Exercise ventilatory inefficiency and mortality in patients with chronic obstructive pulmonary disease undergoing surgery for non-small-cell lung cancer

Abstract

Objective: Surgical resection is the treatment of choice to cure patients with non-small-cell lung cancer (NSCLC); nevertheless, the assessment of the lower limit of surgical tolerance remains difficult. Ventilatory inefficiency (measured as the ventilation to CO(2) production ratio (V'(E)/V'(CO2) slope) is a survival predictor in pulmonary hypertension (PH) and chronic heart failure (CHF) and is considered a marker of PH in chronic obstructive pulmonary disease (COPD). The aim of this study was to investigate the role of V'(E)/V'(CO2) slope as preoperative mortality and morbidity predictor in COPD patients submitted to lung resection for NSCLC and considered operable according to current standards.

Methods: A retrospective analysis was performed in 145 consecutive COPD patients with lung cancer (128 males and 17 females), with a mean age of 64 years (range: 41-82 years) who were referred for preoperatory evaluation. Because of bronchial obstruction or reduced pulmonary diffusion capacity for carbon monoxide (D(L,CO)), all these patients were considered operable only after a cardiopulmonary exercise test showed a preserved cardiopulmonary function.

Results: A total of 98 lobectomies, eight bilobectomies and 39 pneumonectomies (13 left and 26 right) were performed. Twenty-one patients (14.5%) suffered severe cardio-respiratory complications; 15/106 patients (14.2%) after lobectomy/bilobectomy and 6/39 (15.4%) after pneumonectomy. Five patients (3.4%) died within 30 days after surgery (3/106 after lobectomy/bilobectomy (2.8%) and 2/39 after pneumonectomy (5.1%)). Considering all functional parameters before surgery and the postoperative predicted values, a logistic regression analysis individuated the V'(E)/V'(CO2) slope as the only independent mortality predictor (odds ratio (OR): 1.24 z=2.77; p<0.007). The V'(O2 peak) was instead the best predictor for the occurrence of severe cardiopulmonary postoperative complications (OR: 0.05, z=-2.39, p<0.02).

Conclusions: In COPD patients, a high V'(E)/V'(CO2) slope before lung resection is an independent mortality predictor even in the presence of an acceptable cardiopulmonary performance. COPD patients with high V'(E)/V'(CO2) slope before surgery must be carefully screened to exclude pulmonary hypertension, especially before surgical procedures with large parenchymal exeresis.