Objective  To investigate the influence of continuous low-volume ventilation in cardiopulmonary bypass (CPB) on the expression of krebs von den lungen-6 (KL-6) and perioperative pulmonary function in adults undergoing valve surgery.

  Methods  From 2017 Sept. to 2018 Jan., 60 patients who received valve replacement surgery were prospectively comprised in this study. We randomly allocated these patients into control group (n=30, non-ventilation) and experimental group (n=30, continuous low-volume ventilation during CPB). At different perioperative time points, we identified the dynamic changes of pulmonary function and biomarkers which expressed in serum and bronchoalveolar lavage fluid (BALF). Meanwhile, we also compared perioperative clinical outcomes of the two groups.

  Results   The expression of serum KL-6 and BALF KL-6 in the two groups were both statistically significant（P＜0.05）. The oxygenation index increased with time and reached to the top point at T₁, then subsequently decreased with time (P＜0.05). The alveolar-arterial oxygen tension difference (P_A-aO₂) in the two groups fluctuate with time, the differences have no statistical significance. According to linear correlation, the serum KL-6 level was negatively correlated with oxygenation indexes (r=－0.525, P=0.003), while it was positively correlated with P_A-aO₂ (r=0.489, P=0.006). There were no significant differences between the two groups in clinical outcomes.

  Conclusion  Continuing low-volume ventilation during CPB could decrease the expression level of KL-6, while it has no significant influence on perioperative outcomes.