Healthy African Americans have an Increased Prevalence of Low Exhaled Breath Condensate pH values

Article Outline

• Rationale
• Methods
• Results
• Conclusions
• Copyright

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Rationale 

Exhaled Breath Condensate (EBC) pH values are used as a marker of disease activity in asthma and other inflammatory conditions. Previous reports of mixed ethnicity cohorts cohorts have shown that only 3-5% of healthy subjects have an EBC pH <6.5.

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Methods 

Two hundred and seventy healthy, non-asthmatic, non-smoking African American subjects between the ages of 18 and 40 were evaluated. Subjects had simultaneous measurement of EBC pH (before and after argon deaeration), EBC Nitrite, Nitrate and exhaled Nitric Oxide (FeNO).

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Results 

In the sample of 270 subjects, the median EBC pH was 6.17 (interquartile range 5.50-6.78) prior to argon deaeration and 8.14 (interquartile range 7.83-8.28) after argon deaeration. There were 11.9% of subjects with a post-argon pH < 6.5. EBC pH did not correlate with FeNO except at low pH. Low pH subjects (n = 32) showed an inverse correlation between pH and FeNO (r² = 0.158, p = 0.0245). In the entire cohort, there was a direct relationship between pH and EBC Nitrite (r² = 0.163, p < 0.0001), there was no correlation between nitrite and FeNO.

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Conclusions 

We report increased prevalence (11.9%) of low EBC pH values (<6.5) in healthy non-smoking African Americans. EBC pH and Nitrite showed a direct correlation, however there was not correlation between Nitrite and FeNO. FeNO was not correlated with EBC pH except at pH values <6.5. This is important as EBC pH is used as a diagnostic tool for asthma and other inflammatory lung diseases. Use of this tool in African Americans must account for the increased incidence of low pH values (11.9%).