Reduction of pulmonary function after resection: less than expected in COPD patients: 025

Introduction: Patients often undergo limited lung resection (LR) instead of lobectomy for non-small cell lung cancer (NSCLC) because of a low FEV₁. However paradoxical improvement of pulmonary function after LR surgery has been reported in some patients, especially those with advanced emphysema [¹]. Experience with Lung Volume Reduction Surgery suggests that predicted postoperative FEV₁ (ppoFEV₁) may underestimate pulmonary function after lung resection [²]. Our aim was: 1) to study changes in pulmonary function after LR, 2) to compare predicted postoperative FEV₁ and diffusing capacity of the lung for carbon monoxide (DLCO), with values measured 6 months after surgery and 3) to identify which preoperative pulmonary function test (PFTs) may help to predict patients likely to have less decrease in postoperative pulmonary function.

Method: Seventy three patients undergoing lung resection were studied. We prospectively studied: 1) PFTs (FEV₁, DLCO, FEV₁/FVC ratio) prior to and 6 months after surgery; 2) ppoFEV₁ and ppoDLCO calculated by the perfusion scan. Preoperative, predicted postoperative and 6 months postoperative values were compared.

Results: A loss of 15 ± 17% of FEV₁ and 20 ± 17% of DLCO were observed 6 months after resection. Correlation with the predicted postoperative values were: r = −0.787 and r = −0.493 respectively (P < 0.001), although measured values were higher than the predicted (280 ± 50 ml and 8 ± 2% respectively). Preoperative FEV₁ (as % of predicted) was the best correlated parameter to functional impairment after resection (r = −0.421, P < 0.01). The decrease of FEV₁ (in mL/removed segments) was 75 mL/segment if preoperative FEV₁ > 60% and 26mL/segment if FEV₁ < 60%.

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Discussion: A good correlation was found between postoperative predicted PFTs and the measured values 6 months after surgery, the last being underestimated. A decrease in postoperative FEV₁ after LR surgery was lower in severe COPD patients. These findings suggest that properly selected patients with a low preoperative FEV₁ could undergo lung resection.