Obstructive airway lesion in infants and small children with congenital heart disease

New 133Xe lung function test which is applicable in infants and small children was designed and successfully applied to the patient from 6 months to 10 years of age. 133Xe washout curve was analysed by back projection method into fast and slow compartment and 3 washout indices was calculated from the data of slow compartment. These washout indices which express the grade of washout delay of poorly ventilated area of the lung made it clear that the obstructive airway lesion is present in the patient who has a sign of respiratory failure. Washout indices well correlated with the grade of alveolar septal hypertrophy (correlation coefficient = index 1:0.842, index 2:0.632, index 3:0.864) and also well correlated with the numbers of postoperative day during which intensive respiratory care was necessary (correlation coefficient = index 1:0.686, index 2:0.648, index 3:0.736). So that it can be concluded that washout indices will diagnose the alveolar histopathological change which is seen in patient with congenital heart disease without having a biopsy and give a usefull information when the planning of postoperative respiratory care is made up. (J.P.N.)