Gas trapping in normal infants and in infants with cystic fibrosis

• Published in: Pediatric pulmonology 2004-05, Vol.37 (5), p.461-469
• Main Authors: Castile, Robert G., Iram, Durdana, McCoy, Karen S.
• Format: Article
• Language: English
• Subjects: Air; Airway Obstruction; Biological and medical sciences; body plethysmography; Cystic Fibrosis - diagnosis; Cystic Fibrosis - physiopathology; Female; Functional Residual Capacity; Gastroenterology. Liver. Pancreas. Abdomen; General aspects; Helium; Humans; Infant; infant pulmonary function; Liver. Biliary tract. Portal circulation. Exocrine pancreas; Male; Maximal Expiratory Flow-Volume Curves; Medical sciences; nitrogen washout; Other diseases. Semiology; Plethysmography; Pneumology; Total Lung Capacity
• ISSN: 8755-6863; 1099-0496
• DOI: 10.1002/ppul.10446

Two different methods for estimating trapped gas volume have been described in the literature. The purpose of this study was to use both of these methods to estimate and compare trapped gas volumes in normal infants and infants with cystic fibrosis (CF). Thirty normal infants and 29 infants with CF, ages 1 month to 3 years, were studied. Pulmonary function tests, including raised volume forced expiratory flows, plethysmographic functional residual capacity (FRCpleth), and fractional lung volumes, were measured. Then functional residual capacity was measured by nitrogen washout (FRCnitrogen). Following nitrogen washout, lungs were then inflated three times to 30 cm H2O, using 100% oxygen. This process was repeated until no further nitrogen could be washed from the lungs. The volume of trapped gas (tg) was calculated from the total additional amounts of nitrogen expired following lung inflations. The difference between FRCpleth and FRCnitrogen provided a second estimate of trapped gas volume (delta V). Mean tg and delta V values for normal infants were 2.5 ± 3.5 ml and 15.6 ± 30.4 ml, respectively. Mean tg and delta V values for infants with CF were 5.8 ± 7.7 ml and 33.2 ± 43.8 ml, respectively. Both tg and delta V did not differ significantly between normal infants and infants with CF. Measured following raised volume forced expiratory maneuvers, delta V and tg do not distinguish infants with CF from normal infants as well as do other currently available tests of infant lung function. Pediatr Pulmonol. 2004; 37:461–469. © 2004 Wiely‐Liss, Inc.