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Eur J Med Res. 1999 Aug 25;4(8):335-40.

Characteristics of flow dependency of nitric oxide in exhaled air in children with cystic fibrosis and asthma.

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Kinderklinik und Kinderpoliklinik im Dr. von Haunerschen Kinderspital, Pettenkoferstrasse 8a, D-80336 M√ľnchen, Germany.


Nitric oxide (NO) is a free radical produced by the lungs which can easily be measured in exhaled air. NO may serve as a non-invasive marker for airway inflammation in chronic inflammatory diseases like asthma. However in patients with cystic fibrosis (CF) and severe airway involvemen normal or low levels of NO have been reported. To investigate this further we measured NO levels in exhaled air at 5 different flow rates in 14 asthmatics, 15 CF-patients and 13 healthy children. A dependency of exhaled NO on expiratory flow was demonstrated in all three groups. At slow flows lower NO levels in CF-patients and significantly higher levels in asthmatics compared to healthy individuals were found. When the data were fitted to a one compartment model of the lung described by NO(MOUTH) = NO(LUNG) - NO(LUNG) x e(-T/Vex) (T = transfer factor; Vex = expiratory flow), NO(LUNG) was increased in asthmatics (191.9 +/- 53.8 ppb) and low in CF (26.7 +/- 5.7 ppb) compared to healthy individuals (76.9 +/- 50.9 ppb; p(anova) = 0.0213). NO produced in the central compartment of the lung behaved similarly and was distinguished from a peripheral compartment with the two compartment model NO(MOUTH) = NO(central) - (NO(central) - NO(peripher) ) x e(-T/Vex). We conclude that NO in exhaled air is flow dependent and at slow expiratory flows elevated in asthmatics and reduced in CF-patients compared to healthy children. Concentrations extrapolated for the whole lung and for the central airways changed proportionally.

[Indexed for MEDLINE]

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