Assessment of functional residual capacity using nitrogen washout and plethysmographic techniques in infants with and without bronchopulmonary dysplasia.
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.
Wauer
R R
RR
Department of Neonatology, Pediatric Clinic, Medical Faculty (Charité), Humboldt University, Berlin, Germany. Wauer@rz.charité.hu-berlin.de
Maurer
T
T
Nowotny
T
T
Schmalisch
G
G
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
D009584:Nitrogen