An Analysis of the pH of Exhaled Breath Condensate and Its Correlation to Severity of Interstitial Lung Disease

Introduction: Interstitial lung disease [ILD] is a group of heterogeneous lung conditions of varied etiologies. This is a pilot study done in a tertiary care hospital using the resources available. Aim: To assess the pH of exhaled breath condensate [EBC] in ILD patients and to correlate pH of EBC to severity of ILD Materials and methods: This is a prospective observational study involving 30 ILD patients. Spirometry was performed to determine the severity of the disease [flow limitation and degree of restriction] followed by collection of EBC and its analysis without de-aeration using an ABG machine. Data of 30 age and sex matched controls was utilized for cross matching and analysis. Results: Out of 17 cases with FVC values above 60 % of predicted value, i. e. with progression of the ILD, 11 had an EBC pH value of less than 7.45 [64.7 %].9 cases out of 13 with FVC values of less than 60 % of predicted value had an EBC pH value of greater than 7.45 [69.22 %]. Of the total 15 patients with EBC pH of greater than 7.45, 9 had dyspnea of severity grade III and above [60 %]. Conclusion: With a decrease in FVC value below 60 % of predicted i. e. with progression of the ILD, the EBC pH value increased above 7.45. This contradicts the findings of Alfredo Guillen-del Castillo, et al who had found that with progression of ILD in Systemic Sclerosis (SSc), the EBC pH decreased in value. With disease progression, the subjective sensation of dyspnea experienced by the patients also increased in grade which correlated with an EBC pH of greater than 7.45. Our study may not be representative of the entire population but it is a step forward in the study of the enigmatic disease of ILD. A larger study with more number of participants is needed to study this contradiction.