Table 1

 Summary of exhaled breath measures

SourceUseCollectionAnalysisPitfalls
Exhaled NODerived from endothelial, epithelial, and inflammatory cellsMeasure of pulmonary inflammation in ventilated premature newborns and in adults with obstructive sleep apnoea, ARDS and asthma.Airway specimen collected from endotracheal tube in ventilated newbornsChemiluminescenceProduction by paranasal sinuses/nasal passages in both newborns and adults
NO synthesised from arginine by NO synthetaseSingle breath technique in adultsIncreased after arginine infusion
Exhaled COEndogenous production after degradation of haem-containing proteins by haem oxygenaseValidated measure of Coombs positive haemolysis in non-ventilated newbornsIntranasal sampling in non-ventilated newbornsElectrochemical sensorPassive diffusion of CO across the placenta in infants of smoking mothers
Exogenous contaminantInflammatory measure in adults with asthma, cystic fibrosis, and bronchiectasis and in children with sepsisEnd tidal breath collection in adults
Exhaled volatile hydrocarbons (pentane, ethane)Derived from free radical peroxidation of membrane bound polyunsaturated fatty acidsCorrelated with death or later chronic lung disease in premature ventilated infantsExpiratory flow diverted after period of washout in ventilated newbornsGas chromatography with mass spectroscopyHigh concentration in ambient air and infused lipid emulsion
Exogenous contaminantMeasure of inflammation in obstructive sleep apnoea, asthma, and rheumatoid arthritis in adults and in an animal model of colitisSingle breath technique in adults after similar washoutPotential contamination from collection circuit
Exhaled breath condensateDerived from varied components of lung lining fluidPreliminary data as a measure of pulmonary inflammation in adults and childrenActive exhalation with subsequent specimen freezing after prolonged oral breathingVaries with each compound measuredDifficult gas collection especially in young children