title: Assessment of functional residual capacity using nitrogen washout and plethysmographic techniques in infants with and without bronchopulmonary dysplasia.
abstract: OBJECTIVE
  In normal infants, functional residual capacity using plethysmography (FRCpleth) exceeds FRC(N2) (using nitrogen washout) and the within-subject difference FRC(pleth-N2) indicates the part of pulmonary gas volume not ventilated during tidal breathing. We postulated that infants with bronchopulmonary dysplasia (BPD) have an elevated FRC(pleth-N2).
  
  
  METHODS
  In a prospective study, FRC(pleth-N2) in healthy newborns (controls n = 17) was compared to that in neonates recovering from the respiratory distress syndrome without BPD (noBPD, studied at discharge, n = 13) and with BPD (BPD1 n = 14, studied at 36 post-conceptional weeks; BPD2 n = 16, at discharge).
  
  
  RESULTS
  Paired measurements, FRCpleth and FRC(N2), were performed using a plethysmograph (Jaeger, Germany) and an open-circuit nitrogen washout technique (SensorMedics 2600, USA). In comparison to the controls (5.2 ml/kg), FRC(pleth-N2)/kg in noBPD (12.7 ml/kg, p < 0.001), in BPD1 (24.9 ml/kg, p < 0.001) and in BPD2 (13.5 ml/kg, p < 0.001) was significantly higher. Compared with that of the controls FRCpleth was significantly increased in BPD1 (p < 0.001) and FRC(N2) was decreased in noBPD and both BPD groups.
  
  
  CONCLUSIONS
  The FRC(pleth-N2) is a reliable indicator for pulmonary inhomogeneities in infants with respiratory diseases.
authors.affiliation: Department of Neonatology, Pediatric Clinic, Medical Faculty (Charité), Humboldt University, Berlin, Germany. Wauer@rz.charité.hu-berlin.de
authors.forename: R R
authors.initials: RR
authors.lastname: Wauer
authors.forename: T
authors.initials: T
authors.lastname: Maurer
authors.forename: T
authors.initials: T
authors.lastname: Nowotny
authors.forename: G
authors.initials: G
authors.lastname: Schmalisch
mesh_terms: D001944:Breath Tests / Q000379:methods; D001997:Bronchopulmonary Dysplasia / Q000175:diagnosis* / Q000503:physiopathology; D005652:Functional Residual Capacity / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009584:Nitrogen / Q000032:analysis*; D010993:Plethysmography, Whole Body / Q000379:methods* / Q000706:statistics & numerical data; D011446:Prospective Studies; D012016:Reference Values; D012044:Regression Analysis; D012127:Respiratory Distress Syndrome, Newborn / Q000175:diagnosis* / Q000503:physiopathology
chemical_list: D009584:Nitrogen