Doctoral Degrees (Paediatrics and Child Health)

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Browsing Doctoral Degrees (Paediatrics and Child Health) by browse.metadata.advisor "De Boode, Willem-Pieter"

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    Non-invasive cardiac output monitoring in preterm neonates
    (Stellenbosch : Stellenbosch University, 2021-12) Van Wyk, Lizelle; Smith, Johan; De Boode, Willem-Pieter; Lawrenson, John; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Paediatrics and Child Health.
    ENGLISH ABSTRACT: Neonatal hemodynamic compromise is linked to numerous adverse neonatal outcomes. Objective, comprehensive, continuous hemodynamic monitoring of the systemic circulation, in conjunction with the pulmonary system, is required to timeously intervene and improve outcomes. Non-invasive cardiac output monitoring utilising bioreactance, a specific type of thoracic electrical biosensing technology (TEBT), may offer such a solution. The overall aim of this research was to determine the use of bioreactance as a comprehensive, non-invasive cardiac output monitor in preterm neonates (<37 weeks). Research aims included determining (1) agreement (bias and precision) and (2) trending ability of bioreactance. Further aims were to determine the use of bioreactance in monitoring hemodynamic parameters and thoracic fluid content in the transitional period (first 72 hours of life) and during respiratory support in preterm neonates. In a prospective, observational, longitudinal cohort study, the agreement (accuracy and precision) of bioreactance (BR), as compared to transthoracic echocardiography (TTE), for estimating cardiac output (CO) and stroke volume (SV) in a cohort of stable preterm neonates during the transitional period, was investigated. Bland Altman analyses showed a high bias, indicating poor accuracy, and wide limits of agreement, indicating poor precision, of BR as compared to TTE. A high percentage error indicated non- interchangeability of BR with TTE. Bias was shown to be affected by gestational age, birth weight, continuous positive airway pressure (CPAP), patent ductus arteriosus (PDA) and CO category. Despite a new technology’s inaccuracy and lack of absolute number agreement, it could possibly be a valuable trending monitor, if reference values were known. In the same cohort, the average values for BR-derived hemodynamic parameters (heart rate ( HR), blood pressure ( BP), SV, CO, total peripheral resistance ( TPR)) w ere described. All parameters were associated with postnatal age. Changes were in line with expected transitional changes, as described in the literature. BR may therefore be valuable to monitor the transitional period in preterm neonates. In continued accuracy analysis, the ability of BR, as compared to TTE, to track temporal changes in SV and CO was investigated. Four-quadrant and polar plots were used to assess BR trending ability. Concordance rate was lower than the accepted benchmarks, when using a 5% and 10% exclusion zone. Angular bias was high, radial limits were wide and radial concordance was poor; indicating a poor trending ability. Trending parameters were significantly associated with postnatal age, PDA, and CO category but not gestational age, birth weight or CPAP. BR, as compared to TTE, does not provide good trending analysis of CO and SV and should be used with caution in neonatology to direct therapeutic decisions. A narrative systematic review was performed to determine the agreement and trending ability of electrical biosensing technology (EBT) in neonates, including the current research. Only thoracic EBT studies, with TTE as comparator, were available for inclusion, up to December 2020. High heterogeneity was apparent in the eligible studies, due to varying gestational and chronological ages, birth weight, disease states, ventilation requirements, inotropic support and surgical intervention, which made meta-analysis impractical. Only agreement studies were available with no studies reporting trending analysis. Effect direction plots were used to report outcome measures (bias, percentage error). Overall, most studies showed that EBT was not interchangeable with TTE. Results remained similar in sub-analyses for preterm vs term neonatal populations, different respiratory support modes, cardiac anomalies and type of TEBT technology. In a post hoc analysis of the cohort study, BR-derived thoracic fluid content (TFC) parameters were described. TFC, another hemodynamic parameter, may be able to identify pulmonary fluid overload states, that may compromise cardiac function or be the consequence of cardiac dysfunction. Absolute TFC and cumulative TFC change from baseline (TFC and TFCd0, respectively) decreased over the first 72 hours of life. Both TFC and TFCd0 showed significant associations with clinical variables (gestational age, postnatal age, respiratory support mode). Sub-analyses according to respiratory support type and a pre-and post -intervention analysis was performed. TFC and TFCd0 showed significant pre- and post-intervention differences between respiratory intervention groups (CPAP and CPAP+surfactant). Neither TFC nor TFCd0 were associated with PDA in the transitional period. TFC and TFCd0 may offer the ability to monitor lung fluid during the transitional period in preterm neonates. In c onclusion, the agreement and trending of bioreactance in preterm neonates in the transitional period is questionable. Numerous physiological and interventional parameters influence this. However, on an individual level, BR may be able to monitor hemodynamic parameters, as parameters showed changes in the same direction as described in transitional physiology. Currently, bioreactance should be used with caution in the neonatal population to dictate therapeutic interventions. More research is required before bioreactance can be used at the bedside to replace transthoracic echocardiography.