[Day/Night Variability of Coughing Events in Interstitial Lung Disease]

Besides dyspnea a dry cough is one of the main symptoms in patients with pulmonary fibrosis. Little is known about the 24-hour-variability of this symptom. Moreover, it is unclear if other auscultation phenomena occur.

A long-term auscultation for 24-hours was performed in patients with fibrotic lung diseases (LEOSound, Löwenstein Medical GmbH & Co. KG, Medical-Electronics, Bad Ems, Germany). Coughing and wheezing sounds were recorded. For the following analysis the 24-hour period was divided into two intervals of 12 hours each (daytime and nighttime). Events were registered in epochs (at least one event in 30 seconds).

20 patients were included (6 with nonspecific interstitial pneumonia and 14 with idiopathic pulmonary fibrosis). On average 166 coughing epochs were recorded in a 24-hour-period (day/night 116/50; P < 0.001). Moreover, 203 wheezing epochs were registered (day/night 84/119; P = 0.273). Auscultation phenomena did not correlate with spirometric and bodyplethymographic data, nor with data of diffusion capacity.

The study is showing the clinical potential of long-term auscultation in patients with fibrotic lung diseases. Especially the findings concerning the coughing symptoms were remarkable. It could be shown that there was a decrease of coughing during nighttime in comparison to daytime. In contrast to this, wheezing sounds were increasing at nighttime. The clinical relevance of this finding is yet to be assessed. Finally, there was no correlation between the severity of the disease measured by functional diagnostics and the amount of coughing.