The effects of antenatal smoking and substance abuse on ventilatory responsiveness and chemoreceptor sensitivity in infants

    Student thesis: Doctoral ThesisDoctor of Philosophy

    Abstract

    Background: Infants of mothers who smoked (S) or substance misused (SM) during pregnancy have an increased risk of sudden infant death syndrome (SIDS).

    Hypotheses: Infants of SM and S mothers will have poorer ventilatory responsiveness to hypercarbia and hypoxia and reduced chemoreceptor sensitivity compared to controls.

    Impairment of ventilatory responsiveness and chemoreceptor sensitivity will be greater in the infants of mothers who both substance abuse and smoke compared to those whose mothers only smoke

    Methods: Three groups were recruited: 1. Infants of mothers with a history of substance misuse during pregnancy (SM infants) 2. Infants of mothers with a history of smoking during pregnancy (S infants). 3. Infants of mothers who neither smoked nor misused substances during pregnancy (Controls). Ventilatory responses to hypercarbia and hypoxia were assessed in the newborn period and at 6-12 weeks of age.

    Results: In the newborn period both the SM and S infants had a lower ventilatory response to 2% and 4% CO2 than the controls. The ventilatory response to CO2 was lower in the SM infants compared to the S infants. In response to hypoxic challenge in the newborn period, SM infants had a greater magnitude of decline in minute volume than the S infants and the controls. In addition, the rate of decline in minute volume was greater in the SM infants and the S infants compared to the controls. At 6-12 weeks of age S and SM infants had a dampened ventilatory response to hypercarbia and a greater magnitude of decline in minute volume in response to hypoxia compared to controls. Dampening of the ventilatory response to hypercarbia was greater at the peak age of SIDS compared to the perinatal period.
    Date of Award2016
    Original languageEnglish
    Awarding Institution
    • King's College London
    SupervisorAnne Greenough (Supervisor) & Gerrard Rafferty (Supervisor)

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