Abstract: The influence of Deep Hypothermic Circulatory Arrest (DHCA) and Deep Hypothermic low-flow cardiopulmonary bypass （DHLF) on lung was studied. After establishment of DHCA and DHLF model on piglcls according to clinical cardiovascular surgery, measurements of lung compliance、airway resistance. artcry-alvcolar O₂pres-sure ratio、pulmonary vascular resistance and neutrophil sequestration ratio were dctcct-ed at 3 different time, i.e. before institution of Cardiopulmonary bypass (CPB) 、at the end of CPB and 1 hour after cessation of CPB. The results showed that more severe decrement of lung compliance and artery-alveolar O₂ pressure ratio and greater incre-ment of pulmonary vascular resistance and neutrophil sequestration ratio were observed in DHLF than in DHCA. No difference were observed on increments of airway resis-tance between the two groups. It was concluded that DHLF could cause more severe pulmonary injury than DHCA on piglels lung.

Key words: Deep hypothermic circulatory arrest , Deep hypothcrmic low-flow cardiopul-monary bypass , Pulmonary function, Piglet