The side-effects of cardiopulmonary bypass on the lungs: changes in bronchoalveolar lavage fluids

Abstract

Although technical refinements have improved the safety of cardiac operations, postoperative dysfunction of lung and other organs occurs frequently after cardiopulmonary bypass (CPB). The aim of the present study was to search the aetiopathogenesis of pulmonary complications due to CBP. Ten patients with stable coronary artery disease, undergoing coronary artery bypass grafting (CABG) surgery, were included in the study. Forty bronchoalveolar lavage (BAL) fluid samplings were performed in the 10 patients. Samples were obtained at the following time periods: (1) preoperatively; (2) at the end of the first hour after anaesthetic induction; (3) at the conclusion of 30 min of crossclamp on CPB; and (4) at the conclusion of 20 h after the end of CPB, postoperatively. Cell contents of bronchoalveolar lavage fluid, alveolar macrophage viability, eosinophil cationic protein (ECP) levels and myeloperoxidase (MPO) concentrations were analysed in each bronchoalveolar lavage fluids. While the percentage of preoperative macrophages was 85.90% and the percentage of preoperative neutrophils was 2.40%, they were 77.00% and 11.30% in the postoperative samples, respectively. Mean alveolar macrophage viability was 96.20% preoperatively and 90.40% in the postoperative period. Preoperative eosinophil cationic protein mean concentration was < 2 μg/l and mean response value (RV) was 28.80. Pre-operative mean myeloperoxidase concentration was 7.66 ng/ml. Postoperative eosinophil cationic protein mean response value was 63.40 and mean myeloperoxidase concentration was 59.25 ng/ml. There were significant differences between third and final samples with regard to both neutrophil percentages ( p = 0.028) and MPO levels ( p = 0.005). While the preoperative mean PaO2 value was 89.39 mmHg and mean SaO2 value was 97.12%, they were calculated in the postoperative arterial blood specimens of patients, without inhaling O2, as 65.31 mmHg and 93.84%. These changes between blood gas analyses reflect the impairment of the lungs ( p = 0.009 and p = 0.007, respectively). Neither alveolar macrophage viability nor ECP levels changed significantly between consecutive periods. However, when the results of the first and fourth samples were compared, we saw the cumulative effects of CPB, in that alveolar macrophages lost their viability and ECP mean RVs rose. These changes were statistically significant ( p = 0.027 and p = 0.013, respectively). However, postoperative ECP levels were not like those found in a patient with asthma. Also, changes between alveolar macrophage percentages ( p = 0.028), between neutrophil percentages ( p = 0.036) and between MPO concentrations ( p = 0.005) were statistically significant. Again, changes in neutrophil percentages between first and final samples correlated with changes in MPO levels between same periods ( r = 0.657, p = 0.039).