Respiratory responses to hypoxia/hypercapnia in small for gestational age infants influenced by maternal smoking. Issue 3 (1st March 2003)

• Record Type: Journal Article
• Authors: Galland, B C; Taylor, B J; Bolton, D P G; Sayers, R M
• Is Part Of: Archives of disease in childhood. Volume 88:Issue 3(2003)
• Page Start: F217
• Page End: F222
• Publication Date: 2003-03-01
• Subjects: SIDS -- smoking -- asphyxia -- rebreathing; AGA, average for gestatinal age -- AS, active sleep -- HR, heart rate -- IUGR, intrauterine growth retardation -- QS, quiet sleep -- RR, respiratory rate -- SGA, small for gestational age -- SIDS, sudden infant death syndrome -- VAS, ventilatory asphyxial sensitivity -- Ve, minute ventilation -- VT -- tidal volume; Infants -- Diseases -- Periodicals; Newborn infants -- Diseases -- Periodicals; Fetus -- Diseases -- Periodicals; 618.920105
• DOI: 10.1136/fn.88.3.F217
• Languages: English
• ISSNs: 1359-2998

Abstract

Abstract : Aim: To determine any variation in the respiratory responses to hypoxia/hypercapnia of infants born small for gestational age (SGA) to smoking and to non-smoking mothers. Methods: A total of 70 average for gestational age (AGA) infants (>36 weeks gestation, >2500 g, >25th centile for gestational age, and no maternal smoking), and 47 SGA infants (<10th centile for gestational age) were studied at 1 and 3 months of age, in quiet and active sleep. Respiratory test gases were delivered through a Perspex hood to simulate face down rebreathing by slowly allowing the inspired air to be altered to a CO2 maximum of 5% and O2 minimum of 13.5%. The change in ventilation with inspired CO2 was measured over 5–6 minutes 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). Results: There was no significant difference in VAS between the AGA and SGA infants (0.25 v 0.24). However within the SGA group, VAS was significantly higher (p = 0.048) in the infants whose mothers smoked during pregnancy (0.26 (0.01); n = 24) than in those that did not (0.23 (0.01); n = 23). The change in minute ventilation was significantly higher in the smokers than the non-smokers group (141% v 119%; p = 0.03) as the result of a significantly larger change in respiratory rate (8 v 4 breaths/min; p = 0.047) but not tidal volume. Conclusions: Maternal smoking appears to be the key factor in enhancing infants' respiratory responses to hypoxia/hypercapnia, irrespective of gestational age.