Correlation of changes in quality of life after lung volume reduction surgery with changes in lung function, exercise, and gas exchange

Study objectives: To evaluate correlations between improvement in quality o f life (QOL) in patients with severe COPD before and after they undergo lun g volume reduction surgery (LVRS) with changes in pulmonary function tests, gas exchange, exercise performance, and alterations in medical management. Design: Case-series analysis. Setting: University hospital. Patients: Forty-two patients (mean [+/- SD] age, 56 +/- 8 years; 53% women) with severe airflow obstruction (FEV1, 0.62 +/- 0.2 L), and moderate to se vere hyperinflation (total lung capacity, [TLC], 6.9 +/- 1.7 L). Intervention and measurements: All patients underwent bilateral LVRS via me dian sternotomy. Measurements of lung function, symptom-limited cardiopulmo nary exercise testing, the total distance the patient was able to walk in 6 min in a corridor, and sickness impact profile (SIP) scores were made befo re and 3 months after LVRS. SIP scores are inversely proportional to the le vel of function and QOL. Results: Compared to baseline, FEV1 increased (0.87 +/- 0.3 vs 0.62 +/- 0.2 L, respectively; p < 0.01) while residual volume significantly decreased ( 3.2 +/- 1.8 vs 6.3 +/- 1.2 L, respectively; p < 0.004) at 3 months post-LVR S. On cardiopulmonary exercise testing, values increased from baseline to p ost-LVRS for total exercise time (9.0 +/- 2.2 vs 6.0 +/- 1.5 min, respectiv ely; p = 0.045), maximum oxygen uptake ((V) over dot o(2)) (16 +/- 3 vs 11 +/- 2 mL/kg/min, respectively; p = 0.01), and maximum minute ventilation (( V) over dot E) (33 +/- 9 vs 28 +/- 5 L/min, respectively; p = 0.03). The pe rcentage change in the oxygen cost of breathing ((V) over dot o(2)/(V) over dot E ratio) from low to high workloads during exercise was significantly lower after LVRS (p = 0.002). There was no significant change in oxygenatio n after LVRS (Pao(2)/fraction of inspired oxygen, 331 +/- 27 vs 337 +/- 39, respectively; p = 0.76), but Paco(2) tended to be lower (41 +/- 9 vs 48 +/ - 6 mm Hg, respectively; p = 0.07). Overall SIP scores were significantly l ower after LVRS than before (8 +/- 4 vs 15 +/- 2, respectively; p = 0.002). Changes in SIP scores correlated with the change in (V) over dot o(2)/(V) over dot E ratio from low to high workloads, with patients ha ting the smal lest changes in (V) over dot o(2)/(V) over dot E ratio having the smallest changes in SIP scores after LVRS (r = 0.6; p = 0.01). Improved or lower SIP scores also tended to correlate with a reduction in residual volume/TLC ra tio (r = 0.45; p = 0.09), and there was a linear correlation with a statist ically significant Pearson r value with decreased steroid requirements (r = 0.7; p = 0.001). Moreover, changes in psychological SIP subscore tended to correlate with diminished oxygen requirements post-LVRS (r = 0.45; p = 0.0 9). However, there was no significant correlation between changes in SLP sc ores and routine measurements of lung function, exercise performance, or ga s exchange. Conclusion: There is an association between an improvement in QOL and reduc ed hyperinflation after LVRS. Reduced hyperinflation may lead to more effic ient work of breathing doting exercise and, therefore, to an increased abil ity to perform daily activities. Changes in QOL scores con elate best with behaviorally based variables that directly affect the patient's well-being, such as systemic steroid administration.