title: Ventilatory response to hypercarbia in newborns of smoking and substance-misusing mothers.
abstract: BACKGROUND
  Infants of mothers who smoked (S) or substance misused (SM) during pregnancy have an increased risk of sudden infant death syndrome (SIDS).
  
  
  OBJECTIVE
  To test the hypothesis that infants of S and SM mothers compared with infants of non-substance-misusing, nonsmoking mothers (control subjects) would have a reduced ventilatory response to hypercarbia and that any reduction would be greater in the SM infants.
  
  
  METHODS
  Infants were assessed before maternity/neonatal unit discharge. Maternal and infant urine samples were obtained and tested for cotinine, cannabinoids, opiates, amphetamines, methadone, cocaine, and benzodiazepines.
  
  
  RESULTS
  Respiratory flow and Vt were measured using a pneumotachograph inserted into a face mask placed over the infant's mouth and nose. The ventilatory responses to three levels of inspired carbon dioxide (0 [baseline], 2, and 4% CO2) were assessed. Twenty-three SM, 34 S, and 22 control infants were assessed. The birth weight of the control subjects was higher than the SM and S infants (P = 0.017). At baseline, SM infants had a higher respiratory rate (P = 0.003) and minute volume (P = 0.007) compared with control subjects and S infants. Both the SM and S infants had a lower ventilatory response to 2% (P < 0.001) and 4% (P < 0.001) CO2 than the control subjects. The ventilatory response to CO2 was lower in the SM infants compared with the S infants (P = 0.009).
  
  
  CONCLUSIONS
  These results are consistent with infants of smoking mothers and substance misuse/smoking mothers having a dampened ventilatory response to hypercarbia, which is particularly marked in the latter group.
authors.affiliation: 1 Division of Asthma, Allergy, and Lung Biology, Medical Research Council & Asthma UK Centre in Allergic Mechanisms of Asthma.
authors.forename: Kamal
authors.initials: K
authors.lastname: Ali
authors.forename: Kim
authors.initials: K
authors.lastname: Wolff
authors.forename: Janet L
authors.initials: JL
authors.lastname: Peacock
authors.forename: Simon
authors.initials: S
authors.lastname: Hannam
authors.forename: Gerrard F
authors.initials: GF
authors.lastname: Rafferty
authors.forename: Ravindra
authors.initials: R
authors.lastname: Bhat
authors.forename: Anne
authors.initials: A
authors.lastname: Greenough
mesh_terms: D000293:Adolescent; D000328:Adult; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D006801:Humans; D006935:Hypercapnia / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D007231:Infant, Newborn; D018811:Maternal Exposure / Q000009:adverse effects*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000503:physiopathology*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D019966:Substance-Related Disorders / Q000150:complications* / Q000503:physiopathology; D013398:Sudden Infant Death / Q000209:etiology*; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide
keywords: carbon dioxide challenge; in utero exposure; sudden infant death syndrome