Medicine of the Future in America

Normative Data for pH of Exhaled Breath Condensate

Normative Data for pH of Exhaled Breath CondensateMeasurement of the pH of body fluids has a long -L and successful history in clinical diagnosis. Exhaled breath condensate (EBC) pH has recently been added to the list as a useful assessment relevant to lung disease diagnosis and management. EBC pH was initially noted to be abnormally low during acute asthma exacerbations. It was subsequently recognized that EBC pH is low in diverse respiratory disease states, including asthma, COPD, chronic cough, bronchiectasis, ARDS, and others. EBC pH correlates with other indexes of airway inflam-mation. Beyond being simply a biomarker of disease status, low EBC pH has provided data supporting the important role of airway acid stress in respiratory diseases. buy ventolin

Two methods of reporting EBC pH have been included in the literature: (1) measurement of pH after gas standardization (sometimes called “deaeration”) to equilibrate EBC with a CO2-free gas; and (2) measurement of pH without this gas standardization step. Although the data from these two different systems may correlate, the resulting pH values are different, and they need to be understood as having different meanings. EBC pH measurement is perhaps the most technically validated of all measurements performed to date on EBC, with diverse subject, collection, storage, and assay system variations having been evaluated. There are multiple published articles presenting normal control data in small numbers of subjects (Table 1). In this article, we present data from 404 self-reported healthy volunteers as a normal reference range for gas standardized EBC pH. Because the EBC pH measurement reproducibly can be performed in laboratories throughout the world, we believe this reference database will serve to enhance interlaboratory communication. Self-described healthy volunteers were recruited from the area surrounding the University of Virginia in the United States. This is a mixed community of urban, suburban, and rural families. To ensure that the population would serve as the most useful control group, subjects were excluded from the study if they affirmed on screening that they smoked tobacco or had any of the following symptoms or diseases: chronic cough, recurrent or chronic wheeze, COPD, emphysema, chronic bronchitis, cystic fibrosis, asthma, recurrent bronchitis, chronic nasal or sinus conditions, or any other respiratory symptom or condition.

Table 1—Articles Presenting Normal Control Data

Source Year EBC pH Healthy Subjects/ Samples, No. Comments
Hunt et al 2000 7.7 ± 0.2t 19/19 Healthy nonsmokers
Kostikas et al2 2002 7.57 (7.51-7.64) 10/10 Adults
Gessner et al 2003 7.46 ± 0.5т 12/12 Adults; samples were gas standardized in a different manner.
Vaughan et al 2003 7.7 ± 0.5т 100/773 Adults
Vaughan et al 2003 7.8 ± 0.3т 32/32 Adults, intubated
Niimi et al 2004 8.26 16/16 Adults; mean age, 43 yr
Tesse, et al 2004 7.78 30/30 Children; mean age, 7 yr
Carpagnano et al 2004 С?Сс±5CC 15/15 Children; mean age, 7 yr
Rosias et al 2004 сс±7сОС 23/23 Children; mean age, 9 yr
Carraro et al 2005 7.85 (7.8-7.9) 13/13 Children; mean age, 10 yr
Borrill et al 2005 7.61 (7.52-7.70) 12/12 Adults; mean age, 26 yr
This entry was posted in Pulmonary function and tagged airway pH, exhaled breath condensate, reference ranges.
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