title: Neonatal respiratory mechanics and development of bronchial hyperresponsiveness in preterm infants.
abstract: BACKGROUND
  In preterm ventilated infants, irreversible damage to the airway mucosa in the neonatal period might be related to the development of bronchial hyperresponsiveness (BHR) in subsequent years.
  
  
  OBJECTIVE
  To evaluate whether neonatal indicators of long-term respiratory morbidity, respiratory system compliance (Crs) and resistance (Rrs), were causally related to bronchial responsiveness at the age of 2 and whether these relationships were affected by other factors.
  
  
  METHODS
  Mean neonatal Crs and Rrs of the first 3 days of life were assessed using the single breath occlusion technique. Bronchial challenge tests were performed at 2 years of age. When wheezing occurred during chest auscultation or oxygen saturation decreased below 90%, the provocative concentration of methacholine was recorded.
  
  
  METHODS
  Forty-five preterm infants of <37 weeks gestation, being mechanically ventilated within 24 h after birth.
  
  
  RESULTS
  Decreased neonatal Crs was related to BHR (beta per ml/kPa, 0.061; 95% confidence interval, 0.019 to 0.103; p=0.006). Correction was required for radiological gradation of respiratory distress syndrome, the maximal peak inspiratory pressure required during mechanical ventilation and postnatal corticosteroid therapy. Neonatal Rrs, gestational age and birth weight were not related to subsequent BHR development.
  
  
  CONCLUSIONS
  In ventilated preterm infants, decreased neonatal Crs was related to the development of BHR at the age of 2.
authors.affiliation: Department of Paediatric Pulmonology, University Medical Centre Utrecht, Utrecht, The Netherlands. yvonne.snepvangers@wanadoo.nl
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Snepvangers
authors.forename: J Peter
authors.initials: JP
authors.lastname: Peter de Winter
authors.forename: Huibert
authors.initials: H
authors.lastname: Burger
authors.forename: Hens
authors.initials: H
authors.lastname: Brouwers
authors.forename: Cornelis K
authors.initials: CK
authors.lastname: Van der Ent
mesh_terms: D000328:Adult; D000403:Airway Resistance / Q000502:physiology*; D001249:Asthma / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000209:etiology / Q000503:physiopathology*; D001985:Bronchial Provocation Tests; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008170:Lung Compliance / Q000502:physiology*; D008297:Male; D047928:Premature Birth; D015656:Respiratory Mechanics