University of Leicester
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Respiratory responses to changes in inspired oxygen levels in infancy : the effect of maternal smoking

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posted on 2014-12-15, 10:31 authored by Kerry Ann. Poole
Deficits in respiratory control have been implicated in the aetiology of sudden infant death syndrome (SIDS). Victims of SIDS show signs consistent with chronic hypoxia prior to death and have abnormalities in both the brainstem and carotid body. Epidemiological studies have shown that maternal smoking is a major independent risk factor for SIDS. Pre and postnatal nicotine exposure may lead to changes in the brainstem and carotid body. This could result in respiratory control deficits which may be involved in SIDS.;The aim of the current work was to investigate the independent effect of maternal smoking on respiratory responses to changes in inspired oxygen in infants. Smoking is associated with other factors which may affect respiratory control, so a matched study design was implemented. Mother/infant pairs were matched for social class, maternal age and parity, gestational age, birthweight, infant gender and feeding intention.;Infants were seen overnight at approximately 10 weeks of age for tests of respiratory control using the alternating breath test. Ventilation was measured using respiratory inductance plethysmography and inspired and end-tidal oxygen levels by mass spectrometry. Fifty-nine infants were studied and data on 40 of these (17 smoking group) was included in the analysis. The respiratory responses were similar in both groups for all respiratory parameters, and there were no significant differences.;The mean end-tidal oxygen level when 40% O2 was delivered was significantly higher in the smoking group even though the measured inspired oxygen levels were similar in the two groups. These unexpected findings seemed to be related to the ongoing nature of the response.;In conclusion, there does not appear to be an independent effect of maternal smoking on respiratory control in infants, and the differences in end-tidal oxygen levels may represent differences in alveolar ventilation during the alternating breath test.


Date of award


Author affiliation

Child Health

Awarding institution

University of Leicester

Qualification level

  • Doctoral

Qualification name

  • PhD



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