The specimens were taken from middle lobe of the right lung before cardiopulmonary bypass and were fixed by formaldehyde solution, paraffin embedding and stained by SP immunohistochemical technique and usual analysis. 体外循环建立前取右肺中叶少许肺组织,福尔马林固定,石蜡包埋,SP法免疫组织化学染色,并进行灰度扫描。