title: Respiratory impedance in healthy unsedated South African infants: effects of maternal smoking.
abstract: OBJECTIVE
  Non-invasive techniques for measuring lung mechanics in infants are needed for a better understanding of lung growth and function, and to study the effects of prenatal factors on subsequent lung growth in healthy infants. The forced oscillation technique requires minimal cooperation from the individual but has rarely been used in infants. The study aims to assess the use of the forced oscillation technique to measure the influence of antenatal exposures on respiratory mechanics in unsedated infants enrolled in a birth cohort study in Cape Town, South Africa.
  
  
  METHODS
  Healthy term infants were studied at 6-10 weeks of age using the forced oscillation technique. Respiratory impedance was measured in the frequency range 8-48 Hz via a face mask during natural sleep. Respiratory system resistance, compliance and inertance were calculated from the impedance spectra.
  
  
  RESULTS
  Of 177 infants tested, successful measurements were obtained in 164 (93%). Median (25-75%) values for resistance, compliance and inertance were 50.2 (39.5-60.6) cmH2 O.s.L(-1), 0.78 (0.61-0.99) mL.cmH2 O(-1) and 0.062 (0.050-0.086) cmH2 O.s(2) .L(-1), respectively. As a group, male infants had 16% higher resistance (P = 0.006) and 18% lower compliance (P = 0.02) than females. Infants whose mothers smoked during pregnancy had a 19% lower compliance than infants not exposed to tobacco smoke during pregnancy (P = 0.005). Neither maternal HIV infection nor ethnicity had a significant effect on respiratory mechanics.
  
  
  CONCLUSIONS
  The forced oscillation technique is sensitive enough to demonstrate the effects of tobacco smoke exposure and sex in respiratory mechanics in healthy infants. This technique will facilitate assessing perinatal influences of lung function in infancy.
authors.affiliation: Department of Paediatrics and Child Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Cape Town, South Africa.
authors.forename: Diane
authors.initials: D
authors.lastname: Gray
authors.forename: Dorottya
authors.initials: D
authors.lastname: Czövek
authors.forename: Emilee
authors.initials: E
authors.lastname: Smith
authors.forename: Lauren
authors.initials: L
authors.lastname: Willemse
authors.forename: Ane
authors.initials: A
authors.lastname: Alberts
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Gingl
authors.forename: Graham L
authors.initials: GL
authors.lastname: Hall
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Zar
authors.forename: Peter D
authors.initials: PD
authors.lastname: Sly
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Hantos
mesh_terms: D017097:Electric Impedance; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects*; D011247:Pregnancy; D012016:Reference Values; D012129:Respiratory Function Tests / Q000379:methods*; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System; D012907:Smoking / Q000009:adverse effects*; D013019:South Africa
keywords: forced oscillation technique; respiratory compliance paediatric; respiratory function test; respiratory resistance