Increased airway mucins after cardiopulmonary bypass associated with postoperative respiratory complications in children

Objective: Airway mucins may play an important role in the mechanism of respiratory complications after cardiopulmonary bypass in infants and children. Our aim was to measure airway mucin levels before and after cardiopulmonary bypass and to determine whether changes in mucin levels were associated with the development of respiratory complications. Methods: Airway glycoprotein and mucins (MUC5AC, MUC513, and MUC2) in serial small-volume airway lavage samples from 39 young children who underwent cardiac operations with cardiopulmonary bypass were measured by slot-blot assay with specific antimucin peptide antibodies. The relationship between mucin changes and post-cardiopulmonary bypass respiratory complications was investigated. Airway lavage samples were also collected from 11 children before and after operation without cardiopulmonary bypass, and changes in mucin levels were compared with those in subjects who underwent cardiopulmonary bypass. Airway lavage sample DNA was also measured to investigate the relationship between mucin changes and lung injury. Results: Glycoprotein, MUC5AC, and MUC513 levels were significantly increased after cardiopulmonary bypass (P < .001) whereas MUC2 level was not. Children with respiratory complications showed significantly higher glycoprotein and MUC5AC levels than did children without respiratory complications before and after cardiopulmonary bypass (P < .05). Increase of total mucin (MUC5AC, MUC5B, and MUC2) during cardiopulmonary bypass showed positive correlation with DNA increase during cardiopulmonary bypass (r = 0.73), Paco(2) (r = 0.62) and alveolar-arteriai oxygen difference (r = 0.55) immediately after cardiopulmonary bypass. Increase of total mucin was associated with postoperative respiratory complications and their severity. There were no significant changes detected in airway mucin during operations without cardiopulmonary bypass. Conclusions: Airway mucins were increased during cardiopulmonary bypass, and this increase was associated with markers of lung injury after cardiopulmonary bypass and with the development of postoperative respiratory complications.