Six-minute Walking and Pulmonary Function Test Outcomes during the Early Period after Lung Cancer Surgery with Special Reference to Patients with Chronic Obstructive Pulmonary Disease

Objective: To evaluate physical dysfunction during the early period after lung resection in patients with lung cancer and coexisting chronic obstructive pulmonary disease (COPD), we examined the relationship between the ratio of the forced expiratory volume in 1 second to the forced vital capacity (FEV ₁/FVC%) and the results of a 6-minute walk (6MW) test before and after surgery. Methods: Eighty-three patients who underwent lobectomy for lung cancer were classified into three groups according to their preoperative FEV₁/FVC: more than 70% (non-COPD, n=61), 60-69% (mild COPD, n=15), and 40-59% (moderate COPD, n=7). The 6MW and pulmonary function tests were performed before surgery and repeated 1 and 2 weeks after surgery. During the 6MW test, the distance covered during a 6MW test (6MWD) and the decrease in oxygen saturation (SpO₂) were measured. Results: During both the preoperative and postoperative 6MW tests, the decrease in SpO₂ correlated significantly with the preoperative FEV₁/FVC% (p<0.001). The percentage decrease in 6MWD at 1 and 2 weeks after surgery correlated significantly with the preoperative FEV₁/FVC% (p<0.001 and p=0.04, respectively), but not with the concomitant percentage reduction in vital capacity (VC). The differences of the decreases in postoperative 6MWD and SpO₂ during the 6MW test were significant between the moderate and mild COPD patients and between the mild COPD and non-COPD patients (p<0.01-0.001). Conclusion: The decreases in 6MWD and SpO₂ after surgery were significantly influenced by the preoperative FEV₁/FVC%, but not by the decrease in VC. COPD patients have a limited capacity for walking during the early period after surgery due to significant oxygen desaturation.