Improvements in lung function, exercise, and quality of life in hypercapnic COPD patients after lung volume reduction surgery.

STUDY OBJECTIVE

To determine the impact of preoperative resting hypercapnia on patient outcome after bilateral lung volume reduction surgery (LVRS).

METHODS

We prospectively examined morbidity, mortality, quality of life (QOL), and physiologic outcome, including spirometry, gas exchange, and exercise performance in 15 patients with severe emphysema and a resting PaCO2 of > 45 mm Hg (group 1), and compared the results with those from 31 patients with a PaCO2 of < 45 mm Hg (group 2).

RESULTS

All preoperative physiologic and QOL indices were more impaired in the hypercapnic patients than in the eucapnic patients. The hypercapnic patients exhibited a lower preoperative FEV1, a lower diffusing capacity of the lung for carbon monoxide, a lower ratio of PaO2 to the fraction of inspired oxygen, a lower 6-min walk distance, and higher oxygen requirements. However, after surgery both groups exhibited improvements in FVC (group 1, p < 0.01; group 2, p < 0.001), FEV1 (group 1, p=0.04; group 2, p < 0.001), total lung capacity (TLC; group 1, p=0.02; group 2, p < 0.001), residual volume (RV; group 1, p=0.002; group 2, p < 0.001), RV/TLC ratio (group 1, p=0.03; group 2, p < 0.001), PaCO2 (group 1, p=0.002; group 2, p=0.02), 6-min walk distance (group 1, p=0.005; group 2, p < 0.001), oxygen consumption at peak exercise (group 1, p=0.02; group 2, p=0.02), total exercise time (group 1, p=0.02; group 2, p=0.02), and the perceived overall QOL scores (group 1, p=0.001; group 2, p < 0.001). However, because the magnitude of improvement was similar in both groups, and the hypercapnic group was more impaired, the spirometry, lung volumes, and 6-min walk distance remained significantly lower post-LVRS in the hypercapnic patients. There was no difference in mortality between the groups (p=0.9).

CONCLUSIONS

Patients with moderate to severe resting hypercapnia exhibit significant improvements in spirometry, gas exchange, perceived QOL, and exercise performance after bilateral LVRS. The maximal achievable improvements in postoperative lung function are related to preoperative level of function; however, the magnitude of improvement can be expected to be similar to patients with lower resting PaCO2 levels. Patients should not be excluded from LVRS based solely on the presence of resting hypercapnia. The long-term benefit of LVRS in hypercapnic patient remains to be determined.