Assessment of lung function in pre-school children with cystic fibrosis by nitrogen washout

Pulmonary function in young children can identify the early manifestations of diseases like cystic fibrosis (CF) and prompt to early intervention. We evaluated in pre-school age children the performance of ventilatory indices obtained from N2 washout (FRC, LCI, Scond, Sacin) as to their feasibility and ability to detect differences between disease and control groups. N2 washout was performed with a novel system that utilizes an ultrasonic flow sensor as well as O2 and CO2 sensors (Exhalyzer, EcoMedics AG). N2 washout was performed during tidal breathing and using 100% Oxygen. Three maneuvers free of artifact were obtained whenever possible and allowing for 2-times the washout time to lapse between maneuvers. This was followed by spirometry and aiming to obtain at least 3 valid flow volume loops. Study groups included children ages 3 to 6 year old with CF (n=20) and asthma (AS, n=15), as well as a group of healthy controls (HC, free from history of respiratory disease or cigarette smoke exposure). Children were studied at a period of freedom from any acute symptomatology. Research quality Nitrogen washout could be completed in 90% of CF, 75% of AS and 70% of HC. FRC was comparable between the groups (p=0.1). The LCI from the N2 washout was elevated in CF with a mean of 10.4 ± 2.6, as well as Scond 0.05 ± 0.03 and Sacin 0.5 ± 0.5, which was statistically significant from the other 2 groups (p