New simple classification for operated bullous emphysema

Objectives: Optimal results in bullectomy depend on both the size of the resected bulla volume and the reexpansion of the adjacent collapsed healthy pulmonary parenchyma. We hypothesized that the bigger the bulla is compared with residual volume, the greater are the possible benefits. We suggested a new prognostic classification according to bulla volume and its relationship with residual volume. Methods: We retrospectively reviewed 121 patients with emphysematous bulla (> 200 mL) who, from 1996 to 2006, underwent unilateral single (n = 64), unilateral multiple (n = 16), bilateral 1-stage (n = 9), and bilateral 2-stage (n = 32) bullectomies. Bulla volume and residual volume were measured by computed tomography and body plethysmography, respectively. Six-month postoperative decrement of residual volume values and their persistence below the baseline for 5 years were considered primary outcomes. Logistic regression was used to select significant variables. The receiver operating characteristic curve was used to identify the cutoff point for a possible classification system. Results: There was no postoperative mortality. Significant postoperative improvements in respiratory function were found and correlated with bulla size. Residual volume improved in 75 patients (62%) and persisted in 20 patients (35% of the patients followed for > 5 years). Logistic regression selected bulla/residual volume ratio as the most predictive variable for both outcomes (P <.0001). The best cutoff individuated by the receiver operating characteristic curve analysis was 20% to achieve a high probability of residual volume improvement and 30% to minimize residual volume recurrence. Conclusions: Bullectomy provides good results, but more significant and long-lasting improvements are achievable with a greater ratio bulla/residual volume: scant for less than 20%, good but temporaneous for 20% to 30%, and good and long-lasting results for more than 30%.