[Analysis of factors of increased phase differences between chest flow and mouth flow at rest breathing in patients...

The factors which increase phase differences between mouth flow and chest flow in patients with obstructive disorders were analyzed. From airway resistance, thoracic gas volume and measured chest flow, phase difference was predicted by the Runge-Kutta (R.K.) method assuming respiratory system to be a single compartment model. The ratio of the measured phase differences to the predicted value by the R.K. method in normal subjects was 0.99 +/- 0.25. These results suggest that a single compartment model can be applied to normal respiratory system. In contrast, predicted phase differences were remarkably higher than measured values in patients with obstructive disorders (CPE: 1.83 +/- 0.63, DPB: 1.50 +/- 0.48). This phenomenon could be explained by the existence of parallel inhomogeneity of alveolar pressure.