PT  - JOURNAL ARTICLE
AU  - Jeppe Hjembaek-Brandt
AU  - Mathias Hindborg
AU  - Andreas K. Jensen
AU  - Christian Ari Dalby Sørensen
AU  - Bodil Steen Rasmussen
AU  - Raluca Georgiana Maltesen
AU  - Morten Heiberg Bestle
TI  - The influence of active and passive air humidification on exhaled breath condensate volume
AID  - 10.1183/23120541.00009-2020
DP  - 2020 Oct 01
TA  - ERJ Open Research
PG  - 00009-2020
VI  - 6
IP  - 4
4099  - http://openres.ersjournals.com/content/6/4/00009-2020.short
4100  - http://openres.ersjournals.com/content/6/4/00009-2020.full
SO  - erjor2020 Oct 01; 6
AB  - Exhaled breath condensate (EBC) is safely collected in mechanically ventilated (MV) patients, but there are no guidelines regarding humidification of inhaled air during EBC collection. We investigated the influence of active and passive air humidification on EBC volumes obtained from MV patients.We collected 29 EBC samples from 21 critically ill MV patients with one condition of active humidification and four different conditions of non-humidification; 19 samples from 19 surgical MV patients with passive humidification and two samples from artificial lungs MV with active humidification. The main outcome was the obtained EBC volume per 100 L exhaled air.When collected with different conditions of non-humidification, mean [95% CI] EBC volumes did not differ significantly (1.35 [1.23; 1.46] versus 1.16 [1.05; 1.28] versus 1.27 [1.13; 1.41] versus 1.17 [1.00; 1.33] mL/100 L, p=0.114). EBC volumes were higher with active humidification than with non-humidification (2.05 [1.91; 2.19] versus 1.25 [1.17; 1.32] mL/100 L, p<0.001). The volume difference between these corresponded to the EBC volume obtained from artificial lungs (0.81 [0.62; 0.99] versus 0.89 mL/100 L, p=0.287). EBC volumes were lower for surgical MV patients with passive humidification compared to critically ill MV patients with non-humidification (0.55 [0.47; 0.63] versus 1.25 [1.17; 1.32] mL/100 L, p<0.001).While active humidification increases EBC volumes, passive humidification decreases EBC volumes and possibly influences EBC composition by other mechanisms. We propose that EBC should be collected from MV patients without air humidification to improve reproducibility and comparability across studies, and that humidification conditions should always be reported.When collected from mechanically ventilated (MV) patients, the volume of exhaled breath condensate (EBC) is influenced by both active and passive air humidification. EBC should be obtained from MV patients without air humidification if possible. https://bit.ly/2WC5G7B