Paediatrics (RCH) - Theses
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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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ItemRespiratory function tracking in survivors of prematurity and low birth weight( 2009)INTRODUCTION: To investigate longitudinal ‘tracking’ in lung growth, decline or stability of adult preterm/very low birth weight survivors over the study period. To investigate whether those who have clinically abnormal lung function fall further behind their contemporaries or demonstrate evidence of ‘catch-up’ growth. METHODS: 210 babies born ≤34 weeks’ gestation and with birth weights ≤ 1500g in 1977-1982 were followed up at 8, 11, 14, 18 and 25 years of age. Respiratory outcome was evaluated using Spirometry. Spirometry was performed at each of the follow-up periods. Mixed model regression was used to assess longitudinal lung function trajectories and the influence of Bronchopulmonary dysplasia, being small for gestational age and abnormal lung function. Restricted maximum likelihood modelling was used for longitudinal FEV1 z-score as it allows for analysis of data from different time points that are not necessarily evenly spaced, without being affected by missing data. RESULTS: 137 VLBW children completed lung function testing at 8 years of age. Twenty VLBW children (14.6%) had abnormal FEV1 z-scores and 26 (21.0%) [Defined as >2 standard deviation’s below the mean]. VLBW survivors showed minimal ‘catch-up’ in FEV1 z-score over the 13 years of the study; those without BPD (Bronchopulmonary dysplasia) FEV1 improved 0.034 (p=0.014) z-scores, those with BPD FEV1 improved 0.033 (p=0.039) z-scores. VLBW with BPD survivors did not return to within normal limits; those with abnormal FEF25-75 z-scores did not show significant ‘catch-up’ growth (p=0.41) and remained abnormal. CONCLUSIONS: Mixed models do not reveal any significant effects from being born with VLBW and its interaction with age; it does lead to a reduction in FEV1/FVC mean z-score. Although those VLBW individuals who were small for gestational age had significantly reduced FEV1, FVC and FEV1/FVC mean z-scores and these small for gestational age individuals show evidence of ‘catch-up’ growth in terms of lung function, with the exception of FEV1/FVC z-score which falls further from their contemporaries. This effect on FEV1 and FVC z-scores may suggest some protective element or compensatory mechanism of being born small for gestational age. Reassuringly, Bronchopulmonary dysplasia as a neonate did not significantly affect lung function variables as these individuals as they age. Those with clinically abnormal lung function show a progressive failure to achieve optimal lung function whether or not they had Bronchopulmonary dysplasia.