TY - JOUR
T1 - Determinants of exhaled breath condensate pH in a large population with asthma
AU - Liu, Lei
AU - Teague, W. Gerald
AU - Erzurum, Serpil
AU - Fitzpatrick, Anne
AU - Mantri, Sneha
AU - Dweik, Raed A.
AU - Bleecker, Eugene R.
AU - Meyers, Deborah
AU - Busse, William W.
AU - Calhoun, William J.
AU - Castro, Mario
AU - Chung, Kian Fan
AU - Curran-Everett, Douglas
AU - Israel, Elliot
AU - Jarjour, W. Nizar
AU - Moore, Wendy
AU - Peters, Stephen P.
AU - Wenzel, Sally
AU - Hunt, John F.
AU - Gaston, Benjamin
N1 - Funding Information:
Funding/Support: This work was supported by the National Institutes of Health [Grants NIH/NHLBI: 2RO1, HL 69170 NHLBI Severe Asthma Research Program] .
Funding Information:
The Severe Asthma Research Program is a multicenter collaborative study sponsored by the National Heart, Lung, and Blood Institute. 24 The goal of the study is to characterize as fully as possible the distinguishing features of severe asthma, as defined by the American Thoracic Society Consensus Meeting and adopted by the SARP Steering Committee. 24,25 All subjects with severe asthma are maintained long-term on high-dose inhaled and/or systemic corticosteroid treatment and remain symptomatic when compared with a large cohort of subjects with nonsevere asthma and with a smaller cohort of control subjects enrolled for comparison. 24,25 The methods of evaluation have been published. 24 All subjects undergo lung function testing, including maximum bronchodilator challenge; they also undergo an extensive, questionnaire-based history, including allergy history, and those subjects who do not have a specific contraindication undergo methacholine challenge and flexible bronchoscopy. Subjects also undergo allergen skin testing (Greer; Lenoir, North Carolina) for tree mix (white ash, American beech, red birch, American elm, shagbark hickory, red oak, cottonwood), timothy grass, ragweed, Alternaria, Cladosporium, Aspergillus, Dermatophagoides farinae, Dermatophagoides pteronyssinus, weed mix (cocklebur, lambs quarter, pigweed, English plantain, Russian thistle), dog, cat, and cockroach. Most subjects in the first phase of SARP, including all patients at the Wake Forest, North Carolina; Emory, Georgia; Cleveland, Ohio; Virginia; and Wisconsin sites, where there was a specific interest in EBC analysis, underwent EBC analysis. The protocol was approved by the Institution Review Board of each participating institution.
PY - 2011/2/1
Y1 - 2011/2/1
N2 - Background: Exhaled breath condensate(EBC) pH is 2 log orders below normal during acute asthma exacerbations and returns to normal with antiinflammatory therapy. However, the determinants of EBC pH, particularly in stable asthma, are poorly understood. We hypothesized that patients with severe asthma would have low EBC pH and that there would be an asthma subpopulation of patients with characteristically low values. Methods: We studied the association of EBC pH with clinical characteristics in 572 stable subjects enrolled in the Severe Asthma Research Program. These included 250 subjects with severe asthma, 291 with nonsevere asthma, and 31 healthy control subjects. Results: Overall, EBC in this population of stable, treated study subjects was not lower in severe asthma (8.02;interquartile range [IQR], 7.61-8.41) or nonsevere asthma (7.90;IQR, 7.52-8.20) than in control subjects (7.9;IQR, 7.40-8.20). However, in subjects with asthma the data clustered below and above pH 6.5. Subjects in the subpopulation with pH < 6.5 had lower fraction of exhaled NO (FENO) values (FENO = 22.6 ± 18.1 parts per billion) than those with pH ≥ 6.5 (39.9 ± 40.2 parts per billion; P<.0001). By multiple linear regression, low EBC pH was associated with high BMI, high BAL neutrophil counts, low prebronchodilator FEV1 ratio, high allergy symptoms, race other than white, and gastroesophageal reflux symptoms. Conclusion: Asthma is a complex syndrome. Subjects who are not experiencing an exacerbation but have low EBC pH appear to be a unique subpopulation.
AB - Background: Exhaled breath condensate(EBC) pH is 2 log orders below normal during acute asthma exacerbations and returns to normal with antiinflammatory therapy. However, the determinants of EBC pH, particularly in stable asthma, are poorly understood. We hypothesized that patients with severe asthma would have low EBC pH and that there would be an asthma subpopulation of patients with characteristically low values. Methods: We studied the association of EBC pH with clinical characteristics in 572 stable subjects enrolled in the Severe Asthma Research Program. These included 250 subjects with severe asthma, 291 with nonsevere asthma, and 31 healthy control subjects. Results: Overall, EBC in this population of stable, treated study subjects was not lower in severe asthma (8.02;interquartile range [IQR], 7.61-8.41) or nonsevere asthma (7.90;IQR, 7.52-8.20) than in control subjects (7.9;IQR, 7.40-8.20). However, in subjects with asthma the data clustered below and above pH 6.5. Subjects in the subpopulation with pH < 6.5 had lower fraction of exhaled NO (FENO) values (FENO = 22.6 ± 18.1 parts per billion) than those with pH ≥ 6.5 (39.9 ± 40.2 parts per billion; P<.0001). By multiple linear regression, low EBC pH was associated with high BMI, high BAL neutrophil counts, low prebronchodilator FEV1 ratio, high allergy symptoms, race other than white, and gastroesophageal reflux symptoms. Conclusion: Asthma is a complex syndrome. Subjects who are not experiencing an exacerbation but have low EBC pH appear to be a unique subpopulation.
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U2 - 10.1378/chest.10-0163
DO - 10.1378/chest.10-0163
M3 - Article
AN - SCOPUS:79551574730
SN - 0012-3692
VL - 139
SP - 328
EP - 336
JO - CHEST
JF - CHEST
IS - 2
ER -