Study objectives: Lung volume reduction surgery (LVRS)
for emphysema has a variable effect on spirometry with improvement
linked to increases in lung elastic recoil. The mechanism by which
recoil increases following LVRS has not been described completely. This
study examines preoperative and postoperative pulmonary function to
describe a mechanism for changes in airflow obstruction.
Design: Change in pulmonary function following LVRS.
Setting : Public teaching hospital in Australia.
Patients: Patients with severe emphysema and pulmonary
function measurements made before and after LVRS.
Measurements: Routine pulmonary function testing performed
with ventilated lung alveolar volume (Va) derived from the
gas transfer measurement used as a proxy for the effective lung
Results: Pulmonary function tests from 36
consecutive patients with measurements made at the same laboratory were
analyzed. The mean FEV1 was 29.1% predicted presurgery and
increased following LVRS from 0.900 L (SD, 0.427 L) to 1.283 L (SD,
0.511 L; p < 0.0001) and TLC (143% predicted) decreased from 8.19 L
(SD, 1.492 L) to 7.07 L (SD, 1.52 L; p < 0.0001; n = 35). The mean
Va increased by 0.674 L (SD, 0.733 L) from 4.04 to 4.72 L
(p < 0.0001; n = 34). The change in FEV1 correlated
well with the change in Va (r = 0.63). The
change in FEV1 in those patients whose Vas did
not increase (n = 7) was not significant.
Conclusions: The increase in Va reflects an
increase of functional or ventilating lung volume and is associated
with an improvement in spirometry following LVRS.