Breathing pattern in sarcoidosis and idiopathic pulmonary fibrosis.

We measured the volume and time components of the breathing cycle together with the P.1 in 16 sarcoidosis and 9 IPF patients. Patients in the IPF group were older, and their lung functions revealed a more restrictive pattern with small TLC, VC, and higher elastance values. We observed that in the two groups of patients there was a significant correlation between VT, f, and P.1 and lung elastance, and that the stiffer IPF patients had higher drive parameters. Hence, the main factor affecting the breathing pattern in both groups is the influence of the elastic load on the control of breathing. A significant relationship was also found between %VD/VT and elastance. We then compared the f values of the 16 sarcoidosis and 9 IPF patients with those of elastically loaded normal subjects. At equivalent levels of elastance, even though the patients and the normals showed qualitatively similar changes, the patients tended to have higher frequencies for the equivalent elastic load. In conclusion, ventilatory and drive parameters in interstitial lung diseases increased as a function of the elastic load, this load being greater in IPF than in sarcoidosis. Inflammation may stimulate the vagal receptors to increase the frequency of breathing, but this requires further study.