Chest
Volume 138, Issue 1, July 2010, Pages 107-113
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ORIGINAL RESEARCH
ASTHMA
Exhaled Nitric Oxide and Exhaled Breath Condensate pH in Severe Refractory Asthma

https://doi.org/10.1378/chest.09-1257Get rights and content

Background

Distinct inflammatory cellular phenotypes of severe refractory asthma (SRA) have been reported. Fractional exhaled nitric oxide (FeNO) primarily is related to eosinophilic inflammation. Exhaled breath condensate (EBC) pH has been suggested as a noninvasive tool in the assessment of patients with asthma. We sought to determine whether FeNO and EBC pH could identify the presence and type of the underlying cellular inflammation in patients with SRA.

Methods

Twenty-nine patients with SRA, 27 patients with moderate asthma, and 17 healthy subjects underwent FeNO measurement, EBC collection for pH measurement, and sputum induction for cell count identification.

Results

FeNO was significantly higher and pH significantly lower in patients with SRA than in the other groups. In SRA, FeNO levels of > 19 parts per billion were associated with a sensitivity of 0.78 and a specificity of 0.73 for sputum eosinophilia, whereas FeNO levels of < 19 parts per billion were associated with a sensitivity of 0.63 and a specificity of 0.9 for sputum neutrophilia irrespective of the presence of eosinophils. The pH failed to predict the cellular profile in SRA, but a cutoff value of < 7.37 could predict sputum eosinophilia in moderate asthma.

Conclusions

In patients with SRA, different FeNO threshold values can identify those with predominant eosinophilia as well as those with neutrophilia. FeNO levels were reduced in patients with predominant neutrophilia regardless of the concomitant presence of eosinophilia. Although pH could not identify the cellular profile in SRA, it seemed to be a better index for predicting eosinophilia in moderate asthma.

Section snippets

Subjects

Subjects were recruited from an open cohort of patients with asthma who were under medical follow-up care in the asthma clinics of the First and Second Respiratory Medicine University Departments in Athens, Greece. The diagnosis of asthma was established according to Global Initiative for Asthma guidelines.1 The diagnosis of SRA was established according to American Thoracic Society criteria.2 Twenty-nine patients with SRA were recruited. All were receiving high doses of ICS (> 1.2 μg

pH and FeNO Values in the Three Study Groups

Subjects' characteristics are summarized in Table 1. The EBC pH in patients with SRA was significantly lower than in patients with moderate asthma and healthy subjects (7.22 ± 0.08 vs 7.36 ± 0.06 vs 7.72 ± 0.1, respectively; P < .0001), (Fig 1A, Table 1). FeNO levels were significantly higher in patients with SRA than in patients with moderate asthma and healthy subjects (43 [18.5-72.5] vs 25 [17–38] vs 12 [9.5–19], respectively; P < .0001) (Fig 1B, Table 1).

Inflammatory Cells in Induced Sputum

Patients with SRA had significantly

Discussion

In this study, different cutoff values of FeNO in patients with SRA identified those with predominant sputum eosinophilia and neutrophilia. Those with sputum eosinophilia had elevated FeNO levels despite high-dose steroid treatment, whereas those with sputum neutrophilia had low FeNO levels regardless of the concomitant presence of eosinophilia. EBC pH could not identify the cellular profiles in SRA; however, it had a better prognostic performance for the eosinophilic profile in moderate asthma.

Acknowledgments

Author contributions: Dr Tseliou: contributed to the performance of the FeNO and pH measurements and sputum induction and processing.

Dr Bessa: contributed to the performance of the FeNO and pH measurements and sputum induction and processing.

Dr. Hillas: contributed to the performance of sputum induction and processing.

Dr Delimpoura: contributed to the performance of the FeNO and pH measurements and sputum induction and processing.

Dr Papadaki: contributed to the performance of the FeNO and pH

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