Background: The effects of breathing pattern and inspired air conditions on the volume and content of exhaled breath condensate (EBC) were investigated. Methods: Total exhaled water (TEW), EBC volume, pH, nitrite and protein concentrations were measured in three groups of 10 healthy subjects breathing into a condenser at different target minute ventilations (Vm), tidal volumes (Vt), and inspired air conditions. Results: The volumes of both TEW and EBC increased significantly with Vm. For Vm 7.5, 15 and 22.5 l/ min, mean (SD) EBC was 627 (258) ml, 1019 (313) ml, and 1358 (364) ml, respectively (p,0.001) and TEW was 1879 (378) ml, 2986 (496) ml, and 4679 (700) ml, respectively (p,0.001). TEW was significantly higher than EBC, reflecting a condenser efficiency of 40% at a target Vm of 7.5 l/min which reduced to 29% at Vm 22.5 l/min. Lower Vt gave less TEW than higher Vt (26.6 v 30.7 ml/l, mean difference 4.1 (95% CI 2.6 to 5.6), p,0.001) and a smaller EBC volume (4.3 v 7.6 ml/l, mean difference 3.4 (95% CI 2.3 to 4.5), p,0.001). Cooler and drier inspired air yielded less water vapour and less breath condensate than standard conditions (p,0.05). Changes in the breathing pattern had no effect on EBC protein and nitrite concentrations and pH. Conclusion: These results show that condensate volume can be increased by using high Vt and increased Vm without compromising the dilution of the sample.
Circassia Ltd (Oxford, UK) provided an unrestricted educational grant to support the meeting in Perth on 9 th October 2018 which formed the basis of this manuscript. Circassia was not present at the meeting and had no input into the preparation of the manuscript.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.