Is chronic obstructive pulmonary disease an independent risk factor for transfusion in coronary artery bypass graft surgery?

OBJECTIVE The literature is inconsistent regarding the role of chronic obstructive pulmonary disease (COPD) as a risk factor for blood product transfusion during coronary artery bypass graft (CABG). One reason may be lack of objective criteria to define COPD in previously published reports. We examined the role of COPD as a risk factor for transfusion using a strict definition based on objective pulmonary function test (PFT) data. METHODS We identified 180 patients, who underwent primary isolated non-emergent CABG and had PFTs performed preoperatively. COPD was defined as forced expiratory volume in 1s/forced vital capacity (FEV1/FVC) <70% and further stratified into mild/moderate/severe/very severe based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. Patients with and without COPD were compared with respect to preoperative and postoperative characteristics and transfusion requirements. RESULTS The overall transfusion rate was 59.4% (107/180). COPD patients (31.1%, 56/180) were older (66.6 ± 11.4 vs 62.3 ± 10.3 years, p = 0.01), had lower body mass index (BMI) (28.5 ± 5.8 vs 31.7 ± 6.0 kg/m(2), p=0.001), and were more often smokers (51.8% vs 36.3%, p = 0.05). COPD patients had shorter cardiopulmonary bypass (CPB) times (99.4 ± 27.9 vs 110.9 ± 32.4 min, p = 0.02), but left internal mammary artery (LIMA) use, number of bypass grafts, mortality, and postoperative complications were similar (p > 0.05). Transfusion rates were similar for patients with and without COPD. Further stratification into mild/moderate/severe/very severe COPD failed to identify COPD as a predictor of blood transfusion. CONCLUSIONS Using objective PFT data, our study clarifies the disagreement in the literature with respect to the role of COPD as a risk factor for transfusion in CABG. Decreased pulmonary function does not appear to increase risk of transfusion during CABG, even for patients with severe COPD.