Minute Ventilation-to-Carbon Dioxide Output ((V) over dotE/(V) over dotCO2) Slope Is the Strongest Predictor of Respiratory Complications and Death After Pulmonary Resection

Background. This study assessed whether the minute ventilation-to-carbon dioxide output ((V) over dotE/(V) over dotCO(2)) slope, a measure of ventilatory efficiency routinely measured during cardiopulmonary exercise testing (CPET), is an independent predictor of respiratory complications after major lung resections. Methods. Prospective observational analysis was performed on 225 consecutive candidates after lobectomy (197 patients) or pneumonectomy (28 patients) from 2008 to 2010. Inoperability criteria were peak oxygen consumption ((V) over dotO(2)) of less than 10 mL/kg/min in association with predicted postoperative forced expiratory volume in 1 second of less than 30% and diffusion capacity of the lung for carbon monoxide of less than 30%. All patients performed a symptom-limited CPET on cycle ergometer. Respiratory complications (30 days or in-hospital) were prospectively recorded: pneumonia, atelectasis requiring bronchoscopy, respiratory failure on mechanical ventilation exceeding 48 hours, adult respiratory distress syndrome, pulmonary edema, and pulmonary embolism. Univariable and multivariable regression analyses were used to identify independent predictors of respiratory complications. Results. Cardiopulmonary morbidity and mortality rates were 23% (51 patients) and 2.2% (5 patients). The 25 patients with respiratory complications had a significantly higher (V) over dotE/(V) over dotCO(2) slope than those without complications (34.8 vs 30.9, p = 0.001). Peak (V) over dot O-2 was not associated with respiratory complications. Logistic regression and bootstrap analyses showed that, after adjusting for other baseline and perioperative variables, the strongest predictor of respiratory complications was (V) over dotE/(V) over dotCO(2) slope (regression coefficient, 0.09; bootstrap frequency, 89%; p = 0.004). Patients with a (V) over dotE/(V) over dotCO(2) slope exceeding 35 had a higher incidence of respiratory complications (22% vs 7.6%, p = 0.004) and mortality (7.2% vs. 0.6%, p = 0.01). Conclusions. (V) over dotE/(V) over dotCO(2) slope is a better predictor of respiratory complications than peak (V) over dotO(2). This inexpensive and operator-independent variable should be considered in the clinical practice to refine operability selection criteria. (Ann Thorac Surg 2012;93:1802-6) (c) 2012 by The Society of Thoracic Surgeons