Neonatal Respiratory Control

    Student thesis: Doctoral ThesisDoctor of Philosophy


    Disruption of the development of a stable and responsive system of respiratory control may be central to neonatal apnoea and Sudden Infant Death Syndrome.

    To test the hypotheses that sleeping position, maternal smoking and substance misuse will alter the ventilatory responses to hypercarbia and hypoxia in term infants; prematurely born infants with a lower ventilatory response to hypercarbia are at greater risk of developing apnoea, caffeine will increase this response; management of gastro-oesophageal reflux varies between NICUs, investigations that detect non-acid reflux will be more sensitive in diagnosing GORD, apnoea frequency will be greater following reflux events than before.

    The hypoxic and hypercarbic ventilatory responses were measured in term infants. The ventilatory response to hypercarbia was measured in preterm infants soon after birth and weekly until discharge. A survey was sent to UK NICUs. Infants on the NICU were investigated with pH/MII and polysomnography. Results of Upper gastro-intestinal contrast studies were compared with the results of pH/MII study.

    Maternal substance misuse alters breathing characteristics and response to hypoxia in newborns. In these infants prone compared to supine sleeping is associated with a lower minute volume. In prematurely born infants, a lower ventilatory response to hypercarbia predicted those that would develop apnoea. Caffeine was associated with an increased ventilatory response to hypercarbia. Investigation and management of gastro-oesophageal reflux in NICUs varies widely. pH/MII increases the detection of reflux events compared to pH alone. The results of pH/MII and upper gastro-intestinal contrast study correlate poorly. Apnoea frequency is no greater following reflux than preceding, or during reflux free periods.

    Risks factors for SIDS alter respiratory control; apnoea of prematurity is associated with a
    reduced response to hypercarbia, which is increased by caffeine; there is little evidence for a
    role of gastro-oesophageal reflux in the pathogenesis of apnoea.
    Date of Award2018
    Original languageEnglish
    Awarding Institution
    • King's College London
    SupervisorGerrard Rafferty (Supervisor) & Anne Greenough (Supervisor)

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