Summary of the data available in chronic obstructive pulmonary disease(COPD) patients for each exhaled breath condensate (EBC) biomarker with respect to diagnosis, disease severity/phenotype, monitoring of exacerbations and therapeutic intervention
| EBC biomarker | Diagnosis | Disease severity/phenotype | Exacerbation monitoring | Therapeutic intervention |
| pH | pH reduced in COPD 20, 37 | pH correlates with sputum neutrophilia 37pH correlates with FEV1 37 or has no correlation with FEV1 20 | No data | No data |
| LTB4 | LTB4 increased in COPD 43, 54 | LTB4 correlates with sputum neutrophilia 37 | Increased LTB4 during exacerbations 13 | Increased LTB4 with ibuprofen 65 |
| PGE2 | PGE2 increased in COPD 43 | No data | No data | Reduced PGE2 with ibuprofen 65 |
| Cytokines | IL-6, TNF-α and IL-10 are increased in COPD 63, 66 | IL-6 correlates with smoking history and FEV1 66 | Increased levels (multiplex array) during exacerbations 67 | No data |
| H2O2 | H2O2 increased in COPD 68, 69 | H2O2 correlates with FEV1, sputum neutrophilia and dyspnoea score 27 | Increased H2O2 during exacerbations 14, 68 | Reduced H2O2 with N-acetylcysteine 70; conflicting data in steroid studies 71, 72 |
| 8-isoprostane | 8-isoprostane increased in COPD 27, 58, 73 | No correlation with smoking, sputum cells or dyspnoea score 27, 58; 8-isoprostane increased in severe COPD 73 | Increased 8-isoprostane during exacerbations 13 | No data |
| NO metabolites | NO2- and RS-NO increased in COPD 73 | No data | No data | No data |
FEV1: forced expiratory volume in one second; LT: leukotriene; PG: prostaglandin; IL: interleukin; TNF: tumour necrosis factor; H2O2: hydrogen peroxide; NO2-: nitrite; RS-NO: nitrosothiols; NO: nitric oxide.