Abstract
To evaluate the validity of the scoring method of small airway function tests, selective alveolo-bronchography (SAB) was performed on 13 patients with bronchial asthma, 7 patients with chronic pulmonary emphysema and 4 patients with other lung diseases. The small airway lesion observed on the SAB film was compared with the pulmonary function data including closing volume (CV), ΔN2/L, volume of isoflow (Visov) ΔV50 and the SAO score. The functional scores of small airway were given, based on the abnormality of each parameter, CV, ΔN2/L, Visov and ΔV50. These scores were totaled and named the SAO score. Additionally, to evaluate the influence of the elastic recoil on the small airway lesion, the mean diameter of ring shadows observed on SAB film were compared with the elastic properties and small airway parameters.
The severity of small airway lesions in SAB was expressed as the mean of maximum diameter/minimum diameter ratios (ratio of bronchial diameter; RBD) in each 1cm-long segment on magnified film (3 to 4 fold).
1. Loose but significant correlation was found between FEV1.0% and RBD although no significant correlation was found between respiratory resistance and RBD.
2. Significant correlation was found between SAO score and RBD.
3. Significant correlation was found between elastic recoil and the mean diameter of ring shadow.
4. The correlation between the SAO score and the mean diameter of ring shadow was significant in all patients with chronic pulmonary emphysema but was not significant in patients with bronchial asthma.
We conclude that the scoring method of small airway function test is useful for evaluating small airway obstruction. The small airway obstruction in bronchial asthma is related to the lesion of airway wall, and that in chronic pulmonary emphysema is related to loss of elastic recoil.
