Ventilatory responses to rebreathing in infants exposed to maternal smoking
Article first published online: 2 JAN 2007
Volume 90, Issue 7, pages 793–800, July 2001
How to Cite
Campbell, A., Galland, B., Bolton, D., Taylor, B., Sayers, R. and Williams, S. (2001), Ventilatory responses to rebreathing in infants exposed to maternal smoking. Acta Paediatrica, 90: 793–800. doi: 10.1111/j.1651-2227.2001.tb02807.x
- Issue published online: 2 JAN 2007
- Article first published online: 2 JAN 2007
This study assessed the effect of maternal smoking during pregnancy on ventilatory and waking responses of infants to a respiratory challenge. This challenge mimicked the time-course and concentration of gases that an infant would experience rebreathing face-down into soft bedding. Control (C; n= 97) and smokers' infants (SM; n= 96) were studied at ages 1 and 3 mo. Asphyxial gas (hypercapnia/hypoxia) was delivered to the supine sleeping baby via a hood by slowly altering the inspired air: CO2 maximum 5% and O2 minimum 13.5%. Respiratory pattern was recorded by inductive plethysmography as the sum of ribcage and abdominal movements. The change in ventilation with inspired CO2 was measured over 5–6 min of the test. The slope of a linear curve fit relating inspired CO2 to the logarithm of ventilation was taken as a quantitative measure of ventilatory asphyxial sensitivity (VAS). Protective responses were graded from 1: no waking and an estimated arterial carbon dioxide tension (PaCO2) ±60mmHg (least protective), to 4: fully awake (most protective). The results showed VAS was higher in SM infants than controls: +0.03 (p= 0.04). The oxygen saturation (SaO2) of SM infants fell -0.4% (p= 0.02) more than SaO2 of controls despite a greater tidal volume increase: +13.0% (p= 0.04). Overall protective responses were the same between groups, but grade 1, although rare, was found in 7 SM infants and only 4 control infants; this difference was not significant.
Conclusion: The study did not confirm the postulate that infants of mothers who smoked during pregnancy have a reduced ventilatory response or raised waking thresholds.