Ventilatory responses to rebreathing in infants exposed to maternal smoking

Citation
Aj. Campbell et al., Ventilatory responses to rebreathing in infants exposed to maternal smoking, ACT PAEDIAT, 90(7), 2001, pp. 793-800
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Pediatrics,"Medical Research General Topics
Journal title
ACTA PAEDIATRICA
ISSN journal
0803-5253 → ACNP
Volume
90
Issue
7
Year of publication
2001
Pages
793 - 800
Database
ISI
SICI code
0803-5253(200107)90:7<793:VRTRII>2.0.ZU;2-D
Abstract
This study assessed the effect of maternal smoking during pregnancy on vent ilatory and waking responses of infants to a respiratory challenge. This ch allenge mimicked the time-course and concentration of gases that an infant would experience rebreathing face-down into soft bedding. Control (C; n = 9 7) and smokers' infants (SM; n = 96) were studied at ages 1 and 3 mo. Asphy xial gas (hypercapnia/hypoxia) was delivered to the supine sleeping baby vi a a hood by slowly altering the inspired air: CO2 maximum 5% and O-2 minimu m 13.5%. Respiratory pattern was recorded by inductive plethysmography as t he sum of ribcage and abdominal movements. The change in ventilation with i nspired CO2 was measured over 5-6 min of the test. The slope of a linear cu rve fit relating inspired CO2 to the logarithm of ventilation was taken as a quantitative measure of ventilatory asphyxial sensitivity (VAS). Protecti ve responses were graded from 1: no waking and an estimated arterial carbon dioxide tension (PaCO2) greater than or equal to 60 mmHg (least protective ), to 4: fully awake (most protective). The results showed VAS was higher i n SM infants than controls: +0.03 (p = 0.04). The oxygen saturation (SaO(2) ) of SM infants fell -0.4% (p = 0.02) more than SaO(2) Of controls despite a greater tidal volume increase: +13.0% (p = 0.04). Overall protective resp onses were the same between groups, but grade 1, although rare, was found i n 7 SM infants and only 4 control infants; this difference was not signific ant. 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.