Comparison of two methods for exhaled breath condensate collection

Background: Exhaled breath condensate (EBC) is a noninvasive method to obtain samples from fluids lining the respiratory surfaces. Even though various methods and devices are now available, the relative efficiency of these methods for recovering airway mediators and characterizing EBC has not been established. Aim: To compare the volume, pH, lipid mediator, and protein concentrations in EBCs collected by two commonly used commercially available devices, RTube™ and ECoScreen. Methods: Exhaled breath condensates were obtained consecutively using the RTube™ and ECoScreen methods from 30 healthy, nonallergic adults. Samples were immediately placed on dry ice after collection. pH was measured after argon deaeration. Cysteinyl leukotrienes (cys-LTs) were measured as a representative lipid mediator and eotaxin as the protein mediator by using enzyme-linked immunosorbent assay. Results: The mean volume of samples obtained with ECoScreen (1880 ± 116 μl) was significantly higher than that obtained with RTube™ (1405 ± 82 μl) (P < 0.001). Concentrations of both cys-LTs [205.4 pg/ml (65.5-472.3) with ECoScreen vs 21.6 (11.87-152.2) with RTube™, P < 0.001] and eotaxin [17.0 pg/ml (11.4-22.4) with ECoScreen vs 11.7 (10.5-13.5) with RTube™, P = 0.01] were significantly higher in samples collected with ECoScreen than with RTube™. There was no significant difference between the pH measurements. Conclusion: Compared with RTube™, collection of exhaled breath by ECoScreen allows larger volumes to be collected and detects protein and lipid mediators with greater sensitivity. These differences in mediator recovery may be due to the differences in the collection temperature.