title: Dampened ventilatory response to added dead space in newborns of smoking mothers.
abstract: BACKGROUND
  Term newborns can compensate fully for an imposed dead space (tube breathing) by increasing their minute ventilation.
  
  
  OBJECTIVE
  To test the hypothesis that infants of smoking mothers would have an impaired response to tube breathing.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Perinatal service.
  
  
  METHODS
  Fourteen infants of smoking and 24 infants of non-smoking mothers (median postnatal age 37 (11-85) hours and 26 (10-120) hours respectively) were studied.
  
  
  METHODS
  Breath by breath minute volume was measured at baseline and when a dead space of 4.4 ml/kg was incorporated into the breathing circuit.
  
  
  METHODS
  The maximum minute ventilation during tube breathing was determined and the time constant of the response calculated.
  
  
  RESULTS
  The time constant of the infants of smoking mothers was longer than that of the infants of non-smoking mothers (median (range) 37.3 (22.2-70.2) v 26.2 (13.8-51.0) seconds, p = 0.016). Regression analysis showed that maternal smoking status was related to the time constant independently of birth weight, gestational or postnatal age, or sex (p = 0.018).
  
  
  CONCLUSIONS
  Intrauterine exposure to smoking is associated with a dampened response to tube breathing.
authors.affiliation: Division of Asthma, Allergy and Lung Biology, Guy's, King's and St Thomas' School of Medicine, King's College London, UK.
authors.forename: R Y
authors.initials: RY
authors.lastname: Bhat
authors.forename: S
authors.initials: S
authors.lastname: Broughton
authors.forename: B
authors.initials: B
authors.lastname: Khetriwal
authors.forename: G F
authors.initials: GF
authors.lastname: Rafferty
authors.forename: S
authors.initials: S
authors.lastname: Hannam
authors.forename: A D
authors.initials: AD
authors.lastname: Milner
authors.forename: A
authors.initials: A
authors.lastname: Greenough
mesh_terms: D005260:Female; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D008297:Male; D009035:Mothers; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011446:Prospective Studies; D012044:Regression Analysis; D012126:Respiratory Dead Space; D015656:Respiratory Mechanics; D012907:Smoking