[Recent advance in evaluation of lung function of obstructive lung disease].

Chaos of the abdominal movement was examined in obstructive lung disease. Body inductive plethysmograph was used and the analog record was digitized at sampling interval of 100 ms. Correlation dimension was calculated according to the method of Grassberger-Procaccia. In chronic obstructive lung disease and chronic pulmonary emphysema (CPE), correlation dimension was positively correlated with respiratory frequency. The degrees of freedom were between 3-6. The subjects with CPE with periodic breathing showed a lower correlation dimension, which was comparable with Cheyne-Stokes respiration. One subject with dyspnea due to asthmatic attack showed a higher dimension than at the time of remission. Assessment of respiratory chaos may provide a new way of approach to elucidate breathing impairment in obstructive lung disease.