Increased effective lung volume following lung volume reduction surgery inemphysema

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 postop erative 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 measurement s 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 volume. Results: Pulmonary, function tests from 36 consecutive patients with measur ements made at the same laboratory were analyzed. The mean FEV1 was 29.1% p redicted 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 f rom 8.19 L (SD, 1.492 L) to 7.07 L (SD, 1.52 L; p < 0.0001; n = 35). The me an 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) w as not significant. Conclusions: The increase in VA reflects an increase of functional or venti lating lung volume and is associated with an improvement in spirometry foll owing LVRS.