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Updated: Aug 23, 2026

Fast and Accurate Exhaled Breath Ammonia Measurement
Published on: June 11, 2014
Effects of breathing pattern and inspired air conditions on breath condensate volume, pH, nitrite, and protein
J B McCafferty1, T A Bradshaw, S Tate
1Respiratory Unit, Western General Hospital, Crewe Road, Edinburgh EH2 4XU, UK. john.mccafferty@ed.ac.uk
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) microl, 1019 (313) microl, and 1358 (364) microl, respectively (p<0.001) and TEW was 1879 (378) microl, 2986 (496) microl, and 4679 (700) microl, 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 microl/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 microl/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.
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