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.

We examined the effects of chest wall strapping (CWS) on the response to inhaled methacholine (MCh) and the effects of deep inspiration (DI). Eight subjects were studied on 1 day with MCh inhaled without CWS (CTRL), 1 day with MCh inhaled during CWS (CWSon/on), and 1 day with MCh inhaled during temporary removal of CWS (CWSoff/on). On the CWSon/on day, MCh caused greater increases in pulmonary resistance, upstream resistance, dynamic elastance, residual volume, and greater decreases in maximal expiratory flow than on the CTRL day. On the CWSoff/on day, the changes in these parameters with MCh were not different from the CTRL day. Six of the subjects were again studied using the same protocol on CTRL and CWSon/on days, except that, on a third day, MCh was given after applying the CWS, but the measurements before and after the inhalation were made without CWS (CWSon/off). The latter sequence was associated with more severe airflow obstruction than during CTRL, but less than with CWSon/on. The bronchodilator effects of a DI were blunted when CWS was applied during measurements (CWSon/on and CWSoff/on) but not after it was removed (CWSon/off). We conclude that CWS is capable of increasing airway responsiveness only when it is applied during the inhalation of the constrictor agent. We speculate that breathing at low lung volumes induced by CWS enhances airway narrowing because the airway smooth muscle is adapted at a length at which the contractile apparatus is able to generate a force greater than normal.

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The minute ventilation to carbon dioxide (CO 2 ) production ratio (V' E /V' CO2 slope) was recently identified as a mortality predictor after lung surgery, but the effect of the resection extent was not taken into account. The aim of this study was to investigate the role of V' E /V' CO2 slope as preoperative mortality predictor depending on the type of surgery performed. Retrospective analysis was performed on 263 consecutive patients evaluated before surgery for lung cancer. Death within 30 days and serious respiratory complications were considered. Univariate and multivariate regression analyses were used to identify independent predictors of death. Lobectomy or bilobectomy were performed in 186 patients with 29/186 (15.6%) serious pulmonary complications and 6/186 (3.2%) deaths. Pneumonectomy was performed in 77 patients with 14/77 (18.2%) serious complications and 5/77 (6.5%) deaths. Considering the whole group, the peak oxygen consumption (V' O2peak, L/min; z=-2.66, p<0.008, OR 0.007) and V' E /V' CO2 slope (z=2.80, p<0.005, OR 1.14) were independent predictors of mortality whereas in pneumonectomies V' E /V' CO2 slope (z=2.34, p<0.02, OR 1.22) was the only independent predictor of mortality. High V' E /V' CO2 slope, age and low V' O2peak are predictors of death and severe complications after lung surgery. Before larger resections as pneumonectomies an increased V' E /V' CO2 slope represents the best mortality predictor.