title: Persisting hypoxaemia is an insufficient measure of adverse lung function in very immature infants.
abstract: BACKGROUND
  Bronchopulmonary dysplasia (BPD), defined as protracted neonatal hypoxaemia, is considered a risk factor for respiratory disease in adulthood. The relationship between this diagnosis and the actual lung injury appearing in very immature infants is, however, unknown.
  
  
  OBJECTIVE
  To compare lung function at term in very immature infants and full-term infants, and to determine how degree and duration of neonatal hypoxaemia are related to other aspects of lung function.
  
  
  METHODS
  All surviving, consecutive infants with gestational age below 28 weeks from a geographically defined area were eligible. The alveolar-arterial oxygen pressure difference was assessed as a measure of oxygenation failure. At term, functional residual capacity and gas-mixing efficiency were measured by multiple-breath nitrogen washout, and compliance and conductance of the respiratory system by the occlusion method. The results were compared to those in 50 full-term controls.
  
  
  RESULTS
  Thirty-seven of 46 eligible infants were included. The preterm infants differed markedly from the full-term infants in all lung functions tested. Infants diagnosed as having BPD had more compromised lung function than those without, but the latter group differed markedly from the full-term group in functional residual capacity, compliance and gas-mixing efficiency. Only the mechanical variables were correlated to hypoxaemia at 36 weeks postmenstrual age (PMA).
  
  
  CONCLUSIONS
  Infants with gestational age below 28 weeks at birth have remarkably impaired lung function at term, regardless of whether they carry the diagnosis BPD or not. All very immature infants may be at risk of future respiratory disease and should be monitored appropriately.
authors.forename: Ola
authors.initials: O
authors.lastname: Hjalmarson
authors.forename: Hrolfur
authors.initials: H
authors.lastname: Brynjarsson
authors.forename: Staffan
authors.initials: S
authors.lastname: Nilsson
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Sandberg
mesh_terms: D001997:Bronchopulmonary Dysplasia / Q000503:physiopathology* / Q000628:therapy; D016022:Case-Control Studies; D005260:Female; D005652:Functional Residual Capacity / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008168:Lung / Q000503:physiopathology*; D008170:Lung Compliance / Q000502:physiology; D008176:Lung Volume Measurements / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010102:Oxygen Inhalation Therapy / Q000379:methods; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012129:Respiratory Function Tests / Q000379:methods; D015656:Respiratory Mechanics / Q000502:physiology
chemical_list: D010100:Oxygen