Ambient temperature impacts on pH of exhaled breath condensate.
OBJECTIVE
Analysis of exhaled breath condensate (EBC) pH is a non-invasive method to study airway inflammation. Low pH is correlated with inflammatory diseases like asthma and COPD. The aim of this study was to assess the influence of measurement temperature on pH values of EBC.


METHODS
EBC was collected using the RTube in 10 healthy non-smoking controls, 10 smokers before and after cigarette smoking, 10 stable COPD patients and 10 patients with exacerbated COPD. pH was determined directly after degassing at temperatures of 23 degrees C and 37 degrees C.


RESULTS
When comparing all groups pH was significantly (P = 0.0002) higher (mean +/- SD 7.88 +/- 0.92) at 37 degrees C as compared with 23 degrees C (7.44 +/- 0.90). Specifically, at 23 degrees C pH was significantly lower in the group of exacerbated COPD (6.78 +/- 1.27) and healthy non-smoking controls (8.04 +/- 0.39). In contrast, subgroup analysis of values assessed at 37 degrees C did not display significant differences.


CONCLUSIONS
Our data indicate a considerable influence of temperature on pH values in EBC. Thus the temperature at which pH measurements in EBC studies are performed should be declared.
Koczulla
Andreas R
AR
Department of Internal Medicine, Pulmonology, Philipps-University Marburg, Germany. koczulla@med.uni-marburg.de
Noeske
Sarah
S
Herr
Christian
C
Dette
Frank
F
Pinkenburg
Olaf
O
Schmid
Severin
S
Jörres
Rudolf A
RA
Vogelmeier
Claus
C
Bals
Robert
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000175:diagnosis* / Q000378:metabolism; D001944:Breath Tests; D045853:Exhalation; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis* / Q000378:metabolism; D012907:Smoking / Q000378:metabolism; D013696:Temperature