Table 1
Summary of exhaled breath measures
| Source | Use | Collection | Analysis | Pitfalls | |
|---|---|---|---|---|---|
| Exhaled NO | Derived from endothelial, epithelial, and inflammatory cells | Measure 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 newborns | Chemiluminescence | Production by paranasal sinuses/nasal passages in both newborns and adults |
| NO synthesised from arginine by NO synthetase | Single breath technique in adults | Increased after arginine infusion | |||
| Exhaled CO | Endogenous production after degradation of haem-containing proteins by haem oxygenase | Validated measure of Coombs positive haemolysis in non-ventilated newborns | Intranasal sampling in non-ventilated newborns | Electrochemical sensor | Passive diffusion of CO across the placenta in infants of smoking mothers |
| Exogenous contaminant | Inflammatory measure in adults with asthma, cystic fibrosis, and bronchiectasis and in children with sepsis | End tidal breath collection in adults | |||
| Exhaled volatile hydrocarbons (pentane, ethane) | Derived from free radical peroxidation of membrane bound polyunsaturated fatty acids | Correlated with death or later chronic lung disease in premature ventilated infants | Expiratory flow diverted after period of washout in ventilated newborns | Gas chromatography with mass spectroscopy | High concentration in ambient air and infused lipid emulsion |
| Exogenous contaminant | Measure of inflammation in obstructive sleep apnoea, asthma, and rheumatoid arthritis in adults and in an animal model of colitis | Single breath technique in adults after similar washout | Potential contamination from collection circuit | ||
| Exhaled breath condensate | Derived from varied components of lung lining fluid | Preliminary data as a measure of pulmonary inflammation in adults and children | Active exhalation with subsequent specimen freezing after prolonged oral breathing | Varies with each compound measured | Difficult gas collection especially in young children |
