Abstract： Objective To examine the kinetics of plasma S100A12 and soluble receptor for advanced glycation end products (sRAGE) in infants and young children undergoing cardiopulmonary bypass ( CPB),and to investigate whether they could protective the occurrence of noninfectious pulmonary complication (NPC) after cardiac surgery.Methods This was a case-control study.The subjects included all children aged ＜3 years old who underwent cardiac surgery with CPB during the period from June 1st to July 31st 2011.The patient who showed pulmonary inflammation or had abnormal liver or renal function before surgery was excluded.The remain patients were divided into 2 groups according to whether they had developed NPC postoperatively.Twenty patients were grouped into NPC because they developed the complications of pleural effusion,chylothorax,partial lung collapse,pulmonary hypertensive crisis,airway disorders,pneumothorax,pneumomediastinum,or phrenic nerve palsy.Forty patients were categorized into the no-NPC group.Plasma concentrations of S100A12 and sRAGE were measured using ELISA at baseline,before CPB,immediately after CPB,1 h,12 h and 24 h after operation.Differences concentrations between two groups were analyzed with t test.A stepwise logistic regression analysis was used to indentify the independent risk factor for NPC.A P value ＜0.05 was considered statistically significant.Results Plasma levels of S100A12 and sRAGE dramatically increased immediately after CPB ( P ＜ 0.01 ).The levels of sRAGE dropped to lower than baseline level (P ＜0.05),while S100A12 was still at high level 24h after operation (P ＜0.01 ).Levels of S100A12 and sRAGE immediately after CPB in NPC group were significantly higher than the no-NPC group (P ＜ 0.05).Twenty-four hours after operation,levels of S100A12 were still higher in NPC group than no-NPC (P ＜ 0.01 ),while levels of sRAGE were similar in the two groups ( P ＞ 0.05 ).In the stepwise logistic regression analysis,plasma S100A12 level immediately after CPB remained as a independently predictor for postoperative NPC (OR =1.042,95％ CI:1.010 ～ 1.076,P =0.011 ).Levels of S100A12 immediately after CPB were positively associated with mechanical ventilation time ( r =0.47,P ＜ 0.01 ),duration of surgical Intensive Care Unit ( r =0.407,P =0.002) and hospital stay ( r =0.421,P =0.01 ).Conclusions Plasma levels of S100A12 and sRAGE were significantly increased immediately after CPB and the elevated plasma S100A12 immediately after CPB served as an early reliable biomarker of the occurrence and the prognosis of NPC after CPB in infants and young children.