Backround:
Interstitial lung disease (ILD) patients often have difficulty in performing spirometry. Simple tests of pulmonary functions like the single breath count (SBC) and breath hold time (BHT) have been studied since years. At our institute (TNMC) we used these tests innovatively with modern technology in cases of ILD. The novel measurements and correlations for pulmonary function tests (TNMC-PFT) were compared with standard measures of PFT.

Material and Methods:
A prospective study was conducted in adult ILD patients referred to the PFT laboratory of a tertiary care hospital. The diagnosis of interstitial lung disease was arrived at with multi-disciplinary discussion. Spirometry, SBC and BHT were recorded. SBC was timed to a metronome (downloaded from a free online App) set at 2 counts per second. Six minute walk test was done. The average of SBC and BHT were labelled as TNMC-PFT. Spearmen’s Rho calculator was used to study correlation of TNMC-PFT with spirometry and six- minute walk distance (6MWD). R

Results:
The study included 18 men and 47 women. They consisted of 21 hypersensitivity pneumonitis, 17 CTD-ILD, 7 sarcoidosis, 11 idiopathic pulmonary fibrosis, 5 idiopathic non-specific interstitial pneumonia, and 4 other ILD cases. Mean Age, FVC and 6MWD were 51.1 (14.9) years, 1.3 (0.5) L and 266.2 (75.5) m. SBC, BHT and their average (TNMC-PFT) correlated moderately with FVC (r=0.5, p<0.05) and 6MWD (r=0.5, p<0.05).

Conclusion:
TNMC–PFT correlated well with FVC and six minute walk distance. TNMC-PFT can be a potential alternative to spirometry in ILD in severe disease and resource limited settings.