé avec les soins courants, laissant apparaître un AC « réfractaire » qui nécessite une prise en charge thérapeutique avancée. L’objectif général de ce travail de thèse était d’évaluer de nouvelles approches expérimentales pour la prise en charge de l’AC réfractaire. Nous avons étudié deux stratégies expérimentales chez le porc, consistant à induire une hypothermie ultra-rapide par ventilation liquide ou à mettre en place une assistance circulatoire au cours d’un AC d’origine ischémique.Dans un premier travail, nous avons ainsi évalué la faisabilité d’une hypothermie thérapeutique ultra-rapide par ventilation liquidienne totale (VLT) chez le porc. Cette approche consiste à instiller des perfluorocarbones dans le poumon de façon à induire un refroidissement ultra-rapide. Le poumon est ainsi utilisé comme bio-échangeur thermique, tout en maintenant des échanges gazeux normaux. Dans des travaux préliminaires, le laboratoire a montré que la VLT permettait de réduire la température sanguine jusqu’à 32°C en moins de 10 minutes chez le lapin. Le but de notre étude était de déterminer si la VLT pouvait aussi permettre un refroidissement ultra-rapide chez le porc. L'effet de la VLT a ainsi été évalué dans un premier temps à cœur battant, puis à cœur arrêté sur un modèle d’arrêt cardiaque réfractaire bénéficiant d’une réanimation cardio-pulmonaire prolongée. Dans les conditions physiologiques « à cœur battant », la température de 34°C était atteinte en moins de 10 minutes dans tout l'organisme. Lors de la réanimation prolongée d’un AC réfractaire, le refroidissement corporel était également obtenu rapidement, en moins de 25 minutes, quel que soit le site de mesure de la température. La VLT n’altérait aucunement la qualité du massage cardiaque externe, suggérant un intérêt pour cette approche dans l’induction d‘une hypothermie intra-AC, dans une perspective d’augmentation de l’efficacité des défibrillations ou de préservation d’organe.Dans un deuxième travail, nous nous sommes intéressés à l’AC réfractaire compliquant un syndrome coronaire aigu, traité par assistance circulatoire extracorporelle. Notre but était d’évaluer l'importance de la revascularisation coronaire précoce dans cette situation chez le porc, c’est-à-dire son impact sur le statut hémodynamique et les chances de réanimation. Après anesthésie et instrumentation, les animaux ont ainsi été soumis à une occlusion coronaire, suivie d’un AC par fibrillation ventriculaire non traitée pendant 5 minutes. Ils ont ensuite bénéficié d’une réanimation cardio-pulmonaire de base puis d’une assistance circulatoire extracorporelle. Nous avons comparé les effets d’une revascularisation précoce à ceux d’une revascularisation tardive, c’est-à-dire d’une reperfusion 20 ou 120 min après le début de l'assistance circulatoire. La revascularisation coronaire précoce augmentait significativement les chances de reprise d’activité cardiaque spontanée, limitait l’état de choc, améliorait la perfusion cérébrale et limitait la taille d’infarctus. Cela montre bien l’importance d’une prise en charge rapide du syndrome coronarien en cas d’AC de cause cardiaque présumée, y compris dans une situation d’assistance circulatoire extracorporelle.En conclusion, nous avons montré que la VLT permettait d’induire un refroidissement ultra-rapide dans l’ensemble de l’organisme, tant à cœur battant que pendant une réanimation prolongée. Par ailleurs, la revascularisation précoce d’un AC réfractaire ischémique traité par assistance circulatoire extracorporelle permettait d’améliorer globalement les chances de réanimation et le statut hémodynamique. / Out of hospital cardiac arrest (CA) is a major public health issue, despite the implementation of a “chain of survival”. Resuscitation durations are often extended with irreversible organ damage and poor outcome. Frequently, conventional care does not allow the return of spontaneous circulation, leading to a refractory CA, with the need for advanced therapeutic care. The general objective of this work was to evaluate new therapeutic strategies in the management of refractory cardiac arrest. We studied two experimental strategies in swine, involving ultrafast cooling with total liquid ventilation or extracorporeal cardiopulmonary resuscitation in a CA of ischemic origin.As a first step, we evaluated the feasibility of ultra-fast therapeutic hypothermia using total liquid ventilation (TLV) in swine. This approach involves perfluorocarbon instillation in the lungs to induce ultra-fast cooling. The lungs are thus used as a heat exchanger, while maintaining normal gas exchanges. In previous studies, the laboratory has shown that TLV could reduce blood temperature to 32°C in less than 10 minutes in rabbits. The objective of this study was to determine if TLV could lead to ultra-fast cooling in swine. We first studied the cooling capacity of hypothermic TLV in beating heart pigs, and then during ventricular fibrillation with prolonged chest compressions. In physiological conditions, in “beating heart” animals, the target temperature of 34°C was obtained in less than 10 min in the whole body. In prolonged resuscitation of refractory CA, whole body cooling was also rapidly obtained, within less than 25 min. TLV did not alter the hemodynamic effect of cardiac compressions, suggesting further use of this “intra-resuscitation” cooling in order to increase chances of defibrillation or for organ preservation for the purpose of organ donation.As a second step, we addressed the subject of ischemic refractory CA treated by extracorporeal cardiopulmonary resuscitation (ECPR). Our objective was to evaluate the importance of early coronary reperfusion in this situation, i.e., it’s impact on hemodynamic status and chances of defibrillation. After anesthesia and surgical preparation, animals were submitted to a coronaryocclusion followed by 5 min of CA by ventricular fibrillation. Conventional cardiopulmonary resuscitation was then initiated and followed by extracorporeal cardiopulmonary resuscitation.We compared the effect of early versus late reperfusion, i.e., reperfusion after 20 or 120 min of ECPR. Early reperfusion significantly increased chances of return to spontaneous circulation with limited shock status, increased cerebral perfusion and decreased infarct size. This confirms the need for early treatment of acute coronary syndrome if cardiac cause of CA is suspected, even in the situation of ECPR.In conclusion, we have shown that TLV could provide ultra-fast whole body cooling, both in beating heart swine and during prolonged resuscitation. Secondly, early reperfusion in refractory ischemic CA treated by ECPR globally increases chances of return to spontaneous circulation and improves hemodynamic status.

Extracorporeal membrane oxygenation (ECMO) is a medical treatment that aims to support patients' respiratory and circulatory systems by oxygenation of blood outside of the patient. The therapy exposes blood to an artificial environment, which increases the risk of clot formations in the blood. This thesis proposes a noninvasive method to detect the development of thrombi in the ECMO circuit (which may cause patient complications) by measuring the blood pump motor effect and blood flow. To show the feasibility of this approach, a code that calculates pump efficiency changes due to adjustments of flow resistance shall be written and tested with a mock-up of an extracorporeal life support (ECLS) circuit. Results indicate there exist different flow efficiency relations. Efficiency seems to be influenced by design; certain rotation speeds have higher efficiency than others. As flow increases, so do efficiency (for our values, 3-5 Litres per minute, LPM). For 3 LPM, the highest efficiency was achieved at around 2800 RPM; 4 and 5 LPM start with higher efficiency but decreases as RPM increases. It was concluded that it is possible to differentiate between various flow restrictions using power consumption assessments. Low resistance changes, reduction of cross-section area for flow by 10% on the inlet side, and 16% on the outlet side showed no difference in impeller turning speed nor flow out of the pump. / Extrakorporeal Membranoxygenering (ECMO) är en livräddande behandling för att syresätta patienters blod utanför kroppen vid svår andnings eller cirkulationssvikt. I ECMO-systemet utsätts blodet för en artificiell miljö som medför högre risk för koagulationsaktivering och blodproppsbildning. Detta arbete undersöker möjligheten att icke-invasivt mäta flödesresistanser (som proppar) utifrån att mäta förbrukningseffekten hos den elektriska blodpumpen i ECMO systemet. För att undersöka detta skrivs en kod för att ge en uppskattning av vid varierande flödesrestriktioner uppmätta värden. Dessa värden tas från en befintlig modell på KTH:s Strömningsfysiklaboratorium. Låga flödesrestriktioner påverkar varken flöde, motorrotationshastighet eller motorns effektförbrukning. Detta arbete fann att 10% av slangen till motorn och 16% av slangen från motorn kan vara täckt utan påverkan. Effektiviteten av pumpen varierar beroende på olika variabler. Detta arbete fann att effektiviteten ökar med ökat flöde 3 till 5 liter per minut (LPM). Det verkar även finnas indikationer för att effektiviteten beror på rotationer per minut (RPM), för 3 LPM fanns den högsta effektiviteten kring 2800 RPM, 4 LPM har sin högsta effektivitet vid samma område och 5 LPM har sin högsta effektivitet vid start och avtar därefter. Detta arbete fann att det är möjligt att beräkna flödesrestriktioner utifrån att kontinuerligt notera värdet på en elmätare kopplad till ECMO enheten.

Racial inequality in educational and occupational attainment has been shown to be related to racial inequality in test scores and cognitive skills. Most research and policy attention has been given to the ability of schools to equalize test scores. I argue that a major reason why researchers have been unable to explain why schools have not closed the gap is because by the time children begin school it may be too late. Cognitive skills develop from infancy and as such, it should be unsurprising that by the time children are five years old the differences across groups are firmly established. Thus, this research attempts to uncover where the racial test-score gap begins by examining infants. I perform a series of analyses using ordinary least squares regression (OLS) and structural equation modeling (SEM) using the first wave of the Early Childhood Longitudinal Survey--Birth cohort (ECLS-B). I utilize the mother's race, rather than the child's race, in the analyses because looking at the mother's race makes the most logical sense since the mother's race is more likely than the child's to determine household income, marital status, mother's education, parenting styles, and so on. I demonstrate that there is little to no raw gap in cognitive skills between the infants of White and Black mothers in the United States. However, through SEM I find that when one controls for social, human, and financial capital, and for differences in health and type of childcare, the infants of African American mothers would actually do better than the infants of White mothers because of their precocious motor development. I find no support for genetics and childcare and only limited support for financial and human capital as mediators of the gap. However, there is support for family social capital and low birth weight as key mediators of the small Black-White test score gap in infancy.

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abstract: The purposes of this study were (1) to examine the direct and indirect effect of school-level testing policies on reading achievement though changes in amount and types of reading instruction, (2) to investigate the reading trajectories moderated by school-level testing policies longitudinally, and (3) to examine the relationship between testing policies and the achievement gap by exploring whether certain student characteristics moderate the relationship between testing policy and reading achievement, using Early Childhood Longitudinal Study Kindergarten (ECLS-K) Cohort of 2010-2011 data. Findings from a multilevel full structural mediation model suggest that school-level frequency of state/local standardized tests had an indirect effect on student reading achievement through changes in both amount and the types of instruction at the school-level (cross-sectional fall kindergarten sample =12,241 children nested in 1,067 kindergarten classes). The findings from a three-level growth models indicated only children of Asian background and children from high socio-economic backgrounds who had frequent standardized tests in kindergarten accelerated in their monthly reading growth, whereas other children (e.g., low SES, non-Asian children) did not show any changes in the rate of the reading growth (longitudinal sample from fall of kindergarten to spring of first grade = 7,392 children nested in 744 kindergartens). The findings from the current study suggest that testing policy is not an effective means to reduce the achievement gap of children from disadvantaged family backgrounds, underperforming children or that children from low socieo-economic backgrounds. These children did not seem to benefit from frequent standardized tests longitudinally. Implications for supporting school assessment practices and instruction are discussed. / Dissertation/Thesis / Doctoral Dissertation Curriculum and Instruction 2015

The present study examined how acculturation, mental health problems, and parenting stress are associated with two dimensions of father involvement longitudinally for Latino and Chinese immigrant fathers using a nationally representative sample of young children and their resident fathers from the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B). After controlling for a variety of individual and demographic characteristics and previous levels of father involvement, results from multiple group structural equation modeling revealed that immigrant fathers' English proficiency is negatively associated with care-taking involvement at 2 years, but positively associated with care-taking involvement at 4 years. Interestingly, mothers' English proficiency is also positively associated with fathers' care-taking involvement at 2 years. In addition, fathers' US citizenship is positively associated with care-taking involvement at 2 years. Finally, mothers' US citizenship is negatively associated with fathers' literacy or language involvement at 2 years. In contrast with the hypotheses, no significant differences between Latino and Chinese immigrant fathers were found. Findings suggest that some dimensions of acculturation affect different dimensions of father involvement across different groups of immigrants, and the impacts may remain significant even four years after the child birth.

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This dissertation is a collection of three separate essays on the health of women and children. In the first essay, I along with my co-authors, analyzed the impact of two large, national-level health policies (the Janani Suraksha Yojana (JSY) and the National Rural Health Mission (NRHM)) on maternal health outcomes (proportion of institutional deliveries) in India. We used data from the India Human Development Survey (IHDS) and found that the JSY and the NRHM had a greater impact on institutional deliveries in high-focus states. We also found that the conditions of the public health facilities, did not change after the implementation of the JSY and the NRHM. Finally, we found that adequacy of health facilities was not associated with the likelihood of mothers in high-focus states having an institutional delivery. In the second essay, I examined whether a key social determinant of health in South Asia- gender inequality, is associated with physical health outcomes among Indian women. I found that the gender inequality expressed as the gendered household practice of seclusion was negatively associated with body weight of Indian women. Further, I found that participation in all household decisions by women of the household was generally not associated with body weight outcomes. The association between gendered household practices and women’s body weight outcomes was generally similar among rural and urban Indian women. In the final essay, I examined whether perinatal food environments (FE), maternal gestational weight gain (GWG) and early childhood weight (ECW) outcomes are associated. I used data on mother-children dyads from the Early Childhood Longitudinal Study – Birth cohort (ECLS-B), Area Resource Files (ARF) and Current Business Practices (CBP). I found that maternal GWG was associated with ECW outcomes. I also found that measures of food environment were associated with ECW outcomes. Specifically, I found that having an additional full-service restaurant per one thousand population in the maternal perinatal county of residence was associated with lower Body Mass Index (BMI) among children at age two years. Finally, I found that GWG did not mediate the association between food environment and ECW outcomes.