We studied the N2 washout test in 6 young normal subjects, and 32 patients with chronic pulmonary disease, and performed multiple compartement analysis. Sequential distribution of ventilation fraction was shown, and very different patterns of distribution between normal subjects and patients were obtained. We consider that the mean of ventilation per volume (λi-mean) and its standard deviation (λi-SD) shows the overall ventilation fraction of the lungs, and the severity of unequal ventilation respectively. Especially, λi-SD was higher in patients and correlated well with parameters of pulmonary function. We concluded that our method is very significant for the clinical investigation of unequal ventilation.
