Table 3

Static lung volumes and gas diffusion for 107 patients separated by degree of impairment of FEV1

Impairment of FEV1
None (n=31)Mild (n=19)Moderate (n=36)Severe (n=21)
RV (l)2.02  (0.44)2.45  (0.65)3.09  (0.69)3-160 3.73  (0.79)3-150
RV (% predicted)96.0 (17.1)113.4 (26.6)3-150 138.3 (28.6)3-150 155.1 (31.5)3-150
TLC (l)5.65 (1.24)5.81 (1.14)6.35 (1.31)6.5 (1.28)
TLC (% predicted)102.3 (11.8)103.1 (15.1)110.6 (14.6)106.4 (12.9)
RV/TLC (%)36.3 (5.9)42.1 (7.3)3-150 49.1 (7.7)3-160 57.8 (7.7)3-160
RV/TLC (% predicted)92.4 (12.6)107.1 (14.6)3-150 122.5 (18.4)3-150 142.3 (21.4)3-160
Tlco (mmol/min/kPa)7.66 (2.39)7.6 (2.3)6.28 (2.1)3-164 5.5 (1.67)3-164
Tlco (% predicted)96.9 (23.6)94.6 (21.1)79.4 (21.5)69.3 (18.1)3-170
Kco (mmol/min/kPa/l)1.5 (0.3)1.57 (0.45)1.26 (0.43)3-151 1.22 (0.38)3-151
Kco (% predicted)104.7 (23.9)111.3 (30.8)90.5 (30.9)94.1 (26.3)
• RV = residual volume; TLC = total lung capacity; Tlco = carbon monoxide gas transfer factor; Kco= carbon monoxide gas tranfer coefficient (Tlcodivided by effective alveolar volume).

• All values are means (SD).

• 3-150 p<0.05;

• 3-160 p<0.01;

• 3-165 p<0.001 compared with the adjacent less severe category of FEV1 impairment (one way ANOVA with post-hoc comparison).

• 3-151 p<0.05 severe and moderate versus mild impairment;

• 3-164 p<0.01 severe and moderate versus no impairment;

• 3-170 p<0.001 severe versus no impairment.