The major purpose of this paper was to study the relationship between closing volume (CV) and
133Xe gas distribution at a lung volume level of the CV by means of a scintillation camera system linked with a computer. The comparative study of the CV and
133 distribution was thus performed on 20 subjects in sitting and supine positions. In sitting position, the length of the lung was denned as the distance from the apex to bottom in the case of the lung volume image(A) during repreathing of
133 gas and the length from the apex to the lower border of
133 distribution was measured on bolus inhalation image(B). In supine position, the length of the lung was denned as the distance from the front to the back in the case of the lung volume image(A) during rebreathing of
133 gas, while the lung depth measured from the front to the lower border of
133 distribution on a the bolus inhalation image(B). The correlation between the parameters, B/A and CV, showed significantly negative values such as -0.889 in the sitting position and -0.820 in the supine position. Our result shows that the CVphenomenonappears whenthe local difference of the gas density exists either by the flow limitation or by the airway closure. The detection of CV serves for an early diagnosis of a kind of disturbance of gas distribution.
View full abstract