Do preoperative pulmonary function indices predict morbidity after coronary artery bypass surgery?

CONTEXT: The reported prevalence of chronic obstructive pulmonary disease (COPD) varies among different groups of cardiac surgical patients. Moreover, the prognostic value of preoperative COPD in outcome prediction is controversial. AIMS: The present study assessed the morbidity in the different levels of COPD severity and the role of pulmonary function indices in predicting morbidity in patients undergoing coronary artery bypass graft (CABG). SETTINGS AND DESIGN: Patients who were candidates for isolated CABG with cardiopulmonary bypass who were recruited for Tehran Heart Center-Coronary Outcome Measurement Study. METHODS: Based on spirometry findings, diagnosis of COPD was considered based on Global Initiative for Chronic Obstructive Lung Disease category as forced expiratory volume in 1 s [FEV1]/forced vital capacity <0.7 (absolute value, not the percentage of the predicted). Society of Thoracic Surgeons (STS) definition was used for determining COPD severity and the patients were divided into three groups: Control group (FEV1 >75% predicted), mild (FEV1 60–75% predicted), moderate (FEV1 50–59% predicted), severe (FEV1<50% predicted). The preoperative pulmonary function indices were assessed as predictors, and postoperative morbidity was considered the surgical outcome. RESULTS: This study included 566 consecutive patients. Patients with and without COPD were similar regarding baseline characteristics and clinical data. Hypertension, recent myocardial infarction, and low ejection fraction were higher in patients with different degrees of COPD than the control group while male gender was more frequent in control patients than the others. Restrictive lung disease and current cigarette smoking did not have any significant impact on postoperative complications. We found a borderline P = 0.057 with respect to respiratory failure among different patients of COPD severity so that 14.1% patients in control group, 23.5% in mild, 23.4% in moderate, and 21.9% in severe COPD categories developed respiratory failure after CABG surgery. CONCLUSION: Among post-CABG complications, patients with different levels of COPD based on STS definition, more frequently developed respiratory failure. This finding may imply the prognostic value of preoperative pulmonary function test for determining COPD severity and postoperative morbidities.