UMD Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/3

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.

More information is available at Theses and Dissertations at University of Maryland Libraries.

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Now showing 1 - 4 of 4
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    THE USE OF ACTIGRAPHY FOR RISK STRATIFICATION IN PEDIATRIC OBSTRUCTIVE SLEEP APNEA
    (2018) Bertoni, Dylan Gregory; Isaiah, Amal; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Objectives. (i) To determine the feasibility of using actigraphy to identify sleep interruption in children with suspected obstructive sleep apnea (OSA); (ii) to assess the utility of actigraphy for prediction of OSA severity. Subjects and Methods. Ten healthy children aged 2 to 15 years with suspicion for OSA underwent polysomnography (PSG) with actigraphy. Statistical learning algorithms were used to (i) identify sleep-related respiratory events (awake, asleep, hypopneas and apneas), and (ii) predict OSA severity (mild, moderate and severe) utilizing actigraphy counts. Results. No adverse events were identified. Actigraphy counts were obtained in all 10 children. Linear discriminant analysis identified 100% of patients with severe OSA. Actigraphy counts reliably identified hypopneas and awakenings but not apneas. Conclusions. Actigraphy counts may provide effective risk stratification for pediatric OSA. Further investigations are necessary to investigate the utility of using actigraphy and pulse oximetry together to identify all respiratory events during sleep.
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    FAILURE MECHANISMS OF PEDIATRIC GROWING ROD CONSTRUCTS
    (2017) Hill, Genevieve A-L.; Fisher, John P; Dreher, Maureen L; Bioengineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Early onset scoliosis (EOS) affects a vulnerable population of young children, and occurs at critical ages when the spine and thorax are developing. Children suffering with EOS have higher mortality rates due to cardiopulmonary complications; therefore, treatment for these patients can be life-saving. Pediatric growing rod constructs are an important treatment option for young patients with severe and progressive spinal deformities because they encourage growth and correction of the spinal curvature through successive lengthening procedures. However, growing rod constructs suffer from complication rates as high as 72%, which often lead to unplanned reoperations. To help prevent future failures of the same root cause, the failure mode and mechanism must be identified, which tell us how and why the devices failed respectively. This research included the first study to examine multiple, retrieved pediatric growing rod constructs from various sites to systematically investigate these significant items. The retrieval study revealed that rod fracture (failure mode) was due to bending fatigue (failure mechanism), and stress concentrations play an important role in rod fractures. The information obtained from the retrieval study enhanced the understanding of in vivo loading conditions experienced by the device and established clinically-relevant parameters for a mechanical bench model. This research also included the development and validation of a novel mechanical bench model that successfully replicated rod fracture due to bending fatigue. A mechanical bench model that is predicated on clinical outcomes can serve as a tool for engineers and researchers who are looking to improve pediatric growing rod constructs as it will enable them to make relevant predictions about the device’s resistance to failure. For example, the model was used in this research to investigate how the unique characteristics of pediatric growing rod constructs such as construct configuration and lengthening affect mechanical performance of the device. Key recommendations regarding surgical technique were identified in the retrieval study and verified through bench testing. The data obtained during this research can ultimately be used to reduce failure rates and unplanned revisions in this patient population.
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    OBESITY, METABOLIC SYNDROME, AND CARDIOVASCULAR OUTCOMES IN PEDIATRIC KIDNEY TRANSPLANT RECIPIENTS
    (2017) Sgambat, Kristen; Lei, David; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Cardiovascular (CV) disease is a leading cause of morbidity amongst children after kidney transplant. The contribution of abdominal obesity and metabolic syndrome (MS) to CV risk is not well defined in this population. A prospective controlled longitudinal cohort study was conducted to investigate contributions of obesity and MS to CV morbidity in a multiracial pediatric kidney transplant population. Aims of the study were to 1) identify prevalence of CV and metabolic abnormalities 2) evaluate effects of obesity and MS on adverse CV outcomes, defined by left ventricular hypertrophy (LVH), impaired myocardial strain and increased carotid intima-media thickness (CIMT) and 3) identify the anthropometric measure of obesity, Body Mass Index (BMI), Waist-to-Height ratio (WHr), or Waist Circumference (WC), that best predicts CV risk. Transplant recipients had standard echocardiographic measures of left ventricular size and function, strain by speckle tracking echocardiography, and CIMT measured at 1, 18, and 30 months post-transplant. 35 pre-transplant echocardiograms were analyzed retrospectively. Multivariate longitudinal regression was used to determine associations of obesity and MS with CV outcomes. Results indicated obesity and MS are prevalent among pediatric kidney transplant recipients. WHr is a more sensitive indicator of obesity-associated adverse CV outcomes compared with BMI or WC, due in part to the prevalence of short stature in this population. Obesity, MS, and hypertension are associated with post-transplant LVH. Significant predictors of impaired longitudinal strain include obesity, hypertension, and a combination of MS with elevated LDL-C cholesterol, whereas higher estimated glomerular filtration rate confers a protective effect. African American pediatric kidney transplant recipients have increased CIMT, which is negatively impacted by MS, whereas the CIMT of non-African American children appears unaffected after transplant. In conclusion, obesity and MS adversely affect CV outcomes in pediatric kidney transplant recipients, highlighting the importance of efforts to maintain healthy weight, blood pressure, and lipid profile after transplant. Further studies are needed to investigate the etiology and consequences of increased CIMT in African American transplant recipients. Imaging techniques such as speckle tracking echocardiography and CIMT may provide a means of detecting subclinical myocardial dysfunction and provide opportunity for early intervention in this population.
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    Observed Social Problem Solving and Friendship Quality in Children with a Traumatic Brain Injury
    (2016) Heverly-Fitt, Sara; Rubin, Kenneth; Human Development; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Children who have experienced a traumatic brain injury (TBI) are at risk for a variety of maladaptive cognitive, behavioral and social outcomes (Yeates et al., 2007). Research involving the social problem solving (SPS) abilities of children with TBI indicates a preference for lower level strategies when compared to children who have experienced an orthopedic injury (OI; Hanten et al., 2008, 2011). Research on SPS in non-injured populations has highlighted the significance of the identity of the social partner (Rubin et al., 2006). Within the pediatric TBI literature few studies have utilized friends as the social partner in SPS contexts, and fewer have used in-vivo SPS assessments. The current study aimed to build on existing research of SPS in children with TBI by utilizing an observational coding scheme to capture in-vivo problem solving behaviors between children with TBI and a best friend. The current study included children with TBI (n = 41), children with OI (n = 43), and a non-injured typically developing group (n = 41). All participants were observed completing a task with a friend and completed a measure of friendship quality. SPS was assessed using an observational coding scheme that captured SPS goals, strategies, and outcomes. It was expected children with TBI would produce fewer successes, fewer direct strategies, and more avoidant strategies. ANOVAs tested for group differences in SPS successes, direct strategies and avoidant strategies. Analyses were run to see if positive or negative friendship quality moderated the relation between group type and SPS behaviors. Group differences were found between the TBI and non-injured group in the SPS direct strategy of commands. No group differences were found for other SPS outcome variables of interest. Moderation analyses partially supported study hypotheses regarding the effect of friendship quality as a moderator variable. Additional analyses examined SPS goal-strategy sequencing and grouped SPS goals into high cost and low cost categories. Results showed a trend supporting the hypothesis that children with TBI had fewer SPS successes, especially with high cost goals, compared to the other two groups. Findings were discussed highlighting the moderation results involving children with severe TBI.