抄録
Ventilatory steady state measurement with 133Xe, using Ventil-Con (Radx) and a large area scintillation camera (Searle, LFOV) combined witha mini-computer system (Shimadzu, Scintipac 230)was employed to evaluate regional pulmonary function of 94 patients with chronic obstructive lung disease (COLD), fibrosis, carcinoma and other lung diseases. The functional image and regional pulmonary functions in these patients were compared with the the data in 9 normal subjects. The functional images of V, V, Q, V/V, Q/V, t (mean washout time calculated from the washout curve for equilibrated gas in the steady state) and V/Q were made in each case. The regional distribution indices of ventilation, perfusion and the ventilation-perfusion ratio were calculated for each lung field divided into 9 zones (whole lung, left, right, bilateral upper, middle and lower).
In the patients with COLD, mean washout times (t) were markedly prolonged in whole lung fields (m130± 33sec.) and ventilation indices (V/V) and perfusion indices (Q/V) were reduced in regional zones, especially in bilateral lower lung zones. For the patients with lung fibrosis, I values were short and the distribution of ventilation indices were uniform, and in contrast perfusion indices were reduced in the lower lung fields. In the area most affected by carcinoma, lung volumes (V) were reduced in parallel with the regional ventilation (V) and perfusion (Q). As the tumor approached the hilum, the relative ventilation and perfusion of cancerous side decreased remarkably in patients with obstructive findings on bronchoscopy.
The mean washout times (t) for 133Xe, calculated by a modified height over area method without background subtraction, were significantly longer than indicated by the data yielded by the least squares curve fitting of initial washout curve after background subtraction. Although the accuracy of these data was limited, it appeared that the prolonged t is a good parameter of regional ventilatory disturbance because significant correlations were found between the whole lung t in patients with lung diseases and their FEV 1.0% r=-0.66, RV/TLC r=0.64, %TLC r=0.43, PaCO2 r=0.41, PaO2 r=-0.35.
