Paediatrics (RCH) - Theses

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    Novel technology for the measurement of newborn and infant heart rate
    Kevat, Ajay ( 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.