Measuring lung inhomogeneity in early chronic lung disease

Significant airway obstruction (FEV1 < 70%) appears to be a relatively late onset component of chronic airways disease. As such, early diagnosis of disease that will become COPD is not possible, and therefore opportunities for secondary prevention are lost. The rationale behind this study is that inhomogeneity arising from patchy areas of lung disease may be an earlier feature of such disease, and therefore measuring inhomogeneity may provide earlier diagnosis. Standard lung function testing does not measure inhomogeneity, and other approaches are either too complex or too simplistic. A recent development has been that of in-airway molecular flow sensing (MFS), which improves the measurement precision of gas exchange at the mouth by an order of magnitude. We have now developed a method to identify measures of inhomogeneity from data gathered using MFS. Importantly, the procedure simply requires a patient to breathe through the equipment for ∼ 15 min, with no special breathing manoeuvres required. Very preliminary data have been obtained from four normal individuals (A-D) and from one patient (E) with GOLD stage 1 COPD. Values for repeat determinations for a non-dimensional measure of the variation in compliance within the lung were: A: 0.46, 0.43; B: 0.50, 0.47; C: 0.33, 0.31; D: 0.34, 0.33 and E: 1.12, 1.30, 1.64, 0.94, 1.00, 1.29. Values for the COPD patient appear completely distinct from the normal volunteers. These very preliminary data support the notion that this new technology may provide earlier diagnosis of chronic lung disease, although obviously far more experimentation is required.