Paediatrics (RCH) - Theses
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ItemNo Preview AvailableAutism Spectrum Disorder (ASD) and Anaesthesia( 2019)This thesis addresses the question of what is the best evidence-based management for children with ASD (autism spectrum disorder) coming under anaesthetic care in the hospital setting. The increasing prevalence of ASD (1) has meant that most anaesthetists need to become proficient in understanding and managing children with ASD. Children with ASD have higher hospital contact than their neurotypical peers.(2) Behavioural problems, sensory sensitivities, language deficit, and inflexibility with change contribute to the difficulties experienced by children with ASD in the hospital setting. (3)Hospitals may be inherently challenging to children with ASD: being inflexible places, with the sound of crying children, with invasive monitoring techniques and bright lights.(4) One unpleasant anaesthetic experience can lead to heightened anxiety and future refusal to attend hospital. In order to find the context for best anaesthetic care, we have reviewed the existing literature about ASD and its management in chapter one. The first part of chapter two is a review of anxiety and premedication in general terms. The evidence for current best practices in managing children with ASD in the perioperative period is outlined in the second part of chapter two. To further understand the family and staff perspective of optimal care, we conducted a qualitative study of 29 individuals including 15 parents of children with ASD who had had a recent anaesthetic and 14 staff members that had looked after them in different capacities at two hospitals in Melbourne, Australia in chapter three. Chapter four contains discussion and conclusion. It includes discussion about the discontinued preparation/premedication trial (CLOMID). The flaws in the design and obstacles in its execution are examined. Our data showed important organisational, educational and resource matters. Problems such as prolong waiting for an operation date, lack of training of staff including anaesthetists and nurses, lack of availability of simple equipment and private spaces in the recovery rooms- were to be addressed. Good communication, clear explanation, and friendly attitudes as well as flexibility and individualised care of patients were considered useful. The supplementary material includes a protocol for a preparation /premedication study that has not been concluded as well as two social stories that I have designed.
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ItemInvestigating the biology of paediatric T cell acute lymphoblastic leukaemia to facilitate more effective individualised therapy( 2019)Acute lymphoblastic leukaemia (ALL) takes up the highest percentage of paediatric cancer. The treatment requires intensive chemotherapy for two to three years, as well as haematopoietic stem cell transplantation for poor-prognosis cases. Compared to B cell lineage ALL (B-ALL), T cell lineage ALL (T-ALL) has a lower 5-year event free rate, higher rate of relapse, and a worse outcome for relapsed cases. Individualised therapy, targeting at oncogenic changes in each patient, can make treatment more effective and less harmful. This requires understanding of the oncogenic biology of each individual leukaemia. We have attempted to develop a T-ALL model based on hiPSC-derived T cells, which will be in human origin, maintain normal genetic pattern, mimic in vivo T cell development, and can be massively produced for high throughput lab work. This model may make up for the shortcomings of conventional leukaemia cell lines and mouse models. This project investigates the biology of T-ALL by focusing on two novel fusion genes – TCF7-CSF1R and ETV6-CRX – identified by RNA sequencing of paediatric T-ALL patient samples. We have shown that TCF7-CSF1R is sufficient to immortalise mIL-3 dependent Ba/F3 cells. The ETV6-CRX fusion gene is anticipated to block differentiation. Establishing consistent expression of this fusion will require further optimization. The feasibility of setting up a hiPSC-derived T-ALL model was also assessed, with respect to protein expression in human T-ALL/lymphoma cell lines, hiPSC differentiation efficiency, hiPSC-derived T cell lentiviral infection rate, and cytokine withdrawal during differentiation. This project provides potential directions for improvement of methods for exogenous gene expression, such as the usage of CRISPR-Cas9 based techniques to introduce gene modifications for fusion genes such as ETV6-CRX that are difficult to express, particularly in hiPSC-derived T cells that have a low viral infection level. The T cell differentiation protocols also need to be optimised to make the T cell production easier and efficient. Detailed functional assay during T cell differentiation needs to be conducted in the future. In this thesis, Chapter 1 presents the background of this project; a literature review introducing human haematopoietic system, in vivo thymocyte development, paediatric TALL, novel oncogenic fusion-related genes, and in vitro T cell generation; the aims and hypothesis. Chapter 2 introduces the methods and materials used in this project. Chapter 3 presents the identification, cloning, and expression of novel fusion genes. Chapter 4 investigates the ability of these novel fusion genes to support cell survival and proliferation in conventional Ba/F3 cell line. Chapter 5 assesses the feasibility of setting up the hiPSC-derived T-ALL model. Chapter 6 makes a discussion on the results and concludes the whole project.
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ItemProximal femoral osteotomy in children and adolescents with cerebral palsy( 2018)Background Cerebral Palsy (CP) is the most common cause of physical disability affecting children in developed countries. Approximately one third of children with CP may develop hip displacement. Non-ambulant children at Gross Motor Function Classification System (GMFCS) levels IV and V are at highest risk. Without early detection through surveillance programs, hip displacement can progress to hip dislocation, which is frequently painful and negatively impacts health-related quality of life (HRQoL). Injections of Botulinum Neurotoxin A (BoNT-A) have no role, and soft tissue surgery has a limited role in preventing hip displacement in non-ambulant children with CP. Bony hip reconstruction surgery such as a proximal femoral osteotomy (PFO) is effective in stabilising the hip and HRQoL. PFOs include Femoral Derotation Osteotomies (FDO) which aim to improve the gait of an ambulant child (GMFCS I-III), and Varus Derotation Osteotomies (VDRO) which aim to contain the hips in non-ambulant children (GMFCS IV-V). However, PFOs can carry high risks, especially in children with medical co-morbidities such as respiratory disease, nutritional deficiencies, hypertonia and osteopenia. Aim This thesis involved a series of three studies, which aimed to expand our knowledge of the trainee learning curve, outcomes and adverse events relating to PFO in children and adolescents with CP. Method and Results A new implant combining locking and cannulated technology (Locking Cannulated Blade Plate, LCBP) was recently developed for use in PFO. A pilot study was performed on the first 25 patients who had surgery with the LCBP, at the Royal Children’s Hospital (RCH), Melbourne. This study established safety for use in children as young as three, with weights as low as eleven kilograms. A further prospective, parallel cohort study of 90 consecutive children with CP was conducted to compare the LCBP against with existing non-cannulated, non-locking implant (Angled Blade Plate, ABP). Technical and radiological outcomes of surgery were similar between implants. However, the surgical technique was reported by trainees to be easier when using the LCBP, with less technical errors. Approximately 60 percent of the children experienced minor adverse events including: constipation, inadequate pain control, and respiratory compromise. However, a CP specific tool was not available to classify the severity of events. Study three was performed to clarify the Modified Clavien-Dindo (MCD) system for lower limb surgery in children with CP and test its’ reliability for classifying adverse events. Very good reliability was demonstrated amongst members within a multidisciplinary team. Conclusion Novel findings from these studies may help improve the safety and efficacy of the management of hip displacement in children with CP. Further research should address the long-term outcomes of PFO in children with CP, evaluate the validity of the MCD for children in CP and determine if the MCD can be embedded in the electronic medical records (EMR) as a routine tool for audit and clinical research.
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ItemCirculating microRNAs in Rett syndrome( 2019)Rett Syndrome (RTT) is a severe neurological disorder with diagnostic challenges and undetermined patholophysiology. Small regulatory RNAs known as miRNAs are essential in a multiple biological processes, including brain development. Using next generation sequencing in a mouse model of RTT, I identified circulating, plasma miRNAs that are differentially expressed in RTT mice. Many of these miRNAs were previously shown to have neurological functions or be involved in RTT. The biomarker potential of these miRNAs was further explored using quantitative PCR.
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ItemDaytime predictors of sleep disordered breathing in Duchenne muscular dystrophy( 2017)Sleep disordered breathing (SDB) in Duchenne muscular dystrophy (DMD) progresses to respiratory failure. The gold standard for diagnosis is polysomnography (PSG) but the optimal timing is unknown. Twenty boys with DMD, aged 10 – 16 previously undiagnosed with nocturnal hypoventilation (NH), had repeat PSG. Concurrent clinical data was correlated to outcomes of PSG. 90% had OSA, O% NH (PtcCO2 > 50 mmHg > 25% TST) after 2 years. Boys younger than 10 years of age with DMD need PSG to elicit OSA.
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ItemNovel technology for the measurement of newborn and infant heart rate( 2017)Background: Monitoring heart rate in newborns and infants is crucially important in guiding resuscitation and medical care. Established methods for heart rate assessment of these children have inherent drawbacks. In recent years, novel methods for assessing neonatal and infant heart rate have been developed, with varying levels of evaluation conducted. Digital stethoscopes may provide a better means of heart rate assessment for newborns and infants. Aim: The aim of this thesis was to comprehensively review existing established and novel technologies used to monitor newborn and infant heart rate, and compare new digital stethoscope technology with the gold standard, electrocardiogram (ECG). Methods: This thesis (a) outlines the definition and importance of heart rate in medicine, presented in the context of a review of cardiac anatomy and physiology relevant to understanding this vital sign and aspects of its measurement in neonates and infants; (b) presents a narrative review of established methods for monitoring heart rate; (c) expands the scope of this review from established to emerging methods for monitoring heart rate with a systematic literature review of novel methods for newborn and infant heart rate assessment; (d) describes original research using a prototype digital stethoscope attached to a smart device containing software for detecting and displaying heart rate in real-time that was conducted on infants in the neonatal intensive and special care setting, as well in the delivery room setting using an improved version of the device and software. Results: A review of the literature analysing methods of assessing neonatal and infant heart rate found strengths as well as significant weaknesses in the various methods in clinical use or in development. In the neonatal unit, a prototype digital stethoscope and smartphone device for assessing heart rate had a mean difference (±2 standard deviations) of 7.4 (48.5) beats per minute (bpm) when compared to the gold standard of electrocardiography. The mean (interquartile range) time to first digital stethoscope heart rate display was 4.8 (1 to 7) seconds, and the device failed in 12.3% of use attempts. Repeating the comparison in the delivery room setting using an updated algorithm and new hardware, Bland-Altman analysis revealed a smaller mean difference (±2 standard deviations) between the digital stethoscope and electrocardiography of 0.2 (-18 to +18) bpm including crying periods (Figure 23), and 1.0 (-11 to +12) bpm excluding crying periods. The improved digital stethoscope took a median (interquartile range) of 7 (5 to 11.5) seconds after application to display a heart rate. It failed to detect heart rate in 37% of cases, all of which were in crying infants. Conclusion: A digital stethoscope and smart device with software can rapidly detect neonatal and infant heart rate. In the delivery room, device failure primarily occurred during infant crying, with improved accuracy during non-crying periods.
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ItemA tool for risk profiling and accurate prognostication in paediatric glioma integrating clinical features with epigenetics: it is time to move on from the binary classification( 2016)Paediatric glioma, the most common group of brain tumours in children, encompasses a wide range of entities with highly variable prognoses. Gliomas are grouped by histopathological features into high and low grade glioma but this classification does not take into account many established and emerging risk factors in this disease. Research into the molecular features of these lesions has shown that histology does not always correlate with biology and, where they differ, molecular features are usually superior at predicting outcome. Risk classifications have been developed for other paediatric malignancies which combine clinical, radiological, pathological and molecular factors to predict disease risk and prognosis. A comprehensive risk classification has not been published for paediatric glioma despite many risk factors being established in this disease. Using a clinical cohort of all paediatric glioma treated at a single institution (Royal Children’s Hospital, Melbourne, Australia) over an 18 year period a database was developed incorporating clinical, radiological, pathological and treatment factors. Where sufficient tumour tissue was available genome-wide methylation analysis was performed. The results of this were processed and evaluated by an established cluster analysis algorithm. Breaking the cohort into clinically appropriate subgroups, risk factors for disease progression and death were determined and prognosis estimated for distinct groups. A tool for robust risk profiling and prognostication was established with 5 main risk groups and 10 subgroups. Patients in the very low risk group have a predicted 100% overall survival and the majority require no treatment. In contrast there was a group of patients with 100% mortality within a short space of time where attempts at curative therapy are futile and may be deleterious to quality of life. The intermediate risk group contained a number of entities with a prognosis genuinely falling between that of low grade glioma and that of high grade glioma. Histopathological diagnosis retained prognostic importance for some, but not all, groups and methylation analysis was shown to have a significant role to play, particularly in high grade lesions or where diagnosis was unclear. This is likely to become part of routine care in the future and its place is strongly supported by the analysis presented here. Risk profiling is possible in paediatric glioma with far more accuracy than the current binary classification provides. A combination of established clinical factors and emerging molecular features provides an accurate and nuanced assessment of risk and prognosis.
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ItemAn exploration of multiple imputation strategies for handling missing data in composite scores with incomplete items( 2016)Missing data are common in medical research. One area where missing data can arise is in composite scores (or scale scores) when one or more of the items that form the scale is incomplete. A method that is becoming increasingly popular for handling missing data is multiple imputation (MI). In the context of missing data in scale scores, MI can be applied at either the item level or the scale level. Various strategies have been proposed in the literature for imputing missing data at the scale level and the item level. Yet there is little comparison of these strategies in longitudinal settings and not much guidance is available about how to best implement these strategies. The challenge with using the available strategies in longitudinal studies is that one may want to impute missing data in several scales, each of which comprises a large number of items that have been measured at several waves, leading to large imputation models which may result in convergence problems. It is therefore important to evaluate the performance of these strategies in longitudinal settings to provide proper guidance for users of MI. In this thesis, I used a simulation study and a real example from the Longitudinal Study of Australian Children (LSAC) to compare the performance of the four MI strategies that are available for handling missing data in composite scores within a longitudinal setting. These strategies are: scale-level imputation using scale scores as auxiliary variables; the “standard” item-level imputation, which uses other items as auxiliary variables; item-level imputation using scale scores as auxiliary variables; and item-level imputation using principal components, derived from other items, as auxiliary variables. I also compared the effect of implementing these strategies using two MI approaches, multivariate normal imputation (MVNI) and fully conditional specification (FCS). While the literature recommends item-level imputation over scale level imputation, the research in this thesis demonstrates that when implemented using FCS, item-level imputation, with items from other scales as auxiliary variables, could produce biased parameter estimates. This research also provides support for using scales scores or principal components as auxiliary variables in item-level imputation models when the “standard” item-level imputation strategy cannot be used due to convergence problems.
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ItemCardiovascular associations of HIV infection in children( 2015)Vertically-acquired HIV infection is a devastating disease in childhood that may affect any organ, including the cardiovascular system. With increased survival of HIV infected children due to antiretroviral (ART) treatment availability, chronic cardiovascular problems become a confronting challenge, not only because HIV infection may cause cardiac problems readily manifesting in childhood but also because it potentially increases future cardiovascular disease risk in adulthood. This thesis explores various possible cardiovascular effects of HIV infection in children, particularly the differential effects of ART-naïve compared to ART-exposed HIV infection on left ventricular (LV) remodelling, pulmonary hypertension, and arterial elasticity. We conducted a cross-sectional study enrolling 56 ART-naïve, 59 ART-exposed HIV infected, and 51 healthy children in Jakarta, Indonesia and performed cardiac/vascular ultrasound, and blood tests for biomarkers. There were marked differences in the cardiovascular parameters between the two groups. We found that ART-naïve HIV infection was associated with LV dilation while the ART-exposed seemed to cause concentric hypertrophic remodelling. ART-exposed HIV infected children who showed evidence of higher pulmonary artery pressure than healthy children, whereas the ART-naïve children had reduced right ventricular function. For arterial elasticity, the ART-naïve had higher strain and lower elastic modulus, but thicker intima-media thickness, whereas the ART-exposed had similar vascular properties as healthy children. In conclusion, HIV infection in children have significant impacts on childhood cardiovascular system with particular differential effects between ART-naïve and ART exposed HIV infection. Routine cardiovascular surveillance is needed for children with HIV infection.
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ItemScoliosis in children with cerebral palsy: a population based study( 2015)Introduction Scoliosis is the most common spinal deformity in children with cerebral palsy. Previous published studies have been based on institutionalised patients and not on a total population of individuals with cerebral palsy. Methods This study was based on both prospective and retrospective cross-section analysis of 292 children identified from the Victorian Cerebral Palsy Register. These children were spread across GMFCS levels I–V. The children were assessed during their transition clinic appointment prior to exit from the Royal Children’s Hospital. The research looked at three main sections: clinical review for scoliosis, radiographic assessment of scoliosis, and CHQ and CPCHILD questionnaires survey. Cobb angles were measured by two experienced observers. Results If a Cobb angle of more than 10° was used, then 40% of patients were classified with scoliosis. By changing the definition of scoliosis in cerebral palsy to a Cobb angle greater than 40°, the prevalence of “clinically important scoliosis” was 12.7%. The majority of the severe curves occurred in children at GMFCS levels IV and V. As the GMFCS level increased, the mean Cobb angle increased. The mean score for the questionnaires decreased as the GMFCS level increased. Conclusion The CP scoliosis and the scores for the questionnaire were closely related to the GMFCS levels. The prevalence of CP scoliosis is overestimated in other studies. Our study shows the prevalence of CP scoliosis is 12.7% using a Cobb angle of more than 40°. Non-ambulant children are at high risk of developing scoliosis and formal spine surveillance should be considered.